JPH1161073A - Adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive compsn. excellent in resistance to soldering heat after moisture-absorption by compounding a carboxylated nitrile rubber with an epoxy resin and a curative comprising a polyhydric phenol. SOLUTION: This compsn. contains a carboxylated nitrile rubber (A), an epoxy resin (B) and a curative (C) comprising a polyhydric phenol in wt. ratios represented by 0.2<=B/A<=10.0 and 0.03<=C/B<=1.0. If necessary, another curative (e.g. an aliph. polyamine), a cure accelerator (e.g. an imidazole deriv.), an aliph. thioester stabilizer, etc., are compounded into the compsn. Ingredient A pref. has a molar ratio of acrylonitrile to butadiene of (3/97)-(60/40) and has a carboxyl group content of 0.5-13 wt.%. Ingredient B is a compd. having at least two epoxy groups in the molecule, an example being a glycidyl ether of a polyphenol. An example of ingredient C is a novolak phenol resin prepd. from a trivalent phenol (e.g. p-t-butylphenol).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive composition, and more particularly to an adhesive for a flexible printed circuit board, particularly an adhesive for a coverlay, which is excellent in adhesiveness, heat resistance to moisture absorption solder, B-stage stability and electrical reliability. The present invention relates to an adhesive composition useful as an agent.

[0002]

2. Description of the Related Art Flexible printed wiring materials are used to form electric or electronic circuits in a wide range of fields such as cameras, calculators, telephones, printers, and various other electric or electronic devices, or in-vehicle devices of automobiles. ing. This flexible printed wiring material is a polyimide film,
A metal foil such as a copper foil or an aluminum foil is bonded to a flexible printed circuit board made of a polyester film or the like using an adhesive. By the way, in recent years,
As electric and electronic devices become lighter and thinner, electric and electronic circuits become more complex, and adhesives used in the manufacture of flexible printed wiring materials have higher electrical reliability and heat resistance than adhesives. Sex is being demanded.

However, a fluororesin-based adhesive, which is conventionally known as an adhesive for flexible printed circuit boards,
Epoxy-novolak resin-based adhesives, nitrile-phenol resin-based adhesives, polyester resin-based adhesives, acrylic resin-based adhesives, and the like have not sufficiently satisfied these requirements.

Therefore, in order to improve the adhesiveness, heat resistance, flexibility, chemical resistance and the like, a carboxyl group-containing nitrile rubber, an epoxy resin, dicyandiamide, 4,4 ′
-Adhesives for flexible printed circuit boards comprising a curing agent comprising an aromatic amine such as diaminodiphenyl sulfone as a component have been proposed (JP-A-61-76579, JP-B-63-61351, etc.). . However, adhesives using these dicyandiamides, aromatic amines, and the like as curing agents have high water absorption, and therefore are not sufficient in terms of electrical reliability such as heat resistance to moisture absorption soldering and migration resistance. In addition, when used for bonding a coverlay film, on a work process, after preparing a multilayered substrate by laminating a plurality of base films, rolled and left for several days, as a coverlay film Since it is generally used, long-term B-stage stability is required. However, when the above-mentioned dicyandiamide, aromatic amine or the like was used as a curing agent, a B-stage stability was low and a satisfactory level of adhesive could not be obtained. In addition, conventional acrylic, urethane and acrylic-urethane adhesives were not at a satisfactory level in terms of electrical reliability such as moisture absorption solder heat resistance and migration resistance.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an adhesive for flexible printed circuit boards which is excellent in adhesiveness, heat resistance to moisture absorption solder, B-stage stability and electrical reliability, and has recently been required. An object of the present invention is to provide an adhesive composition having sufficient high properties.

[0006]

Means for Solving the Problems The present inventors have conducted various studies on a curing agent used for an adhesive containing a carboxyl group-containing nitrile rubber and an epoxy resin as main components. It has been found that the above-mentioned problem can be solved if used as the present invention, leading to the present invention.

