JPH09172256A - Manufacture of multilayer board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a multilayer board, which laminates a prepreg on an internal layer board performed a treatment for performing a reduction treatment after an oxidation treatment, heats, presses and molds the laminated material to manufacture the multilayer board, does not make a spot form on an internal layer pattern and obtains the multilayer board of a good finish from the viewpoint of visual appearance. SOLUTION: A water-soluble photosensitive resist is performed on the surface of a copper-clad laminated board and after the resist is exposed, it is subjected to developing and etching, then, the resist is peeled from the surface of the laminated board using a release agent containing a defoaming agent to form an internal layer board having an internal layer pattern on its surface and after a treatment for performing a reduction treatment after an oxidation treatment is performed on the internal layer board, a prepreg is laminated on the internal layer board and the laminated material is thermocompressed and is molded to manufacture a multilayer board.

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 multi-layer board used in electric / electronic equipment.

[0002]

2. Description of the Related Art Conventionally, multilayer boards used in electronic equipment are
After forming an inner layer pattern on the surface of the inner layer substrate and performing an oxidation treatment on the inner layer substrate, the inner layer substrate and / or
Alternatively, it is manufactured by stacking a prepreg underneath, arranging a metal foil on the outermost layer of the prepreg, laminating the prepreg, and then heat-pressing.

As a method of forming the inner layer pattern, for example, a photosensitive resist is applied to the surface of a copper-clad laminate by pressing, pressure bonding, etc., and then a pattern film is brought into close contact with the substrate to expose it to partially cure the photosensitive resist. . Next, the uncured part of the photosensitive resist is removed (developed) using a developing solution, the copper foil in the part where the photosensitive resist of the uncured part is removed is etched using an etching solution, and then the remaining photoresist is removed using a stripping solution. It is generally formed by removing (peeling) the resist. When a photosensitive resist of a type that is soluble in alkali, called a water-soluble photosensitive resist, is used as the photosensitive resist, the photosensitive resist is dissolved in the developer and the viscosity of the liquid increases during the development process, and the liquid with high viscosity is agitated. As a result, a large amount of bubbles are generated, and it becomes difficult for the developing solution to uniformly contact the photosensitive resist, so that the width of the photosensitive resist becomes thicker or the removal becomes insufficient, and there is a problem that the etching accuracy is reduced. Therefore, the developer is generally made to contain an additive called an antifoaming agent to prevent the generation of bubbles and improve the etching accuracy. However, in the stripping step, since the photosensitive resist in the portion cured by light is removed, the photosensitive resist is hardly dissolved in the stripping solution and does not affect the etching accuracy. Therefore, additives are not particularly considered. Is common.

The above-mentioned oxidation treatment is a chemical oxidation treatment called blackening treatment, which is a black oxidation treatment which is applied to the shiny side of the copper foil of the inner layer pattern and has fine irregularities on the copper foil surface. This is a treatment that forms a film and improves the adhesiveness of the shiny side of the copper foil.

With the recent increase in the density of multi-layer boards, when a printed wiring board is manufactured using this multi-layer board, an acid such as a plating solution used in the manufacturing process dissolves the above-mentioned oxidation treatment film, resulting in a black color. Turns into pink, and a phenomenon called haloing may occur, which is a problem in appearance. As a countermeasure against the occurrence of this haloing, a method of subjecting the inner layer pattern formed on the inner layer substrate to an oxidation treatment and a reduction treatment (hereinafter referred to as an acid resistance treatment) in order to improve the acid resistance of the multilayer board is a method. Considered and implemented. In this acid-resistant treatment, the black copper oxide formed when oxidized is eluted by reduction, so the color tone of the treatment becomes lighter than when oxidized. At this time, there may be a part where the color tone is particularly thin, and a multilayer board is manufactured using the inner layer substrate where the part where the color tone is particularly partly generated, and the outermost layer of this multilayer board is manufactured. When the outer layer pattern is formed by etching the metal foil, the phenomenon in which the part of the inner layer pattern whose color tone is particularly thin is partially visible from the insulating portion between the outer layer patterns may be seen through. The part that can be seen through in a spotted shape looks the same as when foreign matter is mixed in the surface of the inner layer pattern or when part of the inner layer pattern is missing and disappears. Since it is indistinguishable from the case where a part of the inner layer pattern is lost and disappears, the multilayer board has to be discarded and the yield is reduced, which is a problem.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. The object of the present invention is to stack an acid-resistant inner layer substrate and a prepreg and heat the substrate. It is an object of the present invention to provide a method for producing a multilayer board produced by pressure molding, in which spots are not formed on an inner layer pattern and a multilayer board having a good appearance is obtained.

