JPS6262880A - Adhesive composition for flexible printed wiring board - Google Patents

Abstract

PURPOSE:The titled composition, consisting essentially of an acrylic elastomer, polyp-vinylphenol resin, epoxy resin, polyvinyl formal resin, curing accelerator and inorganic filler and having improved adhesive properties, heat deterioration resistance, flame retardance, etc. CONSTITUTION:A composition containing (A) an acrylic elastomer having one or more functional groups selected from the group of epoxy group, carboxyl group and OH group, (B) polyp-vinylphenol resin, (C) an epoxy resin, (D) a polyvinyl formal resin, (E) a curing accelerator, e.g. dicyandiamide, and (F) an inorganics filler, e.g. ultrafine particulate anhydrous silica, preferably at 30-70wt% ratio of the component (A) to the total of the components (A), (B), (C) and (D), 0.5-5.0wt% ratio of the component (D) to the total of the components (A), (B), (C) and (D) and within 0.5-7.0 epoxy equivalent ratio (B/C) range of the components (B) to (C).

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a flexible printed wiring board with strong adhesion between a metal tube and a thin synthetic resin material, immersion heat resistance and heat deterioration resistance, and C resistance. The present invention relates to an adhesive composition for flexible printed wiring boards that has flammability and excellent processing properties.

[Technical impropriety of inventions and their problems] In recent years, with the increasing density of electronic devices and their miniaturization, I
There is an increasing demand for flexible printed wiring boards that can mount three-dimensional wiring or functions with N-hanging.

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 metal foil treated surfaces, but also to insulate and protect circuits on the shine (polished) surface of the metal of patterned wiring boards. It would be desirable if it could be used to adhere a coverlay film for applications.
In particular, for coverlay film adhesion, it must be able to firmly adhere to the shine surface of the metal foil, be able to suppress flow to the land portion, and have good embedding properties between pattern circuits.

Moreover, the shelf life is required to be at least 1 month at air temperature and 3 months or more at 5°C. Furthermore, in order to improve productivity and maintain dimensional accuracy, heating is possible at low temperatures and in a short time.
Processability such as crimping is required.

However, conventional adhesives for flexible printed circuit boards are
Even when polyimide film, which has excellent heat resistance and flame retardancy, is used as the base thin film material, it must have adhesion, heat resistance, line insulation resistance, heat deterioration resistance, flame retardancy, etc. in addition to the processing characteristics mentioned above. was extremely difficult. Conventionally,
Nitrile rubber adhesives (JP-A-51-135936, JP-A-5
No. 7-3877), polyamide adhesive (Japanese Patent Application Laid-open No. 1983-
125285), polyester adhesive (Unexamined Japanese Patent Publication No. 125285)
-16866, JP-A-54-7441), polyacrylic adhesive (JP-A-54-162,736), and many others. However, the nitrile rubber type has the disadvantage that it has poor adhesion after heat-resistant deterioration and tends to become extremely hard after a 10-day air deterioration test at 150°C, and the polyamide type has the disadvantage of slightly high hygroscopicity. be.

Polyester-based materials have the disadvantage of weak adhesive strength compared to polyimide films, and polyacrylic-based materials require high temperatures and long periods of time for heat molding, so lowering the molding temperature and shortening the time results in poor moisture resistance. Ta.

[Object of the Invention] The object of the present invention has been made to solve the above-mentioned difficulties and disadvantages. The present invention aims to provide an adhesive composition for flexible printed wiring boards with good properties.

[Summary of the Invention] As a result of intensive studies to achieve the above object, the present inventors found that the adhesive composition described below is suitable as an adhesive for flexible printed wiring boards, and the present invention has been made. This is what we have come to.

The present invention comprises (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, characterized in that the essential components are a resin, (D) a polyvinyl formal resin, (E) a curing agent accelerator, and (F) an inorganic filler.

Examples of the acrylic elastomer having one or more functional groups selected from the group of <A> epoxy group, carboxyl group, and hydroxyl group used in the present invention include Arontac S-15111, S-1511X, S-
1015, S-1017 (manufactured by Toagosei Kagaku Co., Ltd., trade name)
, ΔR-51 (manufactured by Nippon Zeon Co., Ltd., trade name), Noxtite PA-501, r-'A-502 (manufactured by Nippon Metatron Co., Ltd., trade name), Tissant Resin WS○23°5G51
, 5G80.5G90 (manufactured by Teikoku Kagaku Sangyo Co., Ltd., product name)
These may be used alone or in combination 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 blending amount of the acrylic ex-mers is desirably 30 to 70% by weight with respect to the resin component [(Δ)(B)+(C)+(D)] of the adhesive composition.

