JPH11293218A - Heat-resistant adhesive and flexible printed wiring board prepared by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat-resistant adhesive improved in heat resistance, adhesiveness, flexibility, and processability by mixing a specified polyimide copolymer with an epoxy resin. SOLUTION: A heat-resistant adhesive having a viscosity of 1-1,000 P is obtained by mixing a polyimide copolymer comprising recurring units of formula I and 1-80 wt.%, desirably, 5-30 wt.% recurring units of formulae II and/or III (wherein (m) and (n) are each 1 or greater; Ar<1> is a trivalent residue derived by removing the three carboxyl groups from a tricarboxylic acid; Ar<2> is a divalent residue derived by removing the two amine groups from a diamine compound; R<1> is a 1-20C alkylene; R<2> is a 1-20C alkylene or phenylene; and R<3> and R<4> are each H or a 1-4C alkylene) and having a logarithmic viscosity of 0.1-2.5 dl/g, desirably, 0.2-1.0 dl/g (as measured in N-methyl-2-pyrrolidone at 30 deg.C) with 5-90 wt.%, desirably, 20-60 wt.% epoxy resin, and, optionally, a curing catalyst and a solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive for a flexible printed circuit board having excellent heat resistance, adhesiveness, flexibility and the like.
The present invention also relates to a flexible printed board using the same and having excellent heat resistance, adhesiveness, flexibility, workability, and the like.

[0002]

2. Description of the Related Art A conventional flexible printed circuit board is obtained by bonding a polyimide film and a metal foil with a thermosetting adhesive such as an epoxy resin or an acrylic resin. However, the thermal properties of the adhesive are significantly inferior to the performance of polyimide film, which limits its application to chip-on-flex, etc., and causes problems such as "bulging" and "peeling" of the pattern in the soldering process. There was a point.
Further, when a thermal history such as thermocompression bonding is applied during processing, there is a disadvantage that the substrate is curled or twisted, and subsequent conductor patterning becomes impossible.

[0003] In order to solve the above-mentioned disadvantages, techniques for forming a metal foil on an insulating base material without using an adhesive have been studied. For example, JP-A-2-98994 discloses a sputtering method on a polyimide film,
No. 488 proposes a technique of forming a metal layer and then forming a circuit pattern by an ion plating method in Japanese Patent Application Laid-Open No. 57-18357. However, the fact remains that these methods still have a problem in adhesiveness to a conductor. That is, pattern peeling in the electrolytic plating step on the pattern performed for the purpose of increasing the strength of the formed pattern,
Exposure to a temperature of about 100 ° C. for a long time has the disadvantage that the adhesion between the conductor and the polyimide film is significantly reduced.

[0004] Japanese Patent Application Laid-Open No. 56-233791 and Japanese Patent Application Laid-Open
In Japanese Patent Application Laid-Open No. 7-50670, a polyamideimide solution is directly applied to a metal foil.
And JP-A-60-243120 propose a method of molding a flexible printed board without an adhesive layer by directly applying a polyimide solution or a polyimide precursor solution to a metal foil. However, even in this method, there is a problem that the adhesive strength with the insulating base material is insufficient, and further, the flexibility and the tear strength of the insulating base material are weak.

[0005] In order to solve the above-mentioned problems, a heat-resistant adhesive for bonding a polyimide film and a metal foil has been studied. Bismaleimide-based adhesives are well known as heat-resistant adhesives, but these cured films are not suitable for flexible printed circuit boards because of their brittleness.

