JPH0446992B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field The present invention is composed of a bisphenol A type epoxy resin, a poly N-glycidyl type epoxy resin, a nitrile rubber having a carboxyl group, and a hardening agent, and has excellent adhesive properties, soldering heat resistance, flexibility, and chemical resistance. The present invention relates to a printed circuit board using a printed circuit board adhesive. Conventional technology Conventionally, heat-resistant plastic films such as polyimide films and polyester films are commonly used for printed circuit boards, and metal foils such as copper foils and aluminum foils are bonded onto these films using adhesives.
It was used as a printed wiring material in many fields such as cameras, calculators, and telephones. The properties required of this adhesive for printed circuit boards are not only adhesive strength between the film and metal foil, but also electrical properties, soldering heat resistance that does not cause abnormalities such as blistering even when immersed in high-temperature molten solder, and non-circuit These include chemical resistance to solvents such as methylene chloride used when dissolving the parts, and flexibility required for free three-dimensional wiring. With design, there is a need for more reliable and high performance adhesives. However, conventionally known adhesives for printed circuit boards include fluororesins, epoxy-novolacs, nitrile-phenols, polyesters, acrylic adhesives, etc., but they do not have the above-mentioned required characteristics. An adhesive with both properties has not yet been found. PROBLEMS TO BE SOLVED BY THE INVENTION As a result of intensive studies aimed at resolving the disadvantages of conventional adhesives for printed circuit boards, the present invention has developed a high-quality adhesive that fully satisfies the above-mentioned properties such as adhesiveness and soldering heat resistance. This was a successful development of a high-performance adhesive. Means for Solving the Problems That is, the present invention provides a printed circuit board to which a heat-resistant plastic film and a metal foil are bonded.
A print characterized in that an adhesive consisting of (a) bisphenol A type epoxy resin, (b) poly N-glycidyl type epoxy resin, (c) nitrile rubber having a carboxyl group and a curing agent is used as the adhesive. It is a board. Specific Description of the Invention The (a) bisphenol A type epoxy resin of the present invention has the general formula (However, n = integer of 0, 1, 2, 3, ...)
and preferably has an epoxy equivalent of 170 to 4,000. These can be obtained commercially. Next, (b) poly N-glycidyl type epoxy resin has the general formula

