JP5282643B2 - Adhesive composition, coverlay film and flexible copper-clad laminate using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-resistant adhesive composition containing a nylon resin, an epoxy resin, a novolac resin, and a hardening promotor and an adhesive composition which has an excellent adhesion to a polyimide film, exhibits excellent solder heat resistance and moisture-absorption solder heat resistance, and is favorably used for FPC's. <P>SOLUTION: The adhesive composition includes a solvent-soluble nylon resin solid at 25&deg;C, an epoxy resin, a novolac resin having a specific structure, and a hardening promotor having an acid dissociation constant of over 8.3. The nylon resin contains &ge;20 mole% of piperazine, when the total amount of diamine components is 100 mole%, and has an amine value of 1-6 mgKOH/g. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an adhesive composition, and more particularly to an adhesive composition that can be preferably used as an adhesive for a flexible printed wiring board (hereinafter also referred to as “FPC”). Good adhesion to wiring boards, solder heat resistance, resin flowability during heat bonding, and embedding in circuit grooves required for FPC adhesives. The present invention relates to an adhesive film that does not cause a problem and an adhesive composition used for the adhesive film, and belongs to the electronic material technology.

In recent years, with the diversification of electronic devices such as miniaturization and high density, demand for flexible circuit boards or flexible printed wiring boards is increasing. Under such circumstances, high integration and multilayering are also progressing in the manufacture of flexible printed circuit boards.
The flexible copper-clad laminate is a structure in which copper foil is bonded to one or both sides of a flexible insulating base film via an adhesive layer. -A highly reliable polyimide film is often used. Further, this flexible copper-clad laminate is an FPC in which a conductive circuit is formed on a copper foil through steps such as resist layer formation, exposure, development, etching, and resist layer peeling.
These FPCs have adhesives for bonding the insulating base film of the flexible copper clad laminate and the copper foil, coverlay adhesives, interlayer adhesives, etc. for the purpose of protecting and insulating the conductive circuit. Adhesives, semiconductor sealants and the like are widely used.
Conventionally, various adhesives have been proposed for use in bonding insulating base films and metals, insulating base films, and metals. For example, adhesives such as polyvinyl butyral / novolak resin, acrylonitrile butadiene rubber (NBR) / novolak resin, nylon resin / epoxy resin, NBR / epoxy resin, acrylic elastomer / epoxy resin are used. Among these, nylon resin / epoxy resin adhesives are particularly widely used because they exhibit excellent adhesion performance.
For example, Patent Document 1 discloses an adhesive for a TAB tape that is excellent in chemical resistance and heat-resistant adhesiveness and has high adhesiveness. Patent Document 2 discloses a coverlay adhesive having excellent adhesiveness and flame retardancy and high adhesiveness.

Japanese Patent Laid-Open No. 5-29399 Japanese Patent No. 3718357

  However, in the adhesive as shown in Patent Document 1, the storage stability of the adhesive solution after mixing the curing agent and the curing accelerator is inferior, and the viscosity increases and gelation occurs during long-time storage. To do. This phenomenon originates from the fact that the reaction between the epoxy resin, which is a component constituting the adhesive, the curing agent and the curing accelerator proceeds even at a relatively low temperature. In addition, the reaction between the nylon resin and the epoxy resin proceeds at the same time. In particular, the higher the amine value of the nylon resin, the faster the reaction proceeds. Furthermore, when the reaction rate of the adhesive composition is too high, the crosslinking reaction of the composition applied to the insulating base film proceeds by heating during solvent drying. Therefore, in the bonding process with the next copper foil, the resin flow-out property at the time of the heating adhesive is poor, and the embedding property of the circuit groove becomes insufficient. As a result, the insulation between circuits becomes poor. On the other hand, in the adhesive composed of nylon resin and epoxy resin with a low amine value, the curing progress is slow unless a curing agent and a curing accelerator are blended, and high adhesiveness and heat resistance that can be used for FPC applications. Cannot be obtained. Furthermore, when the curing reaction has not progressed, the amount of resin flowing out during heating adhesive is large in the bonding process with the next copper foil. It became a problem that it became impossible.

Moreover, in the adhesive as shown by patent document 2, when the high temperature process by a solder reflow furnace etc. is performed, foaming by moisture absorption of an adhesive will occur and peeling of an adhesive layer will arise. As a result, it has been a problem that insulation reliability deteriorates.
In the present invention, solder heat resistance under moisture absorption conditions is referred to as “moisture absorption solder heat resistance”.

