JPH0250148B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention provides a flexible printed wiring board that has strong adhesion between metal foil and thin synthetic resin material, excellent heat resistance and heat deterioration resistance, as well as moisture resistance and flame retardancy, and The present invention relates to an adhesive composition for flexible printed wiring boards that has excellent processing properties. [Technical background of the invention and its problems] In recent years, as electronic devices have become denser, lighter, thinner, and smaller, there has been an increasing demand for lightweight, flexible printed wiring boards that can be mounted with three-dimensional wiring or functions. ing. In addition, in consumer electronics, from the viewpoint of safety in particular, demands for flame retardant materials and adhesive properties after heat deterioration are becoming stronger. Adhesives for flexible printed wiring boards are used not only to bond thin synthetic resin materials and the treated surface of metal foil, but also to insulate and protect circuits on the shine (polished) surface of the metal foil of patterned wiring boards. It is desirable that it can be used to adhere ray films. In particular, the adhesive for the coverlay film must be able to firmly adhere to the shear-in surface of the metal foil, suppress the flow out to the land portion to a small amount, and have good embedding properties between pattern circuits. Moreover, the shelf life is required to be at least one month at room temperature and three months or more at 5°C. Furthermore, in order to improve productivity and maintain dimensional accuracy, there is a need for workability that allows for heating and compression bonding at low temperatures and in a short time. However, even when polyimide film, which has excellent heat resistance and flame retardancy, is used as a thin base material, in addition to the above-mentioned processing properties of the flexible printed wiring board, there are also problems in adhesiveness, heat resistance, inter-line insulation resistance, heat deterioration resistance, and It has been extremely difficult to provide flame retardancy. Conventionally, nitrile rubber adhesives (JP-A-Show) have been used as adhesives for flexible printed wiring boards.
51-135936, JP-A-57-3877), polyamide adhesives (JP-A-54-125285), polyester adhesives (JP-A-50-16866, JP-A-54-7441)
No.), polyacrylic adhesive (Japanese Patent Application Laid-open No. 162736, 1983)
Many other proposals have been made. However, the nitrile rubber type has poor adhesion after heat-resistant deterioration,
It has the disadvantage that it tends to become extremely hard after a 10-day air deterioration test at 150°C, and polyamide-based materials also have the disadvantage of being somewhat hygroscopic. Polyester-based materials have the disadvantage of weak adhesive strength to polyimide films, and polyacrylic-based materials require high temperatures and long periods of time for heat molding, and when the molding temperature is lowered and the molding time is shortened, they have the disadvantage of poor moisture resistance. [Object of the Invention] The object of the present invention was to solve the above-mentioned difficulties and disadvantages, and to provide an adhesive that has excellent adhesive properties, heat deterioration resistance, flame retardance, and moisture resistance, and which can be used as a coverlay adhesive. The present invention aims to provide an adhesive composition for flexible printed wiring boards that has good processing properties. [Summary of the Invention] As a result of extensive studies aimed at achieving the above object, the present inventors discovered that the adhesive composition described below is suitable as an adhesive for flexible printed wiring boards, and thus arrived at the present invention. It is ivy. That is, the present invention provides (A) an acrylic elastomer having one or more functional groups selected from the group of epoxy groups, carboxyl groups, and hydroxyl groups, (B) polyparavinylphenol resin, (C) epoxy This is an adhesive composition for a flexible printed wiring board, which contains a resin, (D) a saturated polyester resin, (E) a curing accelerator, and (F) an inorganic filler as essential components. Examples of the acrylic elastomer (A) having one or more functional groups selected from the group of epoxy groups, carboxyl groups, and hydroxyl groups used in the present invention include Arontak S-1511L, S-
1511X, S-1015, S-1017 (manufactured by Toagosei Kagaku Co., Ltd.,
(Product name), AR-51 (manufactured by Nippon Zeon Co., Ltd., Product name),
Noxtite PA-501, PA-502 (manufactured by Nippon Mectron Co., Ltd., product name), Teisan Resin WS023,
Examples include SG51, SG80, and SG90 (manufactured by Teikoku Kagaku Sangyo Co., Ltd., trade name), and these may be used alone or in a mixture of two or more. This acrylic elastomer may have a functional group such as an epoxy group, a carboxyl group, or a hydroxyl group, but among these, those having an epoxy group are particularly used because they react at low temperatures. The amount of the acrylic elastomer blended is preferably 30 to 70% by weight based on the resin component of the adhesive composition. If the amount is less than 30% by weight, the flexibility will be poor, and if it exceeds 70% by weight, the flexibility will be improved but the soldering heat resistance and flame retardance after humidification will be poor, which is not preferable. Examples of the polyparavinylphenol resin (B) used in the present invention include Maruzen Resin M, Maruzen Resin MB (manufactured by Maruzen Sekiyu Co., Ltd., trade name), and these may be used alone or in combination depending on the flame retardance desired.
