JP3465276B2 - Adhesive composition for flexible printed wiring boards - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive composition suitable for bonding a plastic film used for a flexible printed wiring board to a reinforcing plate. In particular, the present invention is characterized by using a fine powder catalyst or a microencapsulated catalyst having a unique property as a catalyst used as a curing accelerator in combination with a cationic polymerization type catalyst, for a flexible printed wiring board. The present invention relates to an adhesive composition.

[0002]

2. Description of the Related Art Conventional adhesives for flexible printed wiring are as follows. When a powdery curing agent is used, pressurized water cooling to room temperature is required to prevent distortion, and it is necessary to raise the temperature again to perform the next press, and the cycle time of press is long (see No. 2-202973). When a curing agent and a cationic polymerization catalyst are used, pressurized water cooling is not required, but the pressing conditions are as high as 180 ° C. × 10 hg / cm ² × 5 minutes,
The equipment cost of the press is high, the service life is short, and the workability is poor (Japanese Unexamined Patent Publication No. 3-221578).

Conventionally, epoxy resins, acrylic resins, phenol resins, and the like have been used for this type of adhesive. However, in order to obtain sufficient adhesive performance, an aromatic polyamine or cationic polymerization type is used as a curing agent. Since a curing agent (boron trifluoride amine complex, boron trifluoride-ether complex, etc.) was used, there was a drawback that high-temperature, high-pressure, long-time pressing was required, and workability was poor. In addition, these materials are not suitable for the adhesive between the component mounting reinforcing plate and the flexible printed wiring board because the flow of the adhesive is large.

[0004]

The present inventors have made various studies on the above-mentioned problems and found that (A) an acrylic elastomer having a functional group and (B) two or more epoxy groups in one molecule. And (C) a curing agent thereof, and (D) a curing accelerator thereof, wherein the mixing ratio of the acrylic elastomer (A) and the epoxy resin (B) is 1 / Curing agent in the range of 1 to 10/1
(C) is an aromatic polyamine, curing accelerator (D) is the particle diameter and a cationic polymerization catalyst (a) A is 30μm or less, Lee
The cationic polymerization type catalyst (a) is used in combination with the midazole-based powdery catalyst (b), and the weight of the cationic polymerization type catalyst (a) is 0.5 to 5.0% by weight based on the weight of the solid content of the epoxy resin (B). %, Wherein the weight of the powdered catalyst (b) is 1.0 to 10.0% by weight based on the weight of the solid content of the epoxy resin (B). Also,

A composition comprising (A) an acrylic elastomer having a functional group, (B) an epoxy resin having two or more epoxy groups in one molecule, (C) a curing agent thereof, and (D) a curing accelerator thereof. Wherein the mixing ratio of the acrylic elastomer (A) and the epoxy resin (B) is in the range of 1/1 to 10/1 in terms of solid content weight ratio, the curing agent (C) is an aromatic polyamine, Promoter (D) is a cationic polymerization type catalyst
(a) is used in combination with a microencapsulated modified imidazole-based catalyst (b) ′ having an average particle size of 5 μm or less, and the weight of the cationic polymerization catalyst (a) is 0.5 to the solid weight of the resin (B)
5.0% by weight, and the weight of the microencapsulated catalyst (b) 'is 1.0 to 1 with respect to the solid weight of the epoxy resin (B).
An adhesive composition for a flexible printed wiring board, which is 0.0% by weight.

Hereinafter, the present invention will be described specifically. The adhesive composition of the present invention is, as a catalyst used for the curing accelerator (D) , a powdery catalyst having a particle size of 30 μm or less (b)
By using in combination with the cationic polymerization type catalyst (a) , compared to the case of using a conventional adhesive, the pot life of one month or more, the solder heat resistance by pressing at a relatively low temperature and a short time, It is possible to provide an adhesive composition for a flexible printed wiring board excellent in the adhesive strength of a reinforcing plate. Here, the particle diameter means that the particle diameter of the powdery catalyst (b) has an average particle diameter.

