JPH07224269A - Adhesive composition, composite material and printed wiring board - Google Patents

Abstract

PURPOSE:To obtain an adhesive composition which is flexible and exhibits good workability at the B stage and has a small thermal coefficient of expansion when cured. CONSTITUTION:An adhesive composition comprising 100 parts by weight imide oligomer having at least two amine groups in each molecule, 50 to 200 parts by weight epoxy compound having at least two epoxy groups in each molecule, 10-80 parts by weight bismaleimide-triazine resin compound, and 5 to 80 parts by weight nitrile rubber.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is capable of laminating various metal foils, various polymer films, glass, epoxy substrates and the like to each other, and B stage (before curing by heat pressing in an adhesive composition). Of the adhesive composition having a low coefficient of thermal expansion after curing, a composite using the adhesive composition, and a print formed using the adhesive and the composite. It relates to a wiring board.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
Adhesives such as epoxy resins and acrylic resins have been widely used for flexible printed wiring boards. But,
Since these adhesives have a large coefficient of thermal expansion after curing and the difference from that of the circuit is large, cracks occur in through-hole plating in flexible printed wiring boards with through holes and flexible rigid multilayer printed wiring boards. was there.

To solve this problem, it is possible to use an imide resin-based adhesive, but commercially available adhesives are very hard and brittle in the B stage, which makes them difficult to handle and has a problem in workability.

On the other hand, compositions such as epoxy resin, polyimide resin, phenol resin, bismaleimide-triazine resin, etc., or a laminate obtained by impregnating them into a glass fiber woven cloth have been used as an adhesive for hard printed wiring boards. . However, these adhesives have a small coefficient of thermal expansion but are rigid, and their applications have been limited.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and the B stage has flexibility and good workability,
Further, the present invention provides an adhesive composition having a small coefficient of thermal expansion after curing, a composite using the composition, and a printed wiring board. The adhesive composition is characterized by at least two or more in one molecule. Imide oligomers having amine groups of 100
50 parts by weight to 200 parts by weight of an epoxy compound having at least two epoxy groups in one molecule, 10 to 80 parts by weight of a bismaleimide-triazine resin compound, and 5 to 80 parts by weight of a nitrile rubber component. There is something to do.

[0006]

The adhesive composition of the present invention is designed to suppress the coefficient of thermal expansion by dispersing a soft rubber component in a rigid component and to have flexibility at the B stage. That is, a rigid portion is formed by a mixture of an imide oligomer, an epoxy resin, and a bismaleimide-triazine resin, and a flexible component such as nitrile rubber is dispersed therein.

The imide oligomer is not particularly limited as long as it has at least two amine groups in one molecule. This is a mixture of acid dianhydride and diamine in a molar ratio of 1: 2, and 20% in N-methyl-2-pyrrolidone.
Dissolve to a concentration of about 60 ° C. for 1 hour, then heat at 80 ° C. for 1 hour to react. It can be obtained by filtering after the reaction, washing with ethanol and drying. For example, 3.3 ', 4.4'-benzophenone tetracarboxylic acid dianhydride and 3.3', 4.4'-diphenylsulfone tetracarboxylic acid dianhydride are suitable for the acid dianhydride, and 2.2- [4- (4 -Aminophenoxyl) phenyl]
Examples include propane, bis [4- (4-aminophenoxyl) phenyl] sulfone, trimethylene-bis (4-aminobenzoate), and the like. Acid dianhydride as above,
A desired imide oligomer can be obtained by selecting one kind or two or more kinds of materials from the diamine and polymerizing them, but the manufacturing method and the constituent materials are not limited thereto.

Any epoxy resin may be used as long as it has at least two epoxy groups in one molecule, such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin and glycidyl. Amine type epoxy resins, alicyclic epoxy resins and the like are easy to use, and these may be used alone or in combination of two or more kinds. However, the closer the molecular weight to the imide oligomer as the main component, the better the compatibility and the easier the mixing operation.

The reason why the imide oligomer and the epoxy compound need to have at least two or more amine groups and epoxy groups in one molecule is that the amine group of the imide oligomer and the epoxy group of the epoxy compound are reacted to form a linear chain. This is because the polymer is polymerized by forming a shape or cross-linking, and if there is only one of them, the molecule becomes the termination of the reaction and the polymer cannot be polymerized.

The reason why the epoxy compound is used in an amount of 50 to 200 parts by weight with respect to 100 parts by weight of the imide oligomer is that the compounding ratio is such that the reaction can be carried out without excess or deficiency and the compatibility does not matter. When the amine group and the epoxy group are present in the reaction system in a ratio of 1: 1, the reaction will be performed adequately. That is, when the imide oligomer and the epoxy compound have the same molecular weight, if the weight ratio is 1: 1, the ratio of the amine group and the epoxy group becomes 1: 1 and the reaction is performed without excess or deficiency. But,
When the molecular weights are different, the weight ratio for reacting exactly is not 1: 1. When the difference in molecular weight becomes large, the problem of poor compatibility arises. Therefore, the molecular weights are brought close to each other to some extent, and the range is 50 to 200 parts by weight, and the more preferable range is 80 to 150 parts by weight.

