JPH1126933A - Film-shaped adhesive for electroless plating and manufacture of printed wiring board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film-shaped adhesive for electroless plating in which the adhesion of deposited electroless plating metal is satisfactory. SOLUTION: A deposition face has a rough face whose mean roughness is 1-10 μm. A film-shaped adhesive for electroless formed on the rough face of a carrier film on which a rough face whose DIN mean roughness is 1-10 μm is formed is integrally laminated on a board, so that the film-shaped adhesive for electroless plating can be brought into contact with the board while it is accompanied with the carrier film. Then, the carrier film is removed so that a laminated board with the adhesive for electroless plating can be obtained. This is provided for manufacturing a printed wiring board by an additive method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a film adhesive for electroless plating and a method for manufacturing a printed wiring board using the same.

[0002]

2. Description of the Related Art As one method of manufacturing a printed wiring board, there is a method of forming a conductive circuit on a substrate by electroless plating. This method is called the additive method. In the additive method, an adhesive layer for electroless plating is formed on a substrate in order to ensure adhesion between a metal deposited by electroless plating and the substrate. The adhesive for electroless plating has a thermosetting resin component, a rubber component, and an inorganic filler component as main components. In order to deposit a metal by electroless plating, a plating catalyst serving as a nucleus of the metal deposition is required. The plating catalyst may be included in an adhesive for electroless plating or a method of attaching the plating catalyst to a surface to be plated later. Usually, a method of incorporating the plating catalyst in the adhesive for electroless plating is used.

[0003] As a method of forming an electroless plating adhesive layer on a substrate, a method in which a varnish in which the electroless plating adhesive is dissolved in a solvent is applied and dried, and a film-like adhesive for electroless plating is laminated on the substrate. There is a method of integration. Conventionally, an insulating plate that does not form a circuit was used as a substrate, but a substrate on which a circuit was formed, that is, a circuit was formed by electroless plating on an adhesive layer for electroless plating using a printed wiring board as a substrate, A method of repeating the above and stacking wiring layers to form a multilayer printed wiring board has also been performed. The method of stacking the wiring layers in this manner is called a build-up method. However, in the build-up method, since the work of forming the adhesive layer for electroless plating is easy, the film-like adhesive for electroless plating is used. Are laminated and integrated on a substrate.

[0004]

Various electronic components are mounted on a printed wiring board. Since this electronic component is exposed to a high temperature such as solder reflow in the mounting step, the adhesive for electroless plating also needs to have heat resistance. When electronic components are directly mounted, the hardness must be high. This is because if the surface of the printed wiring board is soft, the printed wiring board is deformed and becomes unstable at the time of mounting components, which hinders automation. Under these circumstances, the ratio of the thermosetting resin component is increased or the thermosetting resin component having a high Tg is used. Sex decreased. With the miniaturization and multifunctionality of electronic devices, it has become necessary to increase the wiring density of printed wiring boards, and the wiring width has been reduced. It goes without saying that the thinner the wire, the more advantageous it is that the adhesive strength is higher.

It is an object of the present invention to provide a film adhesive for electroless plating having good adhesion of the deposited electroless plating metal. Another object of the present invention is to provide a method for manufacturing a printed wiring board using the film adhesive for electroless plating.

[0006]

The first aspect of the present invention is a film adhesive for electroless plating in which a plating deposition surface is a rough surface having an average roughness of 1 to 10 μm. Here, the average roughness means an arithmetic average roughness defined in JIS B0601.

Further, the invention according to claim 2 has an average roughness of 1 to 3.
The film-like adhesive for electroless plating formed on the rough surface of the carrier film having a rough surface of 10 μm is laminated and integrated such that the film-like adhesive for electroless plating contacts the substrate with the carrier film attached. It is a method of manufacturing a printed wiring board, which comprises subjecting a carrier film to removal, followed by electroless plating.

The film-form adhesive for electroless plating, which has a rough surface having an average roughness of 1 to 10 μm on the plating deposition surface, has a varnish of the film-form adhesive for electroless plating having an average roughness of 1 to 1 μm.
It can be manufactured by coating and drying on a 0 μm carrier film and then removing the carrier film.
When laminating and integrating the film adhesive for electroless plating, the substrate and the film adhesive for electroless plating are superposed and heated and pressed. At this time, if heating and pressing are performed except for the carrier film, the rough surface of the film adhesive for electroless plating is lost. Average roughness is 1 to 10 μm
The film adhesive for electroless plating formed on the rough surface of the carrier film having the rough surface is laminated and integrated such that the film adhesive for electroless plating contacts the substrate with the carrier film attached. Then, after removing the carrier film, the rough surface shape of the carrier film is
It is preferable because it is transferred to the surface of the adhesive layer for electroless plating integrated with the substrate.