The fine powder catalyst (b) of the present invention includes Cureazole C17Z (trade name, manufactured by Shikoku Chemicals Co., Ltd.), Curesol 2PHZ (trade name, manufactured by Shikoku Chemicals Co., Ltd.), Curezole 2MZA (Shikoku Chemicals) Imi such as Curesol FFZ (trade name, manufactured by Shikoku Kasei Co., Ltd.)
Refers to a dazole-based powder catalyst. Examples of the cationic polymerization catalyst (a) constituting the curing accelerator (D) include BF ₃ -M
_{EA, SbF 5 -MEA, PF 5} -MEA, FeC
l ₃ and AlCl ₃ . The powdered catalyst (b) has a particle size of 30 μm or less, preferably 3 to 15 μm.
It is necessary that the catalyst be a powdery catalyst finer than m. In this case, if the particle size of the powdered catalyst (b) exceeds 30 μm, the area in contact with the resin composition constituting the adhesive composition is reduced, so that the bonding requires a high temperature and a long time,
On the other hand, if the particle size is too small, the contact area with the cationic polymerization type catalyst (a) becomes too large, and the pot life is shortened.

When the adhesive composition of the present invention is used, the bonding between the plastic film used for the flexible printed wiring board and the reinforcing plate can be performed at a relatively low temperature and in a short time, and at the same time, the pot life can be one month or more. And has the advantage of extremely low flowability. Furthermore, the adhesive composition of the present invention has properties required for adhesion between a plastic film used for a flexible printed wiring board and a reinforcing plate, such as adhesive strength / solder heat resistance, flow-out resistance, and long pot life. All provide satisfactory adhesives.

The adhesive composition of the present invention is characterized in that, as a catalyst used for the curing accelerator (D), a modified imidazole-based catalyst (b) ′ having a unique property and microencapsulated is used as a cationic polymerization type catalyst ( The present invention relates to an adhesive composition for a flexible printed wiring board, which has a technical significance when used in combination with a).

[0010] The microencapsulated modified imidazole-based catalyst having an average particle size of 5 µm or less used in the present invention (b) '
Is a thin layer coated with a coating agent such as polyurethane to such an extent that the microcapsules are easily broken under pressure or temperature.
2, -3741 and -3748 (trade names, manufactured by Asahi Kasei Corporation). Examples of the cationic polymerization catalyst (a) include BF ₃ -MEA and SbF ₅ -ME
A, PF ₅ -MEA, FeCl ₃ , AlCl _{3 and the} like.

The microcapsulated modified a
When the midazole-based catalyst (b) ′ is used in combination with the cationic polymerization type catalyst (a), a longer pot life of at least two months, a relatively low temperature and a shorter With this press, it is possible to provide an adhesive composition for a flexible printed wiring board which is excellent in solder heat resistance and adhesive strength to a reinforcing plate. The reason for this is that, up to the temperature at which the resin composition constituting the adhesive composition is cured, the catalyst constituting the curing accelerator is
This is because the microcapsule-like film does not come into contact with the resin composition or the contact is delayed due to the presence of the film. Modified imidazole catalysts the microencapsulated
(b) ′ needs to be fine, having an average particle size of 5 μm or less, from the viewpoint of easy contact with the cationic polymerization type catalyst.

When the adhesive composition of the present invention is used, the bonding between the plastic film used for the flexible printed wiring board and the reinforcing plate can be carried out at a relatively low temperature and in a short time, and at the same time, the pot life of 2 months or more is obtained. And has the advantage of extremely low flowability. Furthermore, the adhesive composition of the present invention has properties required for adhesion between a plastic film used for a flexible printed wiring board and a reinforcing plate, such as adhesive strength / solder heat resistance, flow-out resistance, and long pot life. All provide satisfactory adhesives.

The components (A), (B), (C) and (D) constituting the adhesive resin composition of the present invention will be specifically described below. In the adhesive composition of the present invention, 1/1 to 10 /
By combining the acrylic elastomer (A) / epoxy resin (B) and the aromatic polyamine (C), it is possible to obtain high adhesive strength, high solder heat resistance, and long pot life. In addition, the amount of the solid content of the epoxy resin (B ) is 0.1%.
5 to 5.0% by weight of the cationic polymerization type catalyst (a) and 1.0 to
10% by weight of microencapsulated modified imidazole-based catalyst (b) ′ or imidazo having a particle size of 30 μm or less
By adding Lumpur based powder catalyst (b) the combined curing accelerator (D), less cold with suppressed and flows a decrease in pot life, since it is possible to obtain an adhesive capable of short curing time is there.

