TWI912401B - Manufacturing method of printed circuit boards - Google Patents

Abstract

This invention provides a planar semi-additive laminate for two-sided interconnection and a printed wiring board using the same. The planar semi-additive laminate for two-sided interconnection does not require surface roughening with chromic acid or permanganate, nor does it require the formation of a surface modification layer using alkali. Furthermore, it does not use a vacuum device, and can form wiring with high density between the substrate and conductor circuits, less undercut, good design reproducibility, and a rectangular cross-sectional shape suitable for circuit wiring.

The inventors have discovered that by sequentially depositing a silver particle layer (M1) and a copper layer (M2) with a thickness of 0.1 μm to 2 μm on both surfaces of an insulating substrate (A), a through-hole is formed. A copper or nickel layer is formed on the surface of the through-hole, and a patterned resist is formed on the conductive silver particle layer (M1). Electroplating with copper is then performed, thereby forming a printed circuit board with good design reproducibility and a rectangular cross-section shape suitable for circuit wiring, thus completing the present invention.

Description

Manufacturing method of printed circuit boards

This invention relates to a planar semi-additive laminate for electrically connecting two sides of a substrate and a printed wiring board using the same.

Printed wiring boards (PCBs) are metal layers with circuit patterns formed on the surface of an insulating substrate. In recent years, with the increasing demands for miniaturization and weight reduction in electronic and mechanical products, the requirements for thinner PCBs (films) and finer circuit wiring have also increased. Previously, the industry widely used the subtractive process as a method for manufacturing circuit wiring. This method involves forming an etching resist with a circuit pattern shape on the surface of a copper layer formed on an insulating substrate, and etching the copper layer in areas where no circuitry is needed, thereby forming copper wiring. However, in the subtractive etching process, copper residue is prone to remain at the edges of the wiring. When the distance between wirings becomes shorter due to the high density of circuit wiring, problems such as short circuits or lack of insulation reliability between wirings may occur. Furthermore, if further etching is performed to prevent short circuits or to improve insulation reliability, the etching solution will surround the lower part of the resist, resulting in side etching and causing the wiring width to become thinner. Especially when there are areas with different wiring densities, fine wirings in areas with lower wiring density may also disappear if etched. Furthermore, the cross-sectional shape of the wiring obtained by the subtractive method is not rectangular, but becomes a trapezoidal or triangular shape with the edge extending towards the substrate. Therefore, it becomes a wiring with different widths in the thickness direction, which also poses a problem as an electrical transmission path.

As a method to solve these problems and fabricate micro-wiring circuits, the industry has proposed a semi-additive method. In the semi-additive method, a conductive seed layer is first formed on an insulating substrate, and then a coating resist is formed on the non-circuit-forming portion of the seed layer. After the wiring portion is formed by electroplating from the conductive seed layer, the resist is peeled off, removing the seed layer of the non-circuit-forming portion, thereby forming a micro-wiring. According to this method, since the coating is precipitated along the shape of the resist, the cross-sectional shape of the wiring can be rectangular, and regardless of the density of the pattern, wiring of the target width can be precipitated, thus making it suitable for forming micro-wiring.

In the semi-additive process, a method is known to form a conductive seed layer on an insulating substrate using electroless copper or nickel plating with a palladium catalyst. Regarding these methods, for example, when using a laminated film, to ensure adhesion between the film substrate and the copper plating film, a roughening process called desmearing is performed on the substrate surface using a strong agent such as permanganate. The plating film forms from the resulting voids, thereby utilizing the anchor effect to ensure adhesion between the insulating substrate and the plating film. However, roughening the substrate surface presents problems such as difficulty in forming fine wiring and degradation of high-frequency transmission characteristics. Therefore, the industry has studied reducing the degree of roughening, but at low roughening, there is a problem that the required tightness between the formed wiring and the substrate cannot be obtained.

On the other hand, a technique for forming conductive seed crystals by performing electroless nickel plating on a polyimide film is also known. In this case, by immersing the polyimide film in a strong alkali, the propylene rings on the surface are opened, making the film surface hydrophilic and simultaneously forming a water-permeable modified layer. Palladium catalyst then permeates into the modified layer to perform electroless nickel plating, thereby forming a nickel seed layer (see, for example, Patent 1). In this technology, a nickel plating layer is formed in the modified layer on the outermost layer of polyimide to obtain a strong bond. However, the modified layer is in a state where the propylene ring has been opened, which leads to the following problem: the film surface becomes a structure that is physically and chemically fragile.

In contrast, as a method that does not involve surface roughening or the formation of a modified layer on the surface, a method for forming conductive seed crystals such as nickel or titanium on an insulating substrate by sputtering is also known (see, for example, Patent 2). Although this method can form a seed layer without roughening the substrate surface, it has the following problems: it requires expensive vacuum equipment, requires a large initial investment, the size or shape of the substrate is limited, the productivity is low, and the process is complicated.

As a solution to the problems of sputtering, the industry has proposed a method that uses a coating layer of conductive ink containing metal particles as a conductive seed layer (see, for example, Patent 3). The technique involves coating a conductive ink containing metal particles with a particle size of 1–500 nm onto an insulating substrate composed of a film or sheet, followed by heat treatment to fix the metal particles in the coated conductive ink as a metal layer onto the insulating substrate, thus forming a conductive seed layer, and then performing plating on the conductive seed layer.

Patent document 3 proposes to form patterns using a semi-additive method. According to the embodiment, conductive ink with dispersed copper particles is coated and heat-treated to form a copper conductive seed layer. The substrate on which the conductive seed layer is formed is used as the substrate for the semi-additive process. A photosensitive resist is formed on the conductive seed layer. After exposure and development, the film thickness of the pattern forming part is increased by electroplating copper. After the resist is peeled off, the copper conductive seed layer is etched to remove it. Furthermore, in the case of forming printed wiring boards by a semi-additive process as previously studied, "a substrate on which a thin copper foil or copper-plated film is disposed as a conductive seed" is used as the substrate for the semi-additive process.

Thus, similar to the combination of a copper conductive seed layer and a copper circuit pattern, when the conductive seed layer and the circuit pattern conductive layer are formed of the same metal, the circuit pattern conductive layer is also etched when the non-patterned conductive seed layer is removed. As a result, the circuit pattern becomes finer and thinner, and the surface roughness of the circuit conductive layer also increases. These become problems that need to be solved when manufacturing high-density wiring and high-frequency transmission wiring.

To address these problems, the inventors have invented a technique in which a conductive silver particle layer is formed on the surface of an insulating substrate. This substrate with the conductive silver particles is used as a substrate for a semi-additive process, thereby preventing circuit pattern thinning or thinning during the seed layer etching step, resulting in a printed circuit board with good design reproducibility and a smooth circuit layer surface. (Non-Patent References 1, 2)

This technology can form circuits on one side and on both sides. However, in order to connect the circuits on both sides, when forming holes in the substrate to connect the two sides in a semi-additive process with conductive silver particle layers on both sides of the insulating substrate, if the previously used electroless copper plating method is adopted for the two-sided electrical connection step, the conductive silver particle layer (M1) may be damaged in the micro-etching step of removing the palladium catalyst adsorbed on the conductive seed layer, and thus cannot be used as a coating seed. Furthermore, since a copper film is formed on the silver particle layer (M1), the conductive seed layer used for circuit pattern formation becomes a copper layer. Therefore, as mentioned above, the problem arises where the circuit pattern becomes thinner or thinner during the seed layer etching step. [Previous Art Documents][Patent Documents]

[Patent Document 1] International Publication No. 2009/004774 [Patent Document 2] Japanese Patent Application Publication No. Hei 9-136378 [Patent Document 3] Japanese Patent Application Publication No. 2010-272837 [Non-Patent Document 1] Akira Murakawa, Norimasa Fukasawa, Wataru Fujikawa, Jun Shirafuji: "Copper Patterning Using a Semi-Additive Method Based on Silver Nanoparticles" "Success Technology", Proceedings of the 28th Microelectronics Symposium, pp. 285-288, 2018. [Non-Patent Reference 2] Akira Murakawa, Shota Shinbayashi, Kenji Fukasawa, Wataru Fujikawa, Jun Shiraha: "Copper Wiring Formation Using a Semi-Additive Method with Silver as a Seed Layer", Proceedings of the 33rd Spring Conference of the Society for Electronic Installations, 11B2-03, 2019.

[Problem Solved by the Invention] The problem to be solved by this invention is to provide a planar semi-additive laminate for two-sided interconnection and a printed circuit board using the same. This planar semi-additive laminate for two-sided interconnection does not require surface roughening with chromic acid or permanganate, nor does it require the formation of a surface modification layer using alkali. Furthermore, it can form a wiring system with high density between the substrate and conductor circuits, less undercut, good design reproducibility, and a rectangular cross-section shape suitable for circuit wiring, without using a vacuum device. [Technical Means for Solving the Problem]

The inventors have conducted intensive research to solve the aforementioned problems and have discovered that, through the following method, a printed circuit board with interconnected two sides can be formed without complex surface roughening or surface modification layer formation and without the use of a vacuum device, thus completing the present invention; the above method involves sequentially depositing a silver particle layer (M1) and a 0.1 μm to 2 μm layer on the two surfaces of an insulating substrate (A). A copper layer (M2) with a thickness of μm is laminated to form a through hole that runs through both sides. A copper or nickel layer is formed on the surface of the through hole. The copper or nickel is replaced with silver. Using the replaced substrate, a patterned resist is formed on the conductive silver particle layer (M1). The two sides of the substrate are electrically connected by electroplating copper, and a circuit pattern is formed at the same time. The printed circuit board has high density of substrate and conductor circuit, less undercut, good design reproducibility, and a rectangular cross-sectional shape that is good for circuit wiring.

That is, the present invention provides the following: 1. A method for manufacturing a printed wiring board, characterized in that it comprises: step 1, wherein a silver particle layer (M1) and a copper layer (M2) are sequentially deposited on two surfaces of an insulating substrate (A), and the thickness of the copper layer (M2) is 0.1 μm to 2 μm. Step 1: A multilayer substrate of μm thickness is formed to create through-holes on both sides; Step 2: An electroless plating catalyst is applied to the substrate having the through-holes and the surface of the through-holes; Step 3: The copper layer (M2) is etched to expose the conductive silver particle layer (M1); Step 4: A copper or nickel layer is formed on the surface of the through-holes and the silver particle layer (M1) by electroless plating; Step 5: The through-holes are replaced with silver. Step 6: A copper or nickel layer is formed on the surface and the silver particle layer (M1); Step 7: A patterned resist is formed on the silver plating layer (M3) formed on the conductive silver particle layer (M1); Step 8: The two sides of the substrate are electrically connected by electroplating copper, and a circuit patterned conductive layer (M4) is formed at the same time; and Step 9: The patterned resist is peeled off, and the silver particle layer (M1) on the non-circuit patterned area is removed by etching solution.

2. A method for manufacturing a printed wiring board, characterized in that it comprises: step 1, wherein a silver particle layer (M1) and a copper layer (M2) are sequentially deposited on two surfaces of an insulating substrate (A), wherein the thickness of the copper layer (M2) is 0.1 μm to 2 μm. Step 1: A multilayer of μm thickness is formed to create through-holes on both sides; Step 2: An electroless plating catalyst is applied to the substrate having the through-holes and the surface of the through-holes; Step 3: The copper layer (M2) is etched to expose the conductive silver particle layer (M1); Step 4: A copper or nickel layer is formed on the surface of the through-holes by electroless plating; Step 5: Silver is used to replace... The copper or nickel formed on the surface of the through hole; step 6, forming a patterned resist on the conductive silver particle layer (M1); step 7, electrically connecting the two sides of the substrate by electroplating copper, and forming a circuit patterned conductive layer (M4); and step 8, peeling off the patterned resist and removing the silver particle layer (M1) of the non-circuit patterned area using an etching solution.

3. A method for manufacturing a printed circuit board, characterized by comprising: step 1, wherein a laminate having a silver particle layer (M1) and a peelable capping layer (RC) sequentially deposited on two surfaces of an insulating substrate (A) to form a through hole penetrating both surfaces; step 2, wherein an electroless silver plating catalyst is applied to the surface of the substrate having the through hole; step 3, wherein the peelable capping layer (RC) is peeled off to expose the conductive silver particle layer (M1); and step 4, wherein an electroless plating is applied to the surface of the through hole and the silver particle layer. Step 5: A copper or nickel layer is formed on the particle layer (M1); Step 6: A patterned resist is formed on the silver plating layer (M3) formed on the conductive silver particle layer (M1); Step 7: The two sides of the substrate are electrically connected by electroplating copper, and a circuit patterned conductive layer (M4) is formed; and Step 8: The patterned resist is peeled off, and the silver particle layer (M1) on the non-circuit patterned area is removed by etching solution.

4. A method for manufacturing a printed circuit board, characterized by comprising: step 1, wherein a laminate having a silver particle layer (M1) and a peelable capping layer (RC) sequentially deposited on two surfaces of an insulating substrate (A) to form through holes penetrating both surfaces; step 2, wherein an electroless silver plating catalyst is applied to the surface of the substrate having the through holes; step 3, wherein the peelable capping layer (RC) is peeled off to expose the conductive silver particle layer (M1); step 4, wherein the method further comprises: Step 5: A copper or nickel layer is formed on the surface of the through-hole without electrolytic plating; Step 6: A patterned resist is formed on the conductive silver particle layer (M1); Step 7: The two sides of the substrate are electrically connected by electroplating copper, and a circuit patterned conductive layer (M4) is formed at the same time; and Step 8: The patterned resist is peeled off, and the silver particle layer (M1) of the non-circuit patterned area is removed by etching solution.

5. A method for manufacturing a laminate using a semi-additive process as described in any of 1 to 4, wherein an undercoat layer (B) is further laminated between the insulating substrate (A) and the silver particle layer (M1).

6. A method for manufacturing a printed wiring board as described in any one of 1 to 5, wherein the thickness of the copper or nickel layer formed on the surface of the through hole is 0.1 to 1 μm.

7. The method of manufacturing a printed wiring board as described in any of 1 to 4, wherein the silver particles constituting the silver particle layer (M1) are coated with a polymeric dispersant.

8. The method for manufacturing a printed circuit board as described in 5, wherein, in the method for manufacturing a printed circuit board as described in 4, the substrate (B) is a layer composed of a resin having a reactive functional group [X], the polymeric dispersant has a reactive functional group [Y], and the reactive functional group [X] and the reactive functional group [Y] can form bonds with each other through a reaction.

9. The method for manufacturing a printed wiring board as described in 6, wherein the aforementioned reactive functional group [Y] is a base containing a nitrogen atom.

10. The method for manufacturing a printed wiring board as described in 7, wherein the polymeric dispersant having the reactive functional group [Y] is selected from one or more of the group consisting of polyalkylimides and polyalkylimides having a polyoxyalkylene structure containing an oxyethyl unit.

11. A method for manufacturing a printed wiring board as described in any one of items 5 to 8, wherein the reactive functional group [X] is selected from one or more of the group consisting of ketone, acetoacetyl, epoxy, carboxyl, N-alkylol group, isocyanate, vinyl, (meth)acrylyl, and allyl. [Effects of the Invention]

By employing the manufacturing method of the present invention, printed circuit boards (PCBs) with high adhesion, smooth surfaces, and well-defined rectangular cross-sectional shapes can be manufactured on various smooth substrates without the use of vacuum devices, achieving good design reproducibility. These PCBs feature double-sided connections and high-density wiring. Therefore, the technology of this invention provides a low-cost, multi-layered, high-density, high-performance PCB capable of handling high-frequency transmissions, making it highly applicable in the printed wiring industry. Furthermore, the manufacturing method of this invention can be used not only for manufacturing conventional PCBs but also for manufacturing various electronic components with patterned metal layers on the substrate surface. Examples include connectors, electromagnetic shielding, RFID antennas, and membrane capacitors.

The manufacturing method of the printed wiring board of this invention is characterized by: Step 1, wherein a silver particle layer (M1) and a copper layer (M2) are sequentially deposited on two surfaces of an insulating substrate (A), and the thickness of the copper layer (M2) is 0.1 μm to 2 μm. Step 1: A multilayer of μm thickness is used to form a through-hole that extends through both sides; Step 2: An electroless plating catalyst is applied to the substrate having the through-hole and the surface of the through-hole; Step 3: The copper layer (M2) is etched to expose the conductive silver particle layer (M1); Step 4: A copper or nickel layer is formed on the surface of the through-hole and the silver particle layer (M1) by electroless plating; Step 5: Silver is used to replace the through-hole. Step 6: Forming copper or nickel on the surface of the hole and the silver particle layer (M1); Step 7: Forming a patterned resist on the silver plating layer (M3) formed on the conductive silver particle layer (M1); Step 8: Electroplating copper to electrically connect the two sides of the substrate and simultaneously forming a circuit patterned conductive layer (M4); and Step 9: Peeling off the patterned resist and using an etching solution to remove the silver particle layer (M1) of the non-circuit patterned area.

Furthermore, the manufacturing method of the printed circuit board of the present invention is characterized by comprising: Step 1, wherein a silver particle layer (M1) and a copper layer (M2) are sequentially deposited on two surfaces of an insulating substrate (A), wherein the copper layer (M2) has a thickness of 0.1 μm to 2 μm, forming a through hole penetrating both surfaces; Step 2, wherein an electroless plating catalyst is applied to the substrate having the through hole and the surface of the through hole; Step 3, wherein the copper layer (M2) is etched to expose the conductive silver particle layer (M1); Step 4, wherein the through hole is formed by electroless plating. Step 5: A copper or nickel layer is formed on the surface of the hole; Step 6: A patterned resist is formed on the conductive silver particle layer (M1); and Step 7: The two sides of the substrate are electrically connected by electroplating copper, and a circuit patterned conductive layer (M3) is formed at the same time.