Use by mixing more than one species. Brominated polyparavinylphenol resin has a molecular structure similar to thermoplastic polystyrene resin, and is also called paraoxystyrene resin, but it has excellent crosslinking properties with epoxy resin due to the action of the hydroxyl group at the para position. . (B) The blending amount of polyparavinylphenol resin is
It is desirable that the equivalent ratio ((b)/(c)) between the phenolic hydroxyl group (b) and the epoxy group (c) of the epoxy resin (C) is within the range of 0.5 to 7.0. If this equivalence ratio is less than 0.5, the soldering heat resistance after humidification will decrease, and the
Exceeding this is not preferable because adhesiveness decreases and heat deterioration resistance is poor. Bromination is carried out by introducing a brominated polyparavinylphenol resin, a brominated epoxy resin, or both, and the bromination rate is preferably 8% by weight or more based on the resin component of the adhesive composition. . This is because if the amount is less than 8% by weight, the effect on flame retardancy will be small. The epoxy resin (C) used in the present invention is not particularly limited, and all epoxy resins can be used.
Examples include bisphenol A type epoxy resins, novolak epoxy resins, and brominated epoxy resins thereof, and these may be used alone or in combination of two or more. Examples of the saturated polyester resin (D) used in the present invention include Vylon 200, Vylon 300, Vylon
500 (manufactured by Toyobo Co., Ltd., trade name), Epikote YX, which is made by uniformly dispersing saturated polyester in epoxy resin
-310 (manufactured by Yuka Ciel Epoxy Co., Ltd., trade name), and these may be used alone or in combination of two or more. It is believed that the saturated polyester assumes a sea-island structure in the cured adhesive composition, softening the stiffness of the epoxy resin and improving impact resistance.
In the case of an adhesive composition for a flexible printed wiring board, it has been found that the hardness is alleviated and that this adhesive composition has a remarkable effect particularly on improving heat deterioration resistance. The amount of saturated polyester blended is preferably 0.5 to 5.0% by weight based on the resin component of the adhesive composition. If the amount is less than 0.5% by weight, there is no effect on heat deterioration resistance, and if it exceeds 5.0% by weight, moisture resistance and adhesive strength will decrease, which is not preferable. Examples of the curing accelerator (E) used in the present invention include dicyandiamide, Epicure YPH201 (manufactured by Yuka Ciel Epoxy Co., Ltd., trade name), BF ₃ imidazole complex AC-4B series (manufactured by Maruzen Sekiyu Co., Ltd., trade name), imidazole These can be used alone or in combination of two or more. Crosslinking of epoxy resin is carried out by brominated paravinylphenol resin and acrylic elastomer, so depending on the molding conditions, an epoxy resin curing accelerator may not be necessary, but molding can be carried out at low temperatures for a short time. For this purpose, it is necessary to use an accelerator. The amount to be added is determined depending on the desired molding conditions or shelf life. Examples of the inorganic filler (F) used in the present invention include ultrafine anhydrous silica and aluminum hydroxide, which may be used alone or in combination of two or more. The inorganic filler has the effect of adjusting surface tack (adhesion) and mitigating expansion and contraction of the adhesive composition at high temperatures such as during soldering. The blending amount of the inorganic filler is 3 to 3 based on the solid content of the adhesive composition.