Acrylic elastomer (A) / epoxy resin
The compounding ratio of (B) is 1/1 to 10/1, preferably 2/1 to 6/1 in terms of solid content weight ratio. Acrylic elastomer
If the compounding ratio of (A) is less than 1/1, the solder heat resistance decreases. Conversely, if it is more than 10/1, the adhesive strength will decrease.

Further, the above main component , acrylic elastomer
The curing agent (C) and the curing accelerator (D) are added to (A) and the epoxy resin (B), and at this time, the amount of the curing agent (C) added is from epoxy equivalent to 1/2 epoxy equivalent is desirable. If the amount of the curing agent (C) added is less than 1/2 epoxy equivalent, a sufficient degree of curing cannot be obtained, leading to a decrease in solder heat resistance. Further, even if the epoxy equivalent or more is added, a decomposition gas is generated in the solder heat resistance test, which is not desirable.

As the acrylic elastomer (A) component,
Acrylic elastomer known per se can be used, but generally, one or more acrylates or α-substituted acrylates are used as a main component, and at least one functional group is used as a crosslinking point. It includes a polymer that is included, or a polymer obtained by (grafting) copolymerizing at least one of the functional group-containing monomers with the above-mentioned main component monomer. More specifically, the acrylic elastomer (A) is (a) an acrylate ester or α
One or more of the substituted acrylates constitutes a large proportion of components, which comprise one or two selected from the group of (b) epoxy groups, (c) carboxyl groups, and (d) hydroxyl groups. An acrylic elastomer obtained by copolymerizing a monomer having the above functional group can be given.

Specific examples of the monomers (a) to (d) are shown below. Examples of the acrylate or α-substituted acrylate (a) include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, octyl acrylate and the like. Examples of the epoxy group-containing monomer (b) include glycidyl ethers such as vinyl glycidyl ether and allyl glycidyl ether; and glycidyl (meth) acrylates. Examples of the carboxyl group-containing monomer (c) include (meth) acrylic acid, itaconic acid, maleic acid, and maleic anhydride. Examples of the hydroxyl group-containing monomer (d) include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, and dimethacrylate of a polyhydric alcohol such as polyethylene glycol dimethacrylate. And alkoxyalkyl acrylates such as methoxymethyl acrylate. Further, if necessary, other vinyl monomers such as vinyl chloride, vinylidene chloride, styrene, methacrylonitrile, and vinyl acetate may be copolymerized.

Specific examples of the acrylic elastomer (A) include Alontack S-1511L and S-1511L.
X, S-1015, S-1017 (Toa Gosei Chemical Co., Ltd.)
Noxtite PA-501, PA-50
2 (trade name of Nippon Mektron Co., Ltd.); Teisan Resin WS
022, WS023, SG51, SG80, SG90
(Trade name, manufactured by Teikoku Chemical Co., Ltd.) and AR-51 (trade name, manufactured by Nippon Zane Co., Ltd.). These can be used alone or in combination of two or more. The acrylic elastomer (A) may have any one of an epoxy group, a carboxyl group, and a hydroxyl group, and among these, an epoxy elastomer having a low-temperature reactive epoxy group is preferable.

The epoxy resin (B) is not particularly limited, but generally, any resin having two or more epoxy groups in one molecule may be used. For example, bisphenol A type epoxy resin, phenol novolak type epoxy resin, brominated epoxy resin and the like can be mentioned.

The curing agent (C) is not particularly limited.
Commonly used curing agents such as aliphatic polyamines, aromatic polyamines, and acid anhydrides can be used.
In the present invention, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4 '
- aromatic polyamine such as diaminodiphenylsulfone
Use .

The cationic polymerization type catalyst (a) constituting the curing accelerator (D ) is, for example, BF ₃ -MEA, SbF ₅ -ME
A, PF ₅ -MEA, FeCl ₃ , AlCl _3, etc.
Examples thereof include quaternary ammonium salts, quaternary sulfonium salts, and alkali metal salts of weak organic acids. The weight of the cationic polymerization type catalyst (a) must be 0.5 to 5.0% by weight based on the weight of the solid content of the epoxy resin (B).
There is . 0.5% by weight of cationic polymerization type catalyst (a) added
If it is less than 1, the pot life is prolonged, but the initial performance (adhesive strength, solder heat resistance) is not sufficient. Conversely, 5.0
If the weight percent is exceeded, the pot life is drastically reduced,
Not practically usable.