Furthermore, a preferred embodiment of the manufacturing method of the printed wiring board of the present invention is characterized by having an undercoat layer (B) between the above-mentioned insulating substrate layer (A) and conductive silver particle layer (M1).

Materials used as the aforementioned insulating substrate (A) include, for example: polyimide resin, polyamide-imide resin, polyamide resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, polycarbonate resin, acrylonitrile-butadiene-styrene (ABS) resin, polyarylate resin, polyacetal resin, poly(methyl methacrylate) and other acrylic resins, polyvinylidene fluoride resin, polytetrafluoroethylene resin, polyvinyl chloride resin, polyvinylidene chloride resin, vinyl chloride resin grafted with acrylic resin, polyvinyl alcohol resin, polyethylene resin, polypropylene resin, and urethane resin. Resins, cyclohexene resins, polystyrene, liquid crystal polymers (LCP), polyetheretherketone (PEEK) resins, polyphenylene sulfide (PPS), polyphenylene oxide (PPSU), cellulose nanofibers, silicon, silicon carbide, gallium nitride, sapphire, ceramics, glass, diamond-like carbon (DLC), alumina, etc.

Furthermore, as the aforementioned insulating substrate (A), a resin substrate containing a thermosetting resin and inorganic fillers can preferably be used. Examples of the aforementioned thermosetting resins include: epoxy resins, phenolic resins, unsaturated amide resins, cyanate ester resins, isocyanate ester resins, benzo[a][x ... On the other hand, examples of the aforementioned inorganic fillers include: silica, alumina, talc, mica, aluminum hydroxide, magnesium hydroxide, calcium carbonate, aluminum borate, and borosilicate glass. These thermosetting resins and inorganic fillers can be used individually or in combination.

As for the aforementioned insulating substrate (A), any of the following can be used: planar flexible material, rigid material, or rigid-flexible material. More specifically, commercially available materials formed into films, sheets, or plates can be used for the aforementioned insulating substrate (A), or materials obtained by forming a planar shape from a solution, melt, or dispersion of the aforementioned resin can be used. Furthermore, the aforementioned insulating substrate (A) can be a substrate on which the aforementioned resin material is formed on a conductive material such as a metal, or a substrate on which the aforementioned resin material is deposited on a printed circuit board with a circuit pattern.

Regarding the aforementioned silver particle layer (M1), in the manufacturing method of the printed wiring board of the present invention, the aforementioned silver particle layer (M1) becomes the plating substrate when the conductive layer (M3) that becomes the wiring pattern is formed by the plating step.

Regarding the silver particles constituting the silver particle layer (M1), they may contain metal particles other than silver within the range that allows the following plating steps to be performed normally. However, in terms of further improving the etching removeability of the non-circuit formation portion, the ratio of metal particles other than silver is preferably 5 parts by mass or less, and more preferably 2 parts by mass or less, relative to 100 parts by mass of silver.

As a method for forming the silver particle layer (M1) on both sides of the planar insulating substrate (A), a method of coating both sides of the insulating substrate (A) with a silver particle dispersion can be exemplified. Regarding the coating method of the silver particle dispersion, there are no particular limitations as long as the silver particle layer (M1) can be formed well, and various coating methods can be appropriately selected according to the shape, size, rigidity and flexibility of the insulating substrate (A) used. Specific coating methods include, for example: gravure printing, offset printing, flexographic printing, pad printing, gravure offset printing, letterpress printing, letterpress reversal printing, screen printing, micro-touch printing, reverse printing, pneumatic squeegee coating, squeegee coating, air knife coating, extrusion coating, impregnation coating, transfer roller coating, contact coating, casting coating, spray coating, inkjet coating, die coating, rotary coating, rod coating, and dip coating. At this time, the silver particle layer (M1) can be formed on both sides of the insulating substrate (A) at the same time, or it can be formed on one side of the insulating substrate (A) and then on the other side.

For the aforementioned insulating substrate (A) and the primer layer (B) formed on the aforementioned insulating substrate (A), surface treatment can be performed before applying the silver particle dispersion to improve the coatability of the silver particle dispersion and improve the adhesion of the conductive layer (M4) of the circuit pattern formed in the coating step to the substrate. As for the surface treatment method for the aforementioned insulating substrate (A), there are no particular limitations as long as it does not increase the surface roughness, causing problems with the formation of micro-pitch patterns or signal transmission loss caused by the rough surface; any appropriate method can be selected. Examples of such surface treatment methods include: UV treatment, gas phase ozone treatment, liquid phase ozone treatment, corona treatment, and plasma treatment. These surface treatment methods can be performed using one method or by using two or more methods in combination.

After the silver particle dispersion is applied to the insulating substrate (A) or the primer (B), the coating film is dried to allow the solvent contained in the silver particle dispersion to evaporate, thereby forming the silver particle layer (M1) on the insulating substrate (A) or the primer (B).

The drying temperature and time mentioned above can be appropriately selected according to the heat resistance temperature of the substrate used and the type of solvent used in the above metal particle dispersion. The temperature is in the range of 20 to 350°C, and the time is preferably in the range of 1 to 200 minutes. Furthermore, in order to form a silver particle layer (M1) with excellent adhesion on the substrate, the above drying temperature is more preferably in the range of 0 to 250°C.

Regarding the insulating substrate (A) with the silver particle layer (M1) formed thereon, or the insulating substrate (A) with the primer layer (B) formed thereon, annealing may be performed after drying as needed to reduce the resistance of the silver particle layer or to improve the adhesion between the insulating substrate (A) or the primer layer (B) and the silver particle layer (M1). The annealing temperature and time can be appropriately selected according to the heat resistance temperature of the substrate used, the required resistance, and the production capacity, and can be carried out in the range of 60 to 350°C for 1 minute to 2 weeks. Furthermore, if the temperature range is 60 to 180°C, the optimal time is 1 minute to 2 weeks; if the temperature range is 180 to 350°C, the optimal time is approximately 1 minute to 5 hours.

Regarding the aforementioned drying process, air supply may or may not be required. Furthermore, drying can be carried out in the atmosphere, in an environment with inert gases such as nitrogen or argon, or under airflow, or even under a vacuum.

Regarding the drying of the coated film, in addition to natural drying at the coating site, it can also be carried out in a dryer such as a blower or a constant temperature dryer. Furthermore, when the aforementioned insulating substrate (A) is a roll film or sheet, after the coating step, the roll can be continuously moved within a designated non-heated or heated space to perform drying and baking. Examples of heating methods for this drying and baking include ovens, hot air drying ovens, infrared drying ovens, laser irradiation, microwaves, and light irradiation (flash irradiation devices). One or more of these heating methods can be used simultaneously.

The amount of the metal particle layer (M1) formed on the insulating substrate (A) or the base coat (B) is preferably in the range of 0.01 to 30 g/ ^m² , and more preferably in the range of 0.01 to 10 g/ ^m² . Furthermore, since the formation of the conductive layer (M3) performed by the following coating step is easier, and the removal of the seed layer performed by the following etching step is also easier, the amount of the above-mentioned formation is further preferably in the range of 0.05 to 5 g/ ^m² .

The amount of silver particle layer (M1) formed can be confirmed using commonly used analytical methods such as fluorescent X-ray diffraction, atomic absorption spectrometry, and ICP.

Furthermore, in the step of exposing the circuit pattern to the resist layer using active light, in order to suppress the reflection of active light from the silver particle layer (M1), the silver particle layer (M1) may contain light-absorbing pigments or dyes such as graphite or carbon, anthocyanin compounds, phthalocyanine compounds, dithiol metal complexes, naphthoquinone compounds, diammonium compounds, and azo compounds as light absorbers, within a range that allows the formation of the silver particle layer (M1), enables normal electroplating, and ensures the etching removeability. These pigments or dyes can be appropriately selected according to the wavelength of the active light used. Furthermore, one or more of these pigments or dyes may be used. Furthermore, in order to contain such pigments or dyes in the aforementioned silver particle layer (M1), it is sufficient to add such pigments or dyes to the silver particle dispersion described below.

The silver particle dispersion used to form the silver particle layer (M1) is formed by dispersing silver particles in a solvent. There are no particular restrictions on the shape of the silver particles, as long as they can effectively form the silver particle layer (M1). Various shapes of silver particles, such as spherical, lens-shaped, polyhedral, plate-shaped, rod-shaped, and thread-shaped, can be used. These silver particles can be of a single shape or two or more different shapes can be used together.

When the silver particles are spherical or polyhedral in shape, their average particle size is preferably in the range of 1 to 20,000 nm. Furthermore, when forming microcircuit patterns, to further improve the homogeneity of the silver particle layer (M1) and thus further improve the etchant removal properties, the average particle size is more preferably in the range of 1 to 200 nm, and even more preferably in the range of 1 to 50 nm. Moreover, the "average particle size" of nano-sized particles refers to the average volume obtained by diluting the metal particles with a well-dispersing solvent and measuring it using dynamic light scattering. For this measurement, "Nanotrac UPA-150" manufactured by MICROTRAC can be used.

On the other hand, when silver particles have shapes such as lens-shaped, rod-shaped, or linear, their minor diameter is preferably in the range of 1 to 200 nm, more preferably in the range of 2 to 100 nm, and even more preferably in the range of 5 to 50 nm.

The silver particles described above are preferably silver particles as the main component. However, as long as it does not hinder the following coating steps or impair the etchability of the silver particle layer (M1) described below, a portion of the silver constituting the silver particles may be replaced with other metals or mixed with metals other than silver.

As the metal to be replaced or mixed, examples include one or more metallic elements from the group consisting of free gold, platinum, palladium, ruthenium, tin, copper, nickel, iron, cobalt, titanium, indium and iridium.

The ratio of the metal replaced or mixed with the silver particles is preferably 5% by mass or less in the silver particles, and more preferably 2% by mass or less from the viewpoint of the coating properties and etching solution removal properties of the silver particle layer (M1).

The silver particle dispersion used to form the silver particle layer (M1) is made by dispersing silver particles in various solvents. The particle size distribution of the silver particles in the dispersion can be uniformly monodisperse, or it can be a mixture of particles within the above-mentioned average particle size range.

The solvent used in the dispersion of the silver particles can be an aqueous medium or an organic solvent. Examples of aqueous media include distilled water, ion-exchanged water, pure water, ultrapure water, and mixtures of the above water with organic solvents.

Examples of organic solvents that mix with water include: methanol, ethanol, n-propanol, isopropanol, ethyl carbitol, ethyl cyrrolizol, butyl cyrrolizol, and other alcohol solvents; acetone, methyl ethyl ketone, and other ketone solvents; ethylene glycol, diethylene glycol, propylene glycol, and other alkylene glycol solvents; polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and other polyalkylene glycol solvents; and N-methyl-2-pyrrolidone, and other lactamine solvents. Furthermore, examples of organic solvents used alone include: alcohol compounds, ether compounds, ester compounds, and ketone compounds.

Examples of alcoholic or etheric solvents used as the above-mentioned solvents include: methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, dibutanol, tributanol, heptanol, hexanol, octanol, nonanol, decanol, undecylol, dodecanol, tridecanol, tetradecanol, pentadecylol, stearyl alcohol, allyl alcohol, cyclohexanol, terpineol, dihydroterpineol, 2-ethyl-1,3-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, and dipropylene glycol. 1,2-Butanediol, 1,3-Butanediol, 1,4-Butanediol, 2,3-Butanediol, Glycerin, Ethylene glycol monomethyl ether, Ethylene glycol monoethyl ether, Ethylene glycol monobutyl ether, Diethylene glycol monoethyl ether, Diethylene glycol monomethyl ether, Diethylene glycol monobutyl ether, Tetraethylene glycol monobutyl ether, Propylene glycol monomethyl ether, Dipropylene glycol monomethyl ether, Tripropylene glycol monomethyl ether, Propylene glycol monopropyl ether, Dipropylene glycol monopropyl ether, Propylene glycol monobutyl ether, Dipropylene glycol monobutyl ether, Tripropylene glycol monobutyl ether, etc.

Examples of ketone solvents include acetone, cyclohexanone, and methyl ethyl ketone. Examples of ester solvents include ethyl acetate, butyl acetate, 3-methoxybutyl acetate, and 3-methoxy-3-methylbutyl acetate. Furthermore, other organic solvents include toluene and other hydrocarbon solvents, especially those with 8 or more carbon atoms.

As solvents containing 8 or more carbon atoms, examples of nonpolar solvents include octane, nonane, decane, dodecane, tridecane, tetradecane, cyclooctane, xylene, 1,3,5-trimethylbenzene, ethylbenzene, dodecylbenzene, tetrahydronaphthalene, and trimethylphenylcyclohexane. These can be used in combination with other solvents as needed. Furthermore, they can also be used as mixed solvents such as mineral oil and solvent oil.

There are no particular limitations as long as the solvent can stably disperse the silver particles and effectively form the silver particle layer (M1) on the insulating substrate (A) or the primer layer (B) formed on the insulating substrate (A) as described below. Furthermore, one or more solvents may be used.

Regarding the silver particle content in the above-mentioned silver particle dispersion, it can be appropriately adjusted by using the above-mentioned coating methods to make the amount of the silver particle layer (M1) formed on the above-mentioned insulating substrate (A) range from 0.01 to 30 g/ ^m2 , and adjusted in such a way that the viscosity has the best coating adaptability to match the above-mentioned coating methods. However, it is more preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 20% by mass.

The aforementioned silver particle dispersion is preferably one in which the silver particles do not aggregate, fuse, or precipitate in the aforementioned solvents, thus maintaining long-term dispersion stability. It is also preferable to include a dispersant for dispersing the silver particles in the aforementioned solvents. This dispersant is preferably one with functional groups that coordinate with the metal particles, such as dispersants with functional groups including carboxyl, amino, cyano, acetoacetyl, phosphorus-containing groups, thiols, cyanothiols, and glycinato groups.

As the aforementioned dispersant, commercially available or independently synthesized low or high molecular weight dispersants can be used, as long as they are appropriately selected according to the type of solvent used to disperse the metal particles or the type of insulating substrate (A) used to coat the metal particle dispersion, and according to the purpose. For example, the following are preferred: dodecanthiol, 1-octylthiol, triphenylphosphine, dodecylamine, polyethylene glycol, polyvinylpyrrolidone, polyethylimide, polyvinylpyrrolidone; fatty acids such as myristic acid, caprylic acid, and stearic acid; and polycyclic hydrocarbons with carboxyl groups such as cholic acid, glycyrrhizic acid, and pinoresinic acid. In the case where a silver particle layer (M1) is formed on the underlying coating (B), it is preferable to use a compound having a reactive functional group [Y] that can form a bond with a reactive functional group [X] of the resin used in the underlying coating (B) in order to improve the adhesion between the two layers.

Compounds containing a reactive functional group [Y] include, for example, compounds containing amino, amide, alkanolamide, carboxyl, carboxylic anhydride, carbonyl, acetoacetyl, epoxy, alicyclic epoxy, oxobutane, vinyl, allyl, (meth)acrylyl, (terminated)isocyanate, (alkoxy)silyl, and silsesquioxane compounds. Especially in terms of further improving the adhesion between the base coat (B) and the metal particle layer (M1), the aforementioned reactive functional group [Y] is preferably a group containing a basic nitrogen atom. Examples of such basic nitrogen-containing groups include imine, primary amine, and secondary amine.

The aforementioned alkaline nitrogen atom groups can exist singly or in multiples in one molecule of the dispersant. By containing multiple alkaline nitrogen atom groups in the dispersant, a portion of the alkaline nitrogen atom groups interacts with the metal particles to contribute to the dispersion stability of the metal particles, while the remaining alkaline nitrogen atom groups help improve the adhesion to the aforementioned insulating substrate (A). Furthermore, when a resin having a reactive functional group [X] is used in the following primer layer (B), the alkaline nitrogen atom groups in the dispersant can form bonds with the reactive functional group [X], which can further improve the adhesion of the following circuit pattern conductive layer (M4) on the aforementioned insulating substrate (A), and is therefore preferable.

Regarding the aforementioned dispersant, in terms of being able to form a silver particle layer (M1) with good stability, good coatability, and good adhesion on the aforementioned insulating substrate (A), the dispersant is preferably a polymeric dispersant. The polymeric dispersant is preferably a polyalkylene imide such as polyethylene imide or polypropylene imide, or a compound formed by adding polyoxyalkylene to the aforementioned polyalkylene imide.

As a compound formed by adding polyoxyalkylene to the above-mentioned polyalkylimide, it can be formed by a straight-chain bond between polyethylimide and polyoxyalkylene, or it can be formed by grafting polyoxyalkylene onto the side chain of the main chain composed of the above-mentioned polyethylimide.

Specific examples of compounds formed by adding polyoxyalkylene to the aforementioned polyalkylimide include: block copolymers of polyethylimide and polyethylene oxide; compounds that introduce a polyethylene oxide structure by reacting ethylene oxide with a portion of the imine group present in the main chain of polyethylimide; and compounds formed by reacting the amino group of polyalkylimide, the hydroxyl group of polyethylene oxide, and the epoxy group of epoxy resin.