[0006] As a method of improving the above disadvantages,
Further, Japanese Patent Application Laid-Open No. Sho 62-232475,
JP-A-235282, JP-A-2-138789, etc., a method of forming an adhesive film from a mixture of bismaleimide and an aromatic polyimide, sandwiching the adhesive film between the polyimide film and a metal foil, and performing thermocompression bonding. Although it has been proposed, the condition of thermocompression bonding is a high temperature of 260 to 300 ° C., and a high pressure of about 50 kg / cm ² is required, and there is a problem in practical workability. JP-A-5-112
768 and JP-A-5-179224 also propose a thermoplastic polyimide adhesive which can be thermocompression-bonded. However, similar to JP-A-62-223475, a high temperature and a long time are required for adhesion. It is not practical.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems by providing excellent heat resistance, which can be used as an adhesive between a metal foil and a polyimide film, as well as adhesion, flexibility and workability. It is an object of the present invention to provide an adhesive for a flexible printed board excellent in the above, and a flexible printed board using the same.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above problems, and as a result, as an adhesive between a metal foil and a polyimide film, an uncured polyimide resin having a specific structure mixed with an epoxy resin. It has been found that by using the composition in a state, heat bonding can be performed even at a low temperature of 200 ° C. or less, and further, by curing this, a flexible printed board having excellent heat resistance, adhesiveness, and flexibility can be obtained. Reached. That is, the present invention has the following configuration.

The main component is a polyimide copolymer containing a repeating unit represented by the general formula (1), a repeating unit represented by the general formula (2) and / or the general formula (3) as a constituent, and an epoxy resin. A heat-resistant adhesive characterized in that: 2. The heat-resistant adhesive according to item 1, wherein the epoxy resin is a bisphenol A type epoxy resin and / or a bisphenol F type epoxy resin. A flexible printed circuit board, characterized in that a polyimide film is laminated on one surface of a layer made of the heat-resistant adhesive described in 1 or 2 and a metal foil is laminated on the other surface.

[0010]

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In the formulas (1) to (3), m and n are integers of 1 or more and may be the same or different, and Ar ¹ excludes three carboxyl groups of tricarboxylic acid. A trivalent residue, Ar ² represents a divalent residue excluding two amino groups of a diamine compound, and R ¹ has 1 to 2 carbon atoms.
0 represents an alkylene group, R ² represents an alkylene group having 1 to 20 carbon atoms or a phenylene group; R ³ and R ⁴ represent hydrogen or an alkyl group having 1 to 4 carbon atoms; Is also good.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The polyimide copolymer used in the present invention can be produced by a usual method.
For example, there are an isocyanate method and an acid chloride method. Industrially, the isocyanate method is suitable in that the polymerization dope can be used as it is.

Examples of the polymerization solvent include dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone,
Sulfolane, tetramethylurea, γ-butyrolactone, cyclohexanone, cyclopentanone, dimethylsulfoxide, dimethylsulfone, hexamethylphosphamide, phenol, cresol, and the like can be used. Some of these can be replaced with hydrocarbon-based organic solvents such as toluene and xylene, ether-based organic solvents such as diglyme and tetrahydrofuran, and ketone-based organic solvents such as methyl ethyl ketone and methyl isobutyl ketone. Among them, diglyme, methyl isobutyl ketone and the like are preferable from the viewpoint of polymerizability.

The reaction temperature is usually preferably from 50 to 200 ° C. In addition, the reaction is performed with tertiary amines, alkali metal compounds,
It may be carried out under a catalyst such as an alkaline earth metal compound.
The polymerization concentration is preferably from 10 to 50% by weight.

As a raw material used to include the repeating unit represented by the general formula (1) in the copolymer, as an acid component (Ar ¹ ), for example, trimellitic anhydride, diphenyl ether-3,3 ', 4'-tricarboxylic anhydride, diphenylsulfone-3,3', 4'-tricarboxylic anhydride, benzophenone-3,3 ', 4'-tricarboxylic anhydride, naphthalene-1,2,4-tricarboxylic Acid, tricarboxylic anhydride such as butane 1,2,4-tricarboxylic anhydride, isocyanate component (A
r ² ) is O-tolidine diisocyanate, 4,
4'-diphenylmethane diisocyanate, 4,4'-
Diphenyl ether diisocyanate, 2,4′-tolylene diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, m-xylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, And cyclohexane-1,4-diisocyanate. Among them, it is preferable to use trimellitic anhydride, 4,4'-diphenylmethane diisocyanate and the like in view of heat resistance, adhesiveness and flexibility.