Further, a midazole-based powdery catalyst (b) or a microencapsulated modified imidazole-based catalyst, which constitutes a curing accelerator (D) together with the cationic polymerization type catalyst (a)
It is necessary that the weight of (b) ′ is 1.0 to 10.0% by weight based on the weight of the solid content of the epoxy resin (B). I
If the amount of the midazole-based powdery catalyst (b) or the microencapsulated modified imidazole-based catalyst (b) ′ is less than 1.0% by weight, the function as a curing accelerator (D), particularly the initial performance (solder Heat resistance) cannot be fully exhibited. Also, 1
If the addition exceeds 0.0% by weight, the pot life is undesirably reduced.

As the solvent used in the adhesive composition of the present invention, methyl ethyl ketone, acetone, toluene, dioxane, methyl cellosolve acetate, ethylene glycol monomethyl ether and the like and a mixture thereof can be used. Needless to say, various additives such as a plasticizer, an antioxidant, anhydrous silica, and a fine inorganic filler such as aluminum hydroxide can be appropriately added to the adhesive composition of the present invention. That is.

In order to apply the adhesive composition of the present invention to a film or a reinforcing plate, the components of the adhesive composition are first mixed by a known mixing means, then dissolved in a solvent, and coated in a solution state. I do. In this case, after being applied to one of the adherends, lamination and curing are performed by an arbitrary heating and curing means.
For example, the coated material is dried in a hot air oven to dry the solvent, or is pre-cured to form a B-stage product, which is then combined with another object to be bonded, and then heated using a hot press.
30-180 How to thermocompression bonding at a pressure of 5kg / cm ² ~40kg / cm ² is employed in ° C.. In addition, after the coating and drying are continuously performed, the coating may be continuously passed through a heating roll, and then heat-pressed and integrated to perform post-heating curing.

As the reinforcing plate to which the adhesive composition of the present invention is applied, aluminum plate, silicon steel plate, paper phenol laminate,
Glass epoxy laminates, polypropylene, polyethylene and the like can be mentioned. The film to which the adhesive composition of the present invention is applied is not particularly limited as long as it is a polymer film, and particularly refers to a film used for FPC, and includes a polyimide film, a polyester film, a polyetherketone film, and a polyethersulfone film. And ultra-thin laminates.

[0026]

EXAMPLES The present invention will be described specifically with reference to Examples.
They do not limit the scope of the invention. The present invention is specifically described by the following evaluations. Adhesive force: conforms to JIS C6481 Solder heat resistance: conforms to JIS C6481 Flow-out resistance: A 0.8 mm hole is formed in the FPC, and the amount of bleeding of the adhesive after pressing is measured. Pot life: Number of days until the adhesive strength becomes 0.8 hg / cm

When a cationic polymerization type catalyst (a) and a microencapsulated modified imidazole-based catalyst (b) ′ are used. (Example 1) 93.5 parts of a 20% by weight solution of SG90 (trade name, manufactured by Teikoku Chemical Industry Co., Ltd.) in toluene as an acrylic elastomer, and Epicoat 828 as an epoxy resin
6.25 parts (manufactured by Yuka Shell Epoxy Co., Ltd.), 0.7 parts of 4,4'-diaminodiphenylmethane (manufactured by Sumitomo Chemical Co., Ltd.) as an aromatic polyamine, and cationic polymerization as a curing accelerator Type catalyst BF ₃ -MEA (trade name, manufactured by Hashimoto Kasei Co., Ltd.) and 0.125 parts of microcapsulated catalyst Novacure HX-3741 (trade name, manufactured by Asahi Kasei Kogyo Co., Ltd., modified imidazole coated with polyurethane) 0.60 parts were mixed and stirred to obtain a viscous adhesive solution. Then, it was applied on a release paper so as to have a thickness of 40 μm in solid amount and dried at 120 ° C. for 5 minutes to obtain a B-staged film. Using this, an aluminum reinforcing plate and a flexible printed wiring board are bonded together at 160 ° C. × 10 hg / cm.
Pressing was performed under the conditions of ² × 5 minutes, and immediately after the pressing, the pressure was released and the mixture was allowed to cool.