[0007]

According to a first aspect of the present invention, there is provided a method for producing a multilayer board, which comprises applying a water-soluble photosensitive resist on the surface of a copper-clad laminate, exposing it, developing it, etching it, and then removing a stripping solution. A multilayer board manufactured by peeling using to form an inner layer substrate having an inner layer pattern on the surface, acid-treating the inner layer substrate, then laminating the inner layer substrate and prepreg, and heat-press molding In the production method of, the stripping solution contains an antifoaming agent.

The method for producing a multilayer board according to claim 2 of the present invention is characterized in that, in the method for producing a multilayer board according to claim 1, the defoaming agent is a polyoxyalkylene fatty acid ester.

The method for manufacturing a multilayer board according to claim 3 of the present invention is the method for manufacturing a multilayer board according to claim 1 or 2, wherein the defoaming agent is added to the stripping solution with respect to 100 parts by weight of the stripping solution. It is characterized by containing 0.02 to 0.1 part by weight.

The method for producing a multilayer board according to claim 4 of the present invention is the method for producing a multilayer board according to any one of claims 1 to 3, wherein the water-soluble photosensitive resist has a thickness of 10 to 10.
It is characterized in that it is a sheet-like photosensitive resist of 50 μm.

In order to solve the above-mentioned problems, the inventors have conducted various investigations, and as a result, the photosensitive resist or the like remains thin on a part of the surface of the inner layer pattern, and the thin remaining photosensitive resist or the like has the reactivity of the acid resistance treatment. It has been found that the change is one of the causes that a part where the color tone is particularly thin occurs in the inner layer pattern. Therefore, the inventors have found a manufacturing method in which the photosensitive resist or the like hardly remains on a part of the surface of the inner layer pattern, and solved the problem.

According to the method for producing a multilayer board of the present invention, since the stripping solution contains an antifoaming agent, the strippability of the stripping solution is improved,
It is possible to uniformly remove the photosensitive resist, and it is possible to obtain a multilayer board having a good finish in appearance even when an inner layer substrate subjected to an acid resistance treatment is used.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a multilayer board according to the present invention comprises applying a water-soluble photosensitive resist to the surface of a copper-clad laminate by pressing, pressure bonding, etc., and then exposing a pattern film by bringing it into close contact to expose the photosensitive resist. Harden. Next, the uncured part of the photosensitive resist is removed (developed) using a developing solution, the copper foil in the part where the photosensitive resist of the uncured part is removed is etched using an etching solution, and then the remaining photoresist is removed using a stripping solution. The resist is removed (peeled) to form an inner layer substrate having an inner layer pattern on its surface. Then, after subjecting the inner layer substrate to acid resistance treatment, the inner layer substrate, the prepreg and, if necessary, a metal foil are laminated, and heat-pressed to manufacture.

It is important for the stripping solution used at this time to contain an antifoaming agent. By containing the defoaming agent, the strippability of the stripping solution is improved, and a thin photosensitive resist, a small photosensitive resist, etc. Even in this case, it is hard to remain on the inner layer pattern, and the photosensitive resist can be uniformly removed. The components other than the defoaming agent contained in the stripping solution are generally alkali such as sodium hydroxide and potassium hydroxide and water, the concentration of the alkali is 1 to 4%, and the treating temperature of the stripping solution is 40 to 60. C is common.

Examples of the defoaming agent include polyoxyalkylene fatty acid esters, organic silicon compounds such as silicon oil, and the like. In the case of the polyoxyalkylene fatty acid ester represented by the following formula (A), the dispersibility in the stripping solution and the surface activity are good, and the effect of uniformly removing the photosensitive resist is large, which is preferable. In the formula, R represents hydrogen or an alkyl group having 30 or less carbon atoms, and a, b, and c are 0.
Or, it represents a positive number. However, a, b, and c are numbers that do not become 0 at the same time.

[0016]

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The amount of the defoaming agent contained in the stripping solution is preferably 0.02 to 0.1 part by weight per 100 parts by weight of the stripping solution. If the amount is less than 0.02 part by weight, the surface active force is small, and a thin photosensitive resist or a small photosensitive resist may remain slightly. If the amount exceeds 0.1 part by weight, the defoaming agent may cause an inner layer pattern. When the defoaming agent remains on the surface of the inner layer, the anti-foaming agent may change the reactivity of the acid resistance treatment.