Preferably it is 65% by weight. If the amount is less than 3% by weight, surface tackiness will be strong and processability will be poor, and if it exceeds 65% by weight, wettability with the base thin material will be poor and adhesiveness will be reduced, which is undesirable. Examples of solvents for adhesive compositions containing the above components as essential components include methyl ethyl ketone, acetone,
Toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, dioxane, methyl cellosolve acetate and mixtures thereof can be used. The adhesive composition is dissolved in a solvent and applied in a solution state, but the resin component can also be prepared by mixing the respective raw materials or by proceeding with preliminary curing. The lamination of the synthetic resin thin material and the metal foil via the adhesive composition is achieved by applying the adhesive composition in a solution state to at least either the synthetic resin thin material or the metal foil, and then drying it in a hot air oven. Then volatilize the solvent or perform preliminary curing. Then, any method can be used, such as applying heat and pressure using a heated press, or continuously applying and drying the material, passing it continuously through heated rolls, applying heat and pressure, winding it up, and post-heat curing. Can be adopted. Examples of thin synthetic resin materials include polyimide films and ultra-thin laminates, and examples of metal foils include copper foil, aluminum foil, nichrome foil, and the like. On the other hand, to use for coverlay film adhesion,
The solvent is applied onto the surface of the thin synthetic resin material to a thickness of 15 to 35 μm using a conventional coating device, and dried to volatilize the solvent or precure. After that, a pattern is punched out to match the flexible printed wiring board, and then the printed wiring board is overlapped with the printed wiring board and bonded and laminated by heating and pressing at a temperature of 150 to 180°C and a pressure of 20 to 40 kg/cm ² . [Examples of the Invention] Next, the present invention will be specifically explained using Examples. In Examples and Comparative Examples, "parts" means "parts by weight." Example 1 Acrylic elastomer SG90 (manufactured by Teikoku Kagaku Sangyo Co., Ltd., trade name) was mixed with methyl ethyl ketone/toluene =
400 parts of a 25% solution dissolved in a 1/1 mixed solvent,
50 parts of 60% toluene solution of YDB-400 (manufactured by Toto Kasei Co., Ltd., trade name), 32 parts of YX-310 (manufactured by Yuka Ciel Epoxy Co., Ltd., trade name), Resin MB (brominated polyparavinyl phenol resin, Maruzen Sekiyu Co., Ltd.) company product name) 38
Department, Kyuazol C17Z (manufactured by Shikoku Kasei Co., Ltd., product name)
1.66 parts, H-43M (manufactured by Showa Light Metal Co., Ltd., trade name)
Weighed 10.6 parts of methyl cellosolve, 160 parts of methyl cellosolve, and 118 parts of dioxane, stirred thoroughly with a high-speed stirrer, and filtered through a 100-mesh wire mesh to obtain a resin composition for flexible printed wiring boards with a bromine content of 16 to 17% by weight. An adhesive solution was prepared. Next, Kapton with a thickness of 50 μm (manufactured by DuPont,
Apply the above adhesive solution to a polyimide film (trade name) to a thickness of approximately 22 μm after drying.
It was dried at 100°C for 5 minutes and then at 150°C for 2 minutes.
After that, a 35 μm electrolytic copper foil (manufactured by Fukuda Metal Industry Co., Ltd.) was placed on the adhesive-coated surface, and a hot press was used at a pressing temperature of 160 ± 2°C and a pressure of 30 kg/cm ² for heating time.
Lamination was performed for 60 minutes to produce a flexible printed wiring board. The peel strength of the obtained substrate, adhesiveness after heat deterioration, soldering heat resistance, and flame retardance were tested. The results are shown in Table 1, and the effects of the present invention were confirmed. Comparative Example 1 In Example 1, Epicote 828 (manufactured by Yuka Ciel Epoxy Co., Ltd.,
An adhesive solution and a substrate for a flexible printed wiring board using the adhesive solution were produced under the same conditions as in Example 1 except that 30.4 parts of the adhesive solution (trade name) was used. Next, various tests similar to those in Example 1 were conducted, and the results are shown in Table 1.

[Table] Example 2 Acrylic elastomer AR-51 (manufactured by Nippon Zeon Co., Ltd., trade name) was mixed with methyl ethyl ketone/toluene =
360 parts of a 25% solution dissolved in a 1/1 mixed solvent,
25 parts of 60% toluene solution of YDB-400 (manufactured by Toto Kasei Co., Ltd., trade name), 16 parts of YX-310 (manufactured by Yuka Ciel Epoxy Co., Ltd., trade name), Resin MB (manufactured by Maruzen Sekiyu Co., Ltd.,
Product name) 19 parts, AC-4B50 (manufactured by Maruzen Oil Co., Ltd., product name) 0.84 parts, H-43M (manufactured by Showa Light Metal Company, product name)
90 parts, 3 parts of Aerosil 200 (manufactured by Nippon Aerosil Co., Ltd., trade name), 200 parts of methyl cellosolve acetate,
Weigh and prepare 100 parts of ethyl cellosolve and 100 parts of dioxane, and stir thoroughly with a high-speed stirrer.
An adhesive solution having a bromine content of 11 to 12% by weight in the resin component was prepared by filtration through a 100-mesh wire mesh. Next, Kapton with a thickness of 25 μm (manufactured by DuPont,
The above adhesive solution was applied to a polyimide film (trade name) to a thickness of about 35 μm after drying, and dried at 120° C. for 5 minutes and then at 150° C. for 2 minutes. Next, a UL standard V-0 Kapton base copper clad board (copper foil 35 μm) was placed on the shear side of the etched copper foil for evaluation, and a hot press was used to press at a temperature of 160 ± 2°C and a pressure of 40 kg. / ^cm2 ,
Lamination was performed under conditions of heating time of 20 minutes. The peel strength, heat-resistant deterioration adhesion, solder heat resistance, flame retardance, solder resistance after humidification, and line-to-line insulation resistance were tested on the obtained carbalay coating, and the results are summarized in the second section.