(Example 2) SG80 (trade name ^, manufactured by Teikoku Chemical Industry Co., Ltd.) as an acrylic elastomer ^, Epicoat 1 as epoxy resin
54, as the aromatic polyamine of 4,4'-diaminodiphenyl sulfone (Sumitomo Chemical Co., Ltd., trade name), a cationic polymerization catalyst Sb _5-MEA and microencapsulated modified imidazole catalysts NOVACURE HX as a curing accelerator Except using -3742, it carried out similarly to Example 1.

Example 3 AR-51 (trade name, manufactured by Zeon Corporation) as an acrylic elastomer, Epicoat 1 as an epoxy resin
004, 4,4'-diaminodiphenyl ether as aromatic polyamines, cationic polymerization catalysts PF _5-MEA and microencapsulated modified Imi as a curing accelerator
The procedure was performed in the same manner as in Example 1 except that the dazole- based catalyst Novacure HX-3721 was used.

Comparative Example 1 The procedure of Example 1 was repeated, except that the composition of Example 1 was changed as follows. Curing agent 4,4'-diaminodiphenylmethane 1.25 parts Curing accelerator BF ₃ -MEA 0.125 part (Comparative Example 2) Same as Example 1 except that the composition of Example 1 was changed as follows. Was. Curing accelerator Novacure HX-3741 0.6 parts

Comparative Example 3 The procedure of Example 2 was repeated except that the composition of Example 2 was changed as follows. Acrylic elastomer SG80 (20% by weight solution) 80 parts of Epikote 154, 20 parts of 4,4'-diaminodiphenylsulfone 2.24 parts Sb _5-MEA 0.40 parts Novacure HX-3742 1.92 parts (Comparative Example 4) Example Example 2 was carried out in the same manner as in Example 2 except that the composition of No. 2 was changed as follows. Examples 1 to 3 and Comparative Examples 1 to 4 are summarized in Table 1 below.

[0032]

[Table 1]

Cationic polymerization type catalyst (a) and finely divided imi
When using a dazole-based powdery catalyst (b). (Example 4) SG90 (trade name, manufactured by Teikoku Chemical Industry Co., Ltd.) was used as an acrylic elastomer in methyl ethyl ketone / toluene =
93.5% by weight of a 20% solution dissolved in 1/1 mixed solvent
Parts, 6.25 parts of Epicoat 828 (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.) as an epoxy resin, and 0.7 parts of 4,4'-diaminodiphenylmethane (trade name, manufactured by Sumitomo Chemical Co., Ltd.) as an aromatic polyamine , BF as a curing accelerator
_3- MEA (Hashimoto Kasei Co., Ltd., trade name) 0.125
And 0.3 parts of Curesol C17Z (trade name, particle size: 25 μm, manufactured by Shikoku Chemicals Co., Ltd.) were mixed and stirred to obtain a viscous adhesive solution. Then, on a release paper, 4
It was applied to a thickness of 0 μm and dried at 120 ° C. for 5 minutes to obtain a B-staged film. Using this, the aluminum reinforcing board and the flexible printed wiring board are bonded together at 160 ° C ×
Pressing was performed under the conditions of 10 hg / cm ² × 5 minutes, and immediately after the pressing, the pressure was released and the mixture was allowed to cool.

Example 5 SG80 (trade name, manufactured by Teikoku Chemical Industry Co., Ltd.) as an acrylic elastomer, 4,4 ′ as an aromatic polyamine
-Diaminodiphenyl sulfone (trade name, manufactured by Sumitomo Chemical Co., Ltd.), Epicoat 154 as an epoxy resin, 0.125 part of Sb ₅ -MEA as a curing accelerator, and Cureazole 2PHZ (trade name, particle size: 20 μm, manufactured by Shikoku Chemicals Co., Ltd.) )
The same procedure as in Example 4 was carried out except that 0.30 part was used.

