JP2011100797A - Circuit board - Google Patents

Abstract

Provided is a highly accurate circuit board having high adhesion of circuit layers without causing filler to be broken and exposed on the surface to deteriorate base material characteristics.
A circuit board is formed by embedding a circuit layer made of a conductor on the surface of an insulating base made of a resin containing a filler. The exposed surface of the insulating substrate 1 is formed without the filler 11 being destroyed. The contact surface of the circuit layer 13 with the insulating substrate 1 is formed in an uneven shape following the shape of the filler 11 protruding from the contact surface. Preferably, the contact surface of the circuit layer 13 with the insulating substrate 1 is in contact with at least a part of the filler 11 protruding from the contact surface. Preferably, the filler 11 is not exposed on the exposed surface of the insulating substrate 1.
[Selection] Figure 1

Description

  The present invention relates to a circuit board formed by embedding a circuit layer made of a conductor.

  Conventionally, a circuit board in which a circuit layer made of a conductor is embedded is formed by a CMP method (Chemical Mechanical Polish method) (for example, Patent Document 1).

  FIG. 6 shows an example of the CMP method. In the CMP method, first, as shown in FIG. 6A, circuit grooves 3 (trench portions) are formed on the surface of the insulating base 1 by laser processing. Next, as shown in (b), an electroless plating film 6 is formed on the entire surface of the insulating substrate 1 including the circuit groove 3. Then, as shown in (c), a voltage is applied to the electroless electroplating film 6 to form the electrolytic plating film 21 on the entire surface of the insulating substrate 1. Then, as shown in (d), the site | part which exists in the surface rather than the insulating base material 1 of the electrolytic plating film 21 and the electroless-plating film 6 is grind | polished and removed using the grinder 22, and the insulating base material 1 Expose the surface.

  The circuit board 10 formed by embedding the circuit layer 13 can be obtained through the steps as described above. In this circuit board 10, the distance between the circuit layers 13 can be set to be narrow, for example, about 25 μm to 30 μm, and a highly accurate circuit board 10 can be obtained. is there.

  However, in the circuit board 10 formed as described above, as shown in FIGS. 7A to 7B, the surface of the insulating substrate 1 including the circuit groove 3 is plated, and the excess plating film is polished. Therefore, the surface of the circuit board 10 is roughened by polishing. Then, as shown in FIG. 7C, since the polishing force exerted by the polisher 22 on the insulating base 1 and the plating film is different, the surface of the circuit layer 13 formed by removing the plating film and the insulating group are removed. There is a possibility that a step may be formed on the surface of the material 1 and the surface of the circuit board 10 may not be smooth, resulting in a problem that electrical characteristics are deteriorated. Furthermore, as shown in (b), when the insulating base material 1 contains the filler 11, the filler 11 is exposed on the surface of the insulating base material 1, and the exposed filler 11 is destroyed by polishing. Therefore, the filler 11 on the surface cannot maintain the original shape. The exposed filler 11 has a high frequency of powder falling and may cause contamination by the filler 11 in the subsequent process. Moreover, since the surface of the insulating base material 1 is polished, there is a possibility that microcracks may occur starting from the filler 11 exposed on the surface. Moreover, since the filler 11 exposed on the surface is destroyed, there is a possibility that the base material characteristics such as thermal expansibility and strength are deteriorated.

  As another method for manufacturing a circuit board in which a circuit layer made of a conductor is embedded, a transfer method is known. In the transfer method, a release material having a circuit layer formed on the surface is bonded to the surface of the insulating base material with the circuit layer surface facing, the release material is peeled off from the insulating base material, and the circuit layer is transferred to the insulating base. A circuit board is formed by embedding in a material.

  However, since the circuit layer is pressed and embedded from the surface of the insulating base material according to the transfer method, the circuit layer is formed in contact with the resin film on the outer surface of the insulating base material. There is a problem of low adhesion to the substrate. CZ treatment is known as a method for improving the adhesion, but the CZ treatment treats the surface of the metal foil (bottom surface of the circuit layer) provided on the release material, and the adhesion at the bottom surface of the circuit layer is Although it is enhanced, the adhesion on the side surface cannot be improved, so that a sufficient adhesion cannot be obtained when a narrow circuit layer is formed. Also, in the transfer method, the depth of the circuit layer is generally uniform, and circuit layers having different depths cannot be easily formed. In addition, in forming a circuit layer by a transfer method, there is a limit to shortening the distance between circuit layers, and it is impossible to obtain a high-precision circuit wiring with a short distance between circuit layers.

  In addition, in the case of the transfer method, it is necessary to form a circuit on the release material before transferring the circuit layer to the insulating substrate, and the circuit formation can be performed by a conventional general circuit formation method such as a subtractive method or additive method. Since it is formed by a method or the like, it is difficult to form a fine wiring width of 30 μm or less. Even if fine wiring can be formed, if the adhesion between the release material and the circuit layer is too strong, the transfer cannot be transferred to the insulating base material, and a circuit transfer residue occurs. Moreover, when the adhesion between the release material and the circuit layer is too weak, the circuit layer is peeled off during the circuit formation process or handling. For this reason, it is very difficult to control the adhesion between the release material and the circuit layer. As the wiring becomes finer, the contact area between the release material and the circuit layer becomes smaller, so that the control of the contact becomes more difficult, and there is a problem that the circuit layer of the fine wiring cannot be transferred to the insulating substrate.

  In addition, when the insulating base material is multilayered, in the case of the transfer method, the circuit is not formed on the insulating base material, but is formed by transferring the circuit formed beforehand on the release material onto both surfaces of the insulating substrate. It is difficult to align circuit patterns between layers, and it is difficult to align with high accuracy.

JP 2000-49162 A

  The present invention has been made in view of the above circumstances, and a highly accurate circuit board having high adhesiveness of a circuit layer without the filler being destroyed and exposed to the surface to deteriorate the base material characteristics. It is intended to provide.

  A circuit board according to claim 1 of the present invention is a circuit board 10 formed by embedding a circuit layer 13 made of a conductor on the surface of an insulating base material 1 formed of a resin containing a filler 11. The exposed surface of the insulating base material 1 is formed without the filler 11 being destroyed, and the contact surface of the circuit layer 13 with the insulating base material 1 has an uneven shape following the protruding shape of the filler 11 to the contact surface. It is characterized by being formed.

  The circuit board according to claim 2 is characterized in that, in the circuit board 10 described above, the contact surface of the circuit layer 13 with the insulating base material 1 is in contact with at least a part of the filler 11 protruding from the contact surface. It is what.

  The circuit board according to claim 3 is characterized in that, in the circuit board 10 described above, the exposed surface of the insulating base 1 is not exposed to the filler 11.

  The circuit board according to claim 4 is characterized in that, in the circuit board 10 described above, the contact surface of the insulating base material 1 with the circuit layer 13 is formed in a concavo-convex shape with the filler 11 protruding by laser processing. It is what.

  The circuit board according to claim 5 is characterized in that, in the circuit board 10 described above, the circuit layer 13 is formed by plating of a conductor.

  The circuit board according to claim 6 is characterized in that, in the circuit board 10 described above, the exposed surface of the circuit layer 13 is formed flat and has no step at the boundary with the insulating substrate 1. Is.

  According to the invention of claim 1, since the exposed surface of the insulating base material is formed without breaking the filler, the filler is filled in the insulating base material while maintaining the shape up to the surface. It is possible to prevent the substrate properties such as thermal expansibility and strength from being deteriorated by being broken. In addition, since the contact surface of the circuit layer with the insulating base material is formed in a concavo-convex shape following the protruding shape of the filler, the circuit layer is in contact with the concavo-convex shape so that the circuit layer It is possible to improve the adhesion between the insulating substrate and the insulating substrate.

  According to the invention of claim 2, since the circuit layer is in contact with the filler at the contact surface with the insulating base, the circuit layer is in direct contact with the inside of the insulating base without going through the resin layer. The adhesion of the circuit layer can be further increased. In addition, since the circuit layer is formed so as to be in contact with the filler on the bottom surface and the side surface, which are the embedded surfaces, it forms circuit wiring with high adhesion that does not drop off even when formed narrow. Therefore, a highly accurate circuit board can be obtained.

  According to the invention of claim 3, since the filler is not exposed because the exposed surface of the insulating base material is not exposed, the filler is powdered off or microcracks starting from the filler are generated. It is possible to prevent the occurrence.

  According to the invention of claim 4, the contact surface with the circuit layer of the insulating base material is formed by laser processing, so that this contact surface can be formed by protruding the filler, and the contact surface is formed into an uneven shape. The adhesion can be improved. Further, the depth of the circuit layer can be easily set for each circuit layer by laser processing, and a circuit board having circuit layers having different depths can be easily obtained.

  According to the invention of claim 5, by forming the circuit layer by plating of the conductor, the circuit layer can be obtained by easily forming the concavo-convex shape according to the shape of the insulating base material from which the filler protrudes. It is possible to easily obtain a highly accurate circuit board with high adhesion.

  According to the invention of claim 6, the electrical characteristics can be improved by flattening the exposed surface of the circuit layer, and there is no step at the boundary between the circuit layer and the insulating base material. It can be flat, and a thin and smooth circuit board can be obtained.

It is sectional drawing which shows an example of embodiment of the circuit board of this invention. (A)-(e) is a schematic cross section for demonstrating each process in the method of manufacturing the circuit board of this invention. It is explanatory drawing for demonstrating the test | inspection process for making a resin film contain a fluorescent substance and test | inspecting a film removal defect using the light emission from a fluorescent substance. (A) and (b) are the electroless plating formed when the circuit pattern part (circuit groove) which digs an insulating base material is formed exceeding the thickness of a resin film in a circuit pattern formation process. It is a schematic cross section which shows a film | membrane. (A)-(e) is a schematic cross section for demonstrating each process of manufacturing the circuit board (three-dimensional circuit board) of this invention. (A)-(d) is sectional drawing which shows an example of a mode that a circuit board is manufactured by the conventional method. It is sectional drawing which shows an example of the conventional circuit board, (a) shows the state before grinding | polishing by CMP method, (b), (c) shows the state after grinding | polishing.

