JPH0657826B2 - Adhesive composition for flexible printed circuit board - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an adhesive composition suitable for use in a flexible printed circuit board, and more specifically, a metal foil such as copper or aluminum and a heat resistant resin film or a heat resistant resin film. Used to form metal foil-clad laminates made by adhering a non-woven sheet of heat-resistant resin, heat-resistant resin film or cover lay sheet made of non-woven sheet of heat-resistant resin and adhesive and protective sheet with releasability And an improved water-based acrylic adhesive.

2. Description of the Related Art In recent years, electronic devices have become smaller, lighter, and higher in density, and demands for these performances are becoming more and more advanced. As one of the countermeasures, there is a remarkable spread of a flexible circuit board that enables miniaturization, weight reduction, and high density of electronic devices.

The flexible printed circuit board is basically provided as a metal foil-clad laminate as follows. That is, a polyester resin as a substrate, a polyimide resin, a polyamideimide resin, a film of a heat-resistant resin such as polyparabanic acid resin or a non-woven sheet made of fibers of these resins,
A conductive metal foil such as copper or aluminum is laminated on the base material via an adhesive to provide a metal foil-clad laminate, which is subsequently subjected to printed wiring processing in a predetermined pattern.

Coverlay sheets are also used in this regard.
This is used at the final stage of the printed wiring processing step of the metal foil-clad laminate, and prevents deterioration of the formed metal conductor wiring due to oxidation etc. after the wiring pattern is formed by an etching method or the like. It is to be laminated on a flexible substrate for the purpose. This coverlay sheet is applied with an adhesive agent on the same heat-resistant resin film or non-woven sheet as that used as the base material of the metal foil-clad laminate, and after being semi-cured, it is subjected to a polyolefin film and a release property imparting treatment. It is provided by attaching a protective sheet such as rusted paper.

Disadvantages of conventional technology The adhesive for this flexible metal foil-clad laminate or coverlay sheet (hereinafter, generically referred to as a flexible substrate unless distinction is required) has adhesive strength, heat resistance, and flexibility. , Characteristics such as electrical insulation are required, and in addition to this, various characteristics such as resin flow during lamination processing, so-called wiring part embedding property, storage life in semi-cured state, etc. are also required in coverlay sheets. To be done.

Conventionally, as an adhesive that should meet these requirements, acrylonitrile-butadiene rubber system, butyral resin system,
Crosslinkable acrylic rubber type, nylon / epoxy type, acrylonitrile-butadiene / phenol resin type, acrylonitrile butadiene / epoxy resin type containing carbon
Various adhesives such as acrylic rubber / epoxy type have been proposed. Among these adhesives, an acrylonitrile-butadiene / phenol resin-based adhesive is widely used as an adhesive having a relatively well-balanced overall property. Recently, acrylic rubber / epoxy adhesives have attracted attention because of their excellent electrical insulation properties, embedding properties when used in coverlay sheets, and long shelf life. It became so.

However, since all of these adhesives are supplied as a solution of a flammable organic solvent such as methyl ethyl ketone, toluene, acetone, and ethanol, adhesion and heat resistance between the heat-resistant base material and the metal foil in the production of flexible substrates In the steps of coating the adhesive on the substrate and semi-curing, the work of volatilizing and removing these organic solvents is inevitably required. It was pointed out that this work is highly dangerous and that special consideration must be given to safety and occupational hygiene in the work.

From such a viewpoint, finally, a non-solvent type emulsion polymerization type adhesive has been developed, and typical examples thereof include basic performance such as adhesive strength, heat resistance and flexibility, and characteristics of acrylic. An emulsion polymerization type acrylic rubber / epoxy adhesive having excellent electrical characteristics, embedding property when used for a coverlay sheet, and storage life has been provided.

However, the flexible substrate using this emulsion-polymerization type adhesive has problems such as insufficient solder heat resistance that is considered to be due to hygroscopicity, surface tack problem, and insufficient solder heat resistance under high humidity. . To solve these problems, we have applied for Japanese Patent Application No. 58-126917, Japanese Patent Application No. 58-225419,
As proposed in Japanese Patent Application No. 60-44700, it has become possible to reduce the heat resistance and surface tack of solder under high humidity to the extent that there is no practical problem.