Exposure, development, etching, etc., which are steps other than peeling when forming the inner layer pattern, are not particularly limited, and a general method can be applied depending on the photosensitive resist used.

The method of manufacturing a multilayer board according to the present invention is as follows.
It is limited to the case where the inner layer pattern is subjected to acid resistance treatment. The acid-resistant treatment is a chemical treatment in which oxidation treatment and reduction treatment are performed, and the acid-proof treatment is performed on the shiny side or the copper-plated surface of the copper foil and / or the copper foil of the inner layer pattern formed by copper plating. This is a treatment for improving adhesiveness after ensuring the adhesiveness. Generally, after treating with a liquid containing an oxidizing agent and alkali to form copper oxide, it is treated with an organic reducing agent, active hydrogen or a weak acid chelate solution, etc., and the black copper oxide formed during the oxidizing treatment is eluted by reduction. Then, a light black or dark brown acid resistant film is formed. Therefore, the color tone of the treatment becomes lighter than that of the oxidation. If a thin photosensitive resist, a small photosensitive resist, or the like remains on the inner layer pattern, the reactivity of the acid resistance treatment is changed, and a part where the color tone is particularly thin occurs in the inner layer pattern. However, according to the manufacturing method of the present invention, since the photosensitive resist can be uniformly removed, a portion where the color tone is particularly thin is not likely to occur in the inner layer pattern.

Examples of the photosensitive resist used in the present invention include water-soluble (alkaline developing type) sheet-like dry film and ink. A sheet-shaped photosensitive resist having a thickness of 10 to 50 μm is preferable because it has a proper resolution and a proper adhesion to the metal part. The photosensitive resist is preferably a negative type. The positive type, in which the photosensitive resist in the portion irradiated with light is removed by development, has a poor adhesion to a metal, and thus a chipping defect is likely to occur when forming the inner layer pattern.

The copper-clad laminate used in the present invention may be a plate having a copper foil stretched on one or both sides, and examples thereof include epoxy resin type, phenol resin type, polyimide resin type and unsaturated polyester resin. -Based, polyphenylene ether resin-based thermosetting resin, polyvinyl chloride, a sheet of thermoplastic resin such as polyethylene, a plate with copper foil on one or both sides, inorganic fibers such as glass, polyester, polyamide , Organic fibers such as polyacrylic and polyimide, cloth of natural fibers such as cotton, base materials such as paper are bonded with the thermosetting resin or the thermoplastic resin, and copper foil is stretched on one or both sides. A plate that is used. Examples of the copper foil of the copper-clad laminate used in the present invention include electrolytic copper foil and rolled copper foil, and the thickness of the copper foil is preferably 5 to 70 μm. 5
If it is less than micron, it becomes difficult to obtain the copper foil, and if it exceeds 70 micron, the etching accuracy of the circuit is deteriorated. The copper-clad laminate may be a copper-clad laminate having a copper layer formed by plating the surface of a plate not coated with copper foil, or may be a copper-clad laminate having a copper plated surface. .

The method of laminating the inner layer substrate and the prepreg and heat-pressing is not particularly limited, and a general method can be applied. The prepreg is made of resin,
It is obtained by impregnating a base material such as paper or cloth and semi-curing it. As the resin, epoxy resin type, phenol resin type, polyimide resin type, unsaturated polyester resin type, polyphenylene ether resin type, etc. In general, thermosetting resins such as modified products and mixtures are used, and if necessary, inorganic powder fillers such as silica, calcium carbonate, aluminum hydroxide and talc, glass fibers, pulp fibers, synthetic fibers and ceramics. Contains fibrous fillers such as fibers.
As the base material, inorganic fibers such as glass, organic fibers such as polyester, polyamide, polyacryl and polyimide, cloth of natural fibers such as cotton, paper and the like are used.