In order to include the repeating units represented by the general formulas (2) and / or (3) in the copolymer, the diol of the following general formula (4) and / or the following general formula (5) By reacting the above dicarboxylic acid with the above diisocyanates.

[0017]

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In the formulas (4) and (5), m and n are integers of 1 or more and may be the same or different, and Ar ¹ is the same as that of the tricarboxylic acid except for three carboxyl groups. A trivalent residue, Ar ² represents a divalent residue excluding two amino groups of a diamine compound, and R ¹ has 1 to 2 carbon atoms.
0 represents an alkylene group, R ² represents an alkylene group having 1 to 20 carbon atoms or a phenylene group; R ³ and R ⁴ represent hydrogen or an alkyl group having 1 to 4 carbon atoms; Is also good.

A repeating unit represented by the general formula (1);
The composition ratio of the repeating unit represented by the general formula (2) and / or (3) is 1 to 1 in the weight ratio of the repeating unit represented by the general formula (2) and / or (3) in the whole polymer.
It is 80% by weight, preferably 5 to 30% by weight. When the repeating unit represented by the general formula (2) and / or (3) is 5% by weight or less, high temperature and long time are required for thermocompression bonding, resulting in poor flexibility and workability. , Heat resistance is insufficient.

The molecular weight of the polyimide copolymer used in the present invention is 0.1 to 2.5 dl / g in N-methyl-2-pyrrolidone at 30 ° C., preferably 0.1 to 2.5 dl / g.
2 to 1.0 dl / g. Logarithmic viscosity is 0.
If it is less than 2 dl / g, the flexibility is insufficient.
If it is 0 dl / g or more, the solution viscosity becomes high and molding processing becomes difficult.

A repeating unit represented by the general formula (1),
Another copolymerizable structural unit is formed in the acid component and the amine component (Ar ² component) of the polyimide copolymer containing the repeating unit represented by the general formula (2) and / or (3) as a constituent component. The monomers that can be used are exemplified below in the form of an acid component and an amine component. These isocyanates can be used as the amine component, and their acid anhydrides and acid chlorides can be used as the acid component.