Problems to be Solved by the Invention Recent developments in the electronic device industry have been remarkable, and performance requirements for flexible circuit boards have been gradually increasing.

The flexible circuit board has a wide variety of uses, and deterioration of performance such as adhesive strength has become a problem in the use where it is repeatedly exposed to high temperatures. However, none of the adhesives using the above organic solvent and the emulsion polymerization type adhesives have satisfactory performance after long-term high temperature exposure.

As a result of intensive studies to solve the above problems, we have invented an adhesive composition for a flexible printed circuit board, which has excellent adhesive strength after long-term high temperature exposure.

DISCLOSURE OF THE INVENTION The adhesive composition for a flexible printed circuit board of the present invention comprises
80- of the monomer group (A) consisting of acrylonitrile and acrylic acid esters and styrene optionally added
99.5 parts by weight, 0.5-5 parts by weight of hydroxyalkyl (meth) acrylic acid esters and / or acrylic amides (B) and 0.5-15 of N-methylol acrylic amide (C)
An aqueous copolymer (D) consisting of parts by weight is prepared, and a water-soluble epoxy compound (E) having two or more epoxy groups in one molecule and / or two or more epoxy groups in one molecule are prepared. Emulsion (F) of the solid epoxy compound having a solid content of the copolymer (D) with respect to 100 parts by weight of (E) and (F)
And 20 to 60 parts by weight in total.

By using acrylonitrile as a composition component of the monomer group (A), it is possible to impart resistance and adhesive strength to an adhesive mainly to organic chemicals such as acetone, methylene chloride and trichlene used for printed circuit processing of flexible substrates. For that purpose, preferably 10-60
It is used as necessary in the range of parts by weight.

A part of this acrylonitrile component may be optionally substituted with styrene to give more rigidity to the skeleton of the copolymer (D), which is mainly the function of the adhesive, and preferably 70% of acrylonitrile is used. It can be used by substituting less than%.

These acrylonitrile and styrene components are copolymers
With respect to the flexible properties of acrylic acid esters, which are the other components that constitute the main component of (D), it is possible to adjust the properties such as the glass transition temperature of the entire adhesive composition by changing the composition as desired. it can.

As the acrylic acid ester which is another component of the monomer group (A) of the present invention, one or more common acrylic acid esters such as ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate can be used. These acrylic acid esters are components which mainly give the adhesive strength of the adhesive and also give flexibility which is one of other important required performances. The acrylic ester is 40-8 with respect to 100 parts by weight of the solid content of the aqueous copolymer (D).
It is preferably used in a range such that the amount is 0 parts by weight.

These monomer groups (A) constitute the main component of the adhesive and can be appropriately combined within the above preferred range,
According to the extensive implementation of the present inventors, the glass transition point of the adhesive composition as a whole including the monomer composition components (B) and (C) described below is the flexibility and chemical resistance described above. It is desirable to select within the range of −30 ° C. to 0 ° C. that can satisfy the required performance, and further, the composition with respect to 100 parts by weight of the solid content of the aqueous copolymer (D) as the monomer group (A) as a whole is It is selected from the range of 80-99.5 parts by weight.

Furthermore, N-methylol acrylate (C) is used as a composition component of the aqueous copolymer (D) of the adhesive composition of the present invention. N based on 100 parts by weight of the solid content (D) of the aqueous copolymer
-For the amount of methylol acrylic amide (C) used,
It is in the range of 0.4-15 parts by weight, preferably 0.5-10 parts by weight. If it is less than 0.4 parts by weight, long-term heat resistance is not effective and 1
If it exceeds 5 parts by weight, moisture resistance and insulation resistance will decrease.

Next, in the present invention, hydroxyalkyl (meth) acrylic acid esters and / or acrylic amides are further used as the composition (B). Barefoot These monomers are hydrophilic monomers, and the monomer group (A) in the present invention
This is because, together with (B), these components become essential organisms for stable copolymerization in water. The hydroxyalkyl (meth) acrylic acid esters include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, and 3-hydroxypropylmethacrylate. Various things such as acrylates can be used, and one kind or a mixture of two or more kinds thereof can be used.

As acrylic amides, various ones such as acrylic amide and methacrylic amide can be used, and one kind or two or more kinds may be used.