Commercially available polyalkylimides include, for example, the "EPOMIN (registered trademark) PAO series" manufactured by Nippon Shokubai Co., Ltd., including "PAO2006W", "PAO306", "PAO318", and "PAO718".

The average molecular weight of the aforementioned polyalkylimides is preferably in the range of 3,000 to 30,000.

Regarding the amount of the dispersant used to disperse the silver particles, it is preferably in the range of 0.01 to 50 parts by mass relative to 100 parts by mass of the silver particles. Furthermore, in terms of being able to form a silver particle layer (M1) exhibiting good adhesion on the insulating substrate (A) or the primer layer (B), the amount used is preferably in the range of 0.1 to 10 parts by mass relative to 100 parts by mass of the silver particles. Moreover, in terms of being able to improve the coating properties of the silver particle layer (M1), it is more preferably in the range of 0.1 to 5 parts by mass.

There are no particular limitations on the method for manufacturing the aforementioned silver particle dispersion; various methods can be used. For example, silver particles produced by a gas-phase method such as low-vacuum gas-phase evaporation can be dispersed in a solvent, or a silver particle dispersion can be directly prepared by reducing silver compounds in a liquid phase. Regardless of whether a gas-phase or liquid-phase method is used, the solvent composition of the dispersion during manufacturing and the dispersion during coating can be appropriately changed as needed by changing or adding solvent. Among gas-phase and liquid-phase methods, the liquid-phase method is particularly preferable considering the stability of the dispersion and the simplicity of the manufacturing process. As a liquid-phase method, for example, silver ions can be reduced in the presence of the aforementioned polymeric dispersant.

The silver particle dispersion can be further mixed with organic compounds such as surfactants, leveling agents, viscosity modifiers, film-forming aids, defoamers, and preservatives as needed.

Examples of such surfactants include: nonionic surfactants such as polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene styrene phenyl ether, polyoxyethylene sorbitan tetraoleate, and polyoxyethylene-polyoxypropylene copolymer; anionic surfactants such as fatty acid salts like sodium oleate, alkyl sulfate salts, alkylbenzene sulfonates, alkyl sulfosuccinates, naphthalene sulfonates, polyoxyethylene alkyl sulfates, sodium alkyl sulfonates, and sodium alkyl diphenyl ether sulfonates; and cationic surfactants such as alkylamine salts, alkyl trimethylammonium salts, and alkyl dimethyl benzylammonium salts.

As the leveling agent mentioned above, general leveling agents can be used, such as polysiloxane compounds, acetylene glycol compounds, fluorine compounds, etc.

As the viscosity modifier mentioned above, common thickeners can be used, such as: acrylic polymers that can thicken by adjusting to alkalinity, synthetic rubber latex, amine resins that can thicken by molecular bonding, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, polyvinyl alcohol, hydrogenated castor oil, acetone wax, oxidized polyethylene, metal soap, dibenzyl sorbitol, etc.

As the aforementioned film-forming aids, general film-forming aids can be used, such as anionic surfactants like sodium dioctyl sulfosuccinate, hydrophobic nonionic surfactants like sorbitan monooleate, polyether-modified silicones, and polysiloxanes.

As the aforementioned defoamer, general defoamers can be used, such as: polysiloxane defoamers, nonionic surfactants, polyethers, higher alcohols, polymer surfactants, etc.

As the aforementioned preservatives, general preservatives can be used, such as isothiazolin-based preservatives, trimethylolpropionic acid-based preservatives, imidazole-based preservatives, pyridine-based preservatives, azole-based preservatives, pyrithione-based preservatives, etc.

Furthermore, as a preferred embodiment of the semi-additive process laminate used in the manufacturing method of the printed wiring board of the present invention, an example is a laminate having a base coat (B) between the insulating substrate layer (A) and the conductive silver particle layer (M1). The semi-additive process laminate with this base coat can further improve the adhesion of the conductive layer (M4) of the circuit pattern to the insulating substrate (A), and is therefore preferred.

The aforementioned primer layer (B) can be formed by applying a primer to a portion or the entire surface of the aforementioned insulating substrate (A), and then removing the aqueous medium, organic solvent, and other solvents contained in the primer. Here, the primer refers to a liquid composition formed by dissolving or dispersing various resins in a solvent to improve the adhesion of the conductive layer (M3) to the insulating substrate (A).

As for the method of applying the above-mentioned primer to the above-mentioned insulating substrate (A), there are no particular restrictions as long as the primer layer (B) can be formed well. Various coating methods can be appropriately selected according to the shape, size, rigidity and flexibility of the insulating substrate (A) used. Specific coating methods include, for example: gravure printing, offset printing, flexographic printing, pad printing, gravure offset printing, letterpress printing, letterpress reversal printing, screen printing, micro-touch printing, reverse printing, pneumatic squeegee coating, squeegee coating, air knife coating, extrusion coating, impregnation coating, transfer roller coating, contact coating, casting coating, spray coating, inkjet coating, die coating, rotary coating, rod coating, and dip coating.

Furthermore, as for the method of applying the primer to both sides of the insulating substrate (A) in the form of a film, sheet, or plate, there are no particular limitations as long as the primer layer (B) can be formed well, and the coating method exemplified above can be appropriately selected. In this case, the primer layer (B) can be formed on both sides of the insulating substrate (A) simultaneously, or it can be formed on one side of the insulating substrate (A) and then on the other side.

The insulating substrate (A) described above can be surface-treated before applying the primer to improve the coatability of the primer or to improve the adhesion of the conductive layer (M4) of the circuit pattern to the substrate. As a surface treatment method for the insulating substrate (A), the same method as the surface treatment method used when forming the silver particle layer (M1) on the insulating substrate (A) can be used.

As a method for forming a base coat (B) by applying the primer to the surface of the insulating substrate (A) and then removing the solvent contained in the coating layer, a common method is to use a dryer to dry the substrate and allow the solvent to evaporate. The drying temperature can be set to a range that allows the solvent to evaporate without adversely affecting the insulating substrate (A), and can be either room temperature drying or heated drying. Specifically, the drying temperature is preferably in the range of 20–350°C, and more preferably in the range of 60–300°C. Furthermore, the drying time is preferably in the range of 1–200 minutes, and more preferably in the range of 1–60 minutes.

Regarding the aforementioned drying process, ventilation may or may not be required. Furthermore, drying can be carried out in the atmosphere, in environments with nitrogen or argon exchange, or under airflow, or even under a vacuum.

When the insulating substrate (A) is a single film, sheet, or plate, it can be dried naturally at the coating site or in a dryer such as a blower or constant temperature dryer. Furthermore, when the insulating substrate (A) is a roll film or sheet, it can be dried by continuously moving the roll within a non-heated or heated space after the coating step.

The thickness of the aforementioned base coat (B) can be appropriately selected according to the specifications and applications of the printed wiring board manufactured using the present invention. In terms of further improving the adhesion between the aforementioned insulating substrate (A) and the aforementioned circuit pattern conductive layer (M4), it is preferably in the range of 10 nm to 30 μm, more preferably in the range of 10 nm to 1 μm, and even more preferably in the range of 10 nm to 500 nm.

Regarding the resin forming the base coat (B), when using a resin with a reactive functional group [Y] as a dispersant for the aforementioned metal particles, it is preferable to use a resin with a reactive functional group [X] that is reactive relative to the reactive functional group [Y]. Examples of the aforementioned reactive functional group [X] include: amino, amide, alkanolamide, ketone, carboxyl, carboxylic anhydride, carbonyl, acetylacetyl, epoxy, alicyclic epoxy, oxobutane, vinyl, allyl, (meth)acrylyl, (terminated)isocyanate, (alkoxy)silyl, etc. Furthermore, silsesquioxane compounds may also be used as compounds forming the base coat (B).

In particular, when the reactive functional group [Y] in the above-mentioned dispersant is a base containing a nitrogen atom, in order to further improve the adhesion of the conductive layer (M4) on the above-mentioned insulating substrate (A), the resin forming the base coat (B) is preferably one that has a ketone group, carboxyl group, carbonyl group, acetoacetyl group, epoxy group, alicyclic epoxy group, alkanolamide group, isocyanate group, vinyl group, (meth)acrylyl group, or allyl group as reactive functional groups [X].

Examples of resins used to form the aforementioned base coat (B) include: amine resins, acrylic resins, core-shell composite resins with amine resin as the shell and acrylic resin as the core, epoxy resins, amide resins, amide resins, melamine resins, phenolic resins, urea-formaldehyde resins, and capped isocyanates such as polyvinyl alcohol and polyvinylpyrrolidone obtained by reacting polyisocyanates with capping agents such as phenol. Furthermore, core-shell composite resins with amine resin as the shell and acrylic resin as the core can be obtained, for example, by polymerizing acrylic monomers in the presence of amine resin. Furthermore, one type of resin may be used, or two or more types may be used in combination.

Of the resins used to form the base coat (B), those that can further improve the adhesion of the conductive layer (M3) on the insulating substrate (A) are preferably resins that generate reducing compounds by heating. Examples of such reducing compounds include phenolic compounds, aromatic amine compounds, sulfur compounds, phosphoric acid compounds, and aldehyde compounds. Among these reducing compounds, phenolic compounds and aldehyde compounds are preferred.

When a resin that generates reducing compounds through heating is used as a primer, reducing compounds such as formaldehyde and phenol will be generated during the heating and drying step when forming the primer layer (B). Examples of resins that generate reducing compounds by heating include: resins polymerized from monomers containing N-alkanol (meth)acrylamide; core-shell composite resins with an amine ester resin as the shell and a resin polymerized from monomers containing N-alkanol (meth)acrylamide as the core; urea-formaldehyde-methanol condensates; urea-melamine-formaldehyde-methanol condensates; poly(N-alkoxyhydroxymethyl (meth)acrylamide); formaldehyde adducts of poly(meth)acrylamide; melamine resins; and phenolic resins and phenol-terminated isocyanates that generate phenolic compounds by heating. Among these resins, from the viewpoint of improving adhesion, core-shell composite resins, melamine resins, and phenol-terminated isocyanates are preferred. These resins use amine ester resins as the shell and resins containing N-alkanol (meth)acrylamide monomers as the core.

Furthermore, in this invention, "(meth)acrylamide" means one or both of "methacrylamide" and "acrylamide", and "(meth)acrylic acid" means one or both of "methacrylic acid" and "acrylic acid".

Resins that generate reducing compounds by heating can be obtained by polymerizing monomers with functional groups that generate reducing compounds by heating using polymerization methods such as free radical polymerization, anionic polymerization, and cationic polymerization.

Monomers that have functional groups that generate reducing compounds upon heating include, for example, N-alkanol vinyl monomers. Specifically, examples include: N-hydroxymethyl (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-propoxymethyl (meth)acrylamide, N-isopropoxymethyl (meth)acrylamide, N-n-butoxymethyl (meth)acrylamide, N-isobutoxymethyl (meth)acrylamide, N-pentoxymethyl (meth)acrylamide, N-ethanol (meth)acrylamide, N-propanol (meth)acrylamide, etc.

Furthermore, when manufacturing the resin that generates reducing compounds by heating, various other monomers such as (meth)acrylates can be copolymerized together with monomers having functional groups that generate reducing compounds by heating.

When the aforementioned capped isocyanate is used as the resin for forming the aforementioned base coat (B), a self-reaction occurs between the isocyanate groups to form urea diketone bonds, or the isocyanate groups form bonds with functional groups of other components, thereby forming the base coat (B). These bonds can be formed before applying the aforementioned metal particle dispersion, or they can be formed after applying the metal particle dispersion by heating.

Examples of the aforementioned capped isocyanates include those with functional groups formed by capping isocyanate groups with a capping agent.

The aforementioned capped isocyanate is preferably one in which the aforementioned functional group is present in the range of 350 to 600 g/mol per mol of capped isocyanate.

From the viewpoint of improving adhesion, the aforementioned functional group is preferably 1 to 10 in one molecule of the aforementioned capped isocyanate, and more preferably 2 to 5.

Furthermore, from the viewpoint of improving adhesion, the average molecular weight of the aforementioned capped isocyanate is preferably in the range of 1,500 to 5,000, and more preferably in the range of 1,500 to 3,000.

Furthermore, from the viewpoint of further improving adhesion, the aforementioned end-capped isocyanate is preferably one containing an aromatic ring. Examples of such aromatic rings include phenyl and naphthyl groups.

Furthermore, the aforementioned capped isocyanates can be manufactured by reacting one or all of the isocyanate groups present in the isocyanate compound with a capping agent.

Isocyanate compounds that serve as raw materials for the aforementioned capped isocyanates include, for example, polyisocyanate compounds with aromatic rings such as 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, phenylene diisocyanate, methylphenylene diisocyanate, and naphthalene diisocyanate; aliphatic polyisocyanate compounds or polyisocyanate compounds with alicyclic structures such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isoflavone diisocyanate, dicyclohexylmethane diisocyanate, phenylene dimethyl diisocyanate, and tetramethylphenylene dimethyl diisocyanate. Furthermore, examples of the aforementioned polyisocyanate compounds include biuret, trimer isocyanate, and adduct forms.

Furthermore, the aforementioned isocyanate compounds can also be obtained by reacting the polyisocyanate compounds exemplified above with compounds having hydroxyl or amine groups.

When introducing an aromatic ring into the aforementioned capped isocyanate, it is preferable to use a polyisocyanate compound having an aromatic ring. Furthermore, among the polyisocyanate compounds having an aromatic ring, 4,4'-diphenylmethane diisocyanate, methylene phenyl diisocyanate, trimerized form of 4,4'-diphenylmethane diisocyanate, and trimerized form of methylene phenyl diisocyanate are preferred.

Examples of end-capping agents used in the manufacture of the aforementioned end-capped isocyanates include: phenolic compounds such as phenol and cresol; lactamine compounds such as ε-caprolactam, δ-valerolactam, and γ-butyrolactam; oxime compounds such as methylamine oxime, acetaldehyde oxime, acetone oxime, methyl ethyl ketone oxime, methyl isobutyl ketone oxime, and cyclohexanone oxime; and oxime compounds such as 2-hydroxypyridine, butylceroxoxuron, propylene glycol monomethyl ether, benzyl alcohol, methanol, ethanol, n-butanol, isobutanol, dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetate, acetoacetone, butanethiol, dodecyl mercaptan, acetoaniline, and acetic acid. The end-capping agents include amides, succinimides, cis-butenediamides, imidazoles, 2-methylimidazoles, ureas, thioureas, ethionamides, diphenylaniline, aniline, carbazole, ethionamides, polyethionamides, 1H-pyrazoles, 3-methylpyrazoles, and 3,5-dimethylpyrazoles. Preferably, these end-capping agents are those that can dissociate and generate isocyanate groups upon heating in the range of 70–200°C, and more preferably, those that can dissociate and generate isocyanate groups upon heating in the range of 110–180°C. Specifically, phenolic compounds, lactamine compounds, and oxime compounds are preferred, especially phenolic compounds, because the end-capping agent becomes a reducing compound upon desorption upon heating.

Examples of methods for manufacturing the aforementioned capped isocyanate include: a method of mixing the previously manufactured isocyanate compound with the capping agent and reacting the mixture; and a method of mixing the capping agent with raw materials used to manufacture the isocyanate compound and reacting the mixture.

More specifically, the above-mentioned capped isocyanate can be manufactured by reacting the above-mentioned polyisocyanate compound with a compound having hydroxyl or amine groups to produce an isocyanate compound with isocyanate groups at the end, and then mixing the above-mentioned isocyanate compound with the above-mentioned capping agent and reacting it.

The content of the capped isocyanate obtained by the above method in the resin forming the above-mentioned base coat (B) is preferably in the range of 50 to 100% by mass, and more preferably in the range of 70 to 100% by mass.

Examples of melamine resins mentioned above include: mono- or polyhydroxymethyl melamine obtained by adding 1 to 6 moles of formaldehyde to 1 mole of melamine; etherifications (degree of etherification is arbitrary) of (poly)hydroxymethyl melamines such as trimethoxyhydroxymethyl melamine, tributoxyhydroxymethyl melamine, and hexamethoxyhydroxymethyl melamine; and urea-melamine-formaldehyde-methanol condensates.

Furthermore, besides the method described above that uses resins to generate reducing compounds through heating, methods that add reducing compounds to resins can also be exemplified. In this case, examples of the added reducing compounds include: phenolic antioxidants, aromatic amine antioxidants, sulfur-based antioxidants, phosphate-based antioxidants, vitamin C, vitamin E, sodium ethylenediaminetetraacetate, sulfites, hypophosphite, hydrazine, formaldehyde, sodium borohydride, dimethylamineborane, phenol, etc.

In this invention, the method of adding reducing compounds to resins may result in reduced electrical properties due to the final residue of low molecular weight components or ionic compounds. Therefore, a method using resins that generate reducing compounds by heating is preferred. Furthermore, as a preferred resin for forming the aforementioned base coat (B), examples include those containing compounds with an amino tricyclic ring. These compounds with an amino tricyclic ring can be low molecular weight compounds or resins with higher molecular weights.

As the aforementioned low molecular weight compound having an amino tricyclic ring, various additives having an amino tricyclic ring can be used. Examples of commercially available products include: 2,4-diamino-6-vinyl symmetric tricyclic ring ("VT" manufactured by Shikoku Chemical Co., Ltd.), "VD-3" or "VD-4" (compounds having an amino tricyclic ring and a hydroxyl group) manufactured by Shikoku Chemical Co., Ltd., and "VD-5" (compounds having an amino tricyclic ring and an ethoxysilyl group) manufactured by Shikoku Chemical Co., Ltd. These can be used as additives added to the resin forming the base coat (B).

