JPH1187885A - Production of basic material for lamination - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the thickness of a resist mask at a corner without increasing the viscosity of a liquid resist by subjecting at least the corner of protruding/recessed structure on the surface of a coating layer to surface roughening. SOLUTION: A through hole is made at a required position of an insulating board 10 comprising a laminate board, i.e., a copper clad laminate board, and the inner surface thereof is subjected to copper plating thus forming a through hole 11. The surface of the insulating board 10 is then subjected to polishing and the surface of a metal layer 12 is subjected to oxidation or surface roughening by soft etching before being coated with a photosensitive liquid resist 14. According to the method, dripping of the liquid resist 14 is reduced and the thickness of coating is prevented from decreasing at a part 14a above the corner 12a of the metal layer 12. Consequently, etching resist can be formed with uniform thickness and defect can be suppressed in various surface treatments employing a resist mask.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a laminated substrate, and more particularly to a technique suitable for use in a process for manufacturing a printed wiring board.

[0002]

2. Description of the Related Art Conventionally, as a main manufacturing process of a printed wiring board, for example, a photosensitive resist layer and a resin film are laminated on the surface of a copper foil after cleaning an insulating substrate on which the copper foil is adhered. Attaching a dry film resist, also called a laminated type resist, exposing and developing the dry film resist to form an etching resist of a predetermined pattern, etching a copper foil through the etching resist to a predetermined And a step of forming a conductive pattern of the same.

On the other hand, in a manufacturing process using a photolithography method using a photosensitive resist, not only in a manufacturing process of a printed wiring board but also in a manufacturing process using a photolithography method using a photosensitive resist, a liquid resist composed of a photosensitive liquid is applied and exposed, developed, etc. May be performed.

[0004]

By the way, in the case of a printed wiring board, a through hole is formed in a substrate in advance, and copper plating or the like is applied to an opening edge or an inner surface of the through hole, so that the printed wiring board is electrically driven. There is a case where an insertion portion also serving as an electrode for inserting a leg portion of an element is provided, or a wiring pattern on the front and back of a printed wiring board is conductively connected through a through hole.

In this case, as shown in FIG.
When a liquid resist 14 is applied to the front and back of the metal layer 12 made of a copper foil and a copper plating layer covering the surface of the through hole 11, the portion 14 a applied on the corner 12 a formed at the opening edge of the through hole 11 is liquid. The coating thickness becomes thin due to the sag phenomenon, and the etching resist formed by exposure and development of the liquid resist becomes extremely thin in the portion 14a. As described above, when the etching resist becomes thinner on the corners 12a, the etching resist is destroyed in the pattern etching step of the metal layer 12, and the metal layer 1
There is a problem in that the wiring is cut off at the second corner 12a, and a serious defect occurs in the wiring pattern. In this case, a method of using a high-viscosity liquid resist to secure the thickness of the resist on the corners 12a is disclosed in Japanese Patent Publication No. 61-14680. It is difficult to apply the resist to the uneven portion of the substrate, and there is a possibility that a defect may occur in the etching process.

For this reason, in recent years, a method of attaching a dry film resist has become the mainstream as described above. However, in this method, a portion of the dry film resist covering the through hole 11 is torn and the through hole 11 is broken. An accident that the inner surface of the substrate is etched easily occurs. in this case,
There is also a method in which the inside of the through hole is filled with ink or the like beforehand, and then a dry film is attached. However, the dry film resist has a thin protective film (cover film) overlaid on the photosensitive resist layer. There is a problem in that the resolution of exposure is poor due to the optical action, and precise pattern formation and pattern reproducibility may be insufficient.
Further, when a thin dry film corresponding to the fine pattern is used, the film is more likely to be torn on the through-hole and the adhesion to the metal layer 12 is deteriorated, so that defects are easily generated. Further, if the surface of the metal layer 12 is damaged, an etching solution penetrates between the damaged portion of the metal layer 12 and the dry film resist, and the metal layer 12 is etched to disconnect or chip the wiring pattern. There is also a problem that holes and the like are easily generated.