That is, the present invention provides an adhesive composition comprising (A) a nitrile rubber having a carboxyl group, (B) an epoxy resin, and (C) a curing agent comprising a polyhydric phenol having a valency of 2 or more. To provide.

Hereinafter, the adhesive composition of the present invention (hereinafter referred to as “the composition of the present invention”) will be described in detail.

The composition of the present invention comprises (A) a nitrile rubber having a carboxyl group, (B) an epoxy resin, and (C) a curing agent comprising a dihydric or higher phenol.

The carboxyl group-containing nitrile rubber (hereinafter referred to as “carboxyl group-containing nitrile rubber”) as the component (A) of the composition of the present invention has a repeating structural unit derived from acrylonitrile and butadiene. A rubber made of a copolymer having a carboxyl group in the molecule. Examples of the carboxyl group-containing nitrile rubber include, for example, acrylonitrile-butadiene copolymer rubber obtained by copolymerizing acrylonitrile and butadiene, the terminal of which is carboxylated, or carboxyl group-containing polymer such as acrylic acid together with acrylonitrile and butadiene. And a copolymer rubber obtained by terpolymerizing a reactive monomer. The acrylonitrile-butadiene copolymer rubber preferably has a molar ratio of acrylonitrile to butadiene of from 3/97 to 60/40, and is further cured to form a cured product having excellent heat resistance and flexibility. 5/95 ~
Those having a molar ratio of 45/55 are preferred.

In the composition of the present invention, the carboxyl group content in the carboxyl group-containing nitrile rubber is 0.5
To 13% by weight, in particular, in that an adhesive composition having excellent adhesiveness and excellent heat resistance can be obtained.
1 to 8% by weight is preferred. Specific examples of the carboxyl group-containing nitrile rubber include Hiker CTBN, Hiker CTBNX, Hiker 1072 (manufactured by Goodrich), Nipol 1072 (manufactured by Zeon Corporation), Chemigum 550 (manufactured by Goodyear), and Tylac 221A (standard). And those marketed under the trade name such as “Plans”. Further, the carboxyl group-containing nitrile rubber can be used in a form dissolved or dispersed in an organic solvent, if necessary. As the organic solvent used, for example, methyl ethyl ketone, methyl isobutyl ketone, ethanol, isopropanol, methyl cellosolve and the like are inexpensive and have a low boiling point, so the drying time is short, and the drying in the B-stage is easy. preferable.

The epoxy resin which is the component (B) of the composition of the present invention is a compound having two or more epoxy groups in one molecule. Examples of the epoxy resin include polyphenols, epoxy resins composed of glycidylated compounds such as polynuclear aromatic hydrides, polyhydric phenols, and novolak resins, and brominated epoxy resins, alicyclic epoxy resins, and polyphenols. Examples of the epoxy resin include a polyglycidyl ester of a carboxylic acid ester condensate, a polyglycidylamine-based epoxy resin, and a methyl epichloro-type epoxy resin.

Examples of polyphenols include, for example, 2,
2-bis (4'-oxyphenyl) propane, 2,2-
Bis (4'-hydroxyphenyl) butane, 1,1-bis (4'-hydroxyphenyl) ethane, bis (4-hydroxyphenyl) methane, 1,1,2,2-tetrakis (4'-hydroxyphenyl) ethane , 4-hydroxydiphenyl ether, p- (4-hydroxyphenyl) phenol and the like. Examples of polyhydric phenols include catechol, resorcin, hydroquinone, phloroglucin and the like. Examples of the novolak resin include pt-butylphenol novolak resin. Examples of the alicyclic epoxy resin include vinylcyclohexene dioxide, limonene dioxide, dicyclopentadiene dioxide and the like. Examples of the polycarboxylic acid include phthalic acid and cyclohexane-1,2-dicarboxylic acid. Examples of polyglycidylamine-based epoxy resin include, for example,
Those composed of tetraglycidyl diaminodiphenylmethane, triglycidyl p-aminophenol and the like can be mentioned.