Regarding the amount of the aforementioned low molecular weight compound having an amino tricyclic ring, it is preferably 0.1 to 50 parts by weight relative to 100 parts by weight of the aforementioned resin, and more preferably 0.5 to 10 parts by weight.

As for the aforementioned resins containing amino tricyclic rings, those in which amino tricyclic rings are introduced into the polymer chain of the resin through covalent bonding can also be used more preferably. Specifically, amino tricyclic modified phenolic varnish resins can be cited as an example.

The aforementioned aminotrimethylamine modified phenolic varnish resin is a phenolic varnish resin obtained by bonding the aminotrimethylamine ring structure and the phenolic structure through a methylene group. The aforementioned aminotrimethylamine modified phenolic varnish resin can be obtained, for example, by co-condensing melamine, benzoguanidine, ethylguanidine, and other aminotrimethylamine compounds, and phenolic compounds such as phenol, cresol, butylphenol, bisphenol A, phenylphenol, naphthol, resorcinol, and formaldehyde in the presence of a weakly alkaline catalyst such as an alkylamine, or in the absence of a catalyst, near neutrality; or by reacting alkyl ethers of aminotrimethylamine compounds such as methyl etherified melamine with the aforementioned phenolic compounds.

The aforementioned aminotrimethylamine modified phenolic varnish resin is preferably one that does not substantially contain hydroxymethyl groups. Furthermore, the aforementioned aminotrimethylamine modified phenolic varnish resin may contain molecules formed as a byproduct during its manufacturing process, such as molecules consisting solely of an aminotrimethylamine structure bonded to a methylene group, or molecules consisting solely of a phenolic structure bonded to a methylene group. It may also contain a certain amount of unreacted raw materials.

Examples of phenolic structures include: phenol residue, cresol residue, butylphenol residue, bisphenol A residue, phenylphenol residue, naphthol residue, resorcinol residue, etc. Furthermore, the term "residual" here refers to a structure formed by the removal of at least one hydrogen atom from the carbon atom bonded to the aromatic ring. For example, in the case of phenol, it refers to hydroxyphenyl.

Examples of the aforementioned tri-tri ...

The aforementioned phenolic structure and the aforementioned tri-□ structure may be used individually or in combination. Furthermore, in terms of further improving adhesion, the aforementioned phenolic structure is preferably a phenolic residue, and the aforementioned tri-□ structure is preferably a structure derived from melamine.

Furthermore, in terms of further improving adhesion, the hydroxyl value of the above-mentioned aminotrimethylamine modified phenolic varnish resin is preferably 50 mgKOH/g or higher and 200 mgKOH/g or lower, more preferably 80 mgKOH/g or higher and 180 mgKOH/g or lower, and even more preferably 100 mgKOH/g or higher and 150 mgKOH/g or lower.

The above-mentioned aminotrimethylamine modified phenolic varnish resin can be used in one or more forms.

Furthermore, when using aminotrimorph-modified phenolic varnish resin as the aforementioned compound having an aminotrimorph ring, it is preferable to use an epoxy resin in conjunction.

Examples of the aforementioned epoxy resins include: bisphenol A type epoxy resins, bisphenol F type epoxy resins, biphenyl type epoxy resins, cresol phenolic varnish type epoxy resins, phenol phenolic varnish type epoxy resins, bisphenol A phenolic varnish type epoxy resins, alcohol ether type epoxy resins, tetrabromobisphenol A type epoxy resins, naphthalene type epoxy resins, phosphorus-containing epoxy compounds having a structure derived from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide derivatives, epoxy resins having a structure derived from dicyclopentadiene derivatives, and epoxides of oils such as epoxidized soybean oil. One type of epoxy resin may be used, or two or more types may be used in combination.

Among the aforementioned epoxy resins, those that can further improve adhesion are preferably bisphenol A type epoxy resins, bisphenol F type epoxy resins, biphenyl type epoxy resins, cresol phenolic varnish type epoxy resins, phenolic varnish type epoxy resins, and bisphenol A phenolic varnish type epoxy resins, with bisphenol A type epoxy resins being particularly preferred.

Furthermore, in terms of further improving adhesion, the epoxy equivalent of the aforementioned epoxy resin is preferably 100 g/equivalent or more and 300 g/equivalent or less, more preferably 120 g/equivalent or more and 250 g/equivalent or less, and even more preferably 150 g/equivalent or more and 200 g/equivalent or less.

When the aforementioned base coat (B) is a layer containing aminotrimethylamine modified phenolic varnish resin and epoxy resin, in terms of further improving adhesion, the molar ratio [(x)/(y)] of the phenolic hydroxyl group (x) in the aforementioned aminotrimethylamine modified phenolic varnish resin to the epoxy group (y) in the aforementioned epoxy resin is preferably 0.1 to 5, more preferably 0.2 to 3, and even more preferably 0.3 to 2.

When forming a layer containing an aminotri□-modified phenolic varnish resin and an epoxy resin as the aforementioned primer layer (B), a primer resin composition containing the aforementioned compound having an aminotri□ ring or epoxy resin is used.

Furthermore, in the primer resin composition used to form the primer layer (B) containing the above-mentioned amino-trimethyl-modified phenolic varnish resin and epoxy resin, other resins such as amine ester resins, acrylic resins, end-capped isocyanate resins, melamine resins, and phenolic resins may also be added as needed. One or more of these other resins may be used.

From the viewpoint of coatability and film-forming properties, the primer used to form the above-mentioned base coat (B) preferably contains 1 to 70% by mass of the above-mentioned resin, and more preferably 1 to 20% by mass.

Furthermore, various organic solvents and aqueous media can be used as solvents in the aforementioned primers. Examples of organic solvents include toluene, ethyl acetate, methyl ethyl ketone, and cyclohexanone. Examples of aqueous media include water, organic solvents mixed with water, and mixtures thereof.

Examples of organic solvents that can be mixed with water include: methanol, ethanol, n-propanol, isopropanol, ethyl carbitol, ethyl cyrrolizol, butyl cyrrolizol, and other alcohol solvents; acetone, methyl ethyl ketone, and other ketone solvents; ethylene glycol, diethylene glycol, propylene glycol, and other alkylene glycol solvents; polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and other polyalkylene glycol solvents; and N-methyl-2-pyrrolidone, and other lactamine solvents.

Furthermore, the resin forming the aforementioned base coat (B) may, as needed, possess functional groups such as alkoxysilyl, silyl, hydroxyl, and amino groups that facilitate cross-linking reactions. Regarding the cross-linking structure formed using these functional groups, the cross-linking structure can be formed before the subsequent step of forming the silver particle layer (M1), or it can be formed after the step of forming the silver particle layer (M1). When forming the cross-linking structure after the step of forming the silver particle layer (M1), the cross-linking structure can be pre-formed in the aforementioned base coat (B) before forming the aforementioned conductive layer (M4), or it can be formed in the aforementioned base coat (B) after the formation of the aforementioned conductive layer (M4), for example, by curing.

In the aforementioned base coat (B), known agents such as pH adjusters, film-forming aids, leveling agents, thickeners, water-repellent agents, and defoamers may be added as needed.

Examples of crosslinking agents include metal chelating compounds, polyamine compounds, aziridine compounds, metal salt compounds, and isocyanate compounds. Examples of thermal crosslinking agents that react at relatively low temperatures of around 25–100°C to form crosslinked structures include melamine compounds, epoxy compounds, α-azoline compounds, carbodiimide compounds, and terminal isocyanate compounds that react at relatively high temperatures above 100°C to form crosslinked structures, as well as various photocrosslinking agents. When using the above-mentioned aminotrimethylamine modified phenolic varnish resin and epoxy resin as the above-mentioned primer (B), it is preferable to use a polycarboxylic acid as the crosslinking agent in the primer resin composition. Examples of the aforementioned polycarboxylic acids include 1,2,4-phenyltricarboxylic anhydride, pyrocalcite dianhydride, maleic anhydride, and succinic acid. One or more of these crosslinking agents may be used. Of these crosslinking agents, 1,2,4-phenyltricarboxylic anhydride is preferred in terms of further improving adhesion.

The amount of the crosslinking agent used varies depending on the type, but from the viewpoint of improving the adhesion of the conductive layer (M4) to the substrate, it is preferably in the range of 0.01 to 60 parts by mass relative to the total 100 parts by mass of resin contained in the primer, more preferably in the range of 0.1 to 10 parts by mass, and even more preferably in the range of 0.1 to 5 parts by mass.

When using the aforementioned crosslinking agent, the crosslinking structure can be formed before the subsequent step of forming the silver particle layer (M1), or it can be formed after the step of forming the silver particle layer (M1). When forming the crosslinking structure after the step of forming the silver particle layer (M1), the crosslinking structure can be formed on the aforementioned base coat (B) before forming the aforementioned conductive layer (M3), or it can be formed on the aforementioned base coat (B) after forming the aforementioned conductive layer (M3), for example, by curing.

In this invention, the method of forming the silver particle layer (M1) on the substrate (B) is the same as the method of forming the silver particle layer (M1) on the insulating substrate (A).

Furthermore, the aforementioned base coat (B), like the aforementioned insulating substrate (A), can be surface-treated before coating the silver particle dispersion to improve the coatability of the silver particle dispersion or to improve the adhesion of the conductive layer (M4) to the substrate.

Regarding the thickness of the copper layer (M2) deposited on the conductive silver particle layer, in order to efficiently expose the conductive silver particle layer (M1) without damaging the silver particle layer (M1) in the step of etching the copper layer (M2) in step 3 below, the thickness is preferably 0.1 μm to 2 μm, more preferably 0.5 μm to 1.5 μm.

As a method for depositing the copper layer (M2) onto the conductive silver particle layer (M1), it can be formed by performing a dry or wet copper plating process on the conductive silver particle layer (M1).

Examples of dry copper plating methods include vacuum evaporation, ion plating, and sputtering. Furthermore, examples of wet copper plating methods include electroless copper plating using the aforementioned silver particle layer (M1) as the plating catalyst, electroplating, and combinations of electroless and electroplating. Using electroplating increases the plating deposition rate, thus improving manufacturing efficiency and offering advantages.

There are no particular limitations on the copper plating method used to form a copper layer (M2) on the aforementioned silver particle layer (M1). It can be formed by vacuum evaporation, ion plating, or sputtering, which are dry plating methods. It can also be formed by electroless copper plating, electroplating, or a combination of electroless copper plating and electroplating, which are wet plating methods. Furthermore, it can also be formed by combining dry plating and wet plating. In all cases, commonly known copper plating methods are preferred.

The copper plating is preferably performed by forming a copper layer (M2) of the same thickness on the silver particle layer (A) on both surfaces of the insulating substrate (A).

In the step of forming the copper layer (M2) by the above-described copper plating method, the surface of the silver particle layer (M1) may be surface-treated as needed. Examples of such surface treatments, provided that the surface of the silver particle layer (M1) or the formed resist pattern is not damaged, include: cleaning with acidic or alkaline cleaning solutions, corona treatment, plasma treatment, UV treatment, gas phase ozone treatment, liquid phase ozone treatment, and treatment using surface treatment agents. These surface treatments may be performed using one method or two or more methods simultaneously.

In the semi-additive process laminate of the present invention, the silver plating performed to ensure the conductivity of both sides of the substrate can also be manufactured using the following substrate, which is an insulating substrate (A) on which a conductive silver particle layer (M1) and a peelable capping layer (RC) are sequentially deposited on both surfaces.

By depositing the aforementioned peelable coating layer (RC) onto the aforementioned silver particle layer (M1), during the manufacturing of the semi-additive process laminate of the present invention, in the step of forming the through-holes penetrating both sides, organic or inorganic contaminants (smear) generated are prevented from adhering to the surface of the silver particle layer (M1); furthermore, in the step of making the inner wall surface of the formed through-holes conductive, electroless coating catalyst is prevented from adhering to the conductive silver particle layer (M1), thereby protecting the silver particle layer (M1).

As for the material of the above-mentioned peelable cover layer (RC), as long as the following objective can be achieved in the manufacturing method of the printed circuit board of the present invention, namely, protecting the above-mentioned conductive silver particle layer (M1) in the pretreatment step of the step of using conductive crystals for electroplating copper for forming the circuit pattern layer (M3), there are no particular limitations. Various commercially available resin films can be used, and polyethylene, polypropylene, and polyethylene terephthalate films are preferred.

The aforementioned peelable coating (RC) can also be used on films such as polyethylene, polypropylene, and polyethylene terephthalate that have a polysiloxane layer to improve peelability.

Regarding the thickness of the peelable capping layer (RC) used in this invention, from the viewpoints of film treatment, the protective properties of the aforementioned silver particle layer (M1), and the ease of forming through-holes in the substrate, it is preferably 10 to 100 μm, more preferably 15 to 70 μm.

The peelable capping layer (RC) used in this invention can be deposited on the silver particle layer (M1) after the silver particle layer (M1) is coated. For example, when coating the silver particle layer (M1) using a roller coating machine, the peelable capping layer (RC) can be deposited by taking it up together during winding.

As the material for the aforementioned peelable coating (RC) of this invention, an alkali-soluble resin can also be used. There are no particular limitations on the alkali-soluble resin, as long as it can be developed using an alkaline developer; commonly known resins can be used, such as amide-imide resins, or resins with alkali-soluble functional groups such as carboxyl or phenolic hydroxyl groups. Regarding the alkali-soluble resin, a resin solution can be coated onto the aforementioned silver particle layer (M1) to form a film, or pre-filmed resins can be used. When using pre-coated materials, for example, the silver particle layer (M1) can be coated using a roller coating machine as described above, and the peelable cover layer (RC) can be rolled up together during winding to perform lamination.

Step 1 of the manufacturing method of the printed wiring board of the present invention comprises the following steps: a laminate with a base coat (B) is further laminated between the laminate or the insulating substrate (A) and the silver particle layer (M1) to form a through hole through both sides. The laminate is in which the silver particle layer (M1) and the copper layer (M2) are sequentially laminated on both surfaces of the insulating substrate (A), and the thickness of the copper layer (M2) is 0.1 μm to 2 μm.

Furthermore, step 1 of one of the preferred manufacturing methods of the laminate in the semi-additive process of the present invention is as follows: a laminate with an undercoat layer (B) is further laminated between the laminate, or between the insulating substrate (A) and the silver particle layer (M1), forming a through hole through both sides. The laminate is in which the silver particle layer (M1) and the peelable capping layer (RC) are sequentially laminated on both surfaces of the insulating substrate (A).

In step 1, as a method for forming the through hole in the laminate having the copper layer (M2) described above, any known and commonly used method can be appropriately selected. For example, drilling, laser processing, a combination of laser processing for opening the copper layer and etching of the insulating substrate using an oxide, alkaline agent, or acidic agent, and a combination of etching the hole pattern of the copper foil using an anti-corrosion agent and etching of the insulating substrate using an oxide, alkaline agent, or acidic agent, etc.

Furthermore, in step 1, as a method for forming the through hole in a laminate having the above-mentioned exfoliating cover layer (RC), any known and commonly used method can be appropriately selected, such as drilling or laser processing.

The diameter of the hole formed in the above-mentioned hole-opening process is preferably in the range of 0.01 to 1 mm, more preferably in the range of 0.02 to 0.5 mm, and even more preferably in the range of 0.03 to 0.1 mm.

Organic or inorganic contaminants (slag) generated during the hole-opening process may cause poor deposition or reduced adhesion during the plating steps of electrical bonding and formation of the conductive layer (M4), thus damaging the appearance of the plating. Therefore, it is preferable to remove the contaminants (slag). Methods for removing slag include, for example, dry treatments such as plasma treatment and backsplashing, cleaning treatments using aqueous solutions of oxidizing agents such as potassium permanganate, cleaning treatments using aqueous solutions of alkalis or acids, and wet treatments using organic solvents.

Step 2 of the manufacturing method of the printed circuit board of the present invention is the following step: applying an electroless plating catalyst to the surface of the laminate with through holes formed in step 1 above.

In step 4 of the method for manufacturing the printed circuit board of the present invention, as a method for forming a copper or nickel layer on the surface of the aforementioned through-hole, electroless copper plating or electroless nickel plating is preferred. Various commonly known electroless copper plating and electroless nickel plating methods can be used, and electroless plating using palladium catalyst is particularly preferred. In step 2 of the method for manufacturing the printed circuit board of the present invention, as a method for applying palladium catalyst to the substrate, various commonly known methods can be used, such as simply using a sensitizing activator process or a catalyst accelerator process.

Step 3 of the semi-additive process for manufacturing a laminate of the present invention comprises the following steps: etching the copper layer (M2) to remove the catalyst applied to the copper layer (M2), and exposing the conductive silver particle layer (M1) used to form the conductive layer (M4) in the printed circuit board manufacturing step.

In step 3, regarding the etching agent used to remove the 0.1 μm to 2 μm thick copper layer (M2) deposited on the conductive silver particle layer (M1), there are no particular restrictions as long as it can efficiently etch the copper layer (M2) without damaging the underlying silver particle layer (M1). Commonly known copper micro-etching solutions and soft etching solutions can be used. As the etching solution for the copper layer (M2), aqueous solutions of persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate, or aqueous solutions of sulfuric acid/hydrogen peroxide can be used.