Examples of the acid component include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, eicoic acid diacid, Tetradecane,
Diphenylmethane-4,4'-dicarboxylic acid, diphenylmethane-2,4'-dicarboxylic acid, diphenylmethane-3,4'-dicarboxylic acid, diphenylmethane-3,
3′-dicarboxylic acid 1,2-diphenylethane-4,
4'-dicarboxylic acid, 1,2-diphenylethane-2,
4'-dicarboxylic acid, 1,2-diphenylethane-3,
4'-dicarboxylic acid, 1,2-diphenylethane-3,
3'-dicarboxylic acid, 2,2-bis (4-carboxyphenyl) propane, 2- (2-carboxyphenyl) 2
-(4-carboxyphenyl) propane, 2- (3-carboxyphenyl) 2- (4-carboxyphenyl) propane, 2,2-bis (3-carboxyphenyl) propane, diphenylether-4,4'-dicarboxylic acid,
Diphenyl ether-2,4'-dicarboxylic acid, diphenyl ether-3,4'-dicarboxylic acid, diphenyl ether-3,3'-dicarboxylic acid, diphenyl sulfide-4,4'-dicarboxylic acid, diphenyl sulfide-
2,4′-dicarboxylic acid diphenyl sulfide-3,
4'-dicarboxylic acid, diphenyl sulfide-3,3 '
-Dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, diphenylsulfone-2,4'-dicarboxylic acid, diphenylsulfone-3,4'-dicarboxylic acid, diphenylsulfone-3,3'-dicarboxylic acid, benzophenone- 4,4'-dicarboxylic acid, benzophenone-
2,4'-dicarboxylic acid, cyclohexane-4,4'-
Dicarboxylic acid, cyclohexane-2,4'-dicarboxylic acid, cyclohexane-3,4'-dicarboxylic acid, cyclohexane-3,3'-dicarboxylic acid, trimellitic acid,
Butane-1,2,3,4-tetracarboxylic acid, cyclobutane-1,2,3,4-tetracarboxylic acid, pyromellitic acid, benzophenone-3,3 ', 4,4'-tetracarboxylic acid, diphenyl ether- 3,3 ', 4,4'-
Tetracarboxylic acid, benzene-1,2,3,4-tetracarboxylic acid, biphenyl-3,3 ′, 4,4′-tetracarboxylic acid, biphenyl-2,2 ′, 3,3′-tetracarboxylic acid, Naphthalene-2,3,6,7-tetracarboxylic acid, naphthalene-1,2,4,5-tetracarboxylic acid, naphthalene-1,4,5,8-tetracarboxylic acid,
Decahydronaphthalene-1,4,5,8-tetracarboxylic acid, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic acid, 2,6-dichloronaphthalene-1,4,5,8-
Tetracarboxylic acid, 2,7-dichloronaphthalene-1,
4,5,8-tetracarboxylic acid, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic acid, phenanthrene-1,3,9,10-tetracarboxylic acid, perylene- 3,4,9,10-tetracarboxylic acid, bis (2,3-dicarboxyphenyl) methane, bis (3,4-dicarboxyphenyl) methane, 1,1-
Bis (2,3-dicarboxyphenyl) ethane, 1,1
-Bis (3,4-dicarboxyphenyl) ethane, 2,
2-bis (3,4-dicarboxyphenyl) propane,
Bis (3,4-dicarboxyphenyl) sulfone, bis (3,4-dicarboxyphenyl) ether, cyclopentane-1,2,3,4-tetracarboxylic acid, pyrrolidine-2,3,4,5-tetra Carboxylic acid, pyrazine-2,3,5,6-tetracarboxylic acid, thiophene-2,
3,4,5-tetracarboxylic acid, 2,3,5-tricarboxycyclopentylacetic acid, bicyclo- (2,2,2)
And polycarboxylic acids such as -oct-7-ene-2: 3: 5: 6-tetracarboxylic acid, and monoanhydrides and dianhydrides thereof. These are used alone or as a mixture of two or more.

Examples of the amine component include 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfone,
3,3′-diaminodiphenyl sulfone, 3,4′-diaminobiphenyl, 3,3′-diaminobiphenyl,
3,3′-diaminobenzanilide, 4,4′-diaminobenzanilide, 4,4′-diaminobenzophenone, 3,3′-diaminobenzophenone, 3,4′-diaminobenzophenone, 2,6-tolylenediamine,
4,4′-diaminodiphenyl sulfide, 3,3′-
Diaminodiphenyl sulfide, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylhexafluoropropane, 3,3'-diaminodiphenylhexafluoropropane, 3,3'-diamino Diphenylmethane, 4,
4'-diaminodiphenylhexafluoroisopropylidene, α, α'-diamino-p-xylene, α, α'-
Diamino-m-xylene, 1,4-naphthalenediamine, 2,6-naphthalenediamine, 2,7-naphthalenediamine, 2,2′-bis (4-aminophenyl) propane, 2,2′-bis (4- Aminophenyl) hexafluoropropane, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy)
Benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4 ′-[1,3-phenylenebis (1-methylethylidene)] bisaniline, 4,4 ′-[1,4-
Phenylenebis (1-methylethylidene)] bisaniline, 3,3 ′-[1,3-phenylenebis (1-methylethylidene)] bisaniline, 2,2-bis [4- (4
-Aminophenoxy) phenyl] propane, bis [4-
(4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone,
Bis [4- (3-aminophenoxy) phenyl] propane, bis [4- (3-aminophenoxy) phenyl] hexafluoropropane, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 5
-Amino-1- (4'-aminophenyl) -1,3,
3′-trimethylindane, 6-amino-1- (4′-
Aminophenyl) -1,3,3′-trimethylindane, 5-nitro-metaphenylenediamine, 5-chloro-metaphenylenediamine, tetramethylenediamine,
Alternatively, diisocyanates and the like corresponding thereto may be copolymerized alone or as a mixture of two or more.