If the average roughness of the plating deposition surface is less than 1 μm, the adhesion of the electroless plated metal cannot be improved. On the other hand, if the average roughness of the plating deposition surface exceeds 10 μm, poor adhesion of the plating resist is likely to occur, and the thickness of the adhesive layer is reduced by the amount of the depression, resulting in impaired insulation. For this reason, it is more preferable that the plating deposition surface has an average roughness of 2 to 8 μm.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, as the adhesive for electroless plating, a conventionally known adhesive for electroless plating mainly comprising a thermosetting resin component, a rubber component and an inorganic filler component is used. Can be used.

As the thermosetting resin component, a thermosetting resin having a benzoxazine ring in a resin skeleton, an epoxy resin or the like can be used together with a curing agent. In order to achieve high heat resistance and high hardness, it is preferable to use a thermosetting resin having a benzoxazine ring in the resin skeleton or a polyfunctional phenol novolak-curable epoxy resin.

As the rubber component, a diene rubber, a natural rubber, or the like that can be partially decomposed by treatment with a chromium-sulfuric acid oxidizing agent and roughen the surface of the adhesive for electroless plating is used. Among them, acrylonitrile butadiene rubber, which is a kind of diene rubber, is preferably used.

As the inorganic filler, finely divided silica, aluminum hydroxide and the like are used. This inorganic filler is also decomposed by the treatment with the chromium-sulfuric acid oxidizing agent, and is useful for forming fine irregularities on the surface of the adhesive for electroless plating.

[0014] Plating catalysts usually compounded in the adhesive for electroless plating include Group 1B, 2B, and 8 of the periodic table.
Group metals, such as copper, gold, silver, platinum, palladium,
Iron, cobalt, nickel and the like are used, and a metal simple substance, a salt or an oxide can be used. The plating catalyst can be mixed with the adhesive for electroless plating as a powder, one adhered and supported on the surface of a carrier, or the like.

[0015] The thermosetting resin component contains a curing agent and contains 35%.
To 55% by weight, a rubber component of 15 to 25% by weight and an inorganic filler component of 30 to 40% by weight,
It is appropriately selected according to the required characteristics. If the amount of the rubber component is less than 15% by weight, the flexibility tends to be inferior, and if it exceeds 25% by weight, the insulating property tends to deteriorate. If the amount of the inorganic filler component is less than 30% by weight, the insulating property tends to deteriorate, and if it exceeds 40% by weight, the flexibility tends to deteriorate. When the plating catalyst is compounded, it is preferable that the plating catalyst is compounded in the range of 5 to 15% by weight based on the adhesive. If the amount of the plating catalyst is less than 5% by weight, the effect as a plating catalyst is small, and
If it exceeds 300, the insulating property tends to deteriorate.

The constituents of the adhesive for electroless plating are dissolved in a solvent such as butanone to form a varnish, which is applied to a carrier film and dried. As a coating method, a known method such as a roll coater can be used. By removing the carrier film, the surface shape of the carrier film is transferred and remains on the surface of the film-like adhesive for electroless plating, so that the carrier film has an average roughness of 1 to 1
Any metal film or organic film may be used as long as it has a thickness of 0 μm and the surface shape does not extremely change by heat treatment. Polyethylene terephthalate film,
Paper, copper foil, aluminum foil and the like are preferably used.

The adhesive for electroless plating thus obtained is laminated on a substrate and laminated and integrated using a laminator or a press. The substrate may be any of an insulating plate on which a circuit is not formed and a substrate on which a circuit is formed, that is, a printed wiring board, and is not particularly limited. When using a substrate on which a circuit is formed, in order to improve the adhesion between the circuit and the adhesive for electroless plating, a roughened surface is formed on the circuit surface by oxidation-reduction treatment, and any one of primer treatment or It is preferred to do both.

After laminating and integrating the adhesive for electroless plating on the substrate, the carrier film is removed by drilling for connecting through holes as necessary. The removal of the carrier film can be done by a chemical method of dissolving with acid when copper or aluminum foil is used as the carrier film, or by a physical method of peeling off polyethylene terephthalate film or paper. it can.

Thereafter, a plating resist is adhered, exposed and developed to form a plating resist on portions other than the circuit forming portion, and then the circuit forming portion is roughened with a chromium-sulfuric acid solution, neutralized and washed with water. After the process, the metal is immersed in the electroless plating solution to deposit the metal on the circuit forming portion. When a hole for connecting a through hole is made, it is preferable to perform a seeding process before the neutralization and washing steps to attach a plating catalyst to an inner wall of the hole for connecting a through hole.

By repeating the steps from lamination and integration of the adhesive for electroless plating to electroless plating, a multilayer printed wiring board can be manufactured.