  FIG. 1 is a cross-sectional view showing an example of an embodiment of a circuit board 10 of the present invention. The circuit board 10 is formed by embedding a circuit layer 13 made of a conductor on the surface of an insulating base 1 made of a resin containing a filler 11. As the filler 11, an appropriate shape can be used, but in the illustrated form, a spherical filler 11 is used.

  The surface (exposed surface) of the circuit layer 13 is a flat surface. That is, the height T (depth) of the circuit layer 13 is substantially equal over the width W direction of the circuit layer. Since the height T of the circuit layer 13 is substantially equal, the electrical characteristics can be enhanced. And in the form of illustration, there is no level | step difference between the surface of the circuit layer 13 and the surface of the insulating base material 1. As a result, the entire surface of the circuit board 10 is flat, and a thin and smooth circuit board 10 can be obtained.

  Unlike the case where the exposed surface of the insulating substrate 1 is formed by the CMP method, the filler 11 is formed without being destroyed. That is, when formed by the CMP method, the filler 11 is broken and exposed as shown in FIG. 7 to form the insulating base material 1, but in the illustrated circuit board 10, the insulating base material 1 is exposed. The filler 11 existing in the vicinity of the surface exists without breaking and maintaining its shape. And the exposed surface of the insulating base material 1 does not expose the filler 11, and specifically, the surface resin layer 12 not containing the filler 11 is formed on the exposed surface of the insulating base material 1. The surface resin layer 12 does not contain the filler 11 and consists only of the resin component, and is formed as a thin film so as to cover the entire surface of the insulating base material 1. Here, the resin component is a component other than the filler 11 forming the insulating base material 1 and includes components such as a curing agent and a dispersing agent in addition to the resin, as will be described later. In the drawing, the surface resin layer is a layer on the surface side (outer side) with respect to Y '. By covering the filler 11 with the surface resin layer 12, it is possible to prevent the filler 11 from being exposed on the surface and causing a filler drop or a microcrack.

  Moreover, the surface (contact surface with the insulating base material 1) embedded in the insulating base material 1 of the circuit layer 13 is formed in an uneven shape following the protruding shape of the filler 11 to the contact surface. That is, the contact surface of the insulating substrate 1 with the circuit layer 13 is formed in an uneven shape in which the filler 11 protrudes, and the uneven shape of the circuit layer 13 is formed following the uneven shape of the insulating substrate 1. Has been. In this way, when the concavo-convex shape is formed and the circuit layer 13 and the insulating base material 1 are in contact with each other, the adhesion between the circuit layer 13 and the insulating base material 1 is increased, and a highly accurate circuit can be formed. It is.

  The contact surface of the circuit layer 13 with the insulating base material 1 may be in contact with the resin layer of the insulating base material 1 that does not include the filler 11. However, in the illustrated embodiment, the circuit layer 13 is connected to the circuit layer 13. It is in contact with the filler 11 protruding toward the contact surface. That is, the surface of the insulating base material 1 in contact with the circuit layer 13 (exposed surface of a circuit groove 3 to be described later) is not provided with the surface resin layer 12, and the filler 11 is exposed. 11 is formed in contact with the circuit layer 13. Thus, since the circuit layer 13 is in direct contact with the inside of the insulating substrate 1 without the surface resin layer 12, the adhesion of the circuit layer 13 can be further increased.

  As shown in the figure, the filler 11 in contact with the circuit layer 13 is preferably in contact with the filler 11 being maintained without being broken. When the filler 11 is spherical, it is in contact with the circuit layer 13 with a hemispherical spherical surface protruding without being destroyed. As described above, when the filler 11 is brought into direct contact with the circuit layer 13 without passing through other layers, the bottom surface and the side surface of the circuit layer 13 are formed in contact with the inside of the resin base material 11. , Adhesion can be further increased. As described above, in order to further improve the adhesion, it is more preferable that a part of the filler 11 protrudes from the exposed surface of the circuit groove 3 and is exposed.

  The circuit layer 13 is formed so as to come into contact with the filler 11 at the bottom surface and the side surface, which are the embedded surfaces. That is, in addition to the adhesion at the bottom, the adhesion at the side is increased. Therefore, even when the circuit layer 13 is formed with a narrow width, the circuit layer 13 is in close contact with the side surface, so that it is possible to form the circuit layer 13 with high adhesion that does not fall off. A highly accurate circuit board 10 having a narrow W can be obtained. Further, the width between the circuit layers 13 can also be reduced.

  In the circuit board 10 of the present invention, since the adhesion is increased as described above, the circuit layer 13 can be formed narrowly. Specifically, the width (W) and height ( The ratio (W / T) to T) is preferably 0.1 to 30. That is, it is preferable that the circuit board 10 has the circuit layer 13 in which W / T falls within this range. Thereby, the width of the circuit layer 13 can be narrowed, and a highly accurate circuit board 10 can be obtained. If W / T is smaller than this range, it may become impractical. On the other hand, if W / T is larger than this range, there is a risk that high precision (higher circuit density) cannot be achieved. The circuit layer 13 can also be formed on a solid electrode or the like, and in that case, the upper limit of (W / T) need not be set.

  In the circuit board 10 of the present invention, high adhesion can be obtained regardless of the height T of the circuit layer 13, so that the height T (depth) of the circuit layer 13 is easily set for each circuit layer 13. be able to. Therefore, the circuit board 10 having the circuit layers 13 having different depths can be easily obtained.

  In addition, although the flat board | substrate thing was illustrated as the circuit board 10, the circuit board 10 can also be used as the three-dimensional circuit board 60 so that it may mention later. That is, the present invention is not limited to the circuit board 10 in which the circuit layer 13 is formed on the planar insulating base material 1. Specifically, when the insulating base material 1 having a three-dimensional shape having a stepped three-dimensional surface is used as the insulating base material 1, a circuit board having a circuit layer 13 with accurate wiring as shown in FIG. 10 (three-dimensional circuit board 60) can be obtained.

[Circuit board manufacturing method]
A method for manufacturing the circuit board 10 of the present invention will be described.

  The circuit board 10 of the present invention has a coating forming step for forming the resin coating 2 on the surface of the insulating base 1, and a recess having a depth deeper than the thickness of the resin coating 2 with reference to the outer surface of the resin coating 2. A circuit pattern forming step of forming a circuit pattern portion, a catalyst deposition step of depositing a plating catalyst or its precursor 5 on the surface of the circuit pattern portion and the surface of the resin coating 2, and the insulating base material A coating removal step of removing the resin coating 2 from 1, and a plating treatment step of forming the electroless plating film 6 only in the portion where the plating catalyst or its precursor 5 remains after the resin coating 2 is removed. It can be obtained by the method provided. The manufacturing method is not limited to this method, but it is preferable to use this method to form the circuit board 10 as described above.

  According to such a manufacturing method, it is possible to easily leave the plating catalyst or its precursor 5 only in a portion where the plating film is to be formed, and remove the plating catalyst or its precursor 5 from other portions. Therefore, the electroless plating film 6 can be easily formed only in the portion where the plating catalyst or the precursor 5 is left, which is the portion where the plating film is to be formed, by performing the plating treatment step for forming the electroless plating film 6. can do.

  Therefore, the highly accurate circuit layer 13 can be easily formed on the surface of the insulating substrate 1. That is, the outline of the formed circuit can be maintained with high accuracy. As a result, for example, even when a plurality of circuits are formed at regular intervals, it is possible to suppress the remaining pieces of the electroless plating film between the circuits, and thus suppress the occurrence of short circuits and migration. . In addition, a circuit having a desired depth can be formed.

  FIG. 2 is a schematic cross-sectional view for explaining each step in the method of manufacturing a circuit board as described above.

  First, as shown in FIG. 2A, a resin film 2 is formed on the surface of the insulating substrate 1. This process corresponds to a film forming process.

  Next, as shown in FIG. 2 (b), a recess having a depth deeper than the thickness of the resin coating 2 is formed with reference to the outer surface of the resin coating 2, and the filler 11 is exposed to the surface to form a circuit. A pattern portion is formed. The filler 11 is exposed when the recess is deeper than the thickness of the resin coating 2. The circuit pattern portion may be a circuit groove 3 in which the insulating base material 1 is dug. If necessary, the insulating base material 1 may have a through-hole as a part of the circuit groove 3. Drilling to form 4 may be performed. The circuit groove 3 defines a portion where an electroless plating film is formed by electroless plating, that is, a portion where the circuit layer 13 is formed. This step corresponds to a circuit pattern forming step. Hereinafter, the circuit pattern portion will be described focusing on the circuit groove 3.

  Next, as shown in FIG. 2C, a plating catalyst or a precursor 5 thereof is deposited on the surface of the circuit groove 3 and the surface of the resin film 2 on which the circuit groove 3 is not formed. This step corresponds to a catalyst deposition step.

  Next, as shown in FIG. 2 (d), the resin film 2 is removed from the insulating base material 1. By doing so, a plating catalyst or its precursor 5 can be made to remain only on the surface of the insulating substrate 1 where the circuit groove 3 is formed. On the other hand, the plating catalyst or its precursor 5 deposited on the surface of the resin film 2 is removed together with the resin film 2 while being supported on the resin film 2. This process corresponds to a film removal process.