[0023]

【Example】

(Example 1) A copper foil (thickness: 35 μm) of a double-sided glass substrate epoxy resin copper-clad laminate (FR-4 type) having a size of 50 × 50 cm and a thickness of 0.4 mm excluding a copper foil, a thickness of 30 μm, a negative type A sheet-shaped water-soluble photosensitive resist [manufactured by Tokyo Ohka Kogyo Co., Ltd., product name AF-730] was attached. Then, a mask film was brought into contact with the photosensitive resist, and then UV light having a light amount of 50 mJ / cm 2 was irradiated for exposure, and the mask film was released.
It was left for 0 minutes. Then, a solution containing 1 part by weight of sodium carbonate with respect to 100 parts by weight of a developing solution and having a temperature of 28 ° C. is sprayed for 2 minutes to shield with a mask film to dissolve the photosensitive resist in a portion not irradiated with UV light. After developing
Washed with water. Then, using a cupric chloride etching solution, the metal part of the part where the photosensitive resist is dissolved is dissolved and etched, and then washed with water, and then a stripping solution is sprayed for 2 minutes to dissolve and strip the remaining photosensitive resist, followed by washing with water. To form an inner layer substrate having an inner layer pattern on its surface.

As the above-mentioned stripping solution, the stripping solution 100
3 parts by weight of sodium hydroxide and 0.05 parts by weight of a polyoxyalkylene fatty acid ester represented by the above formula (A) [manufactured by Toho Chiba Chemical Co., Ltd., product name Pronal 502] as an antifoaming agent. Contains, liquid temperature 50 ℃
Was used.

After buffing the obtained copper foil surface of the inner layer pattern, it was immersed in a copper chloride solution at 25 ° C. for 25 seconds and washed with water,
Then, soak in hydrochloric acid solution at room temperature for 60 seconds, wash with water, and then
It was immersed for 60 seconds in an aqueous solution containing sodium chlorite, sodium phosphate and sodium hydroxide at 6 ° C. and washed with water to form copper oxide. Next, copper powder is coated on the zinc oxide and immersed in sulfuric acid to generate hydrogen, the copper oxide is reduced by the hydrogen, washed with water, and heated at 100 ° C. for 20 minutes.
After minute drying, the inner layer pattern was subjected to acid resistance treatment.

Next, two glass-based epoxy resin prepregs (FR-4 type) each having a thickness of 0.15 mm and a resin content of 50% were stacked on the upper and lower two layers, respectively, on the acid-resistant inner layer substrate. 18-thick outer layer of prepreg
A copper foil of μm is arranged and laminated, and this laminated body is heated at a temperature of 170
A multilayer plate was obtained by heat and pressure molding under the conditions of ° C, pressure 3.9 MPa, time 60 minutes.

Example 2 A multilayer board was obtained in the same manner as in Example 1 except that the amount of the polyoxyalkylene fatty acid ester contained in the stripping solution was 0.2 part by weight with respect to 100 parts by weight of water. .

Comparative Example 1 A multilayer board was obtained in the same manner as in Example 1 except that the stripping solution did not contain polyoxyalkylene fatty acid ester.

The outer layer copper foils of the multilayer boards obtained in Examples 1 and 2 and Comparative Example 1 were entirely removed by etching, and the presence or absence of spots in the inner layer pattern was visually inspected and evaluated. As a result, as shown in Table 1, it was confirmed that in Examples 1 and 2, spots were less likely to occur in the inner layer pattern as compared with Comparative Example 1.

[0030]

[Table 1]

[0031]

According to the method for producing a multilayer board of the present invention, an inner layer pattern is formed when an inner layer substrate having an inner layer pattern subjected to an acid treatment and a prepreg are laminated and heat-pressed to produce a multilayer board. It is possible to obtain a multi-layer board having a good finished appearance without the formation of dot-like spots.

Claims (4)

[Claims] 1. A surface of a copper-clad laminate is coated with a water-soluble photosensitive resist, exposed, developed, etched, and then peeled using a peeling solution to form an inner layer substrate having an inner layer pattern on the surface, In the method for producing a multilayer board in which the inner layer substrate is subjected to a reduction treatment and then a reduction treatment, and then the inner layer substrate and a prepreg are laminated, and heated and pressed to produce, a defoaming agent is contained in the release liquid. A method for producing a multilayer board, comprising: 2. The method for producing a multilayer board according to claim 1, wherein the defoaming agent is a polyoxyalkylene fatty acid ester. 3. The production of a multilayer board according to claim 1, wherein the stripping solution contains an antifoaming agent in an amount of 0.02 to 0.1 part by weight per 100 parts by weight of the stripping solution. Method. 4. The water-soluble photosensitive resist has a thickness of 10 to 50.
The method for producing a multilayer board according to any one of claims 1 to 3, which is a sheet-like photosensitive resist having a thickness of µm.