  The present invention solves the above-mentioned problems, and its purpose is to provide an adhesive composition that exhibits high adhesion to a polyimide film and that is excellent in solder heat resistance and moisture absorption solder heat resistance and can be preferably used for FPC. To do.

  As a result of intensive studies to solve the above problems, the present inventors thermally cured an adhesive composition containing a solvent-soluble nylon resin, an epoxy resin, a novolak resin having a specific structure, and a specific curing accelerator, It has been found that the adhesion to the adherend is improved and the heat resistance under moisture absorption conditions is improved. In addition, when a specific amount of piperazine is introduced as a component of the solvent-soluble nylon resin, and the amine value of the nylon resin is in a specific range, it has been found that high adhesion to a flexible film such as a polyimide film is exhibited. It was. When the adhesive composition of the present invention is used for FPC, it has been found that the solder heat resistance and the solder heat resistance under moisture absorption conditions are excellent, and the present invention has been completed.

That is, the adhesive composition according to the present invention includes a nylon resin solid at 25 ° C. that dissolves in an alcohol solvent, an epoxy resin, a novolak resin having a structure represented by the following general formula (1), and an acid dissociation constant ( (Hereinafter also referred to as “pKa”)), an adhesive composition containing a curing accelerator exceeding 8.3, wherein the nylon resin has 20 mol of piperazine when the total amount of diamine components is 100 mol%. %, The amine value is 1 to 6 (mgKOH / g), the content of the epoxy resin is 25 to 150 parts by mass with respect to 100 parts by mass of the nylon resin, and the novolac resin Content is the range shown by the following formula .
Hydroxyl equivalent / epoxy equivalent =
{(Content of novolak resin) ÷ (hydroxyl equivalent of novolak resin)} ÷
{(Epoxy resin content) / (epoxy group equivalent of epoxy resin)}
= 0.2 to 1.5

［式（１）におけるＸはメラミン構造又はグアナミン構造であり、Ｙは水素原子又はメチル基である。また、ｎは１〜１０の整数である。］

[X in Formula (1) is a melamine structure or a guanamine structure, and Y is a hydrogen atom or a methyl group. Moreover, n is an integer of 1-10. ]

  The acid value of the nylon resin is preferably 4 to 10 (mgKOH / g).

  The epoxy resin preferably has two or more epoxy groups in one molecule.

  A coverlay film, wherein the adhesive composition according to any one of the above is applied to one side of a polyimide film.

  A flexible copper-clad laminate comprising the adhesive composition according to any one of the above, wherein a copper foil is bonded to at least one surface of a polyimide film.

  As described above, the adhesive composition according to the present invention contains a specific nylon resin, an epoxy resin, a novolak resin having a specific structure, and a specific curing accelerator. Therefore, high adhesiveness is expressed with respect to a polyimide film, and it is excellent in heat resistance. When used in an FPC, high solder heat resistance and moisture absorption heat resistance can be obtained, so that the insulation reliability is improved.

An embodiment of the present invention will be described as follows, but the present invention is not limited to this.

-Adhesive composition The adhesive composition according to the present invention contains a solvent-soluble nylon resin, an epoxy resin, a novolak resin having a specific structure, and a specific curing accelerator, and each resin is as follows. It is.

The solvent-soluble nylon resin used in the present invention is a nylon resin that is soluble in an alcohol solvent and is solid at 25 ° C., dehydration condensation reaction of various dicarboxylic acids and diamines, self-condensation of aminocarboxylic acid, aminocarboxylic acid It can be synthesized by ring-opening polymerization of an intramolecular cyclic compound of the above and a combination of these reactions. The nylon resin according to the present invention contains piperazine as a constituent component. By containing piperazine, the adhesiveness to a flexible film such as a polyimide film is dramatically improved. The content of piperazine needs to be 20 to 100 mol%, preferably 40 to 100 mol%, when the total amount of diamine components is 100 mol%. When the piperazine content is less than 20 mol%, sufficient adhesion to the polyimide film cannot be obtained.

  Examples of diamine compounds other than piperazine used when synthesizing the nylon resin of the present invention include ethylenediamine, tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, p-diaminomethylcyclohexane, bis (p-aminocyclohexyl) methane, Examples include, but are not limited to, m-xylene diamine and isophorone diamine.