  Next, electroless plating is performed on the insulating substrate 1 from which the resin coating 2 has been removed. By doing so, the electroless plating film 6 is formed only in the portion where the plating catalyst or its precursor 5 remains. That is, as shown in FIG. 2 (e), the electroless plating film 6 to be the circuit layer 13 is formed in the portion where the circuit groove 3 is formed. The circuit layer 13 may be composed of the electroless plating film 6, or the electroless plating film 6 is further subjected to electroless plating (fill-up plating) to further increase the thickness. It may be. Specifically, for example, as shown in FIG. 2 (e), a circuit layer 13 made of an electroless plating film 6 is formed so as to fill the circuit groove 3 and the entire through-hole 4, and the insulating base 1 And the circuit layer 13 may be eliminated. This process corresponds to a plating process.

  Through the above steps, a circuit board 10 as shown in FIG. 2E is formed. The circuit board 10 thus formed is obtained by forming the circuit layer 13 on the insulating base 1 with high accuracy.

  Hereinafter, each process will be described.

<Film formation process>
As described above, the film forming process is a process of forming the resin film 2 on the surface of the insulating substrate 1.

(Insulating base material)
The insulating substrate 1 is not particularly limited as long as it is formed of a resin containing the filler 11 (resin substrate).

  Moreover, as said resin, if it is resin which comprises the various organic substrates which can be used for manufacture of a circuit board, it can use without limitation in particular. Specifically, for example, epoxy resin, acrylic resin, polycarbonate resin, polyimide resin, polyphenylene sulfide resin, polyphenylene ether resin, cyanate resin, benzoxazine resin, bismaleimide resin, and the like can be given.

  The epoxy resin is not particularly limited as long as it is an epoxy resin constituting various organic substrates that can be used for manufacturing a circuit board. Specifically, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, aralkyl epoxy resin, phenol novolac type epoxy resin, alkylphenol novolac type epoxy resin, biphenol type epoxy resin, naphthalene type epoxy resin , Dicyclopentadiene type epoxy resins, epoxidized products of condensates of phenols and aromatic aldehydes having a phenolic hydroxyl group, triglycidyl isocyanurate, alicyclic epoxy resins, and the like. Furthermore, the epoxy resin, nitrogen-containing resin, and silicone-containing resin that are brominated or phosphorus-modified to impart flame retardancy are also included. Moreover, as said epoxy resin and resin, said each epoxy resin and resin may be used independently, and may be used in combination of 2 or more type.

  Moreover, in order to comprise a base material with said each resin, in general, in order to make it harden | cure, a hardening | curing agent is contained. The curing agent is not particularly limited as long as it can be used as a curing agent. Specific examples include dicyandiamide, phenolic curing agents, acid anhydride curing agents, aminotriazine novolac curing agents, and cyanate resins. As said phenol type hardening | curing agent, a novolak type, an aralkyl type, a terpene type etc. are mentioned, for example. Moreover, as said hardening | curing agent, said each hardening | curing agent may be used independently, and may be used in combination of 2 or more type.

  As said phenol type hardening | curing agent, a novolak type, an aralkyl type, a terpene type etc. are mentioned, for example. Further examples include phosphorus-modified phenolic resins or phosphorus-modified cyanate resins for imparting flame retardancy. Moreover, as said hardening | curing agent, said each hardening | curing agent may be used independently, and may be used in combination of 2 or more type.

  Although not particularly limited, it is preferable to use a resin or the like that has a good laser light absorption rate in a wavelength region of 100 nm to 400 nm because a circuit pattern is formed by laser processing. For example, specifically, a polyimide resin or the like can be given.

  The insulating base 1 contains a filler 11. The filler 11 may be inorganic fine particles or organic fine particles, and is not particularly limited. By containing the filler 11, it is possible to expose the filler 11 in an unbreakable state in the laser processed portion, and to form an uneven surface due to the protrusion of the filler 11 to improve the adhesion between the plating and the resin.

Specific examples of the material constituting the inorganic fine particles include aluminum oxide (Al ₂ O ₃ ), magnesium oxide (MgO), boron nitride (BN), aluminum nitride (AlN), silica (SiO ₂ ), High dielectric constant fillers such as barium titanate (BaTiO ₃ ) and titanium oxide (TiO ₂ ); magnetic fillers such as hard ferrite; magnesium hydroxide (Mg (OH) ₂ ), aluminum hydroxide (Al (OH) ₂ ), Antimony trioxide (Sb ₂ O ₃ ), antimony pentoxide (Sb ₂ O ₅ ), guanidine salts, zinc borate, molybdate compounds, zinc stannate, and other inorganic flame retardants; talc (Mg ₃ (Si ₄ O ₁₀₎ (OH) 2), barium sulfate (BaSO _4), calcium carbonate (CaCO _3), mica, and the like. As said inorganic fine particle, the said inorganic fine particle may be used independently, and may be used in combination of 2 or more type. These inorganic fine particles have high thermal conductivity, relative dielectric constant, flame retardancy, particle size distribution, color tone flexibility, etc. And high filling can be easily performed.

  The inorganic fine particles may be surface-treated with a silane coupling agent in order to improve dispersibility in the insulating base material. The insulating base material may contain a silane coupling agent in order to increase the dispersibility of the inorganic fine particles in the insulating base material. Specific examples of the silane coupling agent include epoxy silane, mercapto silane, amino silane, vinyl silane, styryl silane, methacryloxy silane, acryloxy silane, titanate silane couplings, and the like. Agents and the like. As said silane coupling agent, the said silane coupling agent may be used independently, and may be used in combination of 2 or more type.

  In addition, the insulating substrate 1 may contain a dispersant in order to improve the dispersibility of the inorganic fine particles in the insulating substrate. Specific examples of the dispersant include alkyl ether-based, sorbitan ester-based, alkyl polyether amine-based, polymer-based dispersants, and the like. As said dispersing agent, the said dispersing agent may be used independently, and may be used in combination of 2 or more type.

  Specific examples of the organic fine particles include rubber fine particles.

  The particle diameter of the filler 11 is preferably an average particle diameter equal to or less than the thickness of the insulating substrate 1, and specifically, the average particle diameter is preferably 0.01 to 10 μm, and the average particle diameter is 0. More preferably, it is 0.05-5 micrometers. When the particle size of the filler 11 falls within this range, the surface resin layer 12 not containing the filler 11 can be easily formed on the surface of the insulating base 1, and the circuit groove in which the filler 11 is exposed is provided. The adhesion of the circuit layer 13 at 3 increases. If the average particle size of the filler 11 is smaller than the above range, the effect of adhesion due to the protruding irregularities may be reduced, and conversely, if the average particle size of the filler 11 is larger than the above range, it is fine. There is a possibility that the circuit groove 3 cannot be formed. The average particle diameter can be measured by a light scattering method using a laser diffraction particle size distribution meter, and is obtained as a sphere equivalent diameter (number average diameter).

  The shape of the filler 11 is not particularly limited, but a spherical one can be used. In addition, a filler 11 having a crushed shape or the like may be used. Among these, it is preferable to use a spherical filler.

As content of the filler 11, it is preferable that it is 10-95 mass% with respect to the resin base material 1 whole quantity after hardening, it is more preferable that it is 30-90 mass%, and it is 50-85 mass%. Is more preferable The content of the filler 11 falls within this range, and further the content of the filler 11 is increased, whereby the thermal expansion of the resin base material 1 can be brought close to the thermal expansion of the formed conductor circuit. The reliability of the substrate when heated can be increased. When the content of the filler 11 is lower than this range, the adhesion between the circuit layer 13 and the insulating base material 1 is deteriorated, the thermal expansion is increased, and the substrate reliability during heat may be reduced. On the contrary, when the content of the filler 11 is higher than this range, the fluidity is poor when the filler 11 is exposed from the surface of the insulating base material 1 or when the insulating base material 1 is laminated and molded with another base material. There is a risk of blurring.

  The insulating substrate 1 is formed by appropriately molding a resin composition containing the above components. A solvent may be added to the resin composition. In that case, the surface resin layer 12 which does not contain the filler 11 can be formed on the surface of the insulating base material 1 by curing after the insulating base material 1 is shaped in a fluid state. That is, since the resin composition has fluidity, the filler 11 is not directly exposed to the surface before being cured and is embedded in the resin composition (layer other than the filler 11). Is formed on the surface of the uncured insulating substrate 1. And since it hardens | cures with this state maintained and the insulating base material 1 is formed, the surface resin layer 12 can be formed and the filler 11 can be prevented from being exposed to the surface of the insulating base material 1. It is.

  The formation of the surface resin layer 12 is confirmed by observing the surface of the insulating substrate 1 and not exposing the filler 11. In addition, according to the method of polishing the surface of the insulating substrate 1 as in the CMP method, the surface resin layer 12 is removed by polishing, and the filler 11 close to the surface layer is also polished, so that the filler 11 is polished. The exposed state is observed by surface observation.

  Further, the form of the insulating substrate 1 is not particularly limited. Specifically, a sheet | seat, a film, a prepreg, a molded object of a three-dimensional shape etc. are mentioned. The thickness of the insulating substrate 1 is not particularly limited. Specifically, in the case of a sheet, film, or prepreg, for example, the thickness is preferably 10 to 200 μm, and more preferably about 20 to 100 μm. The insulating substrate 1 may contain inorganic fine particles such as silica particles.

(Resin coating)
The resin film 2 is not particularly limited as long as it can be removed in the film removal step. Specifically, for example, a soluble resin that can be easily dissolved in an organic solvent or an alkaline solution, a swellable resin film made of a resin that can be swollen with a predetermined liquid (swelling liquid) described later, and the like. Among these, a swellable resin film is particularly preferable because accurate removal is easy. Moreover, as said swelling resin film, it is preferable that the swelling degree with respect to the said liquid (swelling liquid) is 50% or more, for example. By using a resin film having such a swelling degree, the resin film can be easily peeled from the insulating substrate. Therefore, the highly accurate circuit layer 13 can be easily formed on the surface of the insulating substrate 1. In addition, the resin coating 2 includes a material that has a high degree of swelling with respect to the liquid and that dissolves in the liquid.