If the blending amount is less than 30% by weight, the flexibility will be poor;
If it exceeds % by weight, the flexibility will be improved, but the soldering heat resistance and flame retardance after humidification will be poor, which is not preferable.

(B) Polybarabinischif 1-nor resin used in the present invention, for example, Maruzen Resin M, Maruzen Resin M
BC Maruzen Sekiyu Co., Ltd. ¥1, trade name), etc., and these may be used alone or in combination of two or more depending on the desired flame retardance. Polyparavinylphenol resin is similar in molecular structure to thermoplastic borisdyrene resin, and although it is also called paraoxystyrene resin, it has excellent crosslinkability with epoxy resins due to the action of the hydroxyl group at the para position.

(B) The blending amount of the polyparavinylphenol resin is such that the equivalent ratio [(b)/(C)] between its phenolic hydroxyl group (b) and the epoxy (c) of the (C) epoxy resin is 0. It is desirable that it be within the range of .5 to 7.0. If this equivalence ratio is less than 0.5, the soldering heat resistance after humidification will decrease, and if it exceeds 7.0, the adhesiveness will decrease and the heat deterioration resistance will be poor, which is not preferred.

Bromination is carried out by introducing brominated polyparavinylphenol resin, brominated epoxy resin, or both.
The bromination rate is desirably 8% or more based on the resin component of the adhesive composition.

This is because r less than 8Φ amount % has little effect on flammability.

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 resin, novolak epoxy resin, and brominated epoxy resins thereof, and these may be used alone or in combination of two or more.

Examples of the polyvinyl formal resin (D) used in the present invention include Denka Formal #20. #30, #100
(manufactured by Denki Kagaku Kogyo Co., Ltd., trade name), Vinylec F 1-
, E (manufactured by Chisso Corporation, trade name), etc., and these may be used alone or in a mixture of two or more. It is believed that the polyparavinyl formal resin takes a sea-island structure in the adhesive composition after curing, softens the hardness of the epoxy resin, and improves 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 it has a remarkable effect particularly on improving heat deterioration resistance. The blending amount of polyvinyl formal resin is 0.5 to 5.01 fi% based on the resin component of the adhesive composition.
It is desirable that When the blending ω is less than 0.5% by weight, there is no effect on heat deterioration resistance, and when it exceeds 5.0% by weight, moisture resistance and adhesive strength are undesirably lowered.

As the curing accelerator (E) used in the present invention, for example, dicyandiamide, Ebicure Y P l-1-201 (manufactured by Yuka Shell Epoxy Co., Ltd., trade name), BF, imidazole complex AC-4B series (Marube Oil Co., Ltd.) (product name),
Examples include imidazole, which may be used alone or in combination of two or more. Crosslinking of epoxy resin is also carried out by paravinylphenol resin and acrylic elastomer, so depending on the molding conditions, there may be no need for an epoxy resin curing accelerator, but in order to perform short molding at low temperatures, curing It is necessary to use an accelerator. The amount to be added (determined depending on the molding conditions employed or the desired 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 preferably 3 to 65 Φ% based on the solid content of the adhesive composition. If the content is less than 3% by weight, surface tackiness will be strong and processability will be poor, and if it exceeds 1% by weight, the coating properties with the thin base material will be poor and the adhesion will be low, which is undesirable.

Methyl ethyl ketone, acetone, toluene, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether, dioxane, methylhyrosolve acetate, and mixtures thereof can be used as the solvent for the adhesive composition containing each of the above components as essential components. . The adhesive composition is dissolved in a solvent and applied in a solution state, but the resin component before being dissolved can 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. A method can be adopted in which the solvent is volatilized or preliminary curing is performed, and then heat and pressure bonding is performed using a hot press.