The bismaleimide-triazine resin compound is a known thermosetting resin composition, for example, a thermosetting resin having an imide group and a triazine ring obtained from a bismaleimide component and a triazine monomer having a cyanate group or a prepolymer component. Resin composition. The reason why the bismaleimide-triazine resin compound is 10 to 80 parts by weight is that the lower limit for promoting the reaction is 10 parts by weight and the upper limit for preventing the reaction from becoming rigid is 80 parts by weight. It has been confirmed that the reactivity is higher when the bismaleimide-triazine resin compound is added than when the imide oligomer and the epoxy compound are reacted alone, and the range is as described above, and a more preferable value. Is
10 to 60 parts by weight.

Various rubbers are conceivable as the rubber component, for example, acrylic rubber, chloropyrene rubber, acrylonitrile rubber, butadiene rubber, styrene butadiene rubber, urethane rubber and the like. These rubbers are compatible with the above imide oligomer and epoxy compound. And is reactive. As a result of examining various rubber components and their addition amounts, it was found that nitrile rubber was the most suitable.

The nitrile rubber is a random copolymer of butadiene and acrylonitrile (AN), which is a non-crystalline and irregular rubber, and a medium-high nitrile having an AN amount of 31 to 35% is suitable. However, depending on the type of the imide oligomer or the epoxy compound, the one having a higher AN content may be more compatible and easier to work in some cases. In that case, there is a problem that flexibility in the B stage decreases,
The type of nitrile rubber is not particularly limited, but it is necessary to use it properly according to the application.

The reason why the nitrile rubber component is 5 to 80 parts by weight is that the lower limit for imparting flexibility at the B stage is 5
The upper limit is 80 parts by weight in order to prevent the thermal expansion coefficient from being increased too much. It has been confirmed that a mixture of only an imide oligomer, an epoxy compound, and a bismaleimide-triazine resin compound has flexibility in the B stage and improves workability, and the range is as described above, and more preferably 10 ~ 60 parts by weight.

As described above, with the adhesive composition of the present invention, it is possible to obtain an adhesive composition having a small coefficient of thermal expansion and good workability which does not cause chipping in the B stage. Then, by impregnating a glass fiber woven cloth with this adhesive, an adhesive layered product (referred to as a layered product A) having a lower expansion coefficient, which does not cause chipping during use, is obtained although the flexibility is reduced. To be By coating the adhesive composition on a polymer film, a coverlay film laminate (laminate B) that functions as a protective layer of a printed wiring board can be obtained.

By using the adhesive composition of the present invention and the laminate 2 alone or in combination, it is possible to obtain a flexible printed wiring board having high reliability against environmental temperature changes. For example, as shown in FIG. 1, a copper circuit layer 2 is formed from a copper foil of a double-sided copper-clad polyimide base film 1 and a polymer film coverlay film 3 is formed.
A flexible printed wiring board is prepared by laminating a laminate B5 formed by laminating the adhesive layer 4 of the present invention. By laminating two such wiring boards with the adhesive layer 4 interposed therebetween, a flexible multilayer printed wiring board as shown in the figure can be obtained.

By using the adhesive composition of the present invention and the laminates A and B alone or in combination, it is possible to obtain a hard printed wiring board having high reliability against environmental temperature changes. For example, as shown in FIG. 2, a copper circuit layer 2 is formed from a copper foil surface of a copper-clad glass / epoxy substrate 6, a plurality of such substrates 6 are prepared, and an adhesive layer of the present invention is provided between them. 4 or by laminating the laminate A8, and then the copper circuit layer 2 on the surface is resist-coated to obtain a hard printed wiring board as shown in the figure.
In this case, if it is desired to improve reliability, a laminate B5 in which the adhesive layer of the present invention is laminated on the coverlay film of the polymer film may be used instead of the resist coating 7.

Further, the adhesive composition of the present invention and the laminate B5 are used alone or in combination in the flexible portion, and the adhesive composition and the laminate A8 are used alone or in combination in the rigid portion. It is possible to obtain a flexible / rigid multilayer printed wiring board having high reliability against environmental changes. For example, as shown in FIG. 3, a copper circuit layer 2 is formed from a copper foil surface of a base film 1 of double-sided copper-clad polyimide, and a cover lay film 3 is laminated with an adhesive layer 4 of the present invention on both surfaces thereof. The laminated body B5 thus obtained is laminated to obtain the flexible printed wiring board 11. Then, a separately prepared circuit-formed copper-clad glass / epoxy substrate 6 and the flexible printed wiring board are provided with an adhesive layer 4 or a laminated body A in which a glass fiber woven fabric is impregnated with the adhesive composition.
8 to form the rigid portion 10, and then the rigid portion 10 is perforated, plated 9 is applied to form a through hole, and the surface is resist-coated 7 to form a flexible rigid multilayer print as shown in the figure. Get the wiring board. At this time, instead of the resist coating 7, the laminated body B
5 may be used.