The epoxy resin used in the present invention includes, for example, phenol novolak type epoxy resin, O-cresol novolak type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, glycidylamine type epoxy resin, glycidyl ether type Epoxy resin, glycidyl ester type epoxy resin, amine modified epoxy resin such as N, N, N ', N'-tetraglycidyl metaxylene diamine, isocyanurate type epoxy resin such as triglycidyl isocyanurate, or hydrogenation thereof And halides can be used regardless of the epoxy equivalent.

From the viewpoint of compatibility with the polyimide copolymer,
Particularly preferred are bisphenol A type epoxy resins,
Alternatively, it is a bisphenol F type epoxy resin. Since these epoxy resins have good compatibility, post-curing after the purpose of the crosslinking reaction can be performed under milder conditions.

The amount of the epoxy resin to be mixed with the polyimide copolymer is 5 to 9 by weight ratio of the epoxy resin in the whole resin composition.
0%, preferably 20 to 60%. 20% blended amount
Below, the thermocompression bonding property at lower temperature is insufficient,
Above, the heat resistance such as solder resistance and chip-on-flexibility is not sufficient.

After the polymerization is completed, the epoxy resin is mixed with the polyimide copolymer either directly or by adding a solution prepared by dissolving the epoxy resin in a solvent usable for the polymerization of the polyimide copolymer. At this time, an appropriate amount of a commonly used epoxy curing agent such as an imidazole compound, a tertiary amine compound, a hydrazine compound, a diamine compound, an organic peroxide or an organic phosphorus compound may be added as a curing catalyst.

The heat-resistant adhesive resin solution obtained as described above can be directly applied to a polyimide film. Further, in consideration of coating properties, the coating solution can be diluted with the same solvent or another solvent to prepare a coating solution. The solution viscosity is preferably from 1 to 1000 poise.

The thickness of the polyimide film is not particularly limited. For example, a film having a thickness of 5 to 125 μm can be used. Further, as the metal foil, it is possible to use copper foil, aluminum foil, steel foil, nickel foil, and the like.A composite metal foil obtained by combining these, or a metal foil treated with another metal such as zinc or chromium can be used. It can also be used. There is no particular limitation on the thickness of the metal foil.
A metal foil of 50 μm can be used.

The coating method is not particularly limited, and a conventionally well-known method can be applied. For example, the coating is performed by a roll coater, a knife coater, a doctor, a blade coater, or the like. be able to. Drying the coating layer at a temperature of 60 to 200 ° C.
The solvent can be removed for about 0.5 to 100 minutes. The thickness of the dried coating film is preferably from 3 to 150 μm, more preferably from 10 to 60 μm. 10μ
If it is less than m, the adhesiveness is insufficient, and if it is more than 60 μm, the flexibility is insufficient. Further, the coating and the drying may be repeated a plurality of times to repeatedly apply.

In order to form a flexible printed circuit board by bonding the polyimide film and the metal foil, the surface of the adhesive applied to the polyimide film or the metal foil is dried, and then the polyimide film and the metal foil are laminated via the adhesive layer. Then, thermocompression bonding is performed at a temperature of 100 to 200 ° C. for about 10 seconds to 5 minutes. The pressure is about 5 to 40 kg / cm ² . As a method of thermocompression bonding, it is possible to apply a conventionally known method, for example, roll lamination,
A method such as press lamination can be used. Thereafter, the laminated product is heated to 50 to 300 ° C.
By performing post-curing at a temperature of 1 to 40 hours to crosslink the adhesive layer, a flexible printed board excellent in heat resistance, adhesiveness, and flexibility can be easily manufactured.