Alternatively, any method can be adopted, such as continuously coating and drying, then continuously passing through heated rolls, heat-pressing, winding, and post-heat curing. 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, in order to use it for adhesion of Burley film, the above solution is applied onto the surface of a thin synthetic resin material using an ordinary coating device to a film thickness of 15 to 35 μm, and then dried to evaporate the solvent or Perform preliminary curing. After that, the pattern is formed to match the flexible printed wiring board, and the wiring board is superimposed on the printed circuit board.
They are 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 .

[Embodiments of the invention] Next, the present invention will be specifically explained with reference to Examples.

In Examples and Comparative Examples, "parts" means "parts by weight."

Example 1 Acrylic Elas] Hemer 5G90 (manufactured by Teikoku Kagaku Sangyo Co., Ltd., trade name) was mixed with methyl ethyl ketone/toluene = 1/1
into a mixed solvent? 400 parts of 25% solution, YD[3
50 parts of a 60% toluene solution of -400 (manufactured by Tobu Kasei Co., Ltd., trade name), 28.8 parts of R-140 (manufactured by Mitsui Petrochemical Epoxy Co., Ltd., trade name), K of polyvinyl formal resin Niretsu F (manufactured by Chisso Corporation) , trade name) 3.2 parts, brominated polybarabinyl phenol resin Maruzen Resin MB (manufactured by Maruzen Sekiyu Co., Ltd., trade name) 38 parts, Curesol C17Z (
Manufactured by Shikoku Kasei Co., Ltd., trade name) 1.66 parts, l-1-43M<
(manufactured by Showa Light Metal Co., Ltd., trade name) 10.6 parts, methyl cellosolve 160 parts and diokiri.

118δIS was weighed and charged, stirred for 10 minutes using a high-speed stirrer, and filtered through a 100-mesh wire mesh to prepare an adhesive solution for flexible printed wiring boards with a bromine content of 16 to 171 m% in the resin component. did.

Next, the above adhesive solution was applied to Kapton (manufactured by DuPont, polyimide film trade name) with a thickness of 50 μm so that the thickness after drying would be 22 μm, and the mixture was heated at 100°C for 5 minutes and then at 150°C for 2 minutes. Dry.

After that, a 35 μm electrolytic copper foil (manufactured by Fukuyama Metal Industry Co., Ltd.) was placed on the adhesive-applied surface, and a heat press was applied under the conditions of a press temperature of 160 ± 2°C, a pressure J of 30 kg/cm2, and a heating time of 60 minutes. Lamination 1 to 1 was carried out to produce a flexible printed wiring board. The peel strength, adhesiveness after heat deterioration, soldering heat resistance, and flame retardance of the 1q board were tested. The results are shown in Table 1, and the effect of the present invention was confirmed w1.

Comparative Example 1 Example 1 except that in Example 1, polyvinyl polymer resin Niretsu F K (manufactured by Chisso Corporation, trade name) was not added and 30.4 parts of R-140 was used as the epoxy resin. An adhesive solution and a flexible printed wiring board substrate using the adhesive solution were manufactured under the same conditions as described above. Next, various tests similar to those in Example 1 were conducted, and the results are shown in the first example.
Shown in the table.

Table 1 Example 2 360 parts of a 25% solution of acrylic elastomer ΔR-51 (manufactured by Nippon Zeon Co., Ltd., trade name) dissolved in a mixed solvent of methyl ethyl ketone/toluene = 1/1, YDB-400
(manufactured by Kyoto Kasei Co., Ltd., trade name) 25 parts of 60% toluene solution, R-140 (manufactured by Mitsui Petrochemical Epoxy Co., Ltd., trade name)
14.4 parts, polyvinyl polymer resin #100 (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name) 1.6 parts, Maruzen Resin MB
(manufactured by Marukubi Oil Co., Ltd., trade name) 19 parts, AC-4850 (manufactured by Marukubi Sekiyu Co., Ltd., trade name) 0.84 parts, l-1-43M
<Manufactured by Showa Ya T Metal Co., Ltd., product name) 90 copies, Aerosil 2
00 (manufactured by Nippon Aerosil Co., Ltd., trade name) 3 parts, Methyl Rosolve Acetate 200 parts, Ethyl Cellosolve 10
0 parts and 100 parts of dioxane were each added to a weighing scale, thoroughly stirred using a high-speed stirrer, and filtered through a 100-mesh wire gauze to prepare an adhesive solution having a bromine content of 11 to 12% by weight in the resin component.