  The swellable resin film is not limited to the resin film that does not substantially dissolve in the liquid (swelling liquid) and easily peels off from the surface of the insulating substrate 1 due to swelling. A resin film that swells with respect to the swelling liquid), dissolves at least partly and easily peels off from the surface of the insulating substrate 1 due to the swelling or dissolution, or the liquid (swelling liquid). Moreover, the resin film which peels from the said insulating base material 1 surface easily by the melt | dissolution is also contained.

  A method for forming the resin coating 2 is not particularly limited. Specifically, for example, it is formed by applying a liquid material capable of forming a resin film on the surface of the insulating base material 1 and then drying it, or by applying the liquid material to a support substrate and then drying it. And a method of transferring the resin film to be transferred onto the surface of the insulating substrate 1. The method for applying the liquid material is not particularly limited. Specifically, for example, conventionally known spin coating method, bar coater method and the like can be mentioned.

  The thickness of the resin coating 2 is preferably 10 μm or less and more preferably 5 μm or less from the viewpoint that a fine circuit can be formed with high accuracy. On the other hand, the thickness of the resin coating 2 is preferably 0.1 μm or more, and more preferably 1 μm or more. When the thickness of the resin coating 2 is too thick, the accuracy of circuit pattern portions such as the circuit grooves 3 and the through holes 4 formed by laser processing or machining in the circuit pattern forming process tends to be lowered. Moreover, when the thickness of the resin film 2 is too thin, it tends to be difficult to form the resin film 2 having a uniform film thickness.

  Next, a swellable resin film suitable as the resin film 2 will be described as an example.

  As the swellable resin film, a resin film having a swelling degree with respect to the swelling liquid of 50% or more can be preferably used. Furthermore, a resin film having a swelling degree with respect to the swelling liquid of 100% or more is more preferable. In addition, when the said swelling degree is too low, there exists a tendency for a swelling resin film to become difficult to peel in the said film removal process.

  The formation method of the said swellable resin film is not specifically limited, What is necessary is just the method similar to the formation method of the resin film 2 mentioned above. Specifically, for example, a liquid material capable of forming a swellable resin film is applied to the surface of the insulating base material 1 and then dried, or the liquid material is applied to a support substrate and then dried. And a method of transferring the swellable resin film formed by the method to the surface of the insulating substrate 1.

  Examples of the liquid material that can form the swellable resin film include an elastomer suspension or emulsion. Specific examples of the elastomer include a diene elastomer such as a styrene-butadiene copolymer, an acrylic elastomer such as an acrylate ester copolymer, and a polyester elastomer. According to such an elastomer, the swellable resin film 2 having a desired degree of swelling can be easily formed by adjusting the degree of crosslinking or gelation of the elastomer resin particles dispersed as a suspension or emulsion.

  Thus, the resin coating 2 is preferably a resin coating 2 formed by applying an elastomer suspension or emulsion to the surface of the insulating substrate 1 and then drying. If such a resin film 2 is used, a resin film can be easily formed on the surface of the insulating substrate 1. Therefore, the highly accurate circuit layer 13 can be easily formed on the surface of the insulating substrate 1.

  Moreover, it is preferable that the said resin film 2 is the resin film 2 formed by transcribe | transferring the resin film 2 formed on the support substrate to the said insulating base material 1 surface. The resin film used for this transfer is more preferably a resin film 2 formed by applying an elastomer suspension or emulsion to the surface of the support substrate and then drying. If such a resin film 2 is used, a large number of resin films 2 can be prepared in advance, which is preferable from the viewpoint of excellent mass productivity.

  The elastomer is preferably selected from the group consisting of a diene elastomer, an acrylic elastomer, and a polyester elastomer having a carboxyl group. The diene elastomer is more preferably a styrene-butadiene copolymer. According to such an elastomer, it is possible to easily form a resin film having a desired degree of swelling by adjusting the degree of crosslinking or the degree of gelation. In addition, the degree of swelling of the liquid used in the film removal step can be increased, and a resin film that dissolves in the liquid can be easily formed.

  Moreover, as the resin film, a film mainly composed of a resin composed of an acrylic resin having a carboxyl group with an acid equivalent of 100 to 800 is also preferably used.

  The swellable resin film is particularly preferably a film whose degree of swelling changes depending on the pH of the swelling liquid. When such a coating is used, the liquid condition in the catalyst deposition step is different from the liquid condition in the coating removal step, so that the swellable resin can be obtained at the pH in the catalyst deposition step. The coating maintains high adhesion to the insulating substrate, and the swellable resin coating can be easily peeled off at the pH in the coating removal step.

  More specifically, for example, the catalyst deposition step includes a step of treating in an acidic plating catalyst colloid solution (acid catalytic metal colloid solution) having a pH in the range of 1-3, for example, and the coating removal step has a pH of 12-12. When the step of swelling the swellable resin film in an alkaline solution in the range of 14 is provided, the swelling degree of the swellable resin film with respect to the acidic plating catalyst colloid solution is 60% or less, and further 40% or less. The resin film preferably has a degree of swelling with respect to the alkaline solution of 50% or more, more preferably 100% or more, and even more preferably 500% or more.

  Examples of such a swellable resin film include photocuring used for a sheet formed from an elastomer having a predetermined amount of carboxyl groups, a dry film resist (hereinafter also referred to as DFR) for patterning printed wiring boards, and the like. And a sheet obtained by curing the entire surface of a curable alkali-developing resist, and thermosetting or alkali-developing sheet.

  Specific examples of the elastomer having a carboxyl group include a diene elastomer such as a styrene-butadiene copolymer having a carboxyl group in the molecule by containing a monomer unit having a carboxyl group as a copolymerization component; acrylic acid Examples include acrylic elastomers such as ester copolymers; and polyester elastomers. According to such an elastomer, a swellable resin film having a desired alkali swelling degree can be formed by adjusting the acid equivalent, the degree of crosslinking or the degree of gelation of the elastomer dispersed as a suspension or emulsion. . The carboxyl group in the elastomer swells the swellable resin film with respect to the alkaline aqueous solution and acts to peel the swellable resin film from the surface of the insulating substrate. The acid equivalent is the polymer weight per equivalent of carboxyl groups.

  Specific examples of the monomer unit having a carboxyl group include (meth) acrylic acid, fumaric acid, cinnamic acid, crotonic acid, itaconic acid, maleic anhydride, and the like.

  The content ratio of the carboxyl group in the elastomer having such a carboxyl group is preferably 100 to 2000, more preferably 100 to 800 in terms of acid equivalent. When the acid equivalent is too small, the compatibility with the solvent or other composition tends to decrease, whereby the resistance to the plating pretreatment liquid tends to decrease. Moreover, when an acid equivalent is too large, there exists a tendency for the peelability with respect to aqueous alkali solution to fall.

  The molecular weight of the elastomer is preferably 10,000 to 1,000,000, more preferably 20,000 to 60,000. When the molecular weight of the elastomer is too large, the releasability tends to decrease, and when it is too small, the viscosity decreases, so that it is difficult to maintain a uniform thickness of the swellable resin film, and plating pretreatment The resistance to the liquid also tends to deteriorate.

  The resin coating includes (a) at least one monomer of carboxylic acid or acid anhydride having at least one polymerizable unsaturated group in the molecule and (b) the monomer (a). And a polymer resin obtained by polymerizing at least one monomer that can be polymerized with or a resin composition containing the polymer resin. If such a resin film is used, a resin film can be easily formed on the surface of the insulating substrate 1. Therefore, a highly accurate circuit can be easily formed on the surface of the insulating substrate 1. In addition, many of these resin films can be dissolved by the liquid used in the film removal step, and not only peeling and removal but also dissolution and removal can be used effectively.

  As the resin composition, the polymer resin may be an essential component as a main resin, and at least one of oligomers, monomers, fillers, and other additives may be added.

  In addition, as DFR, a photocurable resin containing a photopolymerization initiator containing a predetermined amount of a carboxyl group, an acrylic resin; an epoxy resin; a styrene resin; a phenol resin; A sheet of a resin composition can be used. As specific examples of such DFR, a dry film of a photopolymerizable resin composition as disclosed in JP 2000-231190 A, JP 2001-201851 A, and JP 11-212262 A is used. Sheets obtained by curing, and commercially available as an alkali development type DFR, for example, UFG series manufactured by Asahi Kasei Corporation can be mentioned.

  Furthermore, as another example of the swellable resin film, a resin containing a carboxyl group and containing rosin as a main component (for example, “NAZDAR229” manufactured by Yoshikawa Chemical Co., Ltd.) or a resin containing phenol as a main component (for example, LEKTRACHEM “104F”) and the like.

  The swellable resin film was formed on the surface of the insulating substrate by applying a resin suspension or emulsion using a conventionally known application method such as a spin coat method or a bar coater method, followed by drying or a support substrate. After the DFR is bonded to the surface of the insulating substrate using a vacuum laminator or the like, it can be easily formed by curing the entire surface.

  Moreover, as said resin film, in addition to the above, the following are mentioned. For example, the following are mentioned as a resist material which comprises the said resin film.

  Properties required for the resist material constituting the resin coating include, for example, (1) resistance to a liquid (plating nucleation chemical) in which an insulating substrate on which the resin coating is formed is immersed in a catalyst deposition step described later. (2) The film coating process described later, for example, the resin film (resist) can be easily removed by the step of immersing the insulating base material on which the resin film is formed in alkali, and (3) High film formability. (4) easy dry film (DFR) formation, (5) high storage stability, and the like.