Further, in the present invention, for the purpose of improving various characteristics of the flexible printed circuit board, for example, mechanical characteristics, electric characteristics, slipperiness, etc., other resins, organic compounds and inorganic compounds are mixed or reacted. They may be used together. For example, resins such as silicone compounds and fluorine compounds, organic compounds, and inorganic compounds such as silicon oxide, titanium oxide, and calcium carbonate can be used in combination as long as the object of the present invention is not impaired.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited at all by the examples. The evaluation method of the characteristic value in each embodiment is as follows.

Logarithmic viscosity The polymer was dissolved in N-methyl-2-pyrrolidone to a concentration of 0.5 g / dl, and the solution viscosity and solvent viscosity of the solution were measured at 30 ° C. using an Ubbelose viscometer. Was calculated by the following equation.

[0035]

(Equation 1)

The adhesive strength was measured according to JIS-C-5016.

Folding resistance was measured at a bending radius of 0.38R based on JIS-C-5016.

Solder resistance: Dipped in a solder bath at 300 ° C. for 20 seconds, and discoloration, swelling, peeling, etc. on the appearance were observed.

[0039]

EXAMPLES Example 1 163 g of trimellitic anhydride, 250 g of 4,4'-diphenylmethane diisocyanate, and 85 g of a compound of the following formula (6) (about 2 g) were placed in a reaction vessel.
0% by weight) and 1 kg of dimethylacetamide, and while stirring, the temperature was raised to 130 ° C. in 1 hour.
For 5 hours. After the reaction, Epicoat 828
810 g of a 50% by weight dimethylacetamide solution (epoxy resin manufactured by Yuka Shell Co., Ltd.)
% By weight) and stirred at room temperature for 2 hours.

The obtained resin solution was applied on a 25 μm thick Kapton H film by a doctor blade so that the thickness after drying became 20 μm, and the applied layer was applied at 60 ° C. for 10 minutes.
Dried at 160 ° C. for 10 minutes. Then, a 35 μm electrolytic copper foil was overlaid on the adhesive-applied surface of the Kapton H film and thermocompression bonded at a temperature of 180 ° C. and a pressure of 5 kg / cm ² for 60 seconds. The items shown in Table 1 were evaluated for the flexible printed circuit boards obtained as described above.

[0041]

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Example 2 172 g of trimellitic anhydride, 250 g of 4,4'-diphenylmethane diisocyanate, 69 g (about 17% by weight) of a compound of the following formula (7), and 1 kg of dimethylacetamide were added to a reaction vessel and stirred. The temperature was raised to 130 ° C. in one hour,
The reaction was performed at 5 ° C. for 5 hours. After the reaction, Epicoat 828
806 g of a 50% by weight dimethylacetamide solution (epoxy resin manufactured by Yuka Shell Co., Ltd.)
% By weight) and stirred at room temperature for 2 hours.

The obtained resin solution was applied on a 25 μm-thick Kapton H film with a doctor blade so that the thickness after drying became 20 μm.
And dried at 160 ° C. for 10 minutes. Next, the Kapton H
A 35 μm electrolytic copper foil is superimposed on the adhesive-coated surface of the film, and the temperature is 180 ° C., the pressure is 5 kg / cm ² , and the thickness is 60 μm.
Thermocompression bonding was performed for seconds. The flexible printed circuit board obtained as described above was evaluated for the items shown in Table 1.

[0044]

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Example 3 169 g of trimellitic anhydride, 264 g of O-tolidine diisocyanate were placed in a reaction vessel.
And 90 g (about 20% by weight) of a compound of the following formula (8):
Add 1 kg of dimethylformamide and add 13 kg while stirring.
The temperature was raised to 0 ° C. in 1 hour, and further reacted at 130 ° C. for 5 hours. After completion of the reaction, 870 g (50% by weight of epoxy compound) of a 50% by weight solution of Epicoat 828 (epoxy resin manufactured by Yuka Shell Co., Ltd.) in dimethylformamide was added, and the mixture was stirred at room temperature for 2 hours.