  Examples of the dicarboxylic acid include, but are not limited to, adipic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, dimer acid, isophthalic acid, terephthalic acid, and sodium 5-sulfoisophthalate. In order to ensure solubility in a solvent, it is preferable to use all or part of dicarboxylic acid having relatively low crystallinity such as azelaic acid, undecanedioic acid and dimer acid.

  Examples of aminocarboxylic acid include 11-aminoundecanoic acid, 12-aminododecanoic acid, 4-aminomethylbenzoic acid, 4-aminomethylcyclohexanecarboxylic acid, and the intramolecular cyclic compound of aminocarboxylic acid includes β- Examples include, but are not limited to, lactam, ε-caprolactam, laurin lactam, α-pyrrolidone, α-piperidone and the like.

  Moreover, what was made into the alcohol soluble nylon resin by introduce | transducing the N-alkoxymethyl group which added formalin and alcohol to the polyamide bond in nylon resin can also be used in this invention. The introduction of the N-alkoxymethyl group contributes to a decrease in melting point, an increase in flexibility, and an improvement in solubility, and the introduction rate is determined according to the purpose.

    The adhesive composition in the present invention is an adhesive containing a nylon resin and an epoxy resin, and curing proceeds by the reaction of the amino group and carboxyl group of the nylon resin with the epoxy group of the epoxy resin. . Among them, amino groups are more reactive with epoxy groups than carboxyl groups, and high adhesive strength and solder heat resistance can be obtained by heat treatment in a short time. Generally, when the amine value of a nylon resin is high and the acid value is low, the reaction between the amino group and the epoxy group is fast, and good curability can be obtained with a short heat treatment, but the coated adhesive is dried. The reaction also proceeds depending on the amount of heat for causing the resin viscosity to become too high during heat bonding, resulting in poor embedding in the circuit, resulting in defects in solder characteristics and insulation. In addition, since the reaction proceeds even at room temperature, the reaction gradually proceeds immediately after mixing, and the liquid viscosity may be significantly increased and gelled. On the other hand, if the amine value is low and the acid value is high, the effect of suppressing the reaction between the amino group and the epoxy group works, so that sufficient curability cannot be obtained by heat treatment in a short time. Therefore, it is necessary to set to an appropriate amine value and acid value that can achieve both curability and stability, and the range is an amine value of 1 to 6 (mgKOH / g), and an acid value of 4 to 10 (mgKOH). / G). When the amine value is less than 1 (mgKOH / g) or the acid value exceeds 10 (mgKOH / g), the reactivity with the epoxy resin is inferior, and the adhesive layer is bonded when the adhesive is cured. It protrudes from the end of the surface or foams to cause poor appearance. Further, the curing becomes insufficient, and the adhesive strength and solder heat resistance tend to decrease. When the amine value exceeds 6 (mgKOH / g) or the acid value is less than 4 (mgKOH / g), the reactivity with the epoxy resin is too high, and the amount of heat for drying the coated adhesive The reaction proceeds, the resin viscosity at the time of heat bonding becomes too high, the embedding in the circuit is worsened, and a defect occurs in solder characteristics and insulation. In addition, since the reaction is likely to proceed even in a mixed solution state, viscosity increase and gelation are likely to proceed during storage of the solution, and this is not practical. The amine value of nylon resin means the number of mg of KOH equivalent to hydrochloric acid required to neutralize the amine present in 1 g of resin, and the acid value neutralizes the acid present in 1 g of resin. Means the number of mg of KOH required for. The measuring method will be described later.

  Nylon resin can be synthesized by dehydration condensation reaction, dealcoholization reaction, ring-opening polymerization reaction, etc. by batch preparation in the absence of a solvent. In that case, water can be charged together with the raw material monomer in advance, and the dehydration reaction can be performed while distilling off the water. This reaction may be carried out under normal pressure or reduced pressure. Adjustment of the molecular weight and amine value of the nylon resin is carried out by adjusting the charging ratio of diamine and dicarboxylic acid, the reaction time, and the degree of reduced pressure when the nylon resin is synthesized.