  As the plating nucleating chemical solution, as will be described later, for example, in the case of an acidic Pd—Sn colloid catalyst system, all are acidic (pH 1-2) aqueous solutions. Moreover, in the case of an alkaline Pd ion catalyst system, the catalyst imparting activator is a weak alkali (pH 8 to 12), and the others are acidic. From the above, it is necessary to withstand pH 1 to 11, and preferably pH 1 to 12, as the resistance to the plating nucleating solution. Note that being able to withstand is that when a sample on which a resist is formed is immersed in a chemical solution, swelling and dissolution of the resist are sufficiently suppressed, and the resist serves as a resist. The immersion temperature is generally room temperature to 60 ° C., the immersion time is 1 to 10 minutes, and the resist film thickness is generally about 1 to 10 μm, but is not limited thereto.

  As the alkali stripping chemical used in the film removal step, as will be described later, for example, an aqueous NaOH solution or an aqueous sodium carbonate solution is common. Its pH is 11 to 14, and it is desirable that the resist film can be easily removed preferably at pH 12 to 14. The NaOH aqueous solution concentration is generally about 1 to 10%, the processing temperature is room temperature to 50 ° C., the processing time is 1 to 10 minutes, and the immersion or spray treatment is generally performed, but is not limited thereto.

  Since a resist is formed on an insulating material, film formability is also important. A uniform film formation without repelling or the like is necessary. Moreover, although it is made into a dry film for the simplification of a manufacturing process, reduction of material loss, etc., the flexibility of a film is required in order to ensure handling property. Also, a dry film resist is pasted on the insulating material with a laminator (roll, vacuum). The pasting temperature is room temperature to 160 ° C., and the pressure and time are arbitrary. Thus, adhesiveness is required at the time of pasting. For this reason, the resist formed into a dry film is generally used as a three-layer structure sandwiched by a carrier film and a cover film to prevent dust from adhering, but is not limited thereto.

  The best preservation is that it can be stored at room temperature, but it must also be refrigerated or frozen. As described above, it is necessary to prevent the composition of the dry film from being separated at low temperatures or to be cracked due to a decrease in flexibility.

  The resin composition of the resist material may include a main resin (binder resin) as an essential component, and at least one of oligomers, monomers, fillers, and other additives may be added.

  The main resin is preferably a linear polymer with thermoplastic properties. In order to control fluidity and crystallinity, it may be branched by grafting. The molecular weight is about 1,000 to 500,000 in terms of number average molecular weight, preferably 5,000 to 50,000. If the molecular weight is too small, the flexibility of the film and the resistance to the plating nucleation solution (acid resistance) tend to decrease. Moreover, when molecular weight is too large, there exists a tendency for the sticking property at the time of using alkali peelability or a dry film to worsen. Furthermore, a crosslinking point may be introduced to improve resistance to plating nucleus chemicals, suppress thermal deformation during laser processing, and control flow.

  As the composition of the main resin, (a) a carboxylic acid or acid anhydride monomer having at least one polymerizable unsaturated group in the molecule and (b) (a) a monomer that can be polymerized with the monomer It is obtained by polymerizing. Examples of known techniques include those described in JP-A-7-281437, JP-A-2000-231190, and JP-A-2001-201851. Examples of (a) include, for example, (meth) acrylic acid, fumaric acid, cinnamic acid, crotonic acid, itaconic acid, maleic anhydride, maleic acid half ester, butyl acrylate, etc., alone or 2 More than one type may be combined. Examples of (b) are generally non-acidic and have (one) polymerizable unsaturated group in the molecule, but are not limited thereto. It is selected so as to maintain various properties such as resistance in the plating process and flexibility of the cured film. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert. -Butyl (meth) acrylate, 2-hydroxylethyl (meth) acrylate, 2-hydroxylpropyl (meth) acrylates, etc. are mentioned. Further, esters of vinyl alcohol such as vinyl acetate, (meth) acrylonitrile, styrene, or a polymerizable styrene derivative may be used. It can also be obtained by polymerization of only a carboxylic acid or acid anhydride having one polymerizable unsaturated group in the molecule. Furthermore, a monomer having a plurality of unsaturated groups is selected as a monomer used in the polymer so that it can be three-dimensionally cross-linked, such as an epoxy group, a hydroxyl group, an amino group, an amide group, a vinyl group in the molecular skeleton. Reactive functional groups can be introduced. When the carboxyl group is contained in the resin, the amount of the carboxyl group contained in the resin is preferably 100 to 2000, preferably 100 to 800, as an acid equivalent. Here, the acid equivalent means the weight of the polymer having 1 equivalent of a carboxyl group therein. When the acid equivalent is too low, there is a tendency that compatibility with a solvent or other composition is lowered or plating pretreatment solution resistance is lowered. Moreover, when an acid equivalent is too high, there exists a tendency for peelability to fall. Moreover, the composition ratio of (a) monomer is 5 to 70% by weight.

  Any monomer or oligomer may be used as long as it is resistant to plating nucleation chemicals and can be easily removed with alkali. In order to improve the sticking property of the dry film (DFR), it can be considered that it is used as a plasticizer as a tackifier. Further, a crosslinking agent is added to increase various resistances. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert. -Butyl (meth) acrylate, 2-hydroxylethyl (meth) acrylate, 2-hydroxylpropyl (meth) acrylates, etc. are mentioned. In addition, esters of vinyl alcohol such as vinyl acetate, (meth) acrylonitrile, styrene, or a polymerizable styrene derivative are also included. It can also be obtained by polymerization of only a carboxylic acid or acid anhydride having one polymerizable unsaturated group in the molecule. Furthermore, a polyfunctional unsaturated compound may be included. Any of the above monomers or oligomers obtained by reacting the monomers may be used. In addition to the above monomers, it is possible to include two or more other photopolymerizable monomers. Examples of this monomer include 1,6-hexanediol di (meth) acrylate, 1,4-cyclohexanediol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, Polyoxyalkylene glycol di (meth) acrylate such as polyoxyethylene polyoxypropylene glycol di (meth) acrylate, 2-di (p-hydroxyphenyl) propane di (meth) acrylate, glycerol tri (meth) acrylate, dipentaerythritol penta (Meth) acrylate, trimethylolpropane triglycidyl ether tri (meth) acrylate, bisphenol A diglycidyl ether tri (meth) acrylate, 2,2-bis (4-methyl) Methacryloxy pentaethoxy phenyl) propane, a polyfunctional (meth) acrylate containing urethane groups. Further, any of the above monomers or oligomers obtained by reacting the monomers may be used.

  Furthermore, you may contain a filler. The filler is not particularly limited. Specifically, for example, silica, aluminum hydroxide, magnesium hydroxide, calcium carbonate, clay, kaolin, titanium oxide, barium sulfate, alumina, zinc oxide, talc, mica, glass, titanic acid. Examples include potassium, wollastonite, magnesium sulfate, aluminum borate, and an organic filler. Moreover, since the resist thickness is generally as thin as 1 to 10 μm, a small filler size is preferable. Although it is preferable to use a material having a small average particle size and cut coarse particles, the coarse particles can be crushed during dispersion or removed by filtration.

  Other additives include, for example, photopolymerizable resins (photopolymerization initiators), polymerization inhibitors, colorants (dyes, pigments, coloring pigments), thermal polymerization initiators, and crosslinking agents such as epoxies and urethanes. Can be mentioned.

  In the processing process, for example, laser processing may be used, but in the case of laser processing, it is necessary to impart a laser ablation property to the resist material. As the laser processing machine, for example, a carbon dioxide laser, an excimer laser, a UV-YAG laser, or the like is selected. These laser processing machines have various intrinsic wavelengths, and productivity can be improved by using a material having a high absorption rate for these wavelengths. Among them, the UV-YAG laser is suitable for fine processing, and the laser wavelength is 3rd harmonic 355 nm and 4th harmonic 266 nm. Therefore, it is desirable that the absorption rate is high with respect to these wavelengths. On the other hand, a material having a somewhat low absorption rate may be preferable. Specifically, for example, when a resist having a low UV absorption rate is used, the UV light transmits through the resist, so that energy can be concentrated on the underlying insulating layer processing. That is, since the advantages differ depending on the absorption rate of the laser beam, it is preferable to use a resist in which the absorption rate of the laser beam of the resist is adjusted according to the situation.

<Circuit pattern formation process>
The circuit pattern forming step is a step of forming a circuit pattern portion such as a circuit groove 3 on the insulating substrate 1. As described above, the circuit pattern portion may be not only the circuit groove 3 but also the through hole 4.

  A method for forming the circuit pattern portion is not particularly limited. Specifically, for example, on the insulating base material 1 on which the resin coating 2 is formed, from the outer surface side of the resin coating 2, machining such as laser processing and dicing processing, and mechanical processing such as embossing processing, etc. The method of forming the circuit groove 3 of a desired shape and depth by giving is mentioned. In the case of forming a highly accurate fine circuit, it is preferable to use laser processing. According to laser processing, the cutting depth or the like can be freely adjusted by changing the output of the laser or the like. That is, when the circuit pattern forming step is a step of forming a circuit pattern portion by laser processing, it is preferable because a finer circuit can be formed with high accuracy. It is also preferable from the viewpoint that the cutting depth and the like can be easily adjusted by changing the laser output and the like, and thus the depth of the formed circuit groove 3 and the like can be easily adjusted. Further, by using laser processing, a through hole used for interlayer connection can be formed, or a capacitor can be embedded in the insulating substrate 1.

  Further, as the stamping process, for example, a stamping process using a fine resin mold used in the field of nanoimprinting can be preferably used. Thus, when the circuit pattern forming step is a step of forming a circuit pattern portion using a mold pressing method, it is preferable because the circuit pattern portion can be easily formed by stamping a mold.