In the present invention, the epoxy resin is
As the component (B), one type can be used alone, or two or more types can be used in combination. Among them, glycidyl ether-based epoxy resins of polyphenols and their brominated epoxy resins, novolak-type epoxy resins and their brominated epoxy resins are particularly advantageous in terms of cost, and have sufficient flexibility, heat resistance and adhesiveness. Is preferable since an adhesive composition having the following formula is obtained.

The dihydric or higher polyhydric phenol which is the main component of the curing agent (C) of the composition of the present invention is a phenol compound having two or more hydroxyl groups in one molecule.
Any of a monocyclic compound having two or more hydroxyl groups in a benzene nucleus having one in a molecule and a polycyclic compound having two or more benzene nuclei in a molecule and having two or more hydroxyl groups may be used. Specific examples of the polyhydric phenol include hydroquinone, resorcin, catechol, 2,2-bis (4 ′
-Hydroxyphenyl) propane, 1,1-bis (4 ′
-Hydroxyphenyl) ethane, 1,1-bis (4′-
(Hydroxyphenyl) methane, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl, 2,6-naphthalenediol, divalent phenols such as 2,7-naphthalenediol, phloroglucin,
1,1-tris (4′-hydroxyphenyl) ethane,
Trivalent or more trivalent phenols, such as 2,2,2-tris (4'-hydroxyphenyl) ethylbenzene, and novolak-type phenolic resins, such as novolak-type phenolic resins, composed of p-alkylphenols such as pt-butylphenol and pn-octylphenol Phenol and the like. Also, AO-
30 (manufactured by MARK) and Trisphenol-PA (manufactured by Honshu Chemical Co., Ltd.) can be used. In the present invention, when a dihydric phenol is used as the polyhydric phenol of the component (C),
It is preferable to use a trifunctional or higher functional epoxy resin such as a novolak epoxy resin as the component (B). Also,
When a trihydric or higher phenol is used as the polyhydric phenol of the component (C), any of the above-mentioned epoxy resins can be used as the epoxy resin of the component (B). Among these, pt-butylphenol, pn
-A novolak-type phenol resin composed of p-alkylphenols such as octylphenol, AO-30, and trisphenol-PA are preferable in terms of adhesiveness, solder heat resistance, and electrical reliability.

In the composition of the present invention, the proportions of the components (A), (B) and (C) are as shown in the following formulas, so that excellent adhesion, solder heat resistance,
It is preferable because a composition having electrical reliability and B-stage stability can be obtained. 0.2 ≦ (B) / (A) ≦ 10.0 0.03 ≦ (C) / (B) ≦ 1.0 More preferably 0.5 ≦ (B) / (A) ≦ 5.0 0.0. 07 ≦ (C) / (B) ≦ 0.7.

Further, the composition of the present invention may contain a filler, a curing agent, a curing accelerator and the like according to the use, required characteristics and the like.

The filler can be blended for the purpose of improving flame retardancy, adhesive strength, solder heat resistance, curing shrinkage, electrical insulation, and the ability to flow to lands. Specific examples of the filler include antimony trioxide, silica, ultrafine silica, red phosphorus, triphenylphosphine, alumina,
Examples include talc, aluminum hydroxide, magnesium hydroxide, calcium carbonate, aluminum silicate, zinc borate, and other metal oxides having good electrical insulation. When compounding the filler to the composition of the present invention, the compounding amount can be arbitrarily set according to the application, but usually adhesive, flame retardant, solder heat resistance and flexibility In this respect, the solid content weight is preferably 20% or less.