The obtained resin solution was applied on a 25 μm-thick Kapton H film with a doctor blade so that the thickness after drying became 20 μm.
And dried at 160 ° C. for 10 minutes. Next, the Kapton H
A 35 μm electrolytic copper foil is superimposed on the adhesive-coated surface of the film, and the temperature is 180 ° C., the pressure is 5 kg / cm ² , and the thickness is 60 μm.
Thermocompression bonding was performed for seconds. The flexible printed circuit board obtained as described above was evaluated for the items shown in Table 1.

[0047]

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Example 4 172 g of trimellitic anhydride, 250 g of 4,4'-diphenylmethane diisocyanate, 69 g (about 17% by weight) of a compound of the following formula (7), and 1 kg of dimethylacetamide were added to a reaction vessel and stirred. The temperature was raised to 130 ° C. in one hour,
The reaction was performed at 5 ° C. for 5 hours. After the reaction is completed, Araldite XY
50 of P306 (Ciba Geigy Co., Ltd. epoxy resin)
806 g of a dimethylacetamide solution (by weight, epoxy content: 50% by weight) was added, and the mixture was stirred at room temperature for 2 hours.

The obtained resin solution was applied on a 25 μm-thick Kapton H film with a doctor blade so that the thickness after drying became 20 μm, and the coating layer was applied at 60 ° C. for 10 minutes.
Dried at 160 ° C. for 10 minutes. Then, a 35 μm electrolytic copper foil was overlaid on the adhesive-coated surface of the Kapton H film, and thermocompression bonded at a temperature of 180 ° C. and a pressure of 5 kg / cm ² for 60 seconds. The flexible printed circuit board obtained as described above was evaluated for the items shown in Table 1.

(Comparative Example 1) 192 g of trimellitic anhydride, 250 g of 4,4'-diphenylmethane diisocyanate and 1 kg of dimethylacetamide were added to a reaction vessel, and the temperature was raised to 130 ° C for 1 hour with stirring, and further increased to 130 ° C. The reaction was performed for 5 hours. 25 of the obtained resin solution was used.
2 μm thickness after drying on Kapton H film
It was applied with a doctor blade so as to have a thickness of 0 μm, and the applied layer was dried at 60 ° C. for 10 minutes and at 160 ° C. for 10 minutes. Next, a 35 μm electrolytic copper foil was superimposed on the adhesive-coated surface of the Kapton H film, and the temperature was 180 ° C. and the pressure was 5 kg / c.
Thermocompression bonding was performed for 60 seconds under the condition of m ² . The flexible printed circuit board obtained as described above was evaluated for the items shown in Table 1.

(Comparative Example 2) 96 g of trimellitic anhydride, 250 g of 4,4'-diphenylmethane diisocyanate, 378 g of a compound of the following formula (8) (about 60% by weight) and 1.5 kg of dimethylacetamide were added to a reaction vessel and stirred. While raising the temperature to 130 ° C. in one hour,
The reaction was performed at 30 ° C. for 5 hours. After the reaction, Epicoat 8
50% by weight of 28 (epoxy resin manufactured by Yuka Shell Co., Ltd.)
Was added and the mixture was stirred at room temperature for 2 hours.

The obtained resin solution was applied on a 25 μm-thick Kapton H film with a doctor blade so that the thickness after drying became 20 μm, and the coating layer was applied at 60 ° C. for 10 minutes.
Dried at 160 ° C. for 10 minutes. Then, a 35 μm electrolytic copper foil was overlaid on the adhesive-coated surface of the Kapton H film, and thermocompression bonded at a temperature of 180 ° C. and a pressure of 5 kg / cm ² for 60 seconds. The flexible printed circuit board obtained as described above was evaluated for the items shown in Table 1.