Regarding the concentration of the persulfate aqueous solution or the sulfuric acid/hydrogen peroxide aqueous solution, it can be appropriately selected according to the thickness of the copper layer (M2) of the above-mentioned semi-additive process used to manufacture printed wiring boards and the design of the manufacturing apparatus. In the process used, it is preferable to set the etching rate of the copper layer to be less than 2 μm/min. From the viewpoint of efficiently removing the copper layer (M2) and preventing damage to the conductive silver particle layer (M1) as the bottom layer, it is even more preferable to set the etching rate to be 0.1 μm/min to 1.5 μm/min.

Step 4 of the semi-additive process for manufacturing a laminate of the present invention comprises the following step: using a coating catalyst applied to the surface of the through-hole of the substrate via steps 2 and 3 above, electroless copper plating or electroless nickel plating is performed to form a copper layer or a nickel layer on the surface of the through-hole.

Regarding the copper or nickel layer formed on the surface of the through hole in step 4, in order to ensure efficient and reliable replacement from the copper or nickel layer to the silver layer in step 5, and to ensure the conductivity of the replaced silver layer, the copper or nickel layer is preferably 0.1 μm to 1 μm thick. In the electroless copper or electroless nickel plating steps of this invention, depending on the plating conditions, the silver particle layer (M1) exposed in step 3 above functions as an electroless plating catalyst. Electroless copper or electroless nickel plating is also deposited on the silver particle layer (M1). However, the copper or nickel layer formed on the silver particle layer (M1) is replaced with a silver layer by the replacement silver plating in step 5.

Regarding the replacement silver plating in step 5 of this invention, any known and commonly used plating method can be used, and commercially available electroless replacement silver plating processes can be preferred.

In the manufacturing method of the printed wiring board of the present invention, in step 6, a pattern resist for forming a circuit pattern is formed on the silver plating layer (M3) or the conductive silver particle layer (M1) formed on the silver particle layer (M1). When a copper layer or a nickel layer is formed on the silver particle layer (M1) in step 4 above, the pattern resist for the circuit pattern is formed on the replacement silver plating layer formed on the silver particle layer (M1) in step 5 above.

In step 6, the process of forming the patterned resist, the surface of the silver particle layer (M1) or the replacement silver plating layer may undergo surface treatments such as cleaning with acidic or alkaline cleaning solutions, corona treatment, plasma treatment, UV treatment, gas phase ozone treatment, liquid phase ozone treatment, or treatment with surface treatment agents before forming the resist, in order to improve the adhesion to the resist layer. These surface treatments may be performed using one method or two or more methods in combination.

As for the aforementioned treatment using surface treatment agents, for example, the following methods can be used: the method described in Japanese Patent Application Publication No. 7-258870, which uses a rust inhibitor composed of a triazole compound, a silane coupling agent, and an organic acid; and the method described in Japanese Patent Application Publication No. 2000-286546, which uses an organic acid, a benzotriazole rust inhibitor, and a silane coupling agent. Methods of treatment; the method of treatment using a substance with the following structure as described in Japanese Patent Application Publication No. 2002-363189, wherein the structure is formed by bonding a nitrogen-containing heterocyclic ring such as triazole or thiadiazole with a silicon group such as trimethoxysilyl or triethoxysilyl through an organic group having a sulfide bond; the method of treatment using a substance with the following structure as described in Japanese Patent Application Publication No. WO2013/186941. Methods for treatment using silane compounds having triazole rings and amino groups; methods for treatment using imidazole silane compounds obtained by reacting formylimidazole compounds with aminopropylsilane compounds, as disclosed in Japanese Patent Application Publication No. 2015-214743; methods for treatment using azole silane compounds, as disclosed in Japanese Patent Application Publication No. 2016-134454; methods for treatment using an aromatic compound having an amino group and an aromatic ring in one molecule, a polyacid having two or more carboxyl groups, and a solution containing halide ions, as disclosed in Japanese Patent Application Publication No. 2017-203073; methods for treatment using a surface treatment agent containing triazole silane compounds, as disclosed in Japanese Patent Application Publication No. 2018-16865, etc.

In the manufacturing method of the printed circuit board of this invention, in order to form a metallic pattern on the surface, the photosensitive resist is exposed to the pattern using a photomask or a direct exposure machine with active light. The exposure amount can be set appropriately as needed. A developing solution is used to remove the latent image formed on the photosensitive resist by exposure, thereby forming the patterned resist.

Examples of the aforementioned developing solution include 0.3 to 2% by mass of a dilute alkaline aqueous solution such as sodium carbonate or potassium carbonate. Surfactants, defoamers, or small amounts of organic solvents may be added to the aforementioned dilute alkaline aqueous solution to promote development. Furthermore, by immersing the exposed substrate in the developing solution, or by spraying the developing solution onto the resist using a sprayer, development is performed, thereby forming a pattern resist where the pattern formation area has been removed.

When forming patterned anti-corrosion agents, plasma-based descaling treatment or commercially available anti-corrosion residue removers can be used to remove anti-corrosion residues such as flared edges or anti-corrosion adhesions on the substrate surface at the interface between the hardened anti-corrosion agent and the substrate.

As the photosensitive anti-corrosion agent used in this invention, commercially available anti-corrosion inks, liquid anti-corrosion agents, and dry film anti-corrosion agents can be used. The appropriate choice can be made according to the resolution of the target pattern, the type of exposure machine used, the type of chemical solution used in the subsequent coating process, pH value, etc.

Commercially available corrosion-resistant inks include, for example, those manufactured by Sun Ink Co., Ltd., such as "Coating Corrosion Resist MA-830" and "Etching Corrosion Resist X-87"; etching and coating corrosion resists from NAZDAR Corporation; and "Etching Corrosion Resist PLAS FINE PER" series and "Coating Corrosion Resist PLAS FINE PPR" series from Interactive Chemical Industries Co., Ltd. Furthermore, as electrodeposition corrosion resists, examples include those from Dow Chemical Company, such as the "Eagle Series" and "Pepper Series". Furthermore, commercially available dry films include, for example, the "Photec" series manufactured by Hitachi Chemical Co., Ltd.; the "ALPHO" series manufactured by Nikko-Materials Co., Ltd.; the "Sunfort" series manufactured by Asahi Kasei Corporation; and the "Riston" series manufactured by DuPont.

For efficient manufacturing of printed circuit boards, dry film corrosion inhibitors are more convenient, especially when forming micro-circuits, where semi-additive dry films are sufficient. Commercially available dry films for this purpose include: Nikko Materials Co., Ltd.'s "ALFO LDF500" and "NIT2700"; Asahi Kasei Corporation's "Sunfort UFG-258"; Hitachi Chemical Co., Ltd.'s "RD series (RD-2015, 1225)" and "RY series (RY-5319, 5325)"; and DuPont's "PlateMaster series (PM200, 300)".

In order to form a circuit pattern on the substrate in the manufacturing process of the printed circuit board of the present invention, the conductive silver particle layer (M1) or the replacement silver plating layer formed on the conductive silver particle layer (M1) is used as the cathode of the electroplated copper layer. Electroplating is performed on the silver particle layer (M1) or the replacement silver plating layer exposed by development as described above. This allows the through-holes of the multilayer to be connected by copper plating, and simultaneously forms a conductive layer (M4) for the circuit pattern. (Step 6 of the printed circuit board manufacturing method of the present invention)

Before forming the conductive layer (M4) by the aforementioned electroplating copper method, surface treatment may be performed on the surface of the silver particle layer (M1) or the replacement silver plating layer formed on the conductive silver particle layer (M1), as needed. Examples of such surface treatment, provided that the surface of the silver particle layer (M1) or the conductive silver particle layer (M1) or the formed resist pattern is not damaged, include: cleaning with acidic or alkaline cleaning solutions, corona treatment, plasma treatment, UV treatment, gas phase ozone treatment, liquid phase ozone treatment, and treatment using surface treatment agents. These surface treatments may be performed using one method or two or more methods simultaneously.

When forming a conductive layer (M4) with a circuit pattern on an insulating substrate using the semi-additive process of this invention, annealing can be performed after coating to alleviate the stress of the coating or improve the adhesion. Annealing can be performed before, after, or both before and after the etching steps described below.

The annealing temperature can be appropriately selected within the range of 40–300°C, depending on the heat resistance of the substrate or the intended use, but is preferably within the range of 40–250°C. For the purpose of inhibiting oxidative degradation of the coating, a range of 40–200°C is even more preferable. Furthermore, when annealing at temperatures between 40 and 200°C, the annealing time is preferably 10 minutes to 10 days. If annealing is performed at temperatures exceeding 200°C, the preferred time is approximately 5 minutes to 10 hours. Additionally, a rust inhibitor can be appropriately applied to the surface of the coating during annealing.

In step 7 of the method for manufacturing the printed circuit board of the present invention, after the conductive layer (M4) is formed by plating in step 6 above, the pattern resist formed using the above-mentioned photosensitive resist is peeled off, and the silver particle layer (M1) in the non-patterned area or the silver particle layer (M1) in the non-patterned area is removed and the silver plating layer is replaced using an etching solution. Regarding the peeling of the pattern resist, it can be carried out as recommended in the catalog, instruction manual, etc. of the photosensitive resist used. Furthermore, the corrosion stripping solution used as a patterned corrosion inhibitor can be a commercially available corrosion inhibitor stripping solution, or a 1.5-3% by mass aqueous solution of sodium hydroxide or potassium hydroxide set at 45-60°C. The corrosion inhibitor can be stripped by immersing the substrate with the conductive layer (M4) formed on it in the stripping solution; or by spraying the stripping solution using a sprayer or similar device.

Furthermore, the etching solution used when removing the silver particle layer (M1) and the replacement silver plating layer (excluding the pattern formation area) is preferably one that selectively etches only the silver particle layer (M1) and the replacement silver plating layer, without etching the copper forming the conductive layer (M4). A mixture of carboxylic acid and hydrogen peroxide can be used as an example of such an etching solution.

Examples of the aforementioned carboxylic acids include, for instance: acetic acid, formic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, pearlitic acid, stearic acid, oleic acid, linolenic acid, hypolinolenic acid, arachidic acid, eicosapentaenoic acid, docosahexaenoic acid, oxalic acid, malonic acid, succinic acid, benzoic acid, salicylic acid, phthalic acid, isophthalic acid, terephthalic acid, gallic acid, hexacarboxylic acid, cinnamic acid, pyruvic acid, lactic acid, malic acid, citric acid, fumaric acid, maleic acid, aconitic acid, glutaric acid, adipic acid, and amino acids. One or more of these carboxylic acids may be used. Considering the ease of manufacturing and using self-etching solutions among these carboxylic acids, acetic acid is preferred as the primary component.

It is believed that if a mixture of carboxylic acid and hydrogen peroxide is used as the etching solution, the hydrogen peroxide reacts with the carboxylic acid to generate peroxycarboxylic acid. It is speculated that the generated peroxycarboxylic acid inhibits the dissolution of copper constituting the conductive layer (M3) and preferentially dissolves silver constituting the silver particle layer (M1).

Regarding the mixing ratio of the aforementioned carboxylic acid and hydrogen peroxide, in order to suppress the dissolution of the copper conductive layer (M4), the hydrogen peroxide is preferably in the range of 2 to 100 moles relative to 1 mole of carboxylic acid, and more preferably in the range of 2 to 50 moles of hydrogen peroxide.

The mixture of the aforementioned carboxylic acid and hydrogen peroxide is preferably an aqueous solution obtained by diluting with water. Furthermore, the content ratio of the mixture of the aforementioned carboxylic acid and hydrogen peroxide in the aforementioned aqueous solution is preferably in the range of 2 to 65% by mass, and more preferably in the range of 2 to 30% by mass, in order to suppress the effect of the etching solution temperature rise.

The water used for dilution is preferably ionized water, pure water, ultrapure water, or water with impurities removed.

In the etching solution described above, a protective agent can be added to protect the copper conductive layer (M4) and inhibit its dissolution. Preferably, an azole compound is used as the protective agent.

Examples of the aforementioned azole compounds include imidazole, pyrazole, triazole, tetraazole, succinazole, thiazole, selenazole, diazole, thiadiazole, triazole, and thiatriazole.

Specific examples of the aforementioned azole compounds include: 2-methylbenzimidazole, aminotriazole, 1,2,3-benzotriazole, 4-aminobenzotriazole, 1-diaminomethylbenzotriazole, aminotetrazole, phenyltetrazole, 2-phenylthiazole, benzothiazole, etc. One or more of these azole compounds may be used.

The concentration of the above-mentioned azole compound in the etching solution is preferably in the range of 0.001 to 2% by mass, and more preferably in the range of 0.01 to 0.2% by mass.

Furthermore, in the etching solution described above, it is preferable to add polyalkylene glycol as a protective agent to suppress the dissolution of the copper conductive layer (M4).

Examples of the aforementioned polyalkylene glycols include water-soluble polymers such as polyethylene glycol, polypropylene glycol, and polyoxyethylene-polyoxypropylene block copolymers. Polyethylene glycol is preferred. Furthermore, the number average molecular weight of the polyalkylene glycol is preferably in the range of 200 to 20,000.

The concentration of the aforementioned polyalkylene glycol in the etching solution is preferably in the range of 0.001 to 2% by mass, and more preferably in the range of 0.01 to 1% by mass.

In the above etching solution, additives such as sodium salts, potassium salts, and ammonium salts of organic acids can be added as needed to suppress pH fluctuations.

In the manufacturing method of the printed circuit board of the present invention, the removal of the silver particle layer (M1) and the replacement silver plating layer in the non-pattern forming part can be carried out by the following methods: after forming the above-mentioned conductive layer (M4), the pattern resist formed by the above-mentioned photosensitive resist is peeled off, and the substrate after peeling is immersed in the above-mentioned etching solution; or the etching solution is sprayed onto the above-mentioned substrate using a sprayer or the like.

When using an etching apparatus to remove the silver particle layer (M1) of the non-patterned area and replace the silver plating layer, for example, all the components of the etching solution can be prepared in a specific composition and then supplied to the etching apparatus; or the components of the etching solution can be supplied to the etching apparatus separately and mixed in the apparatus to prepare a specific composition.

The above-mentioned etching solution is preferably used in a temperature range of 10 to 35°C. In particular, when using an etching solution containing hydrogen peroxide, it is preferable to use it in a temperature range below 30°C to suppress the decomposition of hydrogen peroxide.

After removing the silver particle layer (M1) using the aforementioned etching solution, a cleaning operation can be performed in addition to water rinsing to prevent the silver component dissolved in the etching solution from adhering and remaining on the printed circuit board. During the cleaning operation, it is preferable to use a cleaning solution that dissolves silver oxide, silver sulfide, and silver chloride, but hardly dissolves silver. Specifically, it is preferable to use an aqueous solution containing thiosulfate or tris(3-hydroxyalkyl)phosphine, or an aqueous solution containing hydroxycarboxylic acid or its salt.

Examples of the aforementioned thiosulfates include ammonium thiosulfate, sodium thiosulfate, and potassium thiosulfate. Examples of the aforementioned trisodium (3-hydroxyalkyl)phosphine include trisodium (3-hydroxymethyl)phosphine, trisodium (3-hydroxyethyl)phosphine, and trisodium (3-hydroxypropyl)phosphine. One or more of these thiosulfates or trisodium (3-hydroxyalkyl)phosphine may be used.

When using an aqueous solution containing thiosulfate, the concentration can be set appropriately according to the step time and the characteristics of the cleaning device used, but it is preferably in the range of 0.1% to 40% by mass. From the perspective of cleaning efficiency or the stability of the solution during continuous use, it is even more preferably in the range of 1% to 30% by mass.

Furthermore, when using an aqueous solution containing the aforementioned tris(3-hydroxyalkyl)phosphine, the concentration can be set appropriately according to the step time and the characteristics of the cleaning device used, but it is preferably in the range of 0.1% to 50% by mass. From the viewpoint of cleaning efficiency or the stability of the solution during continuous use, it is even more preferably in the range of 1% to 40% by mass.

Examples of the aforementioned hydroxycarboxylic acids include thioglycolic acid, 2-hydroxypropionic acid, 3-hydroxypropionic acid, thiomalic acid, cysteine, and N-acetylglucosamine. Examples of salts of the aforementioned hydroxycarboxylic acids include alkali metal salts, ammonium salts, and amine salts.

When using an aqueous solution of hydroxycarboxylic acid or its salt, the concentration is preferably in the range of 0.1% to 20% by mass, and more preferably in the range of 0.5% to 15% by mass from the viewpoint of cleaning efficiency or process cost when performing large-scale processing.

As a method for performing the above-mentioned cleaning operation, examples include: immersing the printed circuit board obtained after etching and removing the silver particle layer (M1) of the non-pattern forming part in the above-mentioned cleaning solution, or spraying the cleaning solution onto the printed circuit board using a sprayer, etc. Regarding the temperature of the cleaning solution, it can be used at room temperature (25°C), but in order to ensure stable cleaning without being affected by outdoor temperature, the temperature can also be set to 30°C, for example.

Furthermore, the steps of removing the silver particle layer (M1) of the non-patterned area using etching solution and the cleaning operation can be repeated as needed.

As described above, the printed circuit board of this invention, after removing the silver particle layer (M1) and the replacement silver plating layer of the non-pattern forming area using the aforementioned etching solution, can be further cleaned as needed to improve the insulation of the non-pattern forming area. In this cleaning operation, for example, an alkaline permanganate solution obtained by dissolving potassium permanganate or sodium permanganate in an aqueous solution of potassium hydroxide or sodium hydroxide can be used.