Further, in order to further improve the adhesive strength of the composition of the present invention, a curing agent may be further compounded in addition to the above-mentioned dihydric or higher polyhydric phenol. Examples of the curing agent include aliphatic polyamines, aromatic polyamines, acid anhydrides, hydrazide compounds derived from polycarboxylic acids, imidazole derivatives, dicyandiamides, and guanidine derivatives. Specific examples include bis (4-amino-3-methylcyclohexyl) methane, 4,4′-diaminodiphenylmethane,
4,4'-diaminodiphenylsulfone, 4,4'-diamino-3,3'-dichlorodiphenylmethane, phthalic anhydride, chlorendic anhydride and the like. When blending these curing agents with the composition of the present invention, the blending amounts can be arbitrarily selected according to the application.
Usually, it is preferable to keep the solid content to 10% or less in view of adhesiveness, heat resistance to moisture absorption solder, B-stage stability and electric characteristics.

Examples of the curing accelerator include Cureazole 2E4Mz and Cureazole 2E4Mz manufactured by Shikoku Chemicals.
-CN, Curezole 2PZ-CN, Curezole C1
1Z-A, Curezole C11Z, Curezole C17
An imidazole derivative such as Z, a boron trifluoride-methylamine complex, a boron trifluoride-ethylamine complex, or a boron trifluoride-amine complex such as a boron trifluoride-piperidine complex; DBU (1,4-diazabicyclo [5.4] .0]-
7-undecene; manufactured by Sun Abbott) or DBU
Phenol salt (U-CAT-SA No. 1), DBU
DBU salts such as octylate (U-CAT-SA No. 102). When these curing accelerators are blended with the composition of the present invention, the blending amount can be arbitrarily selected according to the application. Usually, it is preferable to keep the solid content at 5% or less from the viewpoint of adhesiveness and solder heat resistance.

Further, the composition of the present invention may contain a stabilizer for the purpose of preventing oxidation or decomposition of the epoxy resin used as the component (B). As the stabilizer used, a non-staining agent which does not cause coloring is preferable, and Irganox 1010 (tetrakis [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate]) is preferable. Methane, CiBa
Ionox 220 (4,4'-methylene-
Bis (2,6-di-tert-butyl) phenol, S
(Hell Chem), Ionox 330
(1,3,5-trimethyl-2,4,6-tris (3
5-di-tert-butyl-4-hydroxybenzyl)
Hindered phenol-based stabilizers such as benzene and Shell Chem), Nocrack 300 (4,4'-thiobis (6-tert-butyl-3-methyl) phenol, manufactured by Ouchi Shinko Co., Ltd.), and CAO-6 (2 , 2'-thiobis (6-tert-butyl-4-methyl) phenol, A
thiobisphenol-based stabilizers such as ldrich Chem, and aliphatic thioester-based stabilizers such as DLTP (dilaurylthiodipropionate, manufactured by Yoshitomi Pharmaceutical Co., Ltd.). When these stabilizers are blended in the composition of the present invention, the blending amounts can be arbitrarily selected according to the use. Usually, the solid content is preferably 5% or less, preferably 3% or less, from the viewpoint of adhesive strength.

The composition of the present invention comprises the above (A) and (B)
And (C) component, and if necessary,
Fillers, other curing agents, curing accelerators, components such as stabilizers,
Usually, they can be simply mixed and produced, and the production method is not particularly limited. Further, depending on the purpose of use such as adjusting viscosity and tackiness, the above (A) and (B),
(B) and (C) or (A) and (C) may be premixed before production.

The composition of the present invention is usually dissolved in a solvent to prepare a solution, and this solution is applied to an adherend such as a base material to form an adhesive layer, and is bonded to another adherend. Is what you can do. As a solvent used for preparing the solution, for example, methyl ethyl ketone, methyl isobutyl ketone, dioxane, ethanol, methyl cellosolve,
Ethyl cellosolve, propylene glycol monomethyl ether, propylene glycol monoethyl ether, N
-Methylpyrrolidone, N, N-dimethylformamide,
Toluene, xylene and the like can be mentioned, and these can be used singly or as a mixture of two or more in an amount selected according to the use. Among these, cost aspects,
From solubility, methyl ethyl ketone, methyl cellosolve,
Propylene glycol monomethyl ether, toluene,
N, N-dimethylformamide is preferred.