These hydrophilic monomers may be used alone or in combination of both hydroxyalkyl acrylic acid esters and acrylic amides, but the amount thereof is selected from the range of 0.1 to 5 parts by weight. If this amount is less than 0.1 parts by weight, the hydrophilicity of the monomer in the aqueous polymerization system is insufficient, a stable dispersed state of the monomer during the polymerization operation cannot be ensured, and the polymerization is forcibly carried out in such a state. In that case, the composition of the copolymer becomes non-uniform and the dispersion of the copolymer in the polymerization solution becomes unstable, so that it cannot be practically used as an adhesive for flexible substrates. On the other hand, when the amount of the hydrophilic monomer exceeds 5 parts by weight, the excellent properties of the composition of the present invention such as adhesiveness, heat resistance, flexibility and the like are impaired, and especially the soldering is performed. The heat resistance is significantly reduced.

The aqueous copolymer solution of the copolymer (D) of the present invention comprising the above monomer group can be produced by the following method. That is, as a polymerization initiator, for example, a solution prepared by dissolving a predetermined amount of potassium persulfate in distilled water at 70 ° C., the monomer groups (A), (B) and (C) of the present invention prepared separately and distilled water The mixed solution was dropwise polymerized with stirring for about 3 to 4 hours, and further 3
After the polymerization is completed for about 4 hours, the temperature is cooled to room temperature, and after oversized particles are passed with an appropriate material, the pH is adjusted to 7-9 with aqueous ammonia. At this time, the resin component as the solid content in the aqueous copolymer D is in the entire reaction system.
It is adjusted to 30-70 parts by weight, that is, within the range where the copolymerization reaction is favorably carried out.

In the present invention, the adhesive composition of the present invention can be obtained by directly mixing and dissolving an emulsion of a water-soluble epoxy resin and / or a solid epoxy compound in the reaction liquid thus prepared.

In the copolymerization operation of the polymer, it is necessary to add a chain transfer agent or the like according to a conventional method, or to use a dispersant within a range that does not impair the characteristics of the produced adhesive composition for flexible substrates. It can also be used as an auxiliary.

The other component of the adhesive composition of the present invention is a water-soluble epoxy compound (E) having two or more epoxy groups in one molecule and / or a solid epoxy compound having two or more epoxy groups in one molecule. It is an emulsion (F) of.

Examples of the water-soluble epoxy compound (E) include ethylene glycol diglycidyl ether and a main chain having 9 carbon atoms.
The following diepoxy compounds having a hydrophilic ether bond in the main chain of a molecule such as polyethylene glycol diglycidyl ether; glycerol polyglycidyl ether, diglycerol polyglycidyl ether, sorbitol polyglycidyl ether, and an alcoholic hydroxyl group together with an ether bond in the molecule. One or more of polyepoxy compounds and the like are used.

The solid epoxy compound emulsion (F) is a novolac type epoxy emulsion, a cresol type epoxy emulsion, a bisphenol A type epoxy emulsion, or bisphenol F.
One or more kinds of emulsions such as epoxy compounds of polyhydric phenol having a phenol skeleton in the molecule such as emulsion of epoxy resin are used.

The mixing ratio of the water-soluble epoxy compound (E) and / or the solid epoxy compound emulsion (F) is appropriately mixed depending on the degree of tackiness of the adhesive surface required, but the preferred range is The total amount of the epoxy compounds (E) and the solid content of the solid epoxy compound emulsion (F) added is 2 with respect to 100 parts by weight of the aqueous copolymer (D).
It is in the range of 0-60 parts by weight. When it is less than this range, it is difficult to obtain sufficient heat resistance and chemical resistance to the adhesive composition, and when it exceeds this range, not only the chemical resistance is lowered but also the folding resistance is insufficient.

The adhesive composition of the present invention obtained as described above is generally an aqueous adhesive having a pH of 7-9 and a viscosity of 50 to 4000 centipoise. This adhesive is applied on a heat-resistant resin film or a non-woven sheet substrate so that the film thickness is usually 10 to 80 μm (dry base), and then dried and cured to obtain a desired flexible substrate. .

Regarding the drying and curing conditions of the adhesive, first, in the coverlay sheet, for example, hot air having a temperature of 80 ° C. to 180 ° C. is used to give a residence time of 0.5 minutes to 20 minutes to dry, semi-cure, and semi-cure. A release polyolefin film or release paper is attached to the resin surface to make the product.