Regarding cleaning using the aforementioned alkaline permanganate solution, examples include: immersing the printed circuit board obtained by the above method in an alkaline permanganate solution set at 20-60°C; and spraying the alkaline permanganate solution onto the printed circuit board using a sprayer. The printed circuit board can be treated by contacting it with a water-soluble organic solvent containing an alcoholic hydroxyl group before cleaning to improve the wetting properties of the alkaline permanganate solution on the substrate surface and increase cleaning efficiency. Examples of such organic solvents include methanol, ethanol, n-propanol, and isopropanol. One or more of these organic solvents can be used.

The concentration of the above-mentioned alkaline permanganate solution can be selected appropriately as needed, but it is preferable to obtain it by dissolving 0.1 to 10 parts by mass of potassium permanganate or sodium permanganate in 100 parts by mass of 0.1 to 10% by mass of potassium hydroxide or sodium hydroxide aqueous solution. From the point of view of cleaning efficiency, it is even more preferable to obtain it by dissolving 1 to 6 parts by mass of potassium permanganate or sodium permanganate in 100 parts by mass of 1 to 6% by mass of potassium hydroxide or sodium hydroxide aqueous solution.

When performing the above-mentioned cleaning with alkaline permanganate solution, it is preferable to treat the cleaned printed circuit board with a neutralizing and reducing liquid after cleaning with the alkaline permanganate solution. Examples of such neutralizing and reducing liquids include 0.5-15% by mass dilute sulfuric acid or aqueous solutions containing organic acids. Examples of such organic acids include formic acid, acetic acid, oxalic acid, citric acid, ascorbic acid, and methionine.

The cleaning with alkaline permanganate solution described above can be performed after the cleaning to prevent the silver component dissolved in the etching solution from adhering to and remaining on the printed circuit board, or the cleaning with alkaline permanganate solution can be performed instead of the cleaning to prevent the silver component dissolved in the etching solution from adhering to and remaining on the printed circuit board.

Furthermore, for the printed wiring board obtained by the manufacturing method of the present invention, nickel/gold plating, nickel/palladium/gold plating, and palladium/gold plating can be applied as appropriate as needed as a means of depositing a cover film on the circuit pattern, forming a solder resist layer, and the final surface treatment of the circuit pattern.

The printed circuit board manufacturing method of this invention, as described above, allows for the fabrication of substrates with high adhesion, good design reproducibility, and smooth surface circuit patterns with a good rectangular cross-section on various smooth substrates without the use of vacuum equipment. Therefore, by using the semi-additive laminar flow method of this invention, various shapes, high-density sizes, and high-performance printed circuit board substrates and printed circuit boards can be provided at low cost, making it highly applicable in the printed circuit board industry. Furthermore, by using laminar flow methods, not only printed circuit boards can be manufactured, but also various components with patterned metal layers on the surface of planar substrates, such as connectors, electromagnetic wave shielding, RFID antennas, and membrane capacitors. [Example]

The invention will now be explained in detail through examples.

[Manufacturing Example 1: Manufacturing of Primer (B-1)] In a nitrogen-exchanged container equipped with a thermometer, a nitrogen inlet tube, and a stirrer, 100 parts by weight of polyester polyol (a polyester polyol obtained by reacting 1,4-cyclohexanediethanol, neopentyl glycol, and adipic acid), 17.6 parts by weight of 2,2-dihydroxymethylpropionic acid, 21.7 parts by weight of 1,4-cyclohexanediethanol, and 106.2 parts by weight of dicyclohexylmethane-4,4'-diisocyanate were reacted in a mixed solvent of 178 parts by weight of methyl ethyl ketone to obtain an amine ester prepolymer solution with isocyanate groups at the end.

Subsequently, 13.3 parts by weight of triethylamine were added to the above amine ester prepolymer solution to neutralize the carboxyl groups present in the above amine ester prepolymer. Then, 380 parts by weight of water were added and stirred thoroughly to obtain an aqueous dispersion of the amine ester prepolymer.

Add 8.8 parts by weight of 25% ethylenediamine aqueous solution to the aqueous dispersion of the obtained amine ester prepolymer and stir to elongate the amine ester prepolymer chain. Then, allow it to mature and be desolventized to obtain an aqueous dispersion of the amine ester resin (30% by weight of non-volatile matter). The weight average molecular weight of the above amine ester resin is 53,000.

Next, 140 parts by mass of deionized water and 100 parts by mass of the aqueous dispersion of the obtained amine ester resin were added to a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet, a thermometer, a dropping funnel for adding the monomer mixture, and a dropping funnel for adding the polymerization catalyst. Nitrogen was blown in and the temperature was simultaneously raised to 80°C. Subsequently, stirring was performed, and while maintaining the temperature inside the reaction vessel at 80°C, a monomer mixture consisting of 60 parts by mass of methyl methacrylate, 30 parts by mass of n-butyl acrylate, and 10 parts by mass of N-n-butoxymethacrylamide, along with 20 parts by mass of a 0.5% ammonium persulfate aqueous solution, were added dropwise from the separated dropping funnel over a period of 120 minutes.

After the dropwise addition was completed, the mixture was stirred at the current temperature for 60 minutes. Then, the temperature inside the reaction vessel was cooled to 40°C. The mixture was diluted with deionized water to a non-volatile fraction of 20% by mass, and then filtered through a 200-mesh filter cloth to obtain an aqueous dispersion of a core-shell composite resin, i.e., a primer resin composition, with the aforementioned amine ester resin as the shell layer and an acrylic resin using methyl methacrylate as a raw material as the core layer. Next, isopropanol and deionized water were added to this aqueous dispersion at a mass ratio of 7/3 (isopropanol to water) and a non-volatile fraction of 2% by mass, and mixed to obtain the primer (B-1).

[Manufacturing Example 2: Manufacturing of Primer (B-2)] 600 parts by mass of formalin containing 37% by mass formaldehyde and 7% by mass methanol, 200 parts by mass of water, and 350 parts by mass of methanol were added to a reaction flask equipped with a reflux cooler, thermometer, and stirrer. Then, 25% by mass sodium hydroxide aqueous solution was added to the aqueous solution, and the pH was adjusted to 10. Next, 310 parts by mass of melamine were added, and the liquid temperature was raised to 85°C for a hydroxymethylation reaction for 1 hour.

Subsequently, formic acid was added and the pH was adjusted to 7, then cooled to 60°C to allow for etherification (secondary reaction). A 25% (w/w) sodium hydroxide aqueous solution was added at a cloudy temperature of 40°C and the pH was adjusted to 9, stopping the etherification reaction (reaction time: 1 hour). Residual methanol was removed under reduced pressure at 50°C (methanol removal time: 4 hours) to obtain a primer resin composition containing melamine resin with 80% (w/w) non-volatile matter. Then, methyl ethyl ketone was added to this resin composition for dilution and mixing, thereby obtaining a primer (B-2) with 2% (w/w) non-volatile matter.

[Example 3: Preparation of Primer (B-3)] 9.2 parts by mass of 2,2-dihydroxymethylpropionic acid, 57.4 parts by mass of polymethylene polyphenyl polyisocyanate (Millionate MR-200 manufactured by Tosoh Corporation), and 233 parts by mass of methyl ethyl ketone were added to a reaction vessel equipped with a thermometer, nitrogen inlet, stirrer, and nitrogen exchange. The reaction was carried out at 70°C for 6 hours to obtain an isocyanate compound. Then, 26.4 parts by mass of phenol were supplied to the reaction vessel as a capping agent, and the reaction was carried out at 70°C for 6 hours. Afterward, the reaction was cooled to 40°C to obtain a solution of capped isocyanate.

Next, 7 parts by mass of triethylamine were added to the obtained solution of the capped isocyanate at 40°C to neutralize the carboxyl groups of the capped isocyanate. Water was added and the mixture was stirred thoroughly. The methyl ethyl ketone was then removed by distillation to obtain a primer resin composition containing capped isocyanate and water with 20% by mass of nonvolatile matter. Then, methyl ethyl ketone was added to the resin composition for dilution and mixing to obtain a primer (B-3) with 2% by mass of nonvolatile matter.

[Manufacturing Example 4: Manufacturing of Primer (B-4)] 35 parts by weight of phenolic varnish resin (PHENOLITE TD-2131 manufactured by DIC Corporation, hydroxyl equivalent 104 g/equivalent), 64 parts by weight of epoxy resin (EPICLON 850-S manufactured by DIC Corporation; bisphenol A type epoxy resin, epoxy equivalent 188 g/equivalent), and 1 part by weight of 2,4-diamino-6-vinyl symmetric tri(VT manufactured by Shikoku Chemical Co., Ltd.) were mixed and then diluted with methyl ethyl ketone to a nonvolatile fraction of 2% by weight to obtain primer (B-4).

[Manufacturing Example 5: Manufacturing of Primer (B-5)] 35 parts by weight of phenolic varnish resin (PHENOLITE TD-2131 manufactured by DIC Corporation, hydroxyl equivalent 104 g/equivalent), 64 parts by weight of epoxy resin (EPICLON 850-S manufactured by DIC Corporation; bisphenol A type epoxy resin, epoxy equivalent 188 g/equivalent), and 1 part by weight of silane coupling agent with tricyclic ring (VD-5 manufactured by Shikoku Chemical Co., Ltd.) were mixed and then diluted with methyl ethyl ketone to a nonvolatile fraction of 2% by weight to obtain primer (B-5).

[Example 6: Preparation of Primer (B-6)] 750 parts by weight of phenol, 75 parts by weight of melamine, 346 parts by weight of 41.5% formalin, and 1.5 parts by weight of triethylamine were added to a flask equipped with a thermometer, condenser, fractionating column, and stirrer. The mixture was heated to 100°C while being careful to prevent exothermic reactions. After reacting at 100°C under reflux for 2 hours, water was removed under normal pressure while the temperature was raised to 180°C for 2 hours. Unreacted phenol was then removed under reduced pressure to obtain an aminotrimethylphenolic varnish resin. The hydroxyl equivalent was 120 g/equivalent. The above-obtained aminotriphenolic varnish resin (65 parts by weight) and epoxy resin ("EPICLON 850-S" manufactured by DIC Corporation; bisphenol A type epoxy resin, epoxy equivalent 188 g/equivalent) were mixed together and then diluted with methyl ethyl ketone to a nonvolatile fraction of 2% by weight to obtain the primer composition (B-6).

[Manufacturing Example 7: Manufacturing of Primer (B-7)] 48 parts by weight of aminotriphenolic varnish resin obtained in Manufacturing Example 6 and 52 parts by weight of epoxy resin ("EPICLON 850-S" manufactured by DIC Co., Ltd.; bisphenol A type epoxy resin, epoxy equivalent 188 g/equivalent) were mixed and then diluted with methyl ethyl ketone to a nonvolatile fraction of 2% by weight to obtain primer composition (B-7).

[Manufacturing Example 8: Manufacturing of Primer (B-8)] The amounts of aminotriphenolic varnish resin and epoxy resin were changed from 48 parts by weight to 39 parts by weight and from 52 parts by weight to 61 parts by weight, respectively. Otherwise, a primer composition (B-8) with 2% by weight of nonvolatile matter was obtained in the same manner as in Manufacturing Example 7.

[Manufacturing Example 9: Manufacturing of Primer (B-9)] The amounts of aminotrimethylphenolic varnish resin and epoxy resin were changed from 48 parts by weight to 31 parts by weight and from 52 parts by weight to 69 parts by weight, respectively. Otherwise, a primer composition (B-9) with 2% by weight of nonvolatile matter was obtained in the same manner as in Manufacturing Example 8.

[Manufacturing Example 10: Manufacturing of Primer (B-10)] 47 parts by weight of the aminotrimethylphenolic varnish resin obtained in Manufacturing Example 7, 52 parts by weight of epoxy resin ("EPICLON 850-S" manufactured by DIC Co., Ltd.; bisphenol A type epoxy resin, epoxy equivalent 188 g/equivalent), and 1 part by weight of 1,2,4-benzenetricarboxylic anhydride were mixed and then diluted with methyl ethyl ketone to a nonvolatile fraction of 2% by weight to obtain primer (B-10).

[Manufacturing Example 11: Manufacturing of Primer (B-11)] Add 350 parts by weight of deionized water and 4 parts by weight of surfactant ("Latemul E-118B" manufactured by Kao Corporation: 25% by weight of active ingredient) to a reaction vessel equipped with a mixer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel. Nitrogen is blown in and the temperature is raised to 70°C at the same time.

Under stirring, a portion (5 parts by weight) of the monomer preemulsion obtained below was added to the reaction vessel. The monomer preemulsion was obtained by mixing a mixture of vinyl monomers consisting of 47.0 parts by weight of methyl methacrylate, 5.0 parts by weight of glycidyl methacrylate, 45.0 parts by weight of n-butyl acrylate, and 3.0 parts by weight of methacrylic acid, 4 parts by weight of surfactant ("Aqualon KH-1025" manufactured by First Industrial Pharmaceutical Co., Ltd.: 25% by weight of active ingredient), and 15 parts by weight of deionized water. Then, 0.1 parts by weight of potassium persulfate was added, and polymerization was carried out for 60 minutes while maintaining the temperature inside the reaction vessel at 70°C.

Next, while maintaining the temperature inside the reaction vessel at 70°C, the remaining monomer preemulsion (114 parts by mass) and 30 parts by mass of an aqueous solution of potassium persulfate (1.0% by mass of active ingredient) were added dropwise over 180 minutes using different dropping funnels. After the addition was completed, the mixture was stirred at the current temperature for 60 minutes.

The temperature inside the reaction vessel was cooled to 40°C, and then deionized water was used to obtain a nonvolatile content of 10.0% by mass. The mixture was then filtered through a 200-mesh filter cloth to obtain the primer resin composition used in this invention. Water was then added to the resin composition for dilution and mixing to obtain a primer (B-11) with a nonvolatile content of 5% by mass.

[Preparation Example 1: Preparation of Silver Particle Dispersion] A compound formed by the addition of p-ethylenediamine to polyethylene oxide was used as a dispersant to disperse silver particles with an average particle size of 30 nm in a mixed solvent of 45 parts by mass of ethylene glycol and 55 parts by mass of ion-exchanged water, thereby preparing a dispersion containing silver particles and a dispersant. Subsequently, ion-exchanged water, ethanol, and a surfactant were added to the obtained dispersion to prepare a 5% by mass silver particle dispersion.

[Preparation Example 2: Preparation of Copper Etching Solution] A copper etching solution was prepared by mixing sulfuric acid (37.5 g/L) and hydrogen peroxide (13.5 g/L) in ion-exchanged water.

Based on the patent document Japanese Patent Application Publication No. 2000-309875, electroless silver plating baths of preparation examples (3) to (5) were prepared.

[Preparation Example 3: Preparation of Electroless Silver Plating Bath (1)] Silver methanesulfonate 10 g/l (as silver), methanesulfonic acid 100 g/l, 1,4-bis(2-hydroxyethylthio)ethane 25 g/l, pH 0.5, bath temperature 40℃

[Preparation Example 4: Preparation of Electroless Silver Plating Bath (2)] Silver nitrate 5 g/l (as silver), 1,4-bis(2-hydroxyethylthio)butane 40 g/l, 2,2'-(epylethyldithio)diethanethiol 90 g/l, pH 3.0 (adjusted using dilute nitric acid), bath temperature 25℃

[Preparation Example 5: Preparation of Electroless Silver Plating Bath (3)] Silver oxide 1 g/l (as silver), p-toluenesulfonic acid 30 g/l, tartaric acid 50 g/l, 2,2’-(ephedrin-2,2’-dithio)diethylthiol 45 g/l, thiourea 20 g/l, β-naphthol polyoxyethylene ether (EO15) 5 g/l, pH 6.5 (adjusted using NaOH), bath temperature 70℃

[Preparation Example 6: Preparation of Silver Etching Solution] 2.6 parts by mass of acetic acid were added to 47.4 parts by mass of water, and then 50 parts by mass of 35% hydrogen peroxide solution were added to prepare silver etching solution (1). The molar ratio of hydrogen peroxide to carboxylic acid (hydrogen peroxide/carboxylic acid) in the silver etching solution (1) was 13.6, and the content ratio of the mixture of hydrogen peroxide and carboxylic acid in the silver etching solution (1) was 22.4 by mass.

(Example 1) (Step 1) On the surface of a polyimide film ("Kapton 100EN-C" manufactured by Toray DuPont, Inc.; thickness 25 μm) serving as the insulating substrate, a desktop small coating machine ("K Printing Proofer" manufactured by RK Print Coat Instruments) was used to coat the silver particle dispersion obtained in Preparation Example 1 with a dried silver particle layer of 0.5 g/ ^m² . Then, it was dried in a hot air dryer at 160°C for 5 minutes. Next, the membrane was flipped over, and the silver particle dispersion obtained in Preparation Example 1 was coated with a silver particle layer of 0.5 g/ ^m² in the same manner as described above. The coating was then dried in a hot air dryer at 160°C for 5 minutes, thereby forming a silver particle layer on both surfaces of the polyimide membrane. The resulting membrane substrate was then calcined at 250°C for 5 minutes, and the conductivity of the silver particle layer was confirmed using a testing machine.

The polyimide film with conductive silver particle layers on both surfaces, obtained above, was fixed to a polyethylene frame and immersed in an electroless copper plating solution (Circuposit 6550 manufactured by Rohm and Haas Electronic Materials Co., Ltd.) at 35°C for 10 minutes to form an electroless copper plating film (M2; thickness 0.2 μm) on both surfaces. Subsequently, a 100 μm diameter through-hole was formed at the connection position of the solid ground (GND) on the back side of the transmission characteristic evaluation terminal of a 100 mm long, 50 Ω microstrip line using a drill bit.