The composition of the present invention comprises a polyimide film,
Applying to a base film such as a polyester film to form an adhesive layer, forming a B-stage, and then pressing a metal foil such as a copper foil or an aluminum foil with a roll or batch press to obtain a flexible printed wiring material Can be done. Usually, the crimping temperature is 50 to 350 ° C and the crimping pressure is in the range of 0.1 to 30 MPa. From the viewpoint of obtaining excellent adhesive strength and solder heat resistance, the crimping temperature is 80 to 300 ° C, and the crimping pressure is 0.5 to It is preferable to carry out in the range of 20 MPa. Moreover, 80-350 degreeC, More preferably, it is 100-3.
Performing post-curing (after-cure) at 00 ° C. is effective because solder heat resistance can be further improved.
When long-term heating is required by press bonding, it is effective to mix a carboxylated nitrile rubber.

[0025]

EXAMPLES Hereinafter, Examples and Comparative Examples of the present invention will be described.
The present invention will be described more specifically, but the present invention is not limited to the following examples.

Measurement of adhesive strength, heat resistance to moisture absorption soldering, B-stage stability, migration resistance, combustion resistance and run-out to the land portion of the flexible printed circuit board samples prepared in the following Examples and Comparative Examples The evaluation was performed according to the following method.

1. Adhesive strength According to JIS C 6471, polyimide film of flexible printed circuit board sample is 90 を (Method B)
And the peel strength at 180 ° (Method A) peeling was measured. 2. Heat absorption solder heat resistance According to JIS C6471, temperature 40 ° C, humidity 80
%, The flexible printed circuit board sample left for 12 hours is immersed in a solder bath set at a predetermined temperature for 10 seconds, and the presence or absence of swelling on the surface of the polyimide film is checked. It was measured as an index of the moisture absorption solder heat resistance.

3. B-stage stability A flexible printed circuit board sample having an adhesive layer on the B-stage is left at 40 ° C. for 2 weeks, and then placed in a minimum gap (about 20 μm) between copper wiring layers of an etching circuit previously formed on a base film. The degree of penetration of the adhesive layer was examined by microscopic observation and evaluated according to the following criteria. Good: Adhesive completely penetrated the circuit. Poor: There is a part where the adhesive does not enter even a little. 4. Migration Resistance A flexible printed circuit board sample having an adhesive layer on the B stage is bonded to a rolled copper foil, and then pressed and post-cured, and then etched to form a wiring circuit (copper wiring layer thickness: 200 μm, copper Distance between wiring layers: 2
00 μm), and the conduction of each wiring layer was confirmed. Next, with respect to the sample on which the wiring layer was formed, a temperature of 12
A pressure cooker test was performed under the conditions of 1 ° C., a humidity of 85%, and an applied voltage of 25 V, and the time until a short circuit occurred between the wiring layers (hereinafter, referred to as “short circuit time”) was measured. 5. Flame resistance According to JIS C 6471, one of flame retardancy, self-digestibility and flammability was measured. 6. Flowability to land portion A flexible printed circuit board sample having an adhesive layer on the B stage and having a hole with a diameter of 5 mm was bonded to a rolled copper foil, pressed at 180 ° C. and 2 MPa for 1 minute, and then 140 ° C. About 2 hours post-cured at
The length of the adhesive flowing into the hole was measured.