The above-mentioned problems occur not only in printed wiring boards but also in the manufacture of semiconductor devices and design materials for forming patterns by photolithography, and generally hinder the manufacture of various laminated base materials. Bring. In addition, similar problems occur not only in etching or patterning in the production of these laminated base materials but also in various surface treatments (for example, surface activation treatment with plasma, etc.) through a mask that covers the surface with a predetermined pattern. there's a possibility that.

Accordingly, the present invention has been made to solve the above-mentioned problems, and has as its object to develop a new method which does not easily cause a partial reduction in the thickness of a resist mask even when a liquid resist is used. It is another object of the present invention to provide a method capable of manufacturing a laminated base material.

[0009]

Means taken by the present invention to solve the above-mentioned problems is to provide a method for forming a coating layer on a substrate having an uneven structure covered with a coating layer on the surface of the substrate. Performing a surface roughening treatment on at least the corners of the uneven structure on the surface, a step of applying a liquid resist on the surface of the coating layer, and a step of performing a treatment on the liquid resist to form a resist mask. A method for producing a laminated base material, comprising:

According to this means, by applying a roughening treatment to the surface of the coating layer, it is possible to secure a coating thickness even at the corners of the uneven structure when applying the liquid resist on the surface of the coating layer. Therefore, the thickness of the resist mask at the corner can be ensured without unnecessarily increasing the viscosity of the liquid resist. Therefore, it is possible to suppress the occurrence of defects in various surface treatments using the resist mask, and to use the liquid resist easily without adjusting the viscosity, thereby making it possible to manufacture the resist at low cost. When a resist mask is formed by exposure and development, halation is suppressed because the surface of the coating layer is roughened, and high-precision patterning is possible even when light is not parallel light. Further, since a positive resist can be used, resist deterioration is reduced, and high-resolution patterning can be performed.

The above-mentioned uneven structure includes a through hole, a concave portion,
It includes all holes, steps, protrusions, etc.
It includes all the portions formed at the edges of the through holes, concave portions, holes, etc., the upper portions of the steps, the periphery of the convex portions, and the like.

Here, it is preferable that the coating layer is made of a metal, and the surface roughening treatment is performed by an oxidation treatment or an etching treatment of a surface layer portion of the coating layer.

According to this means, a rough surface having fine irregularities can be easily formed.

It is preferable that the surface roughening treatment is to make the surface portion of the coating layer acicular or porous.

According to this means, it is possible to hold a thicker liquid resist on the surface than in a case where a roughening treatment for forming only irregularities is performed.

The above means can prevent a defect in patterning of the coating layer, particularly when the method has a step of removing a surface layer portion of the coating layer through the resist mask.

In each of the above-mentioned means, when the laminated base is a printed wiring board, the covering layer is a conductor layer such as a metal layer, and the resist mask is an etching resist, the fine conductor pattern is particularly high. It can be formed with high accuracy, and defects in the conductor pattern can be reduced.

[0018]

Next, an embodiment of a method for manufacturing a laminated base material according to the present invention will be described with reference to FIG. In the present embodiment, a through-hole is formed by drilling or the like at a required position of an insulating substrate 10 made of a copper-clad laminate, which is a laminated base material, and copper plating is performed on the inner surface of the through-hole to form a through-hole. A hole 11 is formed. At this time,
A metal layer 12 made of a copper foil or a plating layer covers the entire surface of the insulating substrate 10 including the inner surface of the through hole 11. Thereafter, if necessary, the surface of the insulating substrate 10 is subjected to a polishing treatment such as buffing, chemical polishing (polishing), or slurry polishing. Next, the surface of the metal layer 12 is subjected to oxidation treatment or surface roughening treatment by soft etching.

