JPH03221578A - Adhesive composition for flexible printed wiring board - Google Patents

Abstract

PURPOSE:To obtain the subject composition suitable for adhesion between a plastic film and a reinforcing board having excellent adhesion and heat resistance in soldering with quickly curable in a short time containing functional group-containing acrylic elastomer, an epoxy resin, curing agent and curing accelerator. CONSTITUTION:The aimed composition contains (A) acrylic elastomer having functional group (e.g. epoxy group or carboxyl group), (B) an epoxy resin having at least two epoxy groups in a molecule, (C) curing agent (preferably 4,4'- diaminodiphenylmethane, etc.) and (D) curing accelerator (preferably cationic polymerization-type catalyst). Besides, content of the component D is preferably 0.5-5 phr to solid content of the component B. Furthermore, mixing ratio of the component A to the component B is preferably 1/1-10/1 by solid weight.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an adhesive composition suitable for bonding a plastic film and a reinforcing plate used in a flexible printed wiring board.

(Prior Art and Section B) Conventionally, adhesives used for flexible printed wiring board substrates and flexible printed wiring board reinforcing plates were disclosed in Japanese Patent Application Laid-Open No. 62-59.
As described in Japanese Patent Application No. 683, heating at high temperature and for a long time was required for curing.

Epoxy resins, acrylic resins, phenolic resins, etc. are used in this type of adhesive, and in order to obtain sufficient adhesive performance, aromatic polyamines, hardeners, etc.
Because it uses phenol, epoxy resin, etc., it had to be heated at high temperatures for a long time to harden.

Moreover, because of the large amount of adhesive flowing out,
It was unsuitable for adhesives between reinforcing plates for component mounting and flexible printed wiring boards.

(Means for Solving the Problems) As a result of repeated studies on the above problems, the present inventors found that
As an adhesive system, an epoxy resin (B) is combined with a functional group-containing acrylic elastomer (A), and a curing agent (C) suitable for them, especially an aromatic polyamine, and a curing accelerator (D), especially a cationic polymerization type catalyst. The present inventors have discovered that by using a combination of the following, the curing speed can be increased, curing can be achieved by heating at a relatively low temperature for a short period of time, and the tendency to flow can be reduced, and the present invention has been completed.

Furthermore, the present invention will be specifically explained.

As the acrylic elastomer (A) used in the present invention,
Acrylic elastomers that are known per se can be used, but in terms of -C, the main component is one or more of acrylic esters or α-1-substituted acrylic esters, and at least one functional group as a crosslinking point. The polymer includes a polymer containing a functional group, or a polymer obtained by copolymerizing (grafting) at least one functional group-containing monomer with the above-mentioned main component monomer.

More specifically, the acrylic elastomer (A) is
(a) A large proportion of one or more of acrylic esters or α-substituted acrylic esters, and (b) epoxy groups, (C) carboxyl groups, (a)
Examples include acrylic elastomers copolymerized with monomers having one or more functional groups selected from the group of hydroxyl groups.

Specific examples will be shown regarding the monomers (a) to (d) above.

Examples of the acrylic ester or α-substituted acrylic ester (a) include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and octyl acrylate.

Examples of the epoxy group-containing monomer 0) include glycidyl ethers such as vinyl glycidyl ether and allyl glycidyl ether; glycidyl (meth)acrylates and the like.

In addition, examples of hydroxyl group-containing monomers include 4-class dimethanorelays of polyhydric alcohols such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, and polyethylene glycol dimethacrylate; Examples include alkoxyalkyl acrylates such as methyl acrylate.

In addition, as a carboxyl group-containing monomer, (meth)
Examples include acrylic acid, itaconic acid, maleic acid, and maleic anhydride.

Furthermore, in some cases, other vinyl monomers such as vinyl chloride, hnylidene chloride, styrene, methacrylonitrile, vinyl acetate, etc. may also be copolymerized.

Specifically, the acrylic elastomer (a) includes:
Arontac S-1511LSS-1511X, S-1
015, S-1017 (Toagosei Kagaku ■Ayu), Noxtite PA-501, PA-502 (manufactured by Nippon Metatron Co., Ltd.); Tisan Resin WSO22, WSO23, SG5
1. SG80.5G90 (manufactured by Teikoku Kagaku ■), AR-51
(Nippon Zeon Porcelain), etc. These can be used alone or in combination of two or more.

Note that this acrylic elastomer (a) may have a functional group such as an epoxy group, a carboxyl group, a hydroxyl group, or a hydroxyl group, but among these, those having a low-temperature-reactive epoxy group are preferable. .

The epoxy resin (B) used in the present invention is not particularly limited, but generally any resin having two or more epoxy groups in one molecule may be used. Examples include bisphenol A type epoxy resin, phenol novolac type epoxy resin, and brominated epoxy resin.