On the user side, this coverlay sheet is laminated on a substrate on which wiring has been formed, and then the temperature is 160 ° C to 180 ° C.
The adhesive is completely cured by hot-pressing at a temperature of 10 ° C., a pressure of 10 kg / cm ² to 60 kg / cm ² , and a time of 30 minutes to 90 minutes to complete the adhesion between the wiring board and the coverlay sheet.

On the other hand, in the production of the metal foil-clad laminate, after obtaining a semi-cured state of the adhesive similar to the case of the above coverlay sheet, rolled copper foil having a thickness of 5 μm to 80 μm and electrolytic copper After laminating foil, rolled aluminum foil, etc., 100 ℃
While contacting a metal roll heated to 150 to 150 ℃, use a heat-resistant rubber roll or cotton roll to achieve a linear pressure of 3-50 kg / c.
Crimping is done at about m, and the layer is cured. After that, usually 8
Post-cure is performed in an atmosphere of 0 ° C. to 200 ° C. for 3 to 48 hours and completely cured to obtain a metal foil-clad laminate.

However, the use conditions shown here are merely examples, and it is natural that the production conditions differ depending on the coating machine used, the structure of the pressure bonding roll, the specifications, etc., and the optimum conditions should be determined at the time of production. In any case, as long as the adhesive of the present invention is used, like the solvent-based adhesive in the above manufacturing process, the organic solvent does not volatilize, and the manufacturing operator is free from the risk of suction of the volatilized solvent and fire. It Further, the flexible printed circuit board using the adhesive of the present invention, solder heat resistance, insulation resistance, folding resistance, adhesive strength,
In addition to being excellent in chemical resistance, particularly the adhesive strength after a long-term heat resistance test is excellent, the adhesive of the present invention has industrially very useful effects.

Examples and Supplements Supplementary explanations are given below with reference to examples.

In addition, it shows in an Example and a comparative example. The characteristics of the printed circuit board were evaluated according to the following methods.

a. Peel strength We measured the adhesive strength between the copper foil and the base heat resistant film based on IPC-FC-241A. In the examples of the present invention, the copper conductor wiring surface on which the printed circuit is formed and the normal state means a test after standing for 48 hours at a temperature of 20 ° C. and a relative humidity of 65%.

b. Solder heat resistance The wiring surface (coverlay sheet laminated side) was brought into contact with the solder in a solder bath at 260 ° C. for 60 seconds to float, and then the appearance was observed. Here, “after moisture resistance” is performed as a measure of water resistance and moisture resistance, and the circuit board is kept at 40 ° C. and 95%.
After left standing for 1 hour in RH, it was taken out, the moisture was wiped off with gauze and the like, and then floated in a solder bath as described above to observe the appearance.

c. Chemical resistance According to JIS-C-6481, test pieces are trichlene,
After immersing in acetone and methylene chloride at room temperature for 15 minutes, the taken out appearance was observed.

d. Folding resistance Using a MIT type repeated bending tester, the test piece is 50
The number of times of bending until the conduction of the conductor was stopped was measured with a weight of 0 g applied.

e. Insulation resistance According to JIS-C-6481, the volume resistivity at room temperature (after standing for 96 hours at a temperature of 20 ° C. and a relative humidity of 65%) was measured.

f. Long-term heat resistance After heat treatment of a test piece at 150 ° C for 240 hours a. The peeling strength described in the section was measured.

Example 1 30 parts by weight of acrylonitrile, 10 parts of ethyl acrylate
By weight, 55 parts by weight of butyl acrylate, 3 parts by weight of 2-hydroxyethyl methacrylate and 2 parts by weight of N-methylol acrylate were mixed in distilled water to prepare a monomer group mixed solution.