  Moreover, a through hole 4 for forming a via hole or the like may be formed as a part of the circuit groove 3. According to this manufacturing method, a through-hole that can be used for a via hole or an inner via hole can be formed when the circuit pattern portion is formed. A via hole or an inner via hole is formed by electroless plating the formed through hole.

  By this step, the shape of the circuit pattern portion such as the shape and depth of the circuit groove 3 and the diameter and position of the through hole 4 is defined. Further, the circuit pattern forming step may dig deeper than the thickness of the resin coating 2, may dig beyond the thickness of the resin coating 2, or may penetrate the insulating substrate 1. .

  Moreover, the filler 11 can be exposed to the exposed surface of the circuit groove 3 by this process. If the circuit groove 3 is formed by a method such as laser processing, the groove can be formed by projecting a part from the exposed surface of the circuit groove 3 while maintaining the shape without destroying the filler 11. . That is, the exposed surface of the circuit groove 3 is a surface formed by laser processing of the inner layer of the insulating substrate 1, and the inner layer in which the filler 11 is dispersed is exposed to the outside. Then, after applying the catalyst to the inner layer of the insulating base material 1 exposed to the outside instead of the outer surface of the hardened insulating base material 1, the inside of the insulating base material 1 is applied to perform electroless plating. And the circuit layer 13 are in direct contact with each other, and adhesion can be improved. The exposure of the filler 11 can be observed by surface observation.

  The width of the circuit pattern portion such as the circuit groove 3 formed in the circuit pattern forming step is not particularly limited. When laser processing is used, a fine circuit having a line width of 20 μm or less can be easily formed. Therefore, it is preferable that the width of the circuit pattern portion has a portion of 20 μm or less because an antenna circuit or the like requiring fine processing can be formed. Further, the depth of the circuit groove 3 is the depth of the circuit layer 13 when the step is eliminated between the circuit layer 13 and the insulating base material 1 by fill-up plating.

<Catalyst deposition process>
The catalyst deposition step is a step of depositing a plating catalyst or its precursor on the surface of the circuit pattern portion such as the circuit groove 3 and the surface of the resin coating 2. At this time, when the through hole 4 is formed, the plating catalyst or its precursor is also applied to the inner wall surface of the through hole 4.

  The plating catalyst or its precursor 5 is a catalyst that is applied to form an electroless plating film only in a portion where it is desired to form an electroless plating film by electroless plating in the plating treatment step. Any plating catalyst can be used without particular limitation as long as it is known as a catalyst for electroless plating. Alternatively, a plating catalyst precursor may be deposited in advance, and the plating catalyst may be generated after removing the resin film. Specific examples of the plating catalyst include, for example, metal palladium (Pd), platinum (Pt), silver (Ag), etc., or a precursor that generates these.

  Examples of the method of depositing the plating catalyst or its precursor 5 include a method of treating with an acidic Pd—Sn colloidal solution treated under acidic conditions of pH 1 to 3 and then treating with an acid solution. It is done. Specific examples include the following methods.

First, oil or the like adhering to the surface of the insulating base material 1 in which the circuit grooves 3 and the through holes 4 are formed is washed in hot water in a surfactant solution (cleaner / conditioner) for a predetermined time. Next, if necessary, a soft etching treatment is performed with a sodium persulfate-sulfuric acid based soft etching agent. And it pickles further in acidic solutions, such as sulfuric acid aqueous solution of pH 1-2, and aqueous hydrochloric acid. Next, a pre-dip treatment is performed in which a chloride ion is adsorbed on the surface of the insulating base material 1 by being immersed in a pre-dip solution mainly composed of a stannous chloride aqueous solution having a concentration of about 0.1%. Then, Pd and Sn are aggregated and adsorbed by further immersing in an acidic plating catalyst colloid solution such as acidic Pd—Sn colloid having pH 1 to 3 containing stannous chloride and palladium chloride. Then, an oxidation-reduction reaction (SnCl ₂ + PdCl ₂ → SnCl ₄ + Pd ↓) is caused between the adsorbed stannous chloride and palladium chloride. Thereby, the metal palladium which is a plating catalyst precipitates.

  In addition, as an acidic plating catalyst colloid solution, a well-known acidic Pd-Sn colloid catalyst solution etc. can be used, and the commercially available plating process using an acidic plating catalyst colloid solution may be used. Such a process is systematized and sold by Rohm & Haas Electronic Materials Co., Ltd., for example.

  Further, the catalyst deposition step includes a step of treating in an acidic catalyst metal colloid solution, the predetermined liquid in the coating removal step is an alkaline solution, and the resin coating swells with respect to the acidic catalyst metal colloid solution. The degree is preferably 60% or less, and the degree of swelling with respect to the alkaline solution is preferably 50% or more.

  According to such a manufacturing method, the resin film is hardly peeled off in the catalyst deposition process treated under acidic conditions, and is easily peeled off in the film removal process treated with an alkaline solution after the catalyst deposition process. Therefore, the resin coating is selectively peeled off in the coating removal step. Accordingly, the portion where the electroless plating film is not formed can be accurately protected in the catalyst deposition step, and the resin coating can be easily peeled off in the coating removal step after deposition of the plating catalyst or its precursor. For this reason, more accurate circuit formation becomes possible.

  By such a catalyst deposition process, the plating catalyst or its precursor 5 can be deposited on the surface of the circuit groove 3, the inner wall surface of the through hole 4, and the surface of the resin coating 2.

<Film removal process>
The coating removal step is a step of removing the resin coating 2 from the insulating base material 1 subjected to the catalyst deposition step.

  The method for removing the resin coating 2 is not particularly limited. Specifically, for example, after the resin film 2 is swollen with a predetermined solution (swelling liquid), the resin film 2 is peeled off from the insulating substrate 1, or the resin with a predetermined solution (swelling liquid). A method of removing the resin film 2 from the insulating substrate 1 after the film 2 is swollen and further partially dissolved, and a method of removing the resin film 2 by dissolving it with a predetermined solution (swelling liquid) Etc. The swelling liquid is not particularly limited as long as it can swell the resin film 2. The swelling or dissolution is performed by immersing the insulating base material 1 covered with the resin coating 2 in the swelling liquid for a predetermined time. And removal efficiency may be improved by irradiating with ultrasonic waves during the immersion. In addition, when it swells and peels, you may peel off with a light force.

  In this film removal step, after the resin film 2 is swollen with a predetermined liquid, or after a part of the resin film 2 is dissolved with a predetermined liquid, the resin film 2 is peeled from the insulating substrate 1. It is preferable that it is a process to perform. According to such a manufacturing method, the resin film can be easily peeled from the insulating base material. Therefore, a highly accurate circuit can be more easily formed on the insulating base material.

  Moreover, it is preferable that the said film removal process is a process of dissolving and removing the said resin film with a predetermined | prescribed liquid. According to such a manufacturing method, the resin film can be easily removed from the insulating base material. Therefore, a highly accurate circuit can be more easily formed on the insulating base material.

  The case where the swellable resin film is used as the resin film 2 will be described.

  As the liquid (swelling liquid) for swelling the swellable resin film 2, the swellable resin film 2 can be used without substantially decomposing or dissolving the insulating substrate 1 and the plating catalyst or its precursor 5. Any liquid that can be swollen or dissolved can be used without particular limitation. Moreover, the liquid which can swell so that the said swellable resin film 2 can be peeled easily is preferable. Such a swelling liquid can be appropriately selected depending on the type and thickness of the swellable resin film 2. Specifically, for example, the swelling resin film is an elastomer such as a diene elastomer, an acrylic elastomer, and a polyester elastomer, or (a) a carboxylic acid or an acid having at least one polymerizable unsaturated group in the molecule. A polymer resin obtained by polymerizing at least one monomer of an anhydride and (b) at least one monomer that can be polymerized with the monomer (a) or the polymer resin In the case where the resin composition is formed from a carboxyl group-containing acrylic resin, an alkaline aqueous solution such as a sodium hydroxide aqueous solution having a concentration of about 1 to 10% can be preferably used.

  In the case of using a plating process that is performed under acidic conditions as described above in the catalyst deposition step, the swelling resin film 2 has a swelling degree of 60% or less, preferably 40% or less under acidic conditions. Yes, such that the degree of swelling is 50% or more under alkaline conditions, for example, elastomers such as diene elastomers, acrylic elastomers, and polyester elastomers, (a) at least one polymerizable unsaturated group in the molecule Polymer resin obtained by polymerizing at least one monomer of carboxylic acid or acid anhydride having at least one monomer and (b) at least one monomer that can be polymerized with monomer (a) Alternatively, it is preferably formed from a resin composition containing the polymer resin and a carboxyl group-containing acrylic resin. Such a swellable resin film easily swells and peels off with an alkaline aqueous solution having a pH of 12 to 14, for example, a sodium hydroxide aqueous solution having a concentration of about 1 to 10%. In addition, in order to improve peelability, you may irradiate with an ultrasonic wave during immersion. Moreover, you may peel by peeling with a light force as needed.

  Examples of the method for swelling the swellable resin film 2 include a method of immersing the insulating base material 1 coated with the swellable resin film 2 in a swelling liquid for a predetermined time. Moreover, in order to improve peelability, it is particularly preferable to irradiate with ultrasonic waves during immersion. In addition, when not peeling only by swelling, you may peel off with a light force as needed.

<Plating process>
The plating process is a process of performing an electroless plating process on the insulating substrate 1 after the resin film 2 is removed.

  As a method of the electroless plating treatment, the insulating base material 1 partially coated with the plating catalyst or its precursor 5 is immersed in an electroless plating solution, and the plating catalyst or its precursor 5 is applied. For example, a method of depositing an electroless plating film (plating layer) only on the portion may be used.