The curing agent (C) used in the present invention is not particularly limited, but
Commonly used curing agents include, for example, aliphatic posiamino, aromatic posiamino, acid anhydride, imidazole, hydrazinode, dicyandiamide, and the like. In particular, it is preferable to use aromatic polyamines such as 4,4[deg.]-diaminodiphenylmethane, 4,4''-diaminodiphenyl ether, and 4,4''-cya5nodiphenyl sulfone.

Curing accelerators used in the present invention (including cationic polymerization catalysts such as B Fs MEA, S b FM
EA, PF, -MEA, Fecl, , ANcl,
Examples include quaternary ammonium salts, quaternary sulfonium salts, and alkali metal salts of organic weak acids.

The blending ratio of the acrylic elastomer (A) and the epoxy resin (B) is in the range of 1/1 to 10/l, preferably 2/l.
1 to 6/1 is good.

If the blending ratio of the acrylic elastomer (A) is less than 1/1, the soldering heat resistance will decrease. On the other hand, if the ratio is more than 1°/1, the adhesive force will decrease.

Furthermore, a curing agent (
C) and a curing accelerator (D) are added, and at this time, the amount of the curing agent (C) added is preferably epoxy equivalent to 1/2 epoxy equivalent.

If the amount of curing agent (C) added is less than 1/2 epoxy equivalent, a sufficient degree of curing will not be obtained, leading to a decrease in soldering heat resistance. Moreover, even if more than the epoxy equivalent is added, gas mainly composed of S is generated in the soldering heat resistance test, which is not desirable.

The amount of the curing accelerator (D) added is preferably 0.5 to 5.0 phr based on the solid content of the epoxy resin.

When the amount of curing accelerator (D) added is 0.5 phr, the pot life becomes longer, but the initial performance (adhesive strength, soldering heat resistance) is not sufficient. On the other hand, if it is added in an amount of 5.0 phr or more, the pot life will be drastically reduced, making it practically unusable.

Adhesive of the present invention &! Examples of solvents that can be used include methyl ethyl ketone, acetone, toluene, dioxane, methyl cellosolve acetate, ethylene glycol monomethyl ether, and mixtures thereof.

It goes without saying that various additives such as plasticizers, antioxidants, anhydrous silica, fine inorganic fillers such as aluminum hydroxide, etc. can be added to the adhesive composition of the present invention as appropriate. That's true.

To apply the adhesive of the present invention to films and reinforcing plates, the constituent components of the adhesive composition are first mixed by a known mixing means, then dissolved in a solvent, and applied in a solution state. In this case, after being applied to either one of the objects to be adhered, the adhesive is laminated and cured using an arbitrary heat curing means. For example, the above-mentioned coating material is dried in a hot air oven to dry the solvent,
Alternatively, precuring is performed to obtain a B-stage product, and then it is combined with other adhered materials and heated to 130% by using a heated press.
A method of heat-pressing at ~180'C and a pressure of 5 kg/c4 to 40 kg/d is employed.

Alternatively, the coating may be continuously coated and dried, then continuously passed through a heated roll, heat-pressed and integrated, and then post-heat-cured.

Examples of reinforcing plates to which the adhesive composition of the present invention is applied include aluminum plates, silicon steel plates, paper phenol laminates, glass epoxy laminates, polypropylene, and polyethylene. In addition, the film to which the adhesive m-parabolic of the present invention is applied is not particularly limited as long as it is a polymer film, but refers to those used particularly for FPC, such as polygon film, polyester film, polyether ketone film, polyester film, polyether ketone film, etc. Examples include ether sulfone film and ultra-thin laminates.

(Function) The adhesive & lI product of the present invention can bond plastic films and reinforcing plates used for flexible printed wiring boards at relatively low temperatures in a short time, and at the same time has a pot life of more than 1 month. It has the advantage of extremely low run-off.

In addition, the adhesive composition of the present invention has adhesive strength, soldering heat resistance,
To provide an adhesive that satisfies all the properties required for adhesion between a plastic film and a reinforcing plate used for flexible printed wiring boards, such as flow resistance, reflow resistance, and long pot life.

Next, the present invention will be specifically explained using examples, but these are not intended to limit the scope of the present invention.

Example 1 93.5 parts of a 20% by weight solution of acrylic elastomer 5G90 (manufactured by Teikoku Kagaku Sangyo ■, trade name) dissolved in a mixed solvent of methyl ethyl ketone/toluene 1/1, Epicoat 828 (manufactured by Yuka Shell Epoxy Co., Ltd., trade name) )6.25
1.25 parts of 4,4-diaminodiphenylmethane (manufactured by Sumitomo Chemical ■, trade name) as an aromatic polyamine, and 125 parts of BFs MEAo (manufactured by Hashimoto Chemical Industry Co., Ltd., trade name) were added as a curing accelerator. After stirring, a viscous adhesive was created. Thereafter, the solid content was coated on release paper to a thickness of 40 μm, and dried at 120° C. for 5 minutes to produce a B-stage film.