Next, the epoxy resin used in the present invention will be described.
The epoxy resin used in the present invention plays a role of a crosslinking agent for curing the nylon resin. Examples of epoxy resins include bisphenol A diglycidyl ether and oligomers thereof, orthophthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, p-hydroxybenzoic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester Glycidyl esters such as succinic acid diglycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, trimellitic acid triglycidyl ester, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol di Glycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol Lug glycidyl ether, tetraphenyl glycidyl ether ethane, triphenyl glycidyl ether ethane, polyglycidyl ethers of sorbitol, but glycidyl ethers such as polyglycidyl ethers of polyglycerol include, without being limited thereto. In addition, a novolac type epoxy resin such as a phenol novolac epoxy resin, an o-cresol novolac epoxy resin, or a bisphenol A novolac epoxy resin can be used.

  Further, examples of epoxy resins include brominated bisphenol A type epoxy resins imparted with flame retardancy, phosphorus containing epoxy resins, dicyclopentadiene skeleton containing epoxy resins, naphthalene skeleton containing epoxy resins, anthracene type epoxy resins, tertiary butyl catechol Type epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, biphenyl type epoxy resin, bisphenol S type epoxy resin and the like can be used.

  In the adhesive used in the present invention, an epoxy resin having two or more epoxy groups in one molecule is used in order to increase the reactivity with the nylon resin and to exhibit high heat resistance. Is preferred. When an epoxy resin having one epoxy group is used, sufficient solder heat resistance may not be obtained due to a low degree of crosslinking with the nylon resin.

The blending ratio of the nylon resin and the epoxy resin in the adhesive composition of the present invention is such that the epoxy resin is in the range of 25 to 150 parts by mass with respect to 100 parts by mass of the nylon resin . More preferably, an epoxy resin exists in the range of 30-120 mass parts. Good performance is exhibited when the blending ratio is within this range. When the blending ratio of the epoxy resin is less than 25 parts by mass, the nylon resin is not sufficiently cured, and a sufficient degree of adhesion and heat resistance cannot be obtained because the degree of crosslinking is low. On the other hand, when the blending ratio of the epoxy resin exceeds 150 parts by mass, the blending ratio of the nylon resin in the adhesive is decreased, and the solder heat resistance tends to be lowered.

Next, the novolak resin having a specific structure used in the present invention will be described.
The novolak resin having a specific structure used in the present invention plays a role of improving the adhesion with a cross-linking agent for curing an epoxy resin and copper.

  The novolak resin having a specific structure used in the present invention has a structure represented by the following general formula (1).

［式（１）におけるＸはメラミン構造又はグアナミン構造であり、Ｙは水素原子又はメチル基である。また、ｎは１〜１０の整数である。］

[X in Formula (1) is a melamine structure or a guanamine structure, and Y is a hydrogen atom or a methyl group. Moreover, n is an integer of 1-10. ]

  X of the novolak resin represented by the general formula (1) used in the present invention is a melamine structure or a guanamine structure. Examples of the guanamine structure include acetoguanamine and benzoguanamine.

The content of the melamine structure and the guanamine structure in the novolak resin having a specific structure used in the present invention can be shown as the nitrogen content, and the preferable nitrogen content is 5 to 30% by mass, more preferably 6 -25% by mass. When the nitrogen content of the novolak resin having a melamine structure and a guanamine structure is less than 5% by mass, the adhesiveness with copper becomes weak, and when a high temperature treatment such as a solder reflow furnace is applied, the adhesive is removed from the copper interface. The insulation reliability deteriorates due to peeling. Furthermore, when the nitrogen content of the novolak resin having a melamine structure and a guanamine structure exceeds 30% by mass, the reaction between the epoxy resin and the amino group is likely to occur, and the viscosity increase and gelation progress during storage of the solution. Easy to use and unbearable.
The nitrogen content in the novolak resin can be quantified by gas chromatography or differential method.

  The novolak resin having a specific structure used in the present invention is widely commercially available. For example, trade names “Phenolite LA-7052”, “Phenolite LA-7054”, “Phenolite LA-7751”, “Phenolite LA-1356”, “Phenolite LA-1398”, Japan Epoxy manufactured by DIC A trade name “YLH-969” manufactured by Resin Co., Ltd. may be mentioned.

The content of the novolak resin having a specific structure used in the present invention is in a range represented by the following calculation formula .
Hydroxyl equivalent / epoxy equivalent =
{(Content of novolak resin) ÷ (hydroxyl equivalent of novolak resin)} ÷
{(Epoxy resin content) / (epoxy group equivalent of epoxy resin)}
= 0.2 to 1.5
When the [hydroxyl equivalent / epoxy equivalent] indicating the content of the novolak resin having a specific structure is less than 0.2, the adhesiveness with copper is weakened, and a high temperature treatment such as a solder reflow furnace is applied. The adhesive peels off from the copper interface, resulting in poor insulation reliability. Further, when the hydroxyl group equivalent / epoxy equivalent exceeds 1.5, the reaction between the epoxy resin and the amino group is likely to occur, and the viscosity increase and gelation at the time of storage of the solution are likely to proceed, which is not practical.