  Examples of the metal used for electroless plating include copper (Cu), nickel (Ni), cobalt (Co), and aluminum (Al). In these, the plating which has Cu as a main component is preferable from the point which is excellent in electroconductivity. Moreover, when Ni is included, it is preferable from the point which is excellent in corrosion resistance and adhesiveness with a solder.

  The film thickness of the electroless plating film 6 is not particularly limited. Specifically, for example, it is preferably about 0.1 to 10 μm, more preferably about 1 to 5 μm. In particular, by increasing the depth of the circuit groove 3, it is possible to easily form a metal wiring having a large thickness and a large cross-sectional area. In this case, it is preferable because the strength of the metal wiring can be improved.

  By the plating process, the electroless plating film 6 is deposited only on the portion where the plating catalyst or its precursor 5 remains on the surface of the insulating base 1. Therefore, it is possible to accurately form the conductive layer only in the portion where the circuit pattern portion is desired to be formed. On the other hand, the deposition of the electroless plating film on the portion where the circuit pattern portion is not formed can be suppressed. Therefore, even when a plurality of fine circuits having a narrow line width with a narrow pitch interval are formed, an unnecessary plating film does not remain between adjacent circuits. Therefore, the occurrence of a short circuit and the occurrence of migration can be suppressed.

  The portion where the electroless plating film 6 is formed becomes the circuit layer 13. That is, the circuit layer 13 is a conductor layer composed of the plating catalyst or its precursor 5 and the electroless plating film 6. Then, since the circuit layer 13 is formed by the process as described above, the bottom surface and the side surface where the circuit layer 13 is embedded are in contact with the filler 11 without interposing other layers, thereby forming the circuit layer 13. Sex is obtained. In the illustrated embodiment, there is no step on the surface of the circuit layer 13 and the insulating base material 1, but the circuit layer 13 is formed so as to protrude from the insulating base material 1, and a part of the circuit layer 13 is insulated base. It may be embedded in the material 1.

<Inspection process>
In the method of manufacturing the circuit board 10, the resin film 2 contains a fluorescent substance, and an inspection process for inspecting defective film removal using light emission from the fluorescent substance after the film removal process. May be further provided. That is, by including a fluorescent substance in the resin film 2, the film removal failure is caused by using light emitted from the fluorescent substance by irradiating the surface to be inspected with ultraviolet light or near ultraviolet light after the film removal step. It is possible to inspect the presence or absence of the film and the location where the film removal is defective. In the circuit board manufacturing method, the circuit layer 13 having an extremely narrow line width and line interval can be formed.

  In the manufacturing method as described above, when the line width and the line interval are extremely narrow, the resin film that should originally be removed is completely between the adjacent circuit pattern portions. There is also a concern that it cannot be removed and remains slightly. There is also a concern that the resin film fragments removed during the formation of the circuit pattern portion may enter and remain in the formed circuit pattern portion. When the resin film 2 remains between the circuit pattern portions, the electroless plating film 6 is formed in that portion, which may cause migration or short circuit. In addition, if a piece of the resin film 2 remains in the formed circuit pattern portion, it may cause a heat resistance failure or propagation loss of the circuit layer 13. In such a case, the resin film is made to contain a fluorescent substance as described above, and after the film removal step, only a portion where the resin film remains by irradiating a predetermined light source on the surface from which the film has been removed. By emitting light with the fluorescent substance, it is possible to inspect the presence or absence of the film removal failure or the location of the film removal failure.

  Specifically, for example, as shown in FIG. 3, in the case where the circuit layer 13 having an extremely narrow line width and line interval is formed, between adjacent circuit wirings 8 formed on the surface of the insulating substrate 1. In addition, there is a concern that the resin coating remains without being completely removed. In such a case, the electroless plating film 6 is formed in that portion, which may cause migration or a short circuit. Even in such a case, if the inspection step is provided, it is possible to inspect the presence / absence of a film removal failure and the location of the film removal failure.

  FIG. 3 is an explanatory diagram for explaining an inspection process for inspecting defective film removal by using a light emission from the fluorescent substance by adding a fluorescent substance to the resin film.

  The fluorescent substance that can be contained in the resin coating 2 used in the inspection step is not particularly limited as long as it exhibits light emission characteristics when irradiated with light from a predetermined light source. Specific examples thereof include Fluoresceine, Eosine, Pyroline G, and the like.

  The portion where light emission from the fluorescent substance is detected by this inspection process is a portion where the residue 2a of the resin coating 2 remains. Therefore, by removing the portion where luminescence is detected, it is possible to suppress the formation of an electroless plating film on that portion. Thereby, generation | occurrence | production of a migration, a short circuit, etc. can be suppressed beforehand.

<Desmear treatment process>
Moreover, in the manufacturing method of the circuit board 10, after performing the said plating process process, specifically, it may further include the desmear process process which performs a desmear process before performing after a fill-up plating. By applying desmear treatment, unnecessary resin adhered to the electroless plating film can be removed. Further, when assuming a multilayer circuit board provided with the obtained circuit board, the surface of the insulating base material where the electroless plating film is not formed is roughened, and the adhesion with the upper layer of the circuit board is improved. Can be improved. Further, a desmear process may be performed on the via bottom. By doing so, unnecessary resin adhered to the via bottom can be removed. Moreover, it does not specifically limit as said desmear process, A well-known desmear process can be used. Specifically, the process etc. which are immersed in a permanganic acid solution etc. are mentioned, for example.

  Through the steps as described above, a circuit board 10 as shown in FIG.

  In the circuit pattern formation step, since the thickness of the resin coating 2 is dug, the circuit layer 13 made of the electroless plating film 6 is formed in a deep portion of the insulating substrate 1 as shown in FIG. Can be formed.

  Specifically, as shown in FIG. 4A, circuits can be formed at positions (electroless plating films 6a to 6d in the drawing) having different depths between a plurality of conductive layers. In this case, the plating process is stopped in the middle of the circuit groove 3, and the electroless plating film 6 has the same thickness. The electroless plating film 6 is formed on the bottom and side surfaces of the circuit groove 3.

  Further, as shown in FIG. 4B, after forming the circuit groove 3 having a predetermined depth in the insulating substrate 1, the circuit layer 13 is formed so as to embed the circuit groove 3 by electroless plating. (Electroless plating films 6e to 6h in the figure). Thus, when the plating is fully filled in the circuit groove 3, when the plating reaches the surface, the plating is stopped without further stacking. This treatment can be performed by selecting a plating chemical solution suitable for such treatment. This form is preferable because it is possible to easily form a circuit having a large cross-sectional area and increase the electric capacity of the circuit.

  Thus, since the depth of the circuit groove 3 can be set for each circuit layer 13, the circuit layer 13 having a different depth (height T) can be easily obtained.

[Method of manufacturing a three-dimensional circuit board]
FIG. 5 is a schematic cross-sectional view for explaining each step of manufacturing the three-dimensional circuit board 60.

  In the three-dimensional circuit board 60, the insulating base material 1 has a stepped surface formed in a step shape, and the surface of the insulating base material 1 is the stepped surface. That is, the insulating base material 1 has a step surface formed in a step shape, and the coating film forming step, the circuit pattern forming step, the catalyst deposition step, the coating film removing step, and the plating treatment are formed on the step surface. It is also preferable to manufacture the three-dimensional circuit board 60 by performing the process. According to such a manufacturing method, the circuit layer 13 that can overcome the step can be easily formed.

  First, as shown in FIG. 5A, the resin coating 2 is formed on the surface of the three-dimensional insulating base 51 having a stepped portion. This process corresponds to a film forming process.

  As the three-dimensional insulating base 51, various resin molded bodies that can be used for manufacturing a three-dimensional circuit board known in the art can be used without any particular limitation. It is preferable from the viewpoint of production efficiency that such a molded body is obtained by injection molding. Specific examples of the resin material for obtaining the resin molding include, for example, polycarbonate resin, polyamide resin, various polyester resins, polyimide resin, polyphenylene sulfide resin, polyphenylene ether resin, cyanate resin, benzoxazine resin, bismaleimide resin, and the like. Can be mentioned. And in this invention, the filler 11 is contained in the resin molding. In FIG. 5, the filler 11 is omitted.

  The method for forming the resin coating 2 is not particularly limited. Specifically, for example, the same formation method as in the case of the planar circuit board 10 may be used.

  Next, as shown in FIG. 5B, a circuit pattern portion such as a circuit groove 3 having a depth deeper than the thickness of the resin coating 2 is formed with the outer surface of the resin coating 2 as a reference. The method for forming the circuit pattern portion is not particularly limited. Specifically, for example, a formation method similar to the case of the circuit board 10 may be used. The circuit pattern portion such as the circuit groove 3 defines a portion where the electroless plating film is formed by electroless plating, that is, a portion where the circuit layer 13 is formed. This step corresponds to a circuit pattern forming step.

  Next, as shown in FIG. 5 (c), a plating catalyst or its precursor 5 is coated on the surface of the circuit pattern portion such as the circuit groove 3 and the surface of the resin film 2 where the circuit pattern portion is not formed. Put on. The method for depositing the plating catalyst or its precursor 5 is not particularly limited. Specifically, for example, the same method as in the case of the circuit board 10 may be used. This step corresponds to a catalyst deposition step. By such a catalyst deposition treatment, the plating catalyst or its precursor 5 can be deposited on the surface of the circuit pattern portion such as the circuit groove 3 and the surface of the resin film 2 as shown in FIG. it can.

  Next, as shown in FIG. 5 (d), the resin coating 2 is removed from the three-dimensional insulating substrate 51. By doing so, the plating catalyst or its precursor 5 can remain only on the surface of the portion of the three-dimensional insulating substrate 51 where the circuit pattern portion such as the circuit groove 3 is formed. On the other hand, the plating catalyst or its precursor 5 deposited on the surface of the resin film 2 is removed together with the resin film 2 while being supported on the resin film 2. The method for removing the resin film 2 is not particularly limited. Specifically, for example, the same method as in the case of the circuit board 10 may be used. This process corresponds to a film removal process.