When the surface of the metal layer 12 is roughened by oxidation, the entire insulating substrate 10 may be immersed in an oxidizing solution, or the oxidizing solution may be sprayed or otherwise applied. May be performed. Examples of the oxidizing solution include a sodium hydroxide aqueous solution, an aqueous solution mainly containing sodium hypochlorite and sodium hydroxide, an aqueous solution of sodium sulfide, a mixed aqueous solution of sodium phosphate, sodium hydroxide, and sodium chlorite, An alkaline aqueous potassium peroxide solution or the like can be used.

When the metal layer 12 is formed of a metal other than copper, for example, a mixed aqueous solution of caustic soda, sodium nitrate, and sodium bichromate, an aqueous solution of sodium sulfide and the like can be used for iron and the like. It can be appropriately selected according to the material of the metal layer. In any case, generally, an alkaline solution (alkaline oxidation treatment liquid) can be used. In this case, the liquid temperature varies depending on the type of the liquid, from normal temperature to about 120 ° C. For example, in the case of an aqueous solution containing sodium hypochlorite and sodium hydroxide as main components, the processing efficiency, reproducibility and 50-90 to maintain uniformity
C. is preferable, and 60-85 C. is more preferable.

The procedure of the oxidation treatment is preferably performed in the order of, for example, degreasing, soft etching, washing with water, acid treatment, washing with water, the above-mentioned oxidation treatment, washing with water, washing with hot water and drying.
Here, for example, an alkaline or acidic degreasing solution can be used for degreasing, a sulfuric acid peroxide solution, an ammonium persulfate solution, a cupric chloride solution or the like can be used for soft etching, and an acid treatment can be used for acid treatment. A sulfuric acid or hydrochloric acid solution of about 5 to 10 vol% can be used.

In this oxidation treatment, a black oxidized portion (CuO) or a brown (brown) oxidized portion (Cu ₂ O) is formed on the surface layer portion 13 near the surface of the metal layer 12 by the oxidizing solution. At this time, the surface layer portion 13 of the metal layer 12 is oxidized, and the structure of the metal layer 12 is also such that a needle-like precipitate layer is formed or the structure becomes an eroded porous structure. For this reason, the surface of the surface layer portion 13 becomes a roughened surface having extremely fine surface roughness.

On the other hand, when the surface roughening treatment is performed by soft etching, the substrate may be immersed in an etchant, or the substrate may be sprayed or otherwise applied with the etchant. Examples of the etchant include inorganic acid solutions such as an aqueous solution mainly containing nitric acid, an aqueous solution mainly containing hydrogen peroxide and sulfuric acid, and organic acids such as an aqueous solution mainly containing formic acid and an aqueous solution mainly containing citric acid. Liquid. The soft etching generally irregularly etches the surface layer portion 13 of the metal layer 12 to form a fine uneven structure or a porous structure due to erosion, roughens the surface, and oxidizes the surface layer portion 13 depending on an etchant. In some cases, light brown Cu ₂ O may be used.

The procedure of soft etching includes, for example, degreasing, washing with water, drying, soft etching (aqueous solution mainly containing nitric acid), washing with water, soft etching (aqueous solution mainly containing formic acid), washing with water, pickling and drying. It is preferable to carry out in order. Here, for example, an acidic or alkaline degreasing treatment liquid can be used for degreasing, and pickling is performed at 3.5 V.
It can be treated by spraying with a hydrochloric acid solution of about ol% at a temperature of 20 to 30 ° C by spraying.

After the above oxidation treatment or soft etching, a photosensitive liquid resist 14 is applied on the roughened surface. In this embodiment, since the surface layer portion 13 is roughened, when the liquid resist 14 is applied thereon, the liquid dripping of the liquid resist 14 is reduced due to surface tension, and the portion 14a on the corner 12a of the metal layer 12 is formed. Also, the decrease in the coating thickness is suppressed. Therefore, the etching resist can be formed to have a more uniform thickness by the process described later, and an etching resist having a thickness that does not hinder the etching can be formed even on the corners 12a of the metal layer 12.

Here, the photosensitive resist may be either a negative type resist or a positive type resist. With conventional dry films, positive resists have poor film formability,
In addition, since the cover film is peeled off by the nitrogen generated in the exposure and development steps, the fact is that only a negative resist can be used. On the other hand, in the present embodiment, since a liquid resist is applied in the manufacturing process, a positive resist can be used.