(Step 2: Applying palladium catalyst to the pores) Dilute the electroless plating prepreg ("OPC-SAL-M", manufactured by Okuno Pharmaceutical Co., Ltd.) with water at a ratio of 260 g/L and maintain at 25°C. Immerse the membrane with the pores formed above in the liquid for 1 minute.

The pre-impregnation solution (OPC-SAL-M, manufactured by Okuno Pharmaceutical Co., Ltd.) and Sn-Pd colloidal catalyst (OPC-90 Catalyst, manufactured by Okuno Pharmaceutical Co., Ltd.) were diluted with water at a ratio of 260 g/L and 30 mL/L, respectively, and the solution was maintained at 25°C. The substrate to be coated after the above pre-impregnation step was immersed in the diluted solution for 5 minutes, followed by rinsing with running water for 2 minutes.

The activation solution ("OPC-505 Accelerator A", manufactured by Okuno Pharmaceutical Co., Ltd.) and the activation solution ("OPC-505 Accelerator B", manufactured by Okuno Pharmaceutical Co., Ltd.) were diluted with water to a concentration of 100 mL/L and 8 mL/L respectively, and the mixture was kept at 30°C. The substrate to be coated after the above-mentioned catalyst compound application step was immersed in the mixed diluted solution for 5 minutes, followed by rinsing with running water for 2 minutes, thereby applying palladium catalyst to the inner wall of the through-hole and the two copper surfaces.

(Step 3) The copper in the film obtained above is removed by using the sulfuric acid/hydrogen peroxide copper etching solution prepared in Preparation Example 2, so as to expose the conductive silver particle layer (M1).

(Step 4: Electroless Copper Plating) The film substrate thus obtained is immersed in an electroless copper plating solution (Circuposit 6550 manufactured by Rohm and Haas Electronic Materials Co., Ltd.) at 35°C for 25 minutes to form an electroless copper plating layer (0.5 μm thick) on the conductive silver particle layer (M1) on the inner wall of the through hole and on both surfaces.

(Step 5: Electroless replacement silver plating) Set the electroless silver plating solution prepared in Preparation Example 3 to 40°C, shake the film prepared above, and immerse it in the electroless silver plating solution for 3 minutes to replace the copper plating layer formed on the inner wall of the through hole and the silver particle layer (M1) to form a silver plating layer (M3).

(Step 6) On the silver-plated layer (M1) thus obtained, a dry film anti-corrosion agent (Photec RD-1225 manufactured by Hitachi Chemical Co., Ltd.; anti-corrosion agent film thickness 25 μm) is laminated at 100°C using a laminator. Then, a direct exposure digital imaging device (Nuvogo1000R manufactured by Orbotech Co., Ltd.) is used to expose the microstrip line pattern with a wiring length of 100 mm and an impedance of 50 Ω, as well as the terminal pad pattern of the through hole for connecting the probe to GND, on the anti-corrosion agent. Next, a 1% sodium carbonate aqueous solution was used for development, thereby forming a microstrip pattern and a pattern of anti-corrosion agent on the silver plating layer (M3) where the probe terminal pads had been removed, exposing the silver particle layer (M1) on the polyimide film.

(Step 7) Next, the silver plating layer (M3) of the substrate with the patterned corrosion inhibitor is placed on the cathode, and phosphorus copper is used as the anode. Electroplating is performed for 41 minutes at a current density of 2 A/dm² using an electroplating solution containing copper sulfate (copper sulfate 60 g/L, sulfuric acid 190 g/L, chloride ions 50 mg/L, additive "Copper Gleam ST-901 manufactured by Rohm and ^Haas Electronic Materials Co., Ltd."). In this way, a circuit pattern layer (M4) with a thickness of 18 μm is formed on the microstrip pattern and probe terminal pad where the corrosion inhibitor has been removed by electroplating copper. Next, the film with the copper metal pattern is immersed in a 3% sodium hydroxide aqueous solution at 50°C to peel off the patterned anti-corrosion agent.

(Step 8) Next, the film obtained above is immersed in the silver etching agent obtained in Preparation Example 3 at 25°C for 30 seconds to remove the silver plating layer (M3) and the silver particle layer (M1) other than the circuit pattern, thereby obtaining a printed circuit board. Regarding the cross-sectional shape of the circuit forming part (microstrip line and probe terminal part) of the printed circuit board, the wiring height and wiring width are not reduced, and it presents a rectangular shape without undercut, which is a circuit pattern layer (M4) with a smooth surface.

(Example 2) In step 1, the immersion time in electroless copper plating solution is changed from 10 minutes to 25 minutes to create a laminate with a 0.5 μm copper layer on both surfaces of the insulating substrate (A), forming a through hole that penetrates both surfaces. Then, steps 2 to 8 are performed in the same manner as in Example 1 to obtain a printed wiring board. Regarding the cross-sectional shape of the circuit forming part (microstrip line and probe terminal part) of the printed wiring board, the wiring height and wiring width are not reduced, and it presents a rectangular shape without undercut, which is a circuit pattern layer (M4) with a smooth surface.

(Example 3) Except that the dried silver particle layer was changed from 0.5 g/m ² to 0.8 g/m ² , the silver particle layer was formed on both surfaces of the polyimide film in the same manner as in Example 1, and then baked at 250°C for 5 minutes. The conductivity of the silver particle layer was confirmed by a testing machine. The polyimide film with conductive silver particle layers on both surfaces, obtained in this way, is fixed to a copper frame. The surface of the silver particle layer is placed at the cathode, and phosphorus-containing copper is used as the anode. Electroplating is performed for 2.5 minutes at a current density of 2 A/ ^dm² using an electroplating solution containing copper sulfate (copper sulfate 60 g/L, sulfuric acid 190 g/L, chloride ions 50 mg/L, additive "Copper Gleam ST-901 manufactured by Rohm and Haas Electronic Materials Co., Ltd."). This creates a silver particle layer (M1) and a 1-layer silver particle layer (M2) on both surfaces of the polyimide film, which serves as the insulating substrate (A). A copper layer (M2) with a thickness of μm is laminated to form through-holes that penetrate both sides. Then, steps 2 to 8 are performed in the same manner as in Example 1 to obtain a printed wiring board. Regarding the cross-sectional shape of the circuit forming parts (microstrip lines and probe terminal parts) of the manufactured printed wiring board, the wiring height and wiring width are not reduced, and it presents a rectangular shape without undercut, which is a circuit pattern layer (M4) with a smooth surface.

(Example 4) On the surface of a polyimide film ("Kapton 100EN-C" manufactured by Toray DuPont, Inc., with a thickness of 25 μm), a desktop small coating machine ("K Printing Proofer" manufactured by RK Print Coat Instruments) was used to coat the primer (B-1) obtained in Manufacturing Example 1 to a thickness of 120 nm after drying. Then, it was dried at 80°C for 5 minutes using a hot air dryer. Subsequently, the film was flipped over, and the primer (B-1) obtained in Manufacturing Example 1 was coated to a thickness of 120 nm after drying using the same method. It was then dried at 80°C for 5 minutes using a hot air dryer, thereby forming a primer layer on both surfaces of the polyimide film.

The insulating substrate (A) is changed from a polyimide film to the polyimide with a primer layer formed on both surfaces of the polyimide film obtained above. Otherwise, a laminate with a primer layer (B-1), a conductive silver particle layer (M1) and a copper layer of 0.5 μm on both surfaces of the insulating substrate (A) is formed in the same manner as in Example 2, forming a through hole that penetrates both surfaces. Then, steps 2 to 8 are performed in the same manner as in Example 2, thereby obtaining a printed wiring board. Regarding the cross-sectional shape of the circuit forming part (microstrip line and probe terminal part) of the printed wiring board, the wiring height and wiring width are not reduced, and it presents a rectangular shape without undercut, which is a circuit pattern layer (M4) with a smooth surface.

(Example 5) In Example 4, the silver particle layer was changed from 0.5 g/ ^m² to 0.8 g/ ^m² , and the plating time was changed from 2.5 minutes to 4.5 minutes. Otherwise, electroplating copper was performed in the same manner as in Example 3, thereby creating a laminate on both surfaces of the polyimide film serving as the insulating substrate (A), which has a base coat (B), a conductive silver particle layer (M1), and a 2 μm thick copper layer (M2). Through-holes were formed through both surfaces. Then, steps 2 to 8 were performed in the same manner as in Example 4, thereby obtaining a printed wiring board. Regarding the cross-sectional shape of the circuit forming part (microstrip line and probe terminal part) of the printed wiring board, the wiring height and wiring width are not reduced, and it presents a rectangular shape without undercut, which is a circuit pattern layer (M4) with a smooth surface.

(Examples 6-8) In Examples 1-3, a 38 μm thick polyester re-peelable adhesive tape (manufactured by Panac Inc., Panaprotect HP/CT) is laminated on the silver particle layer (M1) as a peelable cover layer (RC) instead of forming a copper layer (M2). Otherwise, in the same manner as in Examples 1-3, a conductive silver particle layer (M1) is obtained on both surfaces of the insulating substrate (A), thereby having through holes connecting the two surfaces of the insulating substrate, and the surface of the through holes is a laminate with conductivity ensured by the silver layer. For the laminate, through holes are formed on both sides using a drill bit in the same manner as in Examples 1-3. Then, steps 2 to 8 are performed in the same manner as in Examples 1-3 to obtain a printed wiring board. Regarding the cross-sectional shape of the circuit forming part (microstrip line and probe terminal part) of the printed wiring board, the wiring height and wiring width are not reduced, and it presents a rectangular shape without undercut, which is a circuit pattern layer (M4) with a smooth surface.

(Examples 9 and 10) In Examples 4 and 5, a 38 μm thick polyester re-peelable adhesive tape (manufactured by Panac Corporation, Panaprotect HP/CT) is laminated on the silver particle layer (M1) as a peelable cover layer (RC) instead of forming a copper layer (M2). Otherwise, in the same manner as in Examples 4 and 5, a laminate consisting of a base coat (B), a conductive silver particle layer (M1), and a copper layer (M2) is formed on both surfaces of the insulating substrate (A). For the laminate, through holes are formed on both sides using a drill bit in the same manner as in Embodiments 4 and 5. Then, steps 2 to 8 are performed in the same manner as in Embodiments 4 and 5 to obtain a printed wiring board. Regarding the cross-sectional shape of the circuit forming part (microstrip line and probe terminal part) of the printed wiring board, the wiring height and wiring width are not reduced, and it presents a rectangular shape without undercut, which is a circuit pattern layer (M4) with a smooth surface.

(Examples 11-15) Except for changing the 100 μm diameter through-hole formed by a drill bit to a 70 μm diameter through-hole formed by a laser, steps 1 to 8 are performed in the same manner as in Examples 1-5, thereby obtaining a printed wiring board. Regarding the cross-sectional shape of the circuit forming part (microstrip line and probe terminal part) of the printed wiring board, the wiring height and wiring width are not reduced, and it presents a rectangular shape without undercut, which is a circuit pattern layer (M4) with a smooth surface.

(Examples 16-20) Except for changing the 100 μm diameter through-hole formed by a drill bit to a 70 μm diameter through-hole formed by a laser, steps 1 to 8 are performed in the same manner as in Examples 6-10, thereby obtaining a printed wiring board. Regarding the cross-sectional shape of the circuit forming part (microstrip line and probe terminal part) of the printed wiring board, the wiring height and wiring width are not reduced, and it presents a rectangular shape without undercut, which is a circuit pattern layer (M4) with a smooth surface.

(Examples 21 and 22) In Example 5, the thickness of the electroless copper plating layer formed on the conductive silver particle layer (M1) on both surfaces in step 4 was changed from 0.5 μm to 0.7 μm (Example 21) and 1 μm (Example 22), respectively. The silver plating bath was changed to the plating bath of Preparation Example 4 and Preparation Example 5, respectively. Otherwise, steps 1 to 8 were performed in the same manner as in Example 5, thereby obtaining a printed wiring board. Regarding the cross-sectional shape of the circuit forming part (microstrip line and probe terminal part) of the printed wiring board, the wiring height and wiring width were not reduced, and it presented a rectangular shape without undercut, which was a circuit pattern layer (M4) with a smooth surface.

(Examples 23-39) The type of insulating substrate, the type of primer used for the primer layer and its drying conditions, the amount of silver in the silver particle layer, the type of cover layer of the silver particle layer, the through-hole formation method, the thickness of the copper film to be replaced with silver, and the type of replacement silver plating solution are changed as shown in Table 1 or 2. Otherwise, the printed wiring board is obtained in the same manner as in Examples 1-22. Regarding the cross-sectional shape of the circuit forming part (microstrip line and probe terminal part) of the printed wiring board, the wiring height and wiring width are not reduced, and it presents a rectangular shape without undercut, which is a circuit pattern layer (M4) with a smooth surface.

(Example 40) In Example 5, the electroless copper plating in step 4 is changed to electroless nickel plating. Electroless nickel plating involves immersing the film after step 3 in an electroless nickel plating solution (ICP NiCORON GM (NP) manufactured by Okuno Pharmaceutical Co., Ltd.) set at 80°C for 1.5 minutes, thereby forming an electroless nickel plating layer (0.2 μm thick) on the inner wall of the through-hole. The film thus obtained is then treated for 10 minutes using a replacement silver plating process (DAIN SILVER EL manufactured by Daiwa Chemical Co., Ltd.) set at 25°C, replacing the nickel plating layer formed on the inner wall of the through-hole with a silver plating layer (M3). In step 6, an anti-corrosion pattern is formed on the silver particle layer (M1) instead of forming the anti-corrosion on the silver plating layer (M3) on the silver particle layer (M1). Then, a printed wiring board is obtained in the same manner as in Example 5. Regarding the cross-sectional shape of the circuit forming parts (microstrip lines and probe terminal parts) of the manufactured printed wiring board, the wiring height and wiring width are not reduced, and it presents a rectangular shape without undercut, which is a circuit pattern layer (M4) with a smooth surface.

(Example 41) In Example 40, the electroless nickel plating solution in step 4 was changed from "ICP NiCORON GM (NP)" to TOP CHEM ALLOY 66-LF (manufactured by Okuno Pharmaceutical Co., Ltd.) set at 60°C, and immersed for 2.5 minutes, thereby forming an electroless nickel plating layer (thickness 0.2 μm) on the inner wall of the through-hole and the silver particle layer (M1). The obtained film was then treated for 10 minutes using a replacement silver plating process set at 25°C ("DAIN SILVER EL" manufactured by Daiwa Chemical Co., Ltd.), replacing the nickel plating layer formed on the inner wall of the through-hole and the silver particle layer (M1) with a silver plating layer (M3). In step 6, an anti-corrosion pattern is formed on the replacement silver plating layer (M3) formed on the silver particle layer (M1), and then a printed wiring board is obtained in the same manner as in Embodiment 39. Regarding the cross-sectional shape of the circuit forming parts (microstrip lines and probe terminal parts) of the manufactured printed wiring board, the wiring height and wiring width are not reduced, and it presents a rectangular shape without undercut, which is a circuit pattern layer (M4) with a smooth surface.

(Comparative Example 1) A commercially available 25 μm thick polyimide-based FCCL (UBE EXSYMO Co., Ltd.'s "Upisel") was used as the plating substrate, with a roughened copper foil of 3 μm thickness on both sides. Instead of the polyimide film with silver particle layers formed on both sides, N-BE1310YSB” is used. In addition, through holes are formed on both sides in the same manner as in Examples 1 to 22 above. The black hole process (conditioning-carbon adsorption treatment-etching) of MacDermid is applied to the through holes to make carbon adhere to the surface of the through holes. The copper foil surface with carbon is etched using the sulfuric acid/hydrogen peroxide aqueous solution prepared in Preparation Example 2 to remove it. In this way, copper foil is obtained on both surfaces of the insulating substrate (A), and through holes are formed connecting the two sides of the insulating substrate. The surface of the through holes is carbonized to ensure the conductivity of the substrate. In the following, except that a patterned anti-corrosion agent is formed on the surface of the copper foil instead of on the surface of the silver particle layer (M1), a conductor circuit layer with a microstrip line of 18 μm thickness obtained by copper and a probe terminal pad pattern is formed on the copper foil plating substrate in the same manner as in Examples 1 to 22.

Subsequently, during the removal of the copper seed crystal by immersion in a sulfuric acid/hydrogen peroxide-based rapid etching solution used in copper seed etching, the conductive layer (M3) of the microstrip line was etched, resulting in a film thickness of approximately 3 μm and a reduction in wiring width of approximately 6 μm. Furthermore, the cross-sectional shape could no longer maintain a rectangle and became trapezoidal. Additionally, the surface of the copper conductive layer was roughened due to etching, reducing its smoothness.

(Comparative Example 2) A polyimide film ("Kapton 100EN-C" manufactured by Toray DuPont Co., Ltd.; thickness 25 μm) was obtained by sputtering nickel/chromium (thickness 30 nm, nickel/chromium mass ratio = 80/20) on both sides as a plating substrate, followed by sputtering 70 nm copper, and then electroplating copper to a thickness of 1 μm. In addition, a conductor circuit layer with a microstrip line and probe terminal pad pattern obtained by copper was formed on the copper foil plating substrate in the same manner as in Comparative Example 1.