Example 6 AR-51 (trade name, manufactured by Zeon Corporation) as an acrylic elastomer, Epicoat 1 as an epoxy resin
004, 4,4′-diaminodiphenyl ether as aromatic polyamine, PF ₅ -MEA as curing accelerator
The procedure was performed in the same manner as in Example 4 except that 0.125 part and 0.30 part of Curezole 2MZ-A (trade name, particle size: 18 to 30 μm, manufactured by Shikoku Chemicals Co., Ltd.) were used.

Comparative Example 5 The procedure of Example 4 was repeated except that the composition of Example 4 was changed as follows. Curing agent 4,4'-diaminodiphenylmethane 1.25 parts Curing accelerator BF ₃ -MEA 0.125 part (Comparative Example 6) Performed in the same manner as in Example 4 except that the composition of Example 4 was changed as follows. Was. Cure accelerator Cureazole C17Z 0.4 parts

Comparative Example 7 The procedure of Example 5 was repeated, except that the composition of Example 5 was changed as follows. Acrylic elastomer SG90 80 parts Epicoat 828 20 parts 4,4′-diaminodiphenylmethane 2.24 parts BF ₃ -MEA 0.40 parts Curesol C17Z 0.96 parts Examples 4 to 6 and Comparative Examples 5 to 7 are shown in Table 2 below. Put together.

[0038]

[Table 2]

[0039]

As described above, the adhesive composition for a flexible printed wiring board of the present invention can be generally cured at a low temperature and in a short time, and further has an adhesive strength, a solder heat resistance, and a resistance to flow-out. It has excellent potability and a long pot life, and has a good balance of its properties. Therefore, it is particularly suitable for a reinforcing plate of a flexible printed wiring board. In particular, in the adhesive composition for a flexible printed wiring board of the present invention, the cationic polymerization catalyst (a) and the imidazole-based powdery catalyst (b) or the microencapsulated modified imida
It is characterized by using a sol-based catalyst (b) 'in combination, which allows (a) adhesion between a plastic film used for a flexible printed wiring board and a reinforcing plate to be maintained at a relatively low temperature for a short time. At the same time, it has the advantage of having a pot life of one month or more and having a very low flow-out property. (B) Adhesive strength, solder heat resistance, solder flow-out resistance, and long pot life. Provided is an adhesive that satisfies all the properties required for bonding a plastic film and a reinforcing plate to be used.

Claims (2)

(57) [Claims] (A) an acrylic elastomer having a functional group, (B) an epoxy resin having two or more epoxy groups in one molecule, (C) a curing agent thereof, and (D) a curing accelerator thereof. A composition comprising the acrylic elastomer (A) and the epoxy resin (B) in a ratio by weight of solid content of 1/1 to 10/1, wherein the curing agent (C) is an aromatic polyamine. The curing accelerator (D) is the same as the cationic polymerization type catalyst (a) and the particle size is 30.
μm or less, used in combination with the imidazole-based powdery catalyst (b), and the cationic polymerization type catalyst
The weight of (a) is 0.5 to 5.0% by weight based on the weight of the solid content of the epoxy resin (B), and the weight of the powdery catalyst (b) is based on the weight of the solid content of the epoxy resin (B). An adhesive composition for a flexible printed wiring board, which is 1.0 to 10.0% by weight. 2. An acrylic elastomer having a functional group, (B) an epoxy resin having two or more epoxy groups in one molecule, (C) a curing agent thereof, and (D) a curing accelerator thereof. A composition wherein the mixing ratio of the acrylic elastomer (A) and the epoxy resin (B) is in the range of 1/1 to 10/1 in terms of solid content weight ratio, and the curing agent (C) is an aromatic polyamine. , an average particle diameter of the curing accelerator (D) is a cationic polymerization catalyst (a) is not more 5μm or less, microencapsulated modified Lee
The cationic polymerization catalyst (a) is used in combination with the midazole-based catalyst (b) ', and the weight of the cationic polymerization catalyst (a) is 0.5 to 5.0% by weight based on the weight of the solid content of the epoxy resin (B). The weight of the microencapsulated catalyst (b) 'is 1.0 to 10.0% by weight based on the weight of the solid content of the epoxy resin (B), and the adhesive for flexible printed wiring boards is characterized in that: Composition.