Example 1 170.0 g of methyl ethyl ketone was placed in a 1000 cm ³ Pyrex separable flask equipped with a stirring motor and stirring blades.
Then, 175.0 g of a 20% solution of carboxyl group-containing nitrile rubber (Nipol 1072, manufactured by Nippon Zeon Co., Ltd.) in methyl ethyl ketone as the component (A), and an epoxy resin (Mitsui Petrochemical Industries, Ltd.) as the component (B). R
89.8 g) (301, epoxy equivalent: 465 to 485) and stirred at room temperature for 50 minutes to obtain a homogeneous solution. afterwards,
As a component (C), 38.1 g of trisphenol-PA (manufactured by Honshu Chemical Co., Ltd.) was added to N, N-dimethylformamide 13
The solution dissolved in 0.0 g was further added and stirred again for 5 minutes to dissolve, and the weight ratio of (B) / (A) was 2.57,
An adhesive composition having a weight ratio of (C) / (B) of 0.42 was prepared.

The adhesive composition was applied on a polyimide film (trade name: Kapton H; film thickness: 25 μm; manufactured by Dupont) using a film applicator with a clearance of 180 μm to form an adhesive layer. After drying at 140 ° C. for 3 minutes, the adhesive layer was B-staged. Next, with the adhesive layer in between, 30% in 5% hydrochloric acid.
After laminating a shiny surface of a rolled copper foil (thickness: 40 μm; manufactured by Mitsui Kinzoku Co., Ltd.) and a polyimide film, which were immersed for 2 seconds, they were pressed by a press at 180 ° C. and 3 MPa for 1 minute. Then, at 140 ° C in an air oven, 2
The substrate was post-cured for a time to prepare a flexible printed circuit board sample.

When the adhesive strength of this flexible printed circuit board sample was measured in accordance with the above method, the 90 ° peel strength was 12.8 N / cm, 180
゜ The peel strength was 13.3 N / cm. In addition, temperature 4
After standing at 0 ° C. and 80% humidity for 12 hours, no swelling occurred even when dipped in a solder bath at 260 ° C. for 1 minute. Further, there was no problem in the B-stage stability after being left at 40 ° C. for 2 weeks. Regarding migration resistance,
The short circuit time was 300 hours or more.

(Examples 2 to 7) An adhesive was prepared in the same manner as in Example 1 except that the components (A), (B) and (C), and other components were changed to those shown in Table 1. A composition was prepared. Furthermore, using the obtained adhesive composition, a copper foil mat surface or a copper foil shiny surface is bonded to a polyimide film to prepare a substrate sample for a flexible printed circuit, and the adhesive strength, moisture absorption solder heat resistance, and B-stage stability are obtained. , Migration resistance, combustion resistance and run-out to the land were measured or evaluated. The results are shown in Table 1.

Comparative Example 1 An adhesive composition was prepared in the same manner as in Example 1 except that the component (A) was changed to the one shown in Table 1. Furthermore, using the obtained adhesive composition, a copper foil shiny surface is bonded to a polyimide film to prepare a flexible printed circuit board sample, and the adhesive strength, moisture absorption heat resistance, B stage stability, migration resistance, The measurement or evaluation of the burning resistance and the flowability to the land was performed. Table 2 shows the results.

(Comparative Examples 2 to 5)
An adhesive composition was prepared in the same manner as in Example 1, except that the mixing ratios of the components (A), (B) and (C) were changed to the ratios shown in Table 1. Furthermore, using the obtained adhesive composition, a copper foil shiny surface is bonded to a polyimide film to prepare a flexible printed circuit board sample, and the adhesive strength, moisture absorption solder heat resistance, B stage stability,
The measurement or evaluation of the migration resistance, the combustion resistance, and the ability to flow out to the land was performed. Table 2 shows the results.

Comparative Example 6 An adhesive composition was prepared in the same manner as in Example 4 except that trisphenol-PA was changed to 20.0 g of dicyandiamide. Furthermore, using the obtained adhesive composition, a copper foil shiny surface is bonded to a polyimide film to prepare a flexible printed circuit board sample, and the adhesive strength, moisture absorption heat resistance, B stage stability, migration resistance, The measurement or evaluation of the burning resistance and the flowability to the land was performed. Table 2 shows the results.