Comparative Example 3 207 g of trimellitic anhydride, 264 g of O-tolidine diisocyanate were placed in a reaction vessel.
And 90 g (about 20% by weight) of a compound of the following formula (8):
Add 1 kg of dimethylformamide and add 13 kg while stirring.
The temperature was raised to 0 ° C. in 1 hour, and further reacted at 130 ° C. for 5 hours. After the completion of the reaction, 940 g of a 20% by weight dimethylacetamide solution of Epicoat 828 (epoxy resin manufactured by Yuka Shell Co., Ltd.) (50% by weight of epoxy compound) was added, and the mixture was stirred at room temperature for 2 hours.

The obtained resin solution was applied onto a 25 μm-thick Kapton H film by a doctor blade so that the thickness after drying became 20 μm, and the coating layer was applied at 60 ° C. for 10 minutes.
Dried at 160 ° C. for 10 minutes. Then, a 35 μm electrolytic copper foil was overlaid on the adhesive-coated surface of the Kapton H film, and thermocompression bonded at a temperature of 180 ° C. and a pressure of 5 kg / cm ² for 60 seconds. The flexible printed circuit board obtained as described above was evaluated for the items shown in Table 1.

Comparative Example 4 163 g of trimellitic anhydride, 250 g of 4,4'-diphenylmethane diisocyanate, 85 g of a compound of the following formula (6) (about 20% by weight) and 1 kg of dimethylacetamide were added to a reaction vessel and stirred. The temperature was raised to 130 ° C. in one hour,
The reaction was performed at 5 ° C. for 5 hours. After the reaction, Epicoat 828
3.5 kg (epoxy resin 90% by weight) (epoxy resin manufactured by Yuka Shell Co., Ltd.) was added, and the mixture was stirred at room temperature for 2 hours.

The resulting resin solution was applied on a 25 μm-thick Kapton H film with a doctor blade so that the thickness after drying became 20 μm.
And dried at 160 ° C. for 10 minutes. Next, the Kapton H
A 35 μm electrolytic copper foil is superimposed on the adhesive-coated surface of the film, and the temperature is 180 ° C., the pressure is 5 kg / cm ² , and the thickness is 60 μm.
Thermocompression bonding was performed for seconds. The items shown in Table 1 were evaluated for the flexible printed circuit boards obtained as described above.

[0057]

[Table 1]

[0058]

As described above, the heat-resistant adhesive of the present invention comprises an epoxy resin and a repeating unit represented by the general formula (1) having good compatibility with the epoxy resin; ) And / or a polyimide printed circuit having a structure containing a repeating unit represented by the general formula (3) as a main component, so that a flexible printed board excellent in heat resistance, flexibility and adhesiveness can be obtained under mild processing conditions. Obtainable.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hiroki Yamaguchi 2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo Co., Ltd. Research Laboratory

Claims (3)

[Claims] 1. A polyimide copolymer containing a repeating unit represented by the general formula (1), a repeating unit represented by the general formula (2) and / or the general formula (3) as a constituent, and an epoxy resin. A heat-resistant adhesive characterized by being a component. 2. The heat-resistant adhesive according to claim 1, wherein the epoxy resin is a bisphenol A type epoxy resin and / or a bisphenol F type epoxy resin. 3. A flexible printed circuit board comprising a polyimide film laminated on one surface of a layer made of the heat-resistant adhesive according to claim 1 and a metal foil laminated on the other surface. . Embedded image (In the formulas (1) to (3), m and n are integers of 1 or more, and may be the same or different, and Ar ¹ is a trivalent group obtained by removing three carboxyl groups of a tricarboxylic acid. Ar ² represents a divalent residue excluding two amino groups of the diamine compound, R ¹ represents an alkylene group having 1 to 20 carbon atoms, R ² represents an alkylene group having 1 to 20 carbon atoms or Represents a phenylene group, and R ³ and R ⁴ represent hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different from each other)