Subsequently, during the removal of the copper seed crystal in a sulfuric acid/hydrogen peroxide-based rapid etching solution used in copper seed etching, the conductive layer (M3) of the microstrip line was etched, resulting in a film thickness reduction of approximately 1 μm and a reduction in wiring width of more than 2 μm. Furthermore, the cross-sectional shape could no longer maintain a rectangle and became trapezoidal. Additionally, the surface of the copper conductive layer was roughened due to etching, reducing its smoothness. Moreover, in areas outside the conductive layer (M3) pattern, only the copper layer was removed, while the nickel/chromium layer remained.

[Confirmation of the presence or absence of undercut and the cross-sectional shape of the wiring section] The cross-section of the comb-shaped electrode section of the printed circuit board obtained above was magnified to 500 to 10,000 times using a scanning electron microscope (JSM7800 manufactured by NEC Corporation) to confirm the presence or absence of undercut and the cross-sectional shape of the comb-shaped electrode section.

The surface roughness of the printed circuit board wiring was determined by observing the wiring surface using a laser microscope (manufactured by Keynes Corporation, VK-9710). Widths with an Rz of 3 μm or less were rated as smooth (smoothness: 0), while those with an Rz greater than 3 μm were rated as unsmooth (smoothness: ×). Furthermore, when the difference between the designed width of the wiring obtained by the corrosion inhibitor used to form the wiring and the width of the surface of the formed wiring was less than 2 μm, it was rated as side etching being suppressed and maintaining a rectangular shape (rectangularity: 0). Widths with a difference greater than 2 μm were rated as failing to maintain a rectangular shape (rectangularity: ×), as shown in Tables 1 to 3.

[Table 1] Implementation Example 1 Implementation Example 2 Implementation Example 3 Implementation Example 4 Implementation Example 5 Implementation Example 6 Implementation Example 7 Implementation Example 8 Implementation Example 9 Implementation Example 10 Substrate Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Primer Kind without without without B-1 B-1 without without without B-1 B-1 thickness 120 nm 120 nm 120 nm 120 nm Drying conditions 80℃ for 5 minutes 80℃ for 5 minutes 80℃ for 5 minutes 80℃ for 5 minutes Silver nanoparticle layer Silver 0.5 g/ ^m² 0.5 g/ ^m² 0.8 g/ ^m² 0.5 g/ ^m² 0.8 g/ ^cm² 0.5 g/ ^m² 0.5 g/ ^m² 0.8 g/ ^m² 0.5 g/ ^m² 0.8 g/ ^cm² Drying conditions 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes Film baking conditions 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes Covering layer Kind Cu Cu Cu Cu Cu Polyester peeling tape Polyester peeling tape Polyester peeling tape Polyester peeling tape Polyester peeling tape Film thickness 0.2 μm 0.5 μm 1 μm 0.5 μm 2 μm 38 μm 38 μm 1 μm 38 μm 38 μm Through-hole formation method Drilling tool Drilling tool Drilling tool Drilling tool Drilling tool Drilling tool Drilling tool Drilling tool Drilling tool Drilling tool Through hole diameter 100 μm 100 μm 100 μm 100 μm 100 μm 100 μm 100 μm 100 μm 100 μm 100 μm Replacement coating Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Replacement plating thickness 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm Replace silver plating solution Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Smoothness ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Rectangular ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Implementation Example 11 Implementation Example 12 Implementation Example 13 Implementation Example 14 Implementation Example 15 Implementation Example 16 Implementation Example 17 Implementation Example 18 Implementation Example 19 Implementation Example 20 Substrate Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Primer Kind without without B-1 B-1 B-1 without without B-1 B-1 B-1 thickness 120 nm 120 nm 120 nm 120 nm 120 nm 120 nm Drying conditions 80℃ for 5 minutes 80℃ for 5 minutes 80℃ for 5 minutes 80℃ for 5 minutes 80℃ for 5 minutes 80℃ for 5 minutes Silver nanoparticle layer Silver 0.5 g/ ^m² 0.5 g/ ^m² 0.5 g/ ^m² 0.5 g/ ^m² 0.8 g/ ^cm² 0.5 g/ ^m² 0.5 g/ ^m² 0.5 g/ ^m² 0.5 g/ ^m² 0.8 g/ ^cm² Drying conditions 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes Film baking conditions 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes Covering layer Kind Cu Cu Cu Cu Cu Polyester peeling tape Polyester peeling tape Polyester peeling tape Polyester peeling tape Polyester peeling tape Film thickness 0.2 μm 0.5 μm 1 μm 0.5 μm 2 μm 38 μm 38 μm 38 μm 38 μm 38 μm Through-hole formation method Laser Laser Laser Laser Laser Laser Laser Laser Laser Laser Through hole diameter 70 μm 70 μm 70 μm 70 μm 70 μm 70 μm 70 μm 70 μm 70 μm 70 μm Replacement coating Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Replacement plating thickness 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm Replace silver plating solution Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Smoothness ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Rectangular ○ ○ ○ ○ ○ ○ ○ ○ ○ ○

[Table 2] Implementation Example 21 Implementation Example 22 Implementation Example 23 Implementation Example 24 Implementation Example 25 Implementation Example 26 Implementation Example 27 Implementation Example 28 Implementation Example 29 Implementation Example 30 Substrate Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Kapton 100EN-C Primer Kind B-1 B-1 B-2 B-3 B-4 B-5 B-6 B-7 B-8 B-9 thickness 120 nm 120 nm 100 nm 120 nm 150 nm 150 nm 150 nm 150 nm 150 nm 150 nm Drying conditions 80℃ for 5 minutes 80℃ for 5 minutes 120℃ for 5 minutes 120℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes Silver nanoparticle layer Silver 0.8 g/ ^cm² 0.8 g/ ^cm² 0.8 g/ ^cm² 0.8 g/ ^cm² 1.0 g/ ^cm² 1.0 g/ ^cm² 0.8 g/ ^cm² 0.8 g/ ^cm² 0.8 g/ ^cm² 0.8 g/ ^cm² Drying conditions 160℃ for 5 minutes 160℃ for 5 minutes 150℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes Film baking conditions 250℃ for 5 minutes 250℃ for 5 minutes 220℃ for 5 minutes 220℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 220℃ for 5 minutes 220℃ for 5 minutes 220℃ for 5 minutes Covering layer Kind Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Film thickness 2 μm 2 μm 2 μm 2 μm 2 μm 2 μm 2 μm 2 μm 2 μm 2 μm Through-hole formation method Drilling tool Drilling tool Laser Laser Laser Laser Laser Laser Laser Laser Through hole diameter 100 μm 100 μm 50 μm 70 μm 70 μm 70 μm 50 μm 50 μm 70 μm 50 μm Replacement coating Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Replacement plating thickness 0.7 μm 1.0 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm Replace silver plating solution Preparation Example 4 Preparation Example 5 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Smoothness ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Rectangular ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Implementation Example 31 Implementation Example 32 Implementation Example 33 Implementation Example 34 Implementation Example 35 Implementation Example 36 Implementation Example 37 Implementation Example 38 Implementation Example 39 Implementation Example 40 Substrate Kapton 100EN-C Kapton 100EN-C Upilex 25SGA Upilex 25SGA Upilex 25SGA Upilex 25SGA Upilex 25SGA Upilex 25SGA R-5670 Kapton 100EN-C Primer Kind B-10 B-11 B-6 B-6 B-7 B-8 B-9 B-10 B-2 B-1 thickness 150 nm 150 nm 150 nm 150 nm 150 nm 150 nm 150 nm 150 nm 100 nm 120 nm Drying conditions 160℃ for 5 minutes 200℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 120℃ for 5 minutes 80℃ for 5 minutes Silver nanoparticle layer Silver 0.8 g/ ^cm² 0.8 g/ ^cm² 0.8 g/ ^cm² 0.8 g/ ^cm² 0.8 g/ ^cm² 0.8 g/ ^cm² 0.8 g/ ^cm² 0.8 g/ ^cm² 0.8 g/ ^cm² 0.8 g/ ^cm² Drying conditions 160℃ for 5 minutes 200℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 160℃ for 5 minutes 150℃ for 5 minutes 160℃ for 5 minutes Film baking conditions 220℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes 220℃ for 5 minutes 220℃ for 5 minutes 220℃ for 5 minutes 220℃ for 5 minutes 250℃ for 5 minutes 250℃ for 5 minutes Covering layer Kind Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Film thickness 2 μm 2 μm 2 μm 2 μm 2 μm 2 μm 2 μm 2 μm 2 μm 2 μm Through-hole formation method Laser Laser Drilling tool Laser Laser Laser Laser Laser Laser Drilling tool Through hole diameter 50 μm 100 μm 50 μm 70 μm 50 μm 70 μm 50 μm 50 μm 50 μm 100 μm Replacement coating Cu Cu Cu Cu Cu Cu Cu Cu Cu Ni(P) Replacement plating thickness 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.5 μm 0.2 μm Replace silver plating solution Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 Preparation Example 3 DAIN SILVER EL Smoothness ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Rectangular ○ ○ ○ ○ ○ ○ ○ ○ ○ ○

[Table 3] Implementation Example 41 Substrate Kapton 100EN-C Primer Kind B-1 thickness 120 nm Drying conditions 80℃ for 5 minutes Silver nanoparticle layer Silver 0.8 g/ ^cm² Drying conditions 160℃ for 5 minutes Film baking conditions 250℃ for 5 minutes Covering layer Kind Cu Film thickness 2 μm Through-hole formation method Drilling tool Through hole diameter 100 μm Replacement coating Ni(B) Replacement plating thickness 0.2 μm Replace silver plating solution DAIN SILVER EL Smoothness ○ Rectangular ○ Comparative example 1 Comparative example 2 Substrate Upisel N-BE1310YSB Kapton 100EN-C Interface layer Ni/Cr layer copper layer 3 μm 1 μm Through hole Formation method Drilling tool Drilling tool Diameter (μm) 100 100 Conductive treatment of through holes carbon carbon Smoothness × × Rectangular × ×

1: Insulating substrate 2: Silver particle layer 3: Cover layer (copper layer or peelable cover layer) 4: Through-hole (via) 5: Electroless coating catalyst 6: Electroless copper plating layer or electroless nickel plating layer 7: Replacement silver plating layer 8: Patterned anti-corrosion agent 9: Conductive layer (electroplated copper layer) (1a): Multilayer for semi-additive process (composition of claim 1) (1b) Step Step 1: Forming a through-hole (1c) Step 2: Applying a catalyst for electroless silver plating (1d) Step 3: Exposing the conductive silver particle layer (1e) Step 4: Electroless copper plating or electroless nickel plating on the surface of the through-hole (1f) Step 5: Replacing the copper or nickel plating layer with silver plating (1g) Step 6: Forming a patterned corrosion inhibitor (1h) 7: Forming a conductive layer by electroplating copper (1i) Step 8: Peeling off the patterned corrosion inhibitor (1i) Step 8: Removing the silver seed crystal (2a): Semi-additive process for the laminate (composition of claim 1) (2b) Step 1: Forming a through hole (through hole) (2c) Step 2: Applying a catalyst for electroless silver plating (2d) Step 3: Exposing the conductive silver particle layer (2e) Step 4: Electroless copper plating or electroless nickel plating on the surface of the through-hole and the silver particle layer. (2f) Step 5: Replacement silver plating with copper or nickel plating layer. (2g) Step 6: Forming a patterned resist. (2h) Step 7: Forming a conductive layer by electroplating copper. (2i) Step 8: Peeling off the patterned resist. (2i) Step 8: Removing the silver seed crystal.

[Figure 1] is a step diagram of manufacturing a printed circuit board using a semi-additive process with laminates as described in Request 1 or 3. [Figure 2] is a step diagram of manufacturing a printed circuit board using a semi-additive process with laminates as described in Request 2 or 4.

1: Insulating substrate

2: Silver Particle Layer

3: Covering layer (copper layer or peelable covering layer)

4: Through hole (through hole)

5: Electroless plating using catalysts

6: Electroless copper plating or electroless nickel plating

7: Replace the silver plating layer

8: Patterned Anti-corrosion Agent

9: Conductive layer (electroplated copper layer)

Claims (12)

A method for manufacturing a printed circuit board, characterized by comprising: Step 1, wherein a silver particle layer (M1) and a copper layer (M2) are sequentially deposited on two surfaces of an insulating substrate (A), wherein the thickness of the copper layer (M2) is 0.1 μm to 2 μm. Step 1: A multilayer of μm thickness is used to form a through-hole that extends through both sides; Step 2: An electroless plating catalyst is applied to the substrate having the through-hole and the surface of the through-hole; Step 3: The copper layer (M2) is etched to expose the conductive silver particle layer (M1); Step 4: A copper or nickel layer is formed on the surface of the through-hole and the silver particle layer (M1) by electroless plating; Step 5: The through-hole is replaced with silver. Step 6: A copper or nickel layer is formed on the surface and the silver particle layer (M1); Step 7: A patterned resist is formed on the silver plating layer (M3) formed on the conductive silver particle layer (M1); Step 8: The two sides of the substrate are electrically connected by electroplating copper, and a circuit patterned conductive layer (M4) is formed at the same time; and Step 9: The patterned resist is peeled off, and the silver particle layer (M1) on the non-circuit patterned area is removed by etching solution. A method for manufacturing a printed circuit board, characterized by comprising: Step 1, wherein a silver particle layer (M1) and a copper layer (M2) are sequentially deposited on two surfaces of an insulating substrate (A), wherein the thickness of the copper layer (M2) is 0.1 μm to 2 μm. Step 1: A μm thick layer is formed to create a through-hole penetrating both sides; Step 2: An electroless plating catalyst is applied to the substrate having the through-hole and the surface of the through-hole; Step 3: The copper layer (M2) is etched to expose the conductive silver particle layer (M1); Step 4: A copper or nickel layer is formed on the surface of the through-hole by electroless plating; Step 5: Silver is used to replace... The copper or nickel formed on the surface of the through hole; step 6, forming a patterned resist on the conductive silver particle layer (M1); step 7, electrically connecting the two sides of the substrate by electroplating copper, and forming a circuit patterned conductive layer (M4); and step 8, peeling off the patterned resist and removing the silver particle layer (M1) of the non-circuit patterned area using an etching solution. A method for manufacturing a printed circuit board, characterized by comprising: Step 1, sequentially depositing a laminate having a silver particle layer (M1) and a peelable capping layer (RC) on two surfaces of an insulating substrate (A) to form through holes penetrating both surfaces; Step 2, applying an electroless silver plating catalyst to the surface of the substrate having the through holes; Step 3, peeling off the peelable capping layer (RC) to expose the conductive silver particle layer (M1); Step 4, applying an electroless plating catalyst to the surface of the through holes and the silver particle layer. Step 5: A copper or nickel layer is formed on the particle layer (M1); Step 6: A patterned resist is formed on the silver plating layer (M3) formed on the conductive silver particle layer (M1); Step 7: The two sides of the substrate are electrically connected by electroplating copper, and a circuit patterned conductive layer (M4) is formed; and Step 8: The patterned resist is peeled off, and the silver particle layer (M1) on the non-circuit patterned area is removed by etching solution. A method for manufacturing a printed circuit board, characterized by comprising: Step 1, sequentially depositing a laminate having a silver particle layer (M1) and a peelable capping layer (RC) on two surfaces of an insulating substrate (A) to form through holes penetrating both surfaces; Step 2, applying an electroless silver plating catalyst to the surface of the substrate having the through holes; Step 3, peeling off the peelable capping layer (RC) to expose the conductive silver particle layer (M1); Step 4, using an electroless silver plating catalyst to further process the through holes. Step 5 involves electrolytic plating to form a copper or nickel layer on the surface of the through-hole; Step 6 involves replacing the copper or nickel layer formed on the surface of the through-hole with silver; Step 7 involves forming a patterned resist on the conductive silver particle layer (M1); Step 8 involves electrically connecting both sides of the substrate by electroplating copper, while simultaneously forming a circuit patterned conductive layer (M4); and Step 9 involves peeling off the patterned resist and removing the silver particle layer (M1) on the non-circuit patterned areas using an etching solution. The manufacturing method of the laminate using the semi-additive process of any of claims 1 to 4 further laminates an undercoat (B) between the above-mentioned insulating substrate (A) and the silver particle layer (M1). The method of manufacturing a printed circuit board according to any one of claims 1 to 4, wherein the thickness of the copper or nickel layer formed on the surface of the through hole is 0.1 to 1 μm. As in the method of manufacturing the printed wiring board of claim 5, the thickness of the copper or nickel layer formed on the surface of the through hole is 0.1 to 1 μm. As in the method of manufacturing the printed wiring board of claim 5, the silver particles constituting the silver particle layer (M1) are coated with a polymeric dispersant. As in the method of manufacturing a printed circuit board according to claim 8, in the method of manufacturing a printed circuit board according to claim 4, the substrate (B) is a layer composed of a resin having reactive functional groups [X], the polymeric dispersant has reactive functional groups [Y], and the reactive functional groups [X] and the reactive functional groups [Y] can form bonds with each other through a reaction. As in the method of manufacturing a printed wiring board according to claim 9, wherein the aforementioned reactive functional group [Y] is a base containing a nitrogen atom. As in the method of manufacturing a printed wiring board according to claim 9, wherein the polymeric dispersant having the reactive functional group [Y] is selected from one or more of the group consisting of polyalkylimides and polyalkylimides having a polyoxyalkylene structure containing an oxyethyl unit. As in the method of manufacturing the printed wiring board of claim 9, wherein the reactive functional group [X] is selected from one or more of the group consisting of ketone, acetoacetyl, epoxy, carboxyl, N-alkylol group, isocyanate, vinyl, (meth)acrylyl, and allyl.