Next, the curing accelerator used in the present invention will be described.
The curing accelerator used in the present invention promotes the curing reaction between the epoxy resin and the novolak resin having a specific structure, and plays a role of adjusting the resin flow-out property at the time of heat bonding in the bonding process with the copper foil. ing.

  The pKa of the curing accelerator used in the present invention exceeds 8.3. More preferably, it is 8.7 or more and less than 13. When the pKa of the curing accelerator is 8.3 or less, the curing rate of the adhesive composition becomes slow, so that the melt viscosity of the adhesive composition in the copper foil laminating step becomes low, and the resin at the time of heat bonding Increases flowability. As a result, the connection contacts are not sufficiently energized.

  As the curing accelerator used in the present invention, any compound having a pKa exceeding 8.3 can be used. For example, N, N-dimethylbenzylamine, N, N-diethylbenzylamine, piperidine, 1,8-diazabicyclo [5,4,0] undecene-7,1,5-diazabicyclo [4,3,0] nonene- 5 etc. are mentioned. Moreover, the salt of these hardening accelerators can be used. For example, phenol salts, octylates, oleates, formates, p-toluenesulfonates and the like can be mentioned.

  The usage-amount of the hardening accelerator used by this invention is 0.2-5 mass parts with respect to 100 mass parts of nylon resins in the adhesive composition of this invention. Preferably it is 0.5-3 mass parts. When the amount of the curing accelerator used is less than 0.2 parts by mass, the amount of the resin flowing out at the time of heat bonding is too large, and sufficient conduction for circuit connection cannot be obtained. On the other hand, when the amount exceeds 5 parts by mass, the resin viscosity at the time of heat bonding becomes too high, so that the embedding in the circuit is worsened and a defect occurs in the solder characteristics and insulation.

The adhesive composition of the present invention is generally dissolved in a solvent and used as a solution-type adhesive, but the solvent is preferably one that dissolves a nylon resin or an epoxy resin. Nylon resin is soluble in an alcohol solvent, an epoxy resin ketones, esters, aromatic solvents, to dissolve the chlorinated solvents, alcohol solvents and ketone solvent mixed solvent of, and an alcohol solvent It can be selected from a mixed solvent of an ester solvent, a combination of an alcohol solvent and an aromatic solvent.

Specific examples of the solvent include methanol, ethanol, i-propyl alcohol, n-propyl alcohol, i-butyl alcohol, n-butyl alcohol, benzyl alcohol, ethylene glycol methyl ether, propylene glycol methyl ether, diethylene glycol monomethyl ether, Alcohol solvents such as diacetone alcohol, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, aromatic solvents such as toluene, xylene, ethylbenzene, mesitylene, methyl acetate, ethyl acetate, ethylene glycol Ester solvents such as monomethyl ether acetate and 3-methoxybutyl acetate, chloroform, carbon tetrachloride, dichloromethane, trichloroethylene It is mentioned of chlorinated solvents. In addition, water, phenol, formic acid, acetic acid and the like added to improve the solubility of the nylon resin can be used. Among these solvents, mixed solvents in which one or more alcohol solvents and other solvents are used in combination are preferred for the present invention. For example, methanol / toluene, i-propyl alcohol / toluene, i-isopropyl alcohol / Specific examples include mixed solvents such as dichloromethane. As said mixed solvent, the alcohol amount in all the solvents is preferably 30% by mass or more and 80% by mass or less. When it deviates from this ratio, the solubility of the nylon resin or the epoxy resin is lowered, and an insoluble precipitate is formed, so that the liquid stability is remarkably lowered.

  In addition to the nylon resin and epoxy resin, the adhesive composition of the present invention can optionally contain additives for the purpose of improving adhesiveness and improving solution properties, as long as the object of the present invention is not impaired. is there. For example, resin components such as thermoplastic resins, thermoplastic elastomers and rubbers, coupling agents, thermal aging inhibitors, ultraviolet absorbers, leveling agents, antifoaming agents, thickeners, flame retardants, fillers, dyes, etc. It is done. It is also possible to add and disperse filler components such as titanium oxide, zinc oxide, talc, calcium carbonate, aluminum hydroxide, carbon black and silica. Such additives can be added during or after dissolution of the raw material in the solvent.