Next, the above adhesive solution was applied to Kapton (manufactured by DuPont, polyimide film trade name) with a thickness of 25 μm so that the thickness after drying was approximately 35 μm, and the mixture was heated at 120°C for 5 minutes and then at 150°C for 2 minutes. Dry.

Next, UL standard-O Kapton base copper clad board (copper foil 3
5μm) on the shine side of etched copper foil for evaluation, and using a hot press, press at a temperature of 1.
60±2℃, pressure 40kg/cm2. It was laminated with the strip f [with a heating time of 20 minutes. The peel strength, heat deterioration resistance (adhesiveness of wire, solder heat resistance, flame retardance, solder resistance with 1 change of humidification, and line insulation resistance) were tested for the coverlay coating prepared in 1q. Shown in the table.

Example 3 Acrylic elastomer 5G-80 (manufactured by Teikoku Kagaku Sangyo Co., Ltd.,
300.3 parts of a 20% solution of (trade name) dissolved in a mixed solvent of methyl ethyl ketone/toluene = 1/1, 9 parts of Arontac S-1015 (manufactured by Toagosei Kagaku Co., Ltd., trade name),
3.5 parts of R-140 (mentioned above), 2.0 parts of polyvinyl formal resin Vinylec F E (manufactured by Chisso Corporation, trade name),
27 parts of Maruzen Resin MB (mentioned above), 1 part of dicyandiamide, 0.25 parts of Ebicure YPI-1-201 (manufactured by Yuka Shell Epoxy Co., Ltd., trade name), H-43M (stated above)
152.34 parts, 300 parts of methyl Urosolve, 200 parts of dioxane, and 289 parts of methyl ethyl lactone were weighed, charged, and stirred at high speed + (!
An adhesive solution having a bromine content of 12 to 13% based on the resin component was prepared by filtration through a 00 mesh wire mesh.

Next, the adhesive solution was applied to a Kapton (mentioned above) having a thickness of 25 μm so that the thickness would become approximately 35 μm after drying.
After drying at 20°C for 5 minutes and then at 150°C for 2 minutes, a Kapton base copper clad board (copper foil 35μ
m) was superimposed on the shine surface of etched steel foil for evaluation, and pressed at a pressing temperature of 1f170 using a hot press.
±2℃, pressure 40kg/cm2, heating time 45 minutes! 1 was laminated and covered with a coverlay. The obtained coverlay coating was tested for peel strength, adhesion after heat deterioration, soldering heat resistance, flame retardancy, humidification 1 solder resistance, line insulation II (resistance), and processability. are shown in Table 2.

Comparative Example 2 Example 2 except that 19 parts of Maruzen Resin MB (mentioned above) was replaced with 8.95 parts of 71-nol novolac resin TD-2093 (manufactured by Dainichi Ink Chemical Co., Ltd., trade name). An adhesive solution was prepared and laminated under the same conditions. The coverlay coating thus obtained was subjected to the same tests as in Example 2, and the results are shown in Table 2.

Comparison (C13) An adhesive solution was prepared under the same conditions as in Example 2, except that 90 parts of l-1-43M (mentioned above) and 3 parts of Aerosil 200 (mentioned above) were not added in Example 2, and lamination was performed. The thus obtained coverlay coating was tested in the same manner as in Example 2, and the results are shown in Table 2.

[Effects of the Invention] As explained above, the adhesive composition for flexible printed wiring boards of the present invention has excellent properties in bonding, heat deterioration resistance, flammability, subsequent solderability after humidification, and inter-line insulation resistance. In addition, the adhesive composition has good processability when used for coverlays, and has a good balance of properties, making it suitable for use in flexible printed wiring boards.

Claims (1)

[Scope of 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 as essential components an epoxy resin, (D) a polyvinyl formal resin, (E) a curing agent accelerator, and (F) an inorganic filler. 2 Resin component of adhesive composition [(A)+(B)+(C)
+ (D)], (A) acrylic elastomer 3
0 to 70% by weight, (D) polyvinyl formal resin 0
．． The adhesive composition for flexible printed wiring boards according to claim 1, each containing 5 to 5.0% by weight. 3 (B) Phenolic hydroxyl equivalent of phenolic resin (
Claim 1 or Claim 1, 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. The adhesive composition for flexible printed wiring boards according to item 2. 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.