Comparative Example 7 An adhesive composition was prepared in the same manner as in Example 4, except that the amount of the filler was changed to the amount shown in Table 2. Furthermore, using the obtained adhesive composition, a copper foil shiny surface is bonded to a polyimide film to prepare a flexible printed circuit board sample, and the adhesive strength, moisture absorption heat resistance, B stage stability, migration resistance, The measurement or evaluation of the burning resistance and the flowability to the land was performed. Table-Results
It is shown in FIG.

(Comparative Example 8) In Example 6, C11Z
Example 6 except that the amount of -A was changed to the amount shown in Table 2.
In the same manner as in the above, an adhesive composition was prepared. Furthermore, using the obtained adhesive composition, a copper foil shiny surface is bonded to a polyimide film to prepare a flexible printed circuit board sample, and the adhesive strength, moisture absorption heat resistance, B stage stability, migration resistance, The measurement or evaluation of the burning resistance and the flowability to the land was performed. Table 2 shows the results.

The abbreviations shown in Tables 1 and 2 are as follows:
The following are shown respectively. Nipol 1072: manufactured by Zeon Corporation R301: manufactured by Mitsui Petrochemical Industry Co., Ltd., bisphenol-A type epoxy resin epoxy equivalent 465-485 R230M80: manufactured by Mitsui Petrochemical Industry Co., Ltd., epoxy equivalent: 490-510 Solid content 80% methyl ethyl ketone Solution R2411: manufactured by Mitsui Petrochemical Industry Co., Ltd., epoxy equivalent 690-710 PATOX-M: antimony trioxide, manufactured by Nippon Seika R140P: manufactured by Mitsui Petrochemical Industry Co., Ltd., epoxy equivalent 180-190 Trisphenol-PA: Trifunctional phenol, manufactured by Honshu Chemical MMR: talc, manufactured by Asada Flour Milling R972: hydrophobic Aerosil, manufactured by Nippon Aerosil DiCy15: dicyandiamide, manufactured by Yuka Shell C11Z-A: curing accelerator, imidazole-triazine adduct Shikoku Chemicals BREN-S : Brominated Novola Click type epoxy resin, manufactured by Nippon Kayaku Co., epoxy equivalent 275-295 2,2-bis (4'-hydroxyphenyl) propane:
Bisphenol-A Nipol 1043 manufactured by Honshu Chemical: medium nitrile rubber (carboxyl-free), manufactured by Zeon Corporation

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

[Table 5]

[0044]

The adhesive composition of the present invention is excellent in adhesiveness, heat resistance to solder absorption by moisture, B-stage stability and electrical reliability. Therefore, the adhesive composition of the present invention can sufficiently satisfy the high properties required for recent adhesives for flexible printed circuit boards.

Claims (8)

[Claims] An adhesive composition comprising, as essential components, a curing agent comprising (A) a nitrile rubber having a carboxyl group, (B) an epoxy resin, and (C) a polyhydric phenol having two or more valences. 2. The composition according to claim 1, wherein the curing agent comprises (A) a nitrile rubber having a carboxyl group, (B) an epoxy resin, and (C) a dihydric or higher polyhydric phenol in the following weight ratio. Adhesive composition. 0.2 ≦ (B) / (A) ≦ 10.0 0.03 ≦ (C) / (B) ≦ 1.0 3. An adhesive for a flexible printed circuit board, comprising the adhesive composition according to claim 1. 4. An adhesive for a coverlay of a flexible printed circuit board, comprising the adhesive composition according to claim 1. 5. The adhesive composition according to claim 1, wherein said polyhydric phenol is trivalent or higher. 6. The adhesive composition according to claim 1, further comprising a filler in an amount of not more than 20% by weight of the solid content. 7. The adhesive composition according to claim 1, further comprising 5% by weight or less of a curing accelerator based on the weight of the solid content. 8. The adhesive composition according to claim 1, comprising a curing agent other than the polyhydric phenol at 10% or less based on the weight of the solid content.