  Next, as shown in FIG. 5E, electroless plating is performed on the three-dimensional insulating base material 51 from which the resin film 2 has been removed. By doing so, the electroless plating film 6 is formed only in the portion where the plating catalyst or its precursor 5 remains. That is, the electroless plating film 6 to be the circuit layer 13 is formed in the portion where the circuit groove 3 and the through hole 4 are formed. The formation method of the electroless plating film 6 is not particularly limited. Specifically, for example, a formation method similar to the case of the circuit board 10 may be used. This process corresponds to a plating process.

  Through the above steps, a three-dimensional circuit board 60 in which the circuit layer 13 is formed on the three-dimensional solid insulating base 51 as shown in FIG. The three-dimensional circuit board 60 formed in this way can form circuit wiring with high accuracy even if the line width and the line interval of the circuit layer 13 formed on the insulating base 1 are narrow. In addition, the three-dimensional circuit board 60 formed in this way is accurately and easily formed on the surface of the board having the stepped portion.

  Hereinafter, the manufacturing method of the present embodiment will be described more specifically with reference to examples. The scope of the present invention is not construed as being limited in any way by the following examples.

Example 1
First, the insulating base material 1 was formed on the support substrate.

  As a material of the insulating substrate 1, bisphenol A type epoxy resin (“850S” manufactured by DIC Corporation), dicyandiamide (“DICY” manufactured by Nippon Carbide Industries Co., Ltd.) as a curing agent, and curing accelerator 2-ethyl-4-methylimidazole (“2E4MZ” manufactured by Shikoku Chemicals Co., Ltd.) and spherical fused silica (“FB1SDX” manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 1.7 μm) as an inorganic filler, A resin composition containing a silane coupling agent (“A-187” manufactured by Momentive Performance Materials Japan GK) and methyl ethyl ketone (MEK) and N, N-dimethylformamide (DMF) as a solvent is used. It was.

  A sheet-like insulating base material 1 (thickness 60 μm) made of this resin composition is placed on the circuit forming surface of the support substrate, and a PET film (Toyobo Co., Ltd.) is placed on the outer surface of the sheet made of this resin composition. “TN100” manufactured by Co., Ltd. was placed, and this laminate was press-molded and bonded at 0.4 Pa and 100 ° C. for 1 minute, and then heat-cured at 175 ° C. for 90 minutes. Later, the insulating substrate 1 was cured. Then, the laminated body which laminated | stacked the insulating base material 1 on the support body board | substrate was obtained by peeling a PET film. This insulating base material 1 contains 75 wt% of filler with respect to the cured insulating base material 1.

  Moreover, when the surface and the cross section of the insulating base material 1 were observed with the optical microscope, it was confirmed that the filler 11 is not exposed and the surface resin layer 12 is formed.

  Then, a resin film 2 of styrene-butadiene copolymer (SBR) having a thickness of 2 μm was formed on the surface of the insulating substrate 1. The resin coating 2 is formed on the main surface of the epoxy resin base material with a methyl ethyl ketone (MEK) suspension of styrene-butadiene copolymer (SBR) (manufactured by Nippon Zeon Co., Ltd., acid equivalent 600, particle size 200 nm, (15% solid content) was applied and dried at 80 ° C. for 30 minutes.

  Then, a groove having a substantially rectangular cross section having a width of 20 μm and a depth of 30 μm was formed by laser processing on the insulating base material 1 on which the resin coating 2 was formed, thereby forming a circuit groove 3. For laser processing, MODEL 5330 manufactured by ESI equipped with a UV-YAG laser was used. When the surface after laser processing was observed with an optical microscope, it was confirmed that the filler 11 was exposed on the surface of the insulating base material 1 subjected to laser processing (exposed surface of the circuit groove 3).

  Next, the insulating base material 1 in which the circuit groove 3 was formed was immersed in a cleaner conditioner (surfactant solution, pH <1: C / N 3320 manufactured by Rohm & Haas Electronic Materials Co., Ltd.), and then washed with water. Then, soft etching treatment was performed with a sodium persulfate-sulfuric acid-based soft etchant having a pH <1. And the pre-dip process was performed using PD404 (Shipley Far East Co., Ltd., pH <1). Then, by immersing in an acidic Pd-Sn colloidal solution (CAT44, manufactured by Shipley Far East Co., Ltd.) having a pH of 1 containing stannous chloride and palladium chloride, the palladium serving as the core of electroless copper plating is tin-palladium. It was made to adsorb | suck to the insulating base material 1 in the state of a colloid. As a result, the plating catalyst or its precursor 5 was deposited on the surface of the insulating substrate 1 and the surface of the resin coating 2.

  Next, palladium nuclei were generated by immersing them in an accelerator chemical solution of pH <1 (ACC19E, manufactured by Shipley Far East Co., Ltd.). This palladium nucleus serves as a plating nucleus for electroless plating.

  Then, the insulating substrate 1 was immersed for 10 minutes in a 5% aqueous sodium hydroxide solution of pH 14 while being subjected to ultrasonic treatment. Thereby, the resin film 2 (SBR film) on the surface swelled and peeled cleanly. At this time, no fragments or the like of the resin coating 2 remained on the surface of the insulating substrate 1. Then, the insulating substrate 1 was immersed in an electroless plating solution (CM328A, CM328L, CM328C, manufactured by Shipley Far East Co., Ltd.) to perform an electroless copper plating process.

  The electroless copper plating film 6 having a thickness of 3 to 5 μm was deposited by the electroless copper plating treatment. When the surface of the insulating base material 1 subjected to the electroless copper plating treatment was observed with an SEM (scanning microscope), the electroless plating film 6 was accurately formed only in the cut portion. The electroless plating film 6 becomes the circuit layer 13.

  The swelling degree of the swellable resin film was determined as follows.

  The SBR suspension applied to form a swellable resin film on the release paper was applied and dried at 80 ° C. for 30 minutes. Thereby, a 2 μm thick resin film was formed. And the sample was obtained by forcibly peeling the formed film.

  And about 0.02 g of the obtained sample was weighed. The weight of the sample at this time is defined as the weight m (b) before swelling. The weighed sample was immersed in 10 ml of 5% aqueous sodium hydroxide solution at 20 ± 2 ° C. for 15 minutes. Similarly, another sample was immersed in 10 ml of a 5% aqueous hydrochloric acid solution (pH 1) at 20 ± 2 ° C. for 15 minutes.

  Then, centrifugation was performed at 1000 G for about 10 minutes using a centrifuge to remove moisture and the like attached to the sample. Then, the weight of the swollen sample after centrifugation was measured and set as the weight m (a) after swelling. From the obtained weight m (b) before swelling and weight m (a) after swelling, the formula “swelling degree SW = (m (a) −m (b)) / m (b) × 100 (%)” From this, the degree of swelling was calculated. Other conditions were performed in accordance with JIS L1015 8.27 (measurement method of alkali swelling degree).

  At this time, the degree of swelling with respect to a sodium hydroxide 5% aqueous solution at pH 14 was 750%. On the other hand, the degree of swelling with respect to a 5% hydrochloric acid aqueous solution at pH 1 was 3%.

  The circuit board 10 as shown in FIG. 1 can be obtained through the above steps.

(Example 2)
As the resin film 2, a styrene-butadiene copolymer (SBR) methyl ethyl ketone (MEK) suspension (manufactured by Nippon Zeon Co., Ltd., acid equivalent 600, particle size 200 nm, solid content 15%), a carboxyl group-containing polymer The same procedure as in Example 1 was performed except that Nippon Zeon Co., Ltd., acid equivalent 500, weight average molecular weight 25000, solid content 20% was used.

  At this time, the degree of swelling with respect to a 5% aqueous solution of sodium hydroxide at pH 14 was 1000%. On the other hand, the degree of swelling with respect to a 5% hydrochloric acid aqueous solution at pH 1 was 30%.

  Thereby, the circuit board 10 as shown in FIG. 1 was obtained.

  If the manufacturing method of the above Examples is used, a plating catalyst can be made to adhere only to the part which wants to form the circuit of a base-material surface by peeling a swelling resin film. Therefore, an electroless plating film is accurately formed only on the portion where the plating catalyst is deposited. Further, since the swellable resin film can be easily peeled off by the swelling action, the film removal step can be easily and accurately performed.

DESCRIPTION OF SYMBOLS 1 Insulation base material 2 Resin film 3 Circuit groove 4 Through-hole 5 Plating catalyst or its precursor 6 Electroless plating film 10 Circuit board 11 Filler 12 Surface resin layer 13 Circuit layer 51 Three-dimensional insulation base material 60 Three-dimensional circuit board

Claims (6)

  A circuit board formed by embedding a circuit layer made of a conductor on the surface of an insulating base made of a resin containing a filler, and the exposed surface of the insulating base is formed without breaking the filler. The circuit board is characterized in that the contact surface of the circuit layer with the insulating base material is formed in a concavo-convex shape following the protruding shape of the filler to the contact surface.   The circuit board according to claim 1, wherein the contact surface of the circuit layer with the insulating base material is in contact with at least a part of the filler protruding from the contact surface.   The circuit board according to claim 1, wherein the exposed surface of the insulating base material has no exposed filler.   The circuit board according to any one of claims 1 to 3, wherein the contact surface of the insulating base material with the circuit layer is formed into a concavo-convex shape in which a filler protrudes by laser processing.   The circuit board according to claim 1, wherein the circuit layer is formed by plating of a conductor.   The circuit board according to claim 1, wherein the exposed surface of the circuit layer is formed flat and has no step at the boundary with the insulating base material.

Images