As the negative resist, various negative photosensitive compositions conventionally used in this field can be used. For example, copolymers such as vinyl-cinnamate, benzyl-acetophenone, and acetophenone-cinnamate are exemplified.

Since the negative type resist is desensitized by oxygen, a cover film is necessary to store it in the form of a dry film. However, in this embodiment, it is only necessary to apply a liquid type in the manufacturing process. It is easy to store the resist without desensitization.

On the other hand, as the positive resist, various positive photosensitive compositions usually used for metal etching can be used. For example, phenol novolak resin, naphthoquinonediazide, polyvinyl alcohol and the like can be mentioned. In the present embodiment, by performing the above-described oxidation treatment or soft etching, the liquid resist 14 is dried or polymerized and cured, and the adhesion between the etching resist formed by patterning and the metal layer 12 is improved, and the adhesion is also improved. Therefore, the peelability of the etching resist in the resist peeling step tends to deteriorate. Therefore, if a photodegradable material is used as the resist material, the resist can be easily peeled off. Therefore, it is advantageous to use a photodegradable positive resist.

Various methods can be applied to the method of applying the liquid resist 14. For example, known coating methods such as a dip coater method, a horizontal coater method, a roll coater method, a curtain coater method, and a screen coater method can be used alone or in combination. More specifically, a method in which the through hole and the surface are simultaneously coated by dip, jet, spray, or the like may be used. After this coating, the liquid resist 14 on the surface is once removed or smoothed, and then further subjected to a roll coater method. , Dip coater method, printing method,
A method of recoating by a curtain coater method, a spray method, or the like may be used.

In the present embodiment, the viscosity of the liquid resist 14 is not particularly limited, and the viscosity is appropriately set according to the coating method, the pattern density of the printed wiring board, and the surface condition roughened by the above-described oxidation treatment or soft etching. can do. However, if the viscosity of the liquid resist 14 becomes too high, it becomes difficult for the etching resist to adhere to fine surface irregularities or small-diameter through holes,
Rather, etching defects are likely to occur. Conversely, if the viscosity of the liquid resist 14 becomes too low, the thickness of the resist required as an etching mask cannot be secured at the time of coating.

The viscosity of the liquid resist 14 that can be actually used was measured by the flow rate from the small holes within a range in which the thickness of the etching resist capable of withstanding the etching of the copper foil of the printed wiring board could be secured. 30 cp for horizontal coater
(Centipoise), and a preferable range is 5 to 50.
cp, 65 cp for a dip coater, a preferred range is 10 to 90 cp, and a spray coater is 75 cp, a preferred range is 15 to 1 cp.
00 cp, 180 ps (poise) for the printing method, 150 to 300 ps as a preferred range, 100 ps for a roll coater, 80 to 200 ps as a preferred range, and 75 for a curtain coater.
ps, and a preferable range is 50 to 150 ps.

After the application of the liquid resist 14 as described above, selective exposure is performed through a known mask film. In this step, in the present embodiment, the metal layer 12 is covered with the surface layer portion 13 described above, and the roughened surface has little gloss and is almost matte. Can be effectively prevented. Therefore, the pattern accuracy of the formed etching resist is improved. In the conventional method, exposure with parallel light was necessary to avoid a decrease in pattern accuracy due to halation, whereas in the present embodiment, a sufficiently good pattern shape was obtained even with scattered light instead of strict parallel light. Obtainable.

After the above exposure, the surface is treated with a developing solution to dissolve and remove unnecessary portions to form an etching resist having a required pattern shape. Thereafter, if necessary, the surface layer portion 13 is etched to expose a relatively flat and non-oxidized metal layer 12 in a portion not covered with the etching resist. For example, the surface layer 13 can be removed by spraying a hydrochloric acid solution of about 2 to 5 vol% to the one subjected to the above-described oxidation treatment, and a metal-colored surface can be obtained. By removing the surface layer portion 13 in this manner, the surface layer portion 13 remains only in the portion to be covered with the etching resist, so that a difference in contrast occurs depending on the presence or absence of the surface layer portion 13, and the optical system is inspected when inspecting the etching resist. This has the effect of facilitating observation and automatic determination by a visual inspection machine or the like.