Thereafter, it was transferred to an Af reinforcing plate, bonded to a flexible printed wiring board, and pressed under the conditions of 180'C x 5 minutes x 10 kg/d. However, after pressing, do not cool with water to room temperature.

Example 2 5G80 (Teikoku Kagaku Sangyo ■) as an acrylic elastomer
The same procedure as in Example 1 was carried out except that 44'-diaminodiphenyl ether was used as the aromatic polyamine.

Example 3 WSO23 (manufactured by Teikoku Kagaku Sangyo ■, trade name) was used as the acrylic elastomer, and 4.4゛- as the aromatic polyamine.
The same procedure as in Example 1 was conducted except that diaminodiphenylmethane was used as Epikote 1004 as the epoxy resin.

Example 4 5G80 (manufactured by Teikoku Kagaku Sangyo Co., Ltd., trade name) was used as the acrylic elastomer, 44"-diaminodiphenylsulfone was used as the aromatic polyamine, Epicoat 154 was used as the epoxy resin, and Fec 1. was used as the curing accelerator. Except for this, the same procedure as in Example 1 was carried out.

Example 5 5G80 (manufactured by Teikoku Kagaku Sangyo ■, trade name) was used as the acrylic elastomer, and 4.4'- as the aromatic boria fruit.
Diaminodiphenyl ether as a curing accelerator and Sb
F, -MEA as epoxy resin Epicoat 154
The same procedure as in Example 1 was carried out except that .

Example 6 WSO23 (manufactured by Teikoku Kagaku Sangyo ■, trade name) was used as the acrylic elastomer, and 4,4゛ as the aromatic polyamine.
- Diaminodiphenylsulfone, Epicoat 1004 as an epoxy resin, PF as a curing accelerator, -ME
The same procedure as in Example 1 was carried out except that A was used.

Comparative Example 1 Comparative Example 1 was carried out in the same manner as in Example 1, except that the formulation in Example 1 was changed to the following formulation.

Acrylic elastomer 5G90 80 parts Epicoat 828 20 parts 434'-diaminodiphenylmethane 4 parts BFs MEA 0.4 parts Comparative Example 2 The same procedure as Example 1 was carried out except that the formulation in Example 1 was changed to the following formulation.

Acrylic elastomer SC20 93.5 parts Epicoat 828 6.25 parts 44°-diaminodiphenylmethane 1.25 parts BF, -MEA 01375 parts Comparative Example 3 Same as Example 1 except that the formulation of Example 1 was changed to the following formulation. I did the same.

Epicote 828 100 parts, 4.4゛-
Diaminodiphenylmethane 34.5 parts The above test results were evaluated for the following items and summarized in a table.

In addition, the evaluation method of the characteristics of the flexible printed wiring board (FPC) obtained according to the example (comparative example) is as follows.

■ Adhesive Crab JIS C6481 to 1! Basis.

■Solder heat resistance: Compliant with JIS C6481.

■ Flow resistance: Inlet temperature 300°C1 Outlet temperature 35°C
Pass the FPC through a far-infrared heating furnace at 0°C at a speed of 1 m/min. Visually observe the results.

■ Spill resistance: 0. A hole No. 8111 is opened and the amount of adhesive bleeding after pressing is measured.

(Effects of the Invention) As explained above, the adhesive composition for flexible printed wiring boards of the present invention can be cured in a short time, and
It has excellent adhesive strength, solder heat resistance, reflow resistance, and flow resistance, and has a long pot life. Because it has a good balance of these properties, it is particularly suitable for use as a reinforcing plate for flexible printed wiring boards. be.

Claims (4)

[Claims] (1) Features include an acrylic elastomer (A) having a functional group, an epoxy resin (B) having two or more epoxy groups in one molecule, a curing agent (C), and a curing accelerator (D). An adhesive composition for flexible printed wiring boards. (2) The adhesive composition for a flexible printed wiring board according to claim (1), wherein the curing agent (C) is an aromatic polyamine and the curing accelerator (D) is a cationic polymerization type catalyst. (3) The amount of curing accelerator (D) is different from that of epoxy resin (
The adhesive composition for a flexible printed wiring board according to claim 1 or 2, wherein the adhesive composition is 0.5 to 5 phr based on the solid content of B). (4) Acrylic elastomer (A) and epoxy resin (
The adhesive composition for a flexible printed wiring board according to any one of claims (1) to (3), wherein the blending ratio of B) is in the range of 1/1 to 10/1 in terms of solid content weight ratio.