[Formula] (n=1, 2, 3, 4, 5, 6), all of which are compounds in which several glycidyl groups are substituted on nitrogen. Generally, it can be synthesized from the corresponding amine and epihalohydrin, but it may also be one in which the amino group of the intermediate is further reacted with an epoxy resin to increase the molecular weight. (b) As an example of the component, for example, (However, R and R' above represent hydrogen or an alkyl group.). The nitrile rubber having a carboxyl group as the component (c) is, for example, acrylonitrile-butadiene copolymer rubber copolymerized with acrylonitrile and butadiene in a molar ratio of about 5/95 to 45/55, with carboxylated terminals, or A copolymer rubber obtained by terpolymerizing acrylonitrile, butadiene, and a carboxyl group-containing polymerizable monomer such as acrylic acid is used. The carboxyl group content in the copolymer rubber is preferably about 1 to 8% by weight. As such,
Products from Gutdoritsi, known under product names such as Hiker CTBN and Hiker CTBNX, are well-known. The mixing ratio (weight ratio) of the bisphenol A type epoxy resin which is the component (a) and the poly N-glycidyl type epoxy resin which is the component (b) is 0.05≦(b)/(a)≦19
is preferable, and when it exceeds 19, heat resistance is good but adhesive strength decreases, while when it is less than 0.05, heat resistance and adhesive strength decrease. Furthermore, the mixing ratio (weight ratio) of the nitrile rubber having a carboxyl group, which is the component (c), and the epoxy resin is preferably 0.05≦((a)+(b))/(c)≦2,
If it exceeds 2, the adhesive strength will be significantly reduced, and if it is less than 0.05, the adhesiveness and heat resistance will decrease. and ((a)+
The value of (b))/(c) is more preferably 0.05 to 1.75, particularly 0.15 to 0.7. When preparing an adhesive using the above components, it is usually sufficient to simply mix the three components, but depending on the purpose of use, such as adjusting the viscosity and tackiness, (a) and (b) can be used.
(b) and (c) or (a), (b) and (c) may be pre-reacted in advance. The adhesive composition of the present invention can use conventional epoxy resin curing agents, such as aliphatic and aromatic polyamines, acid anhydrides, hydrazide compounds derived from polycarboxylic acids, imidazole derivatives, dicyandiamide, guanidine derivatives, biquamid derivatives. can be cited as a representative example. More specifically, diaminodicyclomethane, bis(4-amino-3-methylcyclohexyl)methane, diaminodiphenylmethane, diaminodiphenylsulfone, 4,4'-diamino-3,3'dichlorodiphenylmethane, Phthalic anhydride, chlorendic acid anhydride, Kyuazol 2E4MZ- for Shikoku Kasei products
There are A21NE, Kyuazol 2E4MZ-CN, Kyuazol 2PZ-CN, etc. Among such curing agents, it is best to use aromatic polyamines from the viewpoint that they still have solder resistance even after the printed circuit board is left at room temperature and absorbs moisture. imidazole derivatives, to accelerate curing;
Boron trifluoride complex of amines, Sun Abbott product DBU (diazabicycloundecene),
U-CAT-SA No.1 (DBU/phenol salt),
U-CAT-SA No.102 (DBU/octylate)
etc. can be used in combination with the above curing agent as a curing accelerator. The adhesive of the present invention is usually dissolved in a solvent and applied to an adherend. Solvents used in this case include methyl ethyl ketone, methyl isobutyl ketone, dioxane, ethanol, methyl cellosolve, ethyl cellosolve, dimethyl formamide, etc., and these are used alone or in combination. Apply the above adhesive solution to the adherend and turn it into a B-stage (semi-cured state, melts when heated).
Thereafter, by pressing with a roll or batch press, a printed circuit board with excellent properties can be obtained. Compression temperature is 80~300℃, pressure is 5~200Kg
f/cm ² is preferably used. Post-curing at 100 to 350°C can further improve heat resistance. When long-term heating is required during pressure bonding, a stabilizer can be added for the purpose of preventing carboxylated nitrile rubber or epoxy resin from oxidizing or decomposing. The stabilizer is preferably a non-staining stabilizer that does not cause coloring, such as Irganox 1010.
((Ciba Geigy product, Tetrakis-[Methylene-
3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane), Ionox 220 (Shell Chem product, 4,4'-methylene-bis(2,6-di- t-butyl)phenol),
Ionox 330 (Shell Chem product, 1, 3,
5-trimethyl-2,4,6-tris(3,5-
Hindered phenol stabilizers such as di-t-butyl-4-hydroxybenzyl)benzene), Nokrac 300 (Ouchi Shinkosha product, 4,4'-thiobis(6-t-3-methyl)phenol), CAO -6
(Ashland Chem product, 2,2'-thiobis(6)
Examples include thiobisphenol stabilizers such as (-t-butyl-4-methyl)phenol) and stabilizers such as DLTP (manufactured by Yoshitomi Pharmaceutical Co., Ltd., dilauryl thiodipropionate). Furthermore, the shrinkage rate during curing of the adhesive is reduced, B-
For the purpose of adjusting the tackiness of the stage state, fillers such as finely powdered clay, calcium carbonate, silica, alumina, talc, barium carbonate, etc. may be added to the composition. Alternatively, a laminated base material such as glass fiber cloth may be included in the adhesive and laminated in one layer. The thus produced substrate in which the heat-resistant plastic film and the metal foil are firmly bonded is extremely excellent as a printed circuit board, especially a flexible printed circuit board. Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Example 1 R ^- 301 (manufactured by Mitsui Petrochemical Epoxy Co., Ltd., bisphenol A type epoxy resin, epoxy equivalent 470-490, softening point 62-70°C) in 300cm 2 separable flasks
18.0g, Hiker CTBN1300 x 13 (manufactured by Gutsudoritsuchi, carboxylated nitrile rubber, molecular weight approx.
3500, carboxyl group content 2.5% by weight, viscosity
550000 CPS (27°C)) and 80.0g of methyl cellosolve were added, and the mixture was heated and stirred at 50 to 60°C to form a homogeneous solution. After cooling to room temperature, the tetrad
Further add 17.0 g of The mixture was added and stirred again to dissolve and prepare an adhesive. This adhesive solution was applied onto Kapton film (polyimide film made by Dupont), dried in an air oven at 150°C for 12 minutes, and copper foil was pasted ^on . It was crimped with a press for 90 minutes. The thickness of the adhesive layer of this sample is
It was 22-25 μm. T-type peel strength is 1.6Kg/cm
Even when the copper foil was floated in a 280°C solder bath for 2 minutes with the copper foil facing down, no abnormalities such as blistering occurred. Comparative Examples 1 to 3 An adhesive was prepared by removing one of the components used in Example 1, and the same conditions as in Example 1 were used: drying conditions: 150°C, 12 minutes, pressing conditions: 170°C, 25°C.
Kapton film and copper foil were bonded at Kg/cm ² for 90 minutes. The results are shown in Table 1. Examples 2 to 5 Tests similar to those in Example 1 were conducted using the amount of curing agent shown in Table 2 instead of 3,3'-diaminodiphenyl sulfone. *1: 2E4MZ-AZINE as a curing accelerator An additional 0.2g was added. *2: Only in this example, hiker CTBN1300×13
70.0g of was used. *3:

[Formula] The pressing conditions were 170°C, 15Kg/cm ² , and 90 minutes.

[Table] *Solder heat resistance was measured by the time until blistering occurred.

[Table] Example 6 Instead of Tetrado-X and methyl cellosolve used in Example 1, TEPIC (manufactured by Nissan Chemical Co., Ltd., triglycidyl isocyanurate, epoxy equivalent 103 ~
Example 1 was carried out in the same manner as in Example 1, except that 18.0 g of 105 (melting point: 90-115°C) and 80.0 g of N,N-dimethylformamide were used. T-peel strength is 1.6Kg/cm,
As for solder heat resistance, no blistering occurred even when placed on a solder bath for 2 minutes at 280°C. Example 7 The adhesive of Example 3 was used to bond Lumirror film (manufactured by Toray Industries, Inc., polyester film) and copper foil. The T-peel strength was 1.3 kg/cm. Effects of the Invention As detailed above, the substrate of the present invention in which the heat-resistant plastic film and the metal foil are firmly bonded,
It is extremely excellent as a printed circuit board, especially a flexible printed circuit board.

Claims (1)

[Claims] 1. In printed circuit boards to which heat-resistant plastic film and metal foil are adhered, (a)
A printed circuit board characterized by using an adhesive comprising a bisphenol A type epoxy resin, (b) a poly N-glycidyl type epoxy resin, (c) a nitrile rubber having a carboxyl group, and a curing agent.