Next, the metal layer 12 in a region not covered with the etching resist is removed by etching using a method used in a normal printed wiring board manufacturing process. In this step, for example, in the case of the metal layer 12 composed of a copper foil or a copper plating layer, a cupric chloride solution,
An etching solution such as a ferric chloride solution is used. When this etching removal step is completed, the etching resist is removed. For example, when a photo-decomposable phenol novolak resin is used as a resist, 3 ×
The etching resist is washed away with an aqueous solution of caustic soda of about 5 vol%.

Thereafter, the substrate is subjected to ultrasonic wave, spray, jet,
The printed wiring board is completed by appropriately cleaning and cleaning with a vacuum or the like, and finally covering the surface with a permanent resist. Here, in the present embodiment, since the above-described surface layer portion 13 is formed on the surface of the conductor pattern, the adhesion to the permanent resist is improved. In addition, the presence of the surface layer portion 13 can prevent the permanent resist from dripping at the through-hole portion and the corner of the conductor pattern.

In the above embodiment, an example is shown in which the present invention is applied to a printed wiring board having through holes. However, the present invention is not limited to through holes, and any hole having a concave-convex structure on its surface may have a blind hole structure. The effect can be obtained at the corners of various concave-convex structure portions such as the edge portion and the convex portion of the conductive pad. Also, in the middle of the manufacturing process of the multilayer printed wiring board, the edges and corners of the uneven structure portion such as the inner via hole and the blind via hole, or the step of the upper layer caused by the thickness of the lower wiring and the electrode pattern. The effect can be obtained also in the section.

Further, the present invention can be applied not only to the above-mentioned printed wiring board but also to semiconductor devices, various printed matters, and the like. Further, the resist mask formed by the liquid resist is not limited to a mask used as an etching mask, and may be a mask used when performing various surface treatments such as plasma treatment, doping, and ion plantation.

In this embodiment, the entire surface is oxidized or soft-etched. However, in order to obtain an effect on various corners such as edges, corners and steps of the uneven structure on the surface. Alternatively, only the corner portion or only the corner portion and its vicinity may be subjected to the above-described oxidation treatment or soft etching.

[0040]

EXAMPLES Next, more specific examples and their results will be described.

(Example 1) Substrate R-1705SX (material FR-4, plate thickness 1.6 mm, manufactured by Matsushita Electric Works, product number)
A plurality of three types of through-holes having a hole diameter of 0.2 mm, 1.0 mm, and 6.0 mm were respectively formed in the holes, and the thickness was 25 μm.
Copper plating. Thereafter, Enplate MB-438A (manufactured by Meltics Co., Ltd.), which is an aqueous solution mainly containing sodium hypochlorite and sodium hydroxide,
(Trademark, product number) 80 ml / liter, Emplate MB-438B (manufactured by Meltics Co., Ltd.)
(Trademark, product number) mixed with 130 ml / liter of water was kept at 85 ° C., and the substrate was immersed in the mixture for 3 minutes to perform an oxidation treatment. The temperature may not be the above temperature, but is preferably in the range of 50 to 90 ° C, and more preferably in the range of 60 to 85 ° C, in order to ensure processing efficiency, reproducibility and uniformity.

Next, FHWS-10 was used as a liquid resist.
1 (manufactured by Fuji Film Ohlin Co., Ltd., product number) was applied to the substrate by a dipping method, transferred to a drying furnace, and dried at 80 ° C. for 8 minutes. Next, 200mJ /
Exposure was performed with an irradiation amount of cm ² , and development processing was performed for 20 seconds at 30 ° C. using a developing solution composed of a 1% aqueous solution of sodium carbonate. Next, etching treatment was performed at 45 ° C. for 90 seconds using an etching solution containing ferric chloride as a main component to form a conductor pattern.