  Examples of the resin component include acrylonitrile butadiene rubber, acrylic rubber, acrylic ethylene rubber, isoprene rubber, ethylene propylene rubber, ethylene propylene diene rubber, ethylene propylene α olefin rubber, ethylene vinyl acetate elastomer, polyester urethane elastomer, polyether urethane elastomer. , Polycarbonate urethane elastomer, styrene butadiene styrene elastomer, styrene isoprene styrene elastomer, styrene ethylene butylene styrene elastomer, styrene ethylene propylene styrene elastomer, polyester elastomer, polyethylene, polypropylene, polyacrylonitrile styrene, polymethyl methacrylate, polystyrene, polyvinyl alcohol, poly vinegar Vinyl, polyvinyl butyral, polycarbonate, polyacetal, fluorine resin, polyvinyl chloride, melamine resins, urea resins, phenoxy resins. Moreover, what modified | denatured these resin and gave the carboxyl group, the epoxy group, the isocyanate group, the hydroxyl group, the thiol group, etc. is mentioned.

  Examples of coupling agents include vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, N- 2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyltriethoxysilane, etc. Silane coupling agents, titanate coupling agents, aluminate coupling agents, zirconium coupling agents, and the like.

  Examples of antioxidants include 2,6-di-o-butyl-4-methylphenol, n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate, Phenol antioxidants such as tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, dilauryl-3,3′-thiodipropionate, dimyristyl-3,3 Examples include sulfur-based antioxidants such as' -dithiopropionate, phosphorus-based antioxidants such as trisnonylphenyl phosphite and tris (2,4-di-t-butylphenyl) phosphite.

  Examples of UV absorbers include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2-[(2′-hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl Benzotriazole ultraviolet absorbers such as -benzotriazole, benzophenone ultraviolet absorbers such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-n-octylbenzophenone, phenyl salicylate, etc. Salicylate UV absorbers, cyanoacrylate UV absorbers such as ethyl-2-cyano-3,3-diphenyl acrylate, oxalic anilide UV rays such as 2-ethoxy-2'-ethyl oxalic acid bisanilide Absorber, bis- [2,2,6,6-tetra And hindered amine ultraviolet absorbers such as methyl-4-piperidinyl] sebacate and bis- [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate.

  Examples of flame retardants include brominated flame retardants such as tetrabromobisphenol A, hexabromobenzene, decabromodiphenyl ether, hexabromocyclododecane, bis (pentabromophenyl) ethane, bis (tetrabromophthalimide) ethane, triphenyl phosphate , Aromatic phosphate ester flame retardants such as 2-ethylhexyl diphenyl phosphate, cresyl diphenyl phosphate, 1,3-phenylene bis (diphenyl phosphate), 1,3-phenylene bis (dixylenyl) phosphate, bisphenol A bis (diphenyl phosphate) ) Aromatic condensed phosphate esters such as tris (dichloropropyl) phosphate, halogen-containing phosphate ester flame retardants, red phosphorus flame retardants such as red phosphorus, aluminum hydroxide, water Magnesium, inorganic flame retardants such as antimony trioxide, silicon-based flame retardant, such as boron-based flame retardants and the like.

  Examples of the filler include calcium carbonate, titanium oxide, zinc oxide, talc, calcium carbonate, carbon black, silica, copper powder, aluminum powder, silver powder and the like.

  In the present invention, an adhesive composition containing a nylon resin and an epoxy resin as essential components is usually dissolved in the solvent together with the optional additive and used as a solution-type adhesive. The resin concentration when used as a solution-type adhesive is preferably 5 to 50% by mass, more preferably 10 to 40% by mass. If the resin concentration is within this range, the solution viscosity of the prepared adhesive is appropriate, and a uniform coating film can be formed when applied to a flexible film.

The FPC in which the adhesive composition of the present invention is used is formed by laminating the following cover lay film and a flexible copper-clad laminate.
Cover Lay Film Examples of the cover lay film include a polyimide film, a polyester film, a polyether ether ketone film, a polyphenylene sulfide film, and an aramid film. A film preferable for the present invention has a film thickness of 12 to 75 μm, and one having a surface treatment such as a corona discharge treatment, a low temperature plasma treatment or a sand blast treatment on one side or both sides of the film can also be used.