The coefficient of thermal expansion of the laminate A in which the adhesive composition of the present invention is impregnated in a glass fiber woven cloth has a coefficient of thermal expansion of 2 × 10 ^-5.
The reason why it is set to be 9 × 10 ⁻⁵ / ° C. is a value considered to improve the reliability of the printed wiring board. The thermal stress applied to the through-hole part of the printed wiring board during the heat cycle test was calculated, and the results of comparison with the experimental results show that the reliability of the printed wiring board can be improved by using a laminate having a coefficient of thermal expansion within the above range. Was confirmed.

[0020]

Example: An imide oligomer having amine groups at both ends
With respect to 100 parts by weight, as shown in Tables 1 and 2, an epoxy composition, a bismaleimide-triazine resin compound, an adhesive composition prepared by adding a nitrile rubber, etc.,
The following four items of tests were conducted. (1) Coefficient of thermal expansion: Measured by the TMA method under the conditions of a temperature rising rate of 5 ° C./min. (2) Adhesive strength: The adhesive sample was sandwiched between a copper foil and a polyimide film, pressed under the conditions of 30 kg / cm ² , 180 ° C. for 2 hours, and then the peel strength was measured. (3) Solder heat resistance: An adhesive sample and a polyimide film were laminated and pressed on an aluminum plate, and the pressed product was immersed in a solder bath at 290 ° C. and the state after 60 seconds was observed. The case where blistering or peeling did not occur was regarded as acceptable. (4) Flexibility: When the B stage sample was cut by pressing, and when the sample was not impregnated with the glass fiber woven fabric, it was observed about 180 ° bending. The case where no chipping occurred was regarded as acceptable. The test results are shown in Table 1 (Examples) and Table 2 (Comparative Examples).

[0021]

[Table 1]

[0022]

[Table 2]

The brands of materials used in this example are as follows. Imide oligomer: SM-20 (Sumitomo Chemical) Epoxy resin A: Bisphenol A type epoxy resin Epicutron (Dainippon Ink and Chemicals) Epoxy resin B: Cresol novolac type epoxy resin Araldite ENC1273 (Ciba Geigy) Bismaleimide-triazine resin: BT resin BT21
00 (Mitsubishi Gas Chemical) Nitrile rubber: Nipol DN601 (Zeon Corporation)

[0024]

As described above, according to the adhesive composition of the present invention, it is possible to obtain an adhesive having a small thermal expansion coefficient and good workability that does not cause chipping in the B stage. Therefore, by using a laminate in which a glass fiber woven fabric is impregnated with the above adhesive composition or laminated on a polymer film, a flexible printed wiring board or a hard printed wiring in which the volume change of the adhesive layer with respect to the environmental temperature change becomes a problem. The reliability of the board and the flexible / rigid multilayer printed wiring board can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an example of a flexible printed wiring board using the adhesive composition of the present invention.

FIG. 2 is a cross-sectional view of an example of a hard printed wiring board using the adhesive composition of the present invention.

FIG. 3 shows a flexible structure using the adhesive composition of the present invention.
It is sectional drawing of a rigid multilayer printed wiring board.

[Explanation of symbols]

 1 Base Film 2 Copper Circuit Layer 3 Coverlay Film 4 Adhesive Layer 5 Laminate B 6 Glass / Epoxy Substrate 7 Resist Layer 8 Laminate A 9 Through Hole Plating 10 Rigid Part 11 Flexible Part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 79/08 LRC C09J 109/02 JEL 179/08 JGE H05K 1/03 J 7011-4E

Claims (6)

[Claims] 1. 50 to 200 parts by weight of an epoxy compound having at least two epoxy groups in one molecule, and bismaleimide, per 100 parts by weight of an imide oligomer having at least two amine groups in one molecule. An adhesive composition containing 10 to 80 parts by weight of a triazine resin compound and 5 to 80 parts by weight of a nitrile rubber component. 2. A glass fiber woven fabric is impregnated with the adhesive composition according to claim 1 and has a coefficient of thermal expansion in the thickness direction of 2 × 10 ^{−5 to} 9 ×.
A complex characterized by being controllable at 10 ^-5 / ° C. 3. A composite, characterized in that the adhesive composition of claim 1 is applied to the surface of a polyimide film to a thickness equal to or twice the film thickness to bring it to a B-stage state. 4. A flexible printed wiring board comprising the adhesive composition according to claim 1 and the composite according to claim 3 singly or in combination. 5. A hard printed wiring board, wherein the composite according to claim 2 is laminated alone or in combination. 6. A flexible part and a rigid part, characterized in that the composite of claim 3 is used alone or in combination to form a flexible part, and the composites of claims 2 and 3 are combined to form a rigid part. Printed wiring board having.