In this embodiment, the oxidized surface portion formed by the oxidation treatment has a thickness of about 0.5 to 1.0 μm, and is a black needle-like deposition layer. No defect of the conductor pattern was found in any of the through-holes having any diameter.

Example 2 In a process similar to the above,
Instead of the above oxidation treatment, MEC etch bond CZ-5480 (trade name, product number, manufactured by MEC Corporation), which is a liquid containing nitric acid as a main component, is sprayed on the substrate surface for 10 to 20 seconds while being kept at 30 ° C. And soft etching was performed. The processing solution for soft etching is a solution containing formic acid as a main component such as sodium formate.
Almost the same results were obtained with -8100 (manufactured by MEC Corporation, trademark, product number). In any case, the temperature may not be the above temperature, but in order to quickly and uniformly roughen the surface, the temperature is preferably in the range of 25 to 40 ° C, and in the range of 30 to 35 ° C. Is more preferred. In addition, it is most preferable to treat with a liquid containing nitric acid as a main component, then wash with water, and treat with a liquid containing formic acid as a main component in order to surely roughen the surface.

In this embodiment, the erosion of copper by soft etching was about 1 to 3 μm, and fine irregularities were formed on the surface. Further, no defects in the conductor pattern were found in any of the through-holes having any diameter.

(Comparative Example) A printed wiring board manufactured without performing the oxidation treatment and the soft etching was also made to be a comparative example with respect to the above-mentioned Examples 1 and 2. In this comparative example, the through-holes having any diameters were all etched at the corners formed at the edges, and some of the conductor patterns were cut off.

In each of the examples, the average thickness of the etching resist was about 7 μm, but in Examples 1 and 2, the thickness distribution was within the range of 5 to 10 μm. On the other hand, in the comparative example, there were many portions where the thickness of the resist was less than 4 μm at the corners of the opening edges of the through holes.

[0048]

According to the present invention, by applying a roughening treatment to the surface of the coating layer, the coating thickness is ensured even at the corners of the uneven structure when the liquid resist is applied on the surface of the coating layer. Therefore, the thickness of the resist mask at the corner can be ensured without unnecessarily increasing the viscosity of the liquid resist. Therefore, it is possible to suppress the occurrence of defects in various surface treatments using the resist mask, and to use the liquid resist easily without adjusting the viscosity, thereby making it possible to manufacture the resist at low cost. When a resist mask is formed by exposure and development, halation is suppressed because the surface of the coating layer is roughened, and high-precision patterning is possible even when light is not parallel light. Further, since a positive resist can be used, resist deterioration is reduced, and high-resolution patterning can be performed.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view of a printed wiring board showing a coated state of a liquid resist according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a printed wiring board showing a state of applying a conventional liquid resist.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Insulating substrate 11 Through hole 12 Metal layer (coating layer) 12a Corner 13 Surface layer 14 Liquid resist 14a Part Printed wiring board (laminated base material)

Claims (5)

[Claims] A step of subjecting a laminated substrate having an uneven structure covered with a coating layer on the surface of a base material to a surface roughening treatment on at least a corner of the uneven structure on the surface of the coating layer; A method for manufacturing a laminated base material, comprising: a step of applying a liquid resist on a surface of the coating layer; and a step of performing a treatment on the liquid resist to form a resist mask. 2. The method according to claim 1, wherein the coating layer is made of a metal, and the surface roughening treatment is performed by oxidizing or etching a surface portion of the coating layer. Method. 3. The method according to claim 1, wherein the surface roughening is performed by:
A method for producing a laminated base material, wherein the surface layer portion of the coating layer is made acicular or porous. 4. The method according to claim 1, further comprising a step of removing a surface portion of the coating layer through the resist mask. 5. The method according to claim 1, wherein the laminated base is a printed wiring board, the covering layer is a conductor layer, and the resist mask is an etching resist. A method for producing a laminated base material.