Shown in the table. Example 3 Acrylic elastomer SG-80 (manufactured by Teikoku Kagaku Sangyo Co., Ltd., trade name) was mixed with methyl ethyl ketone/toluene.
300.3 parts of a 20% solution dissolved in a 1/1 mixed solvent,
Arontak S-1015 (manufactured by Toagosei Kagaku Co., Ltd., trade name) 9 parts, Epicote 828 (mentioned above) 3.5 parts, Byron 300 (manufactured by Toyobo Co., Ltd., trade name) 2.0 parts, resin
27 parts of MB (mentioned above), 1 part of dicyandiamide, 0.25 parts of Epicure YPH-201, H-43M (mentioned above)
152.34 parts, methyl cellosolve 300 parts, dioxane
Weigh and prepare 200 parts and 289 parts of methyl ethyl ketone, stir thoroughly with a high-speed stirrer, and filter through a 100-mesh wire mesh to determine the bromine content relative to the resin component.
A 12-13% adhesive solution was prepared. Next, the adhesive solution was applied to Kapton (mentioned above) with a thickness of 25 μm so that the thickness after drying was approximately 35 μm, and after drying at 120°C for 5 minutes and further at 150°C for 2 minutes, it passed the UL standard V- 0 Kapton base copper clad board (copper foil 35 μm) was overlaid on the shear side of the etched copper foil for evaluation, using a hot press at a pressing temperature of 170 ± 2°C and a pressure of 40 kg/cm ²
Lamination was performed under conditions of heating time of 45 minutes and coverlay coating was performed. The resulting coverlay coating was evaluated for its peel strength, adhesion after heat deterioration, soldering heat resistance,
Flame retardancy, solder resistance after humidification, line insulation resistance, and workability were tested and are shown in Table 2. Comparative Example 2 Adhesion was carried out under the same conditions as in Example 2, except that 8.95 parts of phenol novolac resin TD-2093 (manufactured by Dainippon Ink & Chemicals Co., Ltd., trade name) was substituted for 19 parts of resin MB (described above) in Example 2. An agent solution was prepared and laminated. The coverlay coating thus obtained was subjected to the same tests as in Example 2, and the results are shown in Table 2. Comparative Example 3 An adhesive solution was prepared under the same conditions as in Example 2, except that 90 parts of H-43M (mentioned above) and 3 parts of Aerosil 200 (mentioned above) were not added.
Laminated. The thus obtained Carvalley coating was tested in the same manner as in Example 2. The results are shown in Table 2.

[Table] Check for abnormalities
*2: ○ Good × Bad [Effects of the invention] As explained above, the adhesive composition for flexible printed wiring boards of the present invention has excellent adhesive properties, heat deterioration resistance, flame retardancy, solder resistance after humidification, and wire resistance. This adhesive composition has excellent interlayer insulation resistance and good processability when used as a coverlay, and is suitable for use in flexible printed wiring boards with well-balanced properties.

Claims (1)

[Claims] 1 (A) an acrylic elastomer having one or more functional groups selected from the group of epoxy groups, carboxyl groups, and hydroxyl groups, (B) polyparavinylphenol resin, (C) An adhesive composition for a flexible printed wiring board, comprising an epoxy resin, (D) a saturated polyester resin, (E) a curing agent accelerator, and (F) an inorganic filler. 2 Resin component of adhesive composition ((A) + (B) + (C) + (D))
The adhesive composition for a flexible printed wiring board according to claim 1, which contains (A) acrylic elastomer in an amount of 30 to 70% by weight, and (D) saturated polyester resin in an amount of 0.5 to 5.0% by weight. 3 (B) Phenolic hydroxyl group equivalent of phenolic resin
Claim 1 or 2, wherein the equivalent ratio ((b)/(c)) between (b) and the epoxy group equivalent (c) of the epoxy resin (C) is within the range of 0.5 to 7.0. Adhesive composition for flexible printed wiring boards. 4. The adhesive composition for a flexible printed wiring board according to any one of claims 1 to 3, which contains 3 to 65% by weight of (F) an inorganic filler based on the solid content of the adhesive composition. . 5. The adhesive composition for a flexible printed wiring board according to any one of claims 1 to 4, wherein the bromination rate of the resin component of the adhesive composition is 8% by weight or more.