Then, a predetermined amount of potassium persulfate as a polymerization initiator is added to 70
2. Prepare an aqueous solution dissolved in distilled water at 0 ° C, and stir this aqueous solution to prepare the monomer group mixture solution prepared above.
The mixture was added dropwise over 5 hours, and after completion of the addition, polymerization was further continued for 4.5 hours to complete the reaction. Then, the reaction solution was cooled to room temperature to remove excess particles, and an aqueous copolymer solution having a resin component of 50% by weight was obtained. The resulting aqueous copolymer solution has a pH of 7.
6. The viscosity was 105 centipoise, and the glass transition point of the resin component was measured by the DSC method and found to be -10 ° C. To 100 parts by weight of this aqueous copolymer D, 20 parts by weight of diethylene glycol diglycidyl ether (trade name: Denacol EX-851, manufactured by Nagase & Co., Ltd.) was mixed and dissolved in the aqueous copolymer solution, and further bisphenol A type epoxy Emulsion (trade name: Eporjon EA-
3, NV = 50%, manufactured by Kanebo NSC Co., Ltd.) 40 parts by weight were mixed and dissolved to obtain an adhesive composition of the present invention. This adhesive composition liquid was applied by a reverse coater to a polyimide film having a thickness of 50 μm (product name: Kapton, manufactured by E. I. Dupont) at a thickness of about 25 μm (dry base), dried, and semi-cured (temperature). 120 ℃,
After a residence time of 5 minutes), a 35 μ thick electrolytic copper foil (manufactured by Fukuda Metal Co., Ltd .: trade name T8) was laminated and pressed under the conditions of a linear pressure of 5 kg / cm and a roll temperature of 140 ° C., and then 160 ° C. ,
It was post-cured for 2 hours to obtain a flexible copper-clad laminate.

Further, the adhesive composition liquid of the present invention obtained in this example was applied to a polyimide film having a thickness of 50 μ (product of E. I. DuPont: trade name, Kapton) by a reverse roll coater to a thickness of about 50 μ (dry base). A cover lay sheet was prepared by applying a film having a thickness, drying and semi-curing (temperature: 120 ° C., residence time: 5 minutes), and laminating a polyester film having a thickness of 25 μm thereon.

Using this and the flexible copper-clad laminate prepared above, printed circuit processing of a test pattern was carried out by the subtract method to obtain a flexible printed circuit board. The characteristics of this circuit board were evaluated for each of the above items.

The pressing conditions for the coverlay sheet are 30 kg of pressing pressure.
/ cm ² , temperature was 160 ° C, and pressing time was 30 minutes.

As a result of the evaluation, the peel strength was 1.8 kg / cm in the normal state and 1.2 kg / cm after the long-term heat resistance test, which was very excellent. The solder heat resistance was good both in the normal state and after the moisture absorption treatment, and no abnormality was observed even after the chemical immersion. The folding endurance test averages 130
The insulation resistance was 10 ¹⁴ Ω.

Example 2 15 parts by weight of acrylonitrile, 15 parts by weight of styrene, 67.5 parts by weight of butyl acrylate, 1 part by weight of 2-hydroxypropyl methacrylate, 1 part by weight of acrylate,
0.5 parts by weight of N-methylol acrylate was mixed in distilled water to prepare a monomer group mixed solution.

Copolymerization was carried out in the same manner as in Example 1, and the resin component was 40
A weight% aqueous copolymer solution was obtained. The obtained aqueous copolymer had a pH of 8.1, a viscosity of 180 centipoise, and a glass transition point of -22 ° C as measured by the DSC method.

To 100 parts by weight of this aqueous copolymer solution, 10 parts by weight of sorbitol tetraglycidyl ether (Nagase Sangyo Co., Ltd .: trade name Denacol EX-611) was mixed and dissolved, and an orthocresol novolac type epoxy resin emulsion (Nagase Sangyo Co., Ltd .: Product name Denacol EM-
40 parts by weight of 125 NV = 25%) were mixed and dissolved to obtain an adhesive composition of the present invention.

This adhesive composition liquid was applied on a polyamide film having a thickness of 50 μ (a film made of a polymer obtained by the method described in Japanese Patent Publication No. 56-44891, etc.) with a reverse roll coater at a thickness of about 40 μ (dry base) and the temperature was applied. 140
After being dried and semi-cured at a temperature of 2 ° C. for 2 minutes, a rolled copper foil having a thickness of 30 μ (manufactured by Nikko Gould Co., Ltd .: trade name, AN-
02) is laminated and the linear pressure is 10 kg / cm and the roll temperature is 110 ° C.
After pressing under the conditions of (1) and then post-curing at 130 ° C. for 16 hours, a flexible copper-clad laminate was obtained.