[0021]

【Example】

Example 1 40 parts of a thermosetting resin having a benzoxazine ring in a resin skeleton (parts by weight, the same applies hereinafter), acrylonitrile butadiene rubber 8 parts, phenol novolak resin 12 parts, finely divided silica 2 parts, aluminum hydroxide 15 parts 6 parts of the electroless plating catalyst was dissolved in 83 parts of butanone to prepare a varnish having a solid content of 50% by weight. The thermosetting resin having a benzoxazine ring in the resin skeleton is HR-1001 (trade name) manufactured by Hitachi Chemical Co., Ltd., and the acrylonitrile butadiene rubber is PNR-H manufactured by Nippon Synthetic Rubber Co., Ltd. (Trade name) as phenol novolak resin, HP85 manufactured by Hitachi Chemical Co., Ltd.
0N (trade name), as finely divided silica, manufactured by Nippon Aerosil Co., Ltd., Aerosil # 200 (trade name), as aluminum hydroxide, manufactured by Sumitomo Chemical Co., Ltd.
CL-310 (trade name) and Cat # 14F (trade name, manufactured by Hitachi Chemical Co., Ltd.) were used as a catalyst for electroless plating.

This varnish is applied to a roughened surface of a copper foil (GTS-35 (trade name) manufactured by Furukawa Circuit Wheel Co., Ltd.) having a thickness of 35 μm and an average roughness of a roughened surface of 8 μm. And dried by heating at 120 ° C for 4 minutes to a thickness of 50 µm.
To form a copper foil with an adhesive.

Next, an adhesive layer of copper foil with an adhesive is placed on both sides of the inner layer plate so as to be on the side of the inner layer plate.
Heating and pressurization was performed at 0 ° C. and a pressure of 2.45 MPa for 60 minutes. Next, the copper foil was dissolved and removed with hydrochloric acid, a plating resist was attached, and exposed and developed to remove the plating resist in the circuit forming portion. Next, the circuit forming portion is roughened with a chromium-sulfuric acid solution, passed through a neutralization and water washing process, immersed in an electroless copper plating solution, and deposited with a thickness of 30 μm on the circuit forming portion to form an outer layer circuit pattern. It was created. In addition, as an inner layer board, circuit processing was performed on a glass cloth base epoxy resin double-sided copper-clad laminate (MCL-E-67) manufactured by Hitachi Chemical Co., Ltd. with a board thickness of 0.6 mm and a copper foil thickness of 18 μm. A double-sided printed wiring board subjected to the process is used. The plating resist is SR-3000 (trade name) manufactured by Hitachi Chemical Co., Ltd. The electroless copper plating solution is manufactured by Hitachi Chemical Co., Ltd.
A 59 plating solution (trade name) was used.

Example 2 In place of using a thermosetting resin having a benzoxazine ring in the resin skeleton, a polyfunctional phenol novolak-curable epoxy resin, VE-100 (trade name, manufactured by Hitachi Chemical Co., Ltd.) was used. Was the same as in Example 1.

Example 3 Instead of copper foil (GTS-35), the thickness was 100 μm,
The procedure was the same as that of Example 1 except that a release treated glassine paper having an average roughness of 5.7 μm was used, and the glassine paper was peeled off. The glassine paper used was a product of Honshu Paper Co., Ltd.

Example 4 In place of copper foil (GTS-35), a polyethylene terephthalate film having a thickness of 75 μm and an average roughness of 4.3 μm subjected to embossing and release treatment was used instead of copper foil (GTS-35). Same as. The polyethylene terephthalate film used was S-31 (trade name) manufactured by Teijin Limited.

Example 5 A bisphenol A type epoxy resin was used in place of the thermosetting resin having a benzoxazine ring in the resin skeleton, and 0.1 part of 2-ethyl-4-methylimidazole was compounded as a curing accelerator. Others were the same as Example 1. In addition, YD-128 (trade name) manufactured by Toto Kasei Co., Ltd. was used as the bisphenol A type epoxy resin.

Comparative Example 1 The procedure of Example 1 was repeated except that the varnish was applied to the glossy surface (average roughness 0.7 μm) of copper foil.

Comparative Example 2 The procedure of Example 2 was repeated except that the varnish was applied to the glossy surface (average roughness 0.7 μm) of the copper foil.

The peel strength of the formed outer layer circuit pattern was examined. Table 1 shows the results. The test method was as follows. In accordance with JIS C 6481, etch so that plated copper with a width of 10 mm and a length of 100 mm remains, peel off one end in the length direction, grasp the peeled part with a gripper, and move in a direction perpendicular to the plating surface. After peeling off 50 mm, the minimum value of the load during this time was taken as the peeling strength.

[0031]

[Table 1]

[0032]

According to the present invention, the adhesion of the deposited electroless plating metal can be improved, and the characteristics of the printed wiring board by the additive method can be improved.

Claims (2)

[Claims] 1. The plating surface has an average roughness of 1 to 10 μm.
Film-like adhesive for electroless plating, which has a rough surface. 2. An electroless plating film-like adhesive formed on a rough surface of a carrier film having a rough surface having an average roughness of 1 to 10 μm is applied to a substrate without a carrier film for electroless plating. After laminating and integrating so that the film adhesive is in contact, and after removing the carrier film,
A method for producing a printed wiring board, comprising electroless plating.