Further, the adhesive composition liquid of the present invention obtained in this Example was applied to a polyamide-imide film similar to that used in the above copper-clad laminate using a reverse roll coater to give a thickness of 7
Apply it to 0μ (dry base) and apply a temperature of 130
After being dried and semi-cured under conditions of a temperature of 7 minutes and a residence time of 7 minutes, a release paper (manufactured by Fujimori Industry Co., Ltd .: trade name VINA sheet) was attached to obtain a cover lay sheet.

Using this and the flexible copper-clad laminate prepared above, printed circuit processing of a test pattern was carried out by the subtract method to obtain a flexible printed circuit board.

The pressing conditions for the coverlay sheet are 50 kg of pressing pressure.
/ cm ^2, temperature of 170 ° C., was 40 minutes pressing time. As a result of the evaluation, the peel strength was 1.6 kg / cm in the normal state and 0.9 kg / cm after the long-term heat resistance test. The solder heat resistance was good both in the normal state and after moisture absorption, and no abnormality was observed even after immersion in chemicals. The folding endurance test was 170 times on average, and the insulation resistance was 10 ¹³ Ω.

Comparative Example 1 Acrylonitrile 30 parts by weight, ethyl acrylate 10
Parts by weight, 55 parts by weight of butyl acrylate, 3 parts by weight of 2-hydroxyethyl methacrylate, acrylate 1.
8 parts by weight and 0.2 parts by weight of N-methylol acrylate were mixed in distilled water to prepare a monomer group mixed solution. This monomer group mixture was copolymerized in the same manner as in Example 1,
An aqueous copolymer having a resin component of 50% by weight was obtained. The obtained aqueous copolymer had a pH of 7.9, a viscosity of 110 centipoise, and a glass transition point measured by a DSC method of -10 ° C.
Met. This aqueous copolymer solution was compounded, coated and processed in exactly the same manner as in Example 1 to obtain a flexible printed circuit board. As a result of evaluating the characteristics of this circuit board for each of the above items, the peel strength was 1.2 kg / cm in the normal state and 0.2 kg / cm after a long-term heat resistance test when the amount of N-methylacrylamide added was low. It was The solder heat resistance was good in the normal state, but blistering occurred after moisture absorption.
The folding endurance was 130 times on average and the insulation resistance was 10 ¹⁴ Ω.

Comparative Example 2 9 parts by weight of acrylonitrile, 5 parts by weight of styrene, 67 parts by weight of butyl acrylate, 1 part by weight of 2-hydroxypropyl methacrylate, 1 part by weight of acrylate and N
-Methylol acrylic amide (17 parts by weight) was mixed with distilled water to prepare a monomer group mixed liquid. This monomer group mixed solution was copolymerized in the same manner as in Example 1 to obtain a resin component of 4
A 0% by weight aqueous copolymer solution was obtained. The obtained aqueous copolymer had a pH of 8.2, a viscosity of 300 centipoise, and a glass transition point of -21 ° C as measured by a DSC method. This aqueous copolymer was compounded in exactly the same manner as in Example 2,
Coating and processing were performed to obtain a flexible printed circuit board. As a result of evaluating the characteristics of this circuit board for each of the above items, the peel strength was 0.9 kg / cm in the normal state and 0.1 kg / cm or less after the long-term heat resistance test when the amount of N-methylolacrylamide added was too large. It was at a level where it could not be used due to deterioration. Also, solder heat resistance was blistered both in the normal state and after moisture absorption. The folding endurance was 100 times on average and the insulation resistance was 10 ¹¹ Ω.

Claims (1)

[Claims] 1. 80-99.5 parts by weight of a monomer group (A) consisting of acrylonitrile and acrylic acid esters and styrene optionally added; hydroxyalkyl (meth) acrylic acid esters and / or acrylic 0.1-5 parts by weight of an acrylic amide (B) selected from the group consisting of amide and methacrylic amide; and N
An aqueous copolymer (D) consisting of 0.4-15 parts by weight of methylol acrylic amide (C) was prepared, and a water-soluble epoxy compound (E) having two or more epoxy groups in one molecule was prepared. ) And / or an emulsion (F) of a solid epoxy compound having two or more epoxy groups in one molecule is added as (E) to 100 parts by weight of the copolymer (D) as a solid content.
An adhesive composition for a flexible printed circuit board, which is excellent in long-term high-temperature exposure property, and is compounded in a total amount of 20 to 60 parts by weight with (F).