○ Flexible copper-clad laminate Flexible copper-clad laminate is a flexible film similar to the above-mentioned coverlay film and copper foil, bonded together by a method such as roll crimping or hot pressing using an adhesive, A copper foil layer is etched into a desired circuit pattern.

Examples of the method for bonding the flexible film and the copper foil using the adhesive composition include the following methods.
1) An adhesive solution is applied to a flexible film, dried to form an adhesive layer, and a copper foil is laminated thereon and heated to cure the adhesive layer between both substrates.
2) The adhesive solution is applied to a copper foil, dried to form an adhesive layer, and a flexible film is laminated thereon and heated to cure the adhesive layer between both substrates.
3) An adhesive solution is applied to a release film and dried to form an adhesive layer. Next, the adhesive layer and the flexible film are bonded together, the release film is peeled off, the exposed adhesive layer and the copper foil are bonded together, and then the adhesive layer between the two substrates is heated. Is cured.
4) The adhesive solution is applied to a release film and dried to form an adhesive layer. Next, the adhesive layer and the copper foil are bonded together, the release film is peeled off, the exposed adhesive layer and the flexible film are bonded together, and then the adhesive layer is heated between the two substrates by heating. Is cured.

  Examples of the release film include PET film, polyethylene film, polypropylene film, silicone release treated paper, polyolefin resin-coated paper, TPX film, and fluorine resin film that have been subjected to a release treatment.

  The adhesive solution is applied by a method such as brush coating, dip coating, spray coating, comma coating, knife coating, die coating, lip coating, roll coater coating or curtain coating. The dry film thickness after coating is preferably 1 to 100 μm, more preferably 10 to 50 μm. The adhesive solution applied to the substrate is preferably dried by heating at a temperature of 40 to 250 ° C., more preferably 70 to 170 ° C., through a furnace such as hot air drying, far infrared heating, high frequency induction heating or the like. As a method for curing the adhesive layer in which the two substrates are overlapped, a method of heating through a furnace such as hot air drying, far-infrared heating, high-frequency induction heating or the like at a temperature of 80 to 250 ° C. is used. Among them, the heating method under pressure by a heating press is preferable for obtaining high adhesiveness.

Below, it demonstrates based on an Example.
[Nylon resin synthesis example]
(Synthesis Example 1)
A flask equipped with a stirrer, a reflux dehydrator and a distillation tube was charged with 65 parts by mass of azelaic acid as a dicarboxylic acid component, 190 parts by mass of dodecanedioic acid, and 100 parts by mass of piperazine and 120 parts by mass of distilled water as a diamine component. After raising the temperature to 120 ° C. to distill water, the temperature was raised to 240 ° C. at a rate of 20 ° C./hour, and the reaction was continued for 3 hours to obtain a nylon resin 1. The amine value at that time was 4.5 (mgKOH / g).

(Synthesis Examples 2 to 7)
Nylon resins 2 to 7 having the compositions shown in Table 1 were synthesized in the same manner as in Synthesis Example 1.

○ Measurement of amine value 3 g of nylon resin is dissolved in a mixed solution of 20 ml of 1-butanol and 20 ml of toluene, and “APB-510-01B” manufactured by the same company is used as a burette in an automatic titrator “AT-510” manufactured by Kyoto Electronics Industry Co., Ltd. The connected one was used. Potentiometric titration was performed using a 0.1 mol / L 2-propanolic hydrochloric acid solution as a titration reagent, and the number of mg of hydrochloric acid and equivalent KOH per 1 g of resin was calculated.

○ Measurement of Acid Value 1 g of nylon resin was dissolved in 40 ml of benzyl alcohol, and an automatic titration apparatus “AT-510” manufactured by Kyoto Denshi Kogyo Co., Ltd. connected with “APB-510-20B” manufactured by the same company as a burette was used. Potentiometric titration was performed using a 0.01 mol / L benzyl alcoholic KOH solution as a titration reagent, and the number of mg of KOH per 1 g of resin was calculated.

Example 1
100 parts by weight of nylon resin 1 obtained in the synthesis example, 64.2 parts by weight of epoxy resin A, 29.3 parts by weight of novolak resin A, and 2.6 parts by weight of methanol / toluene = 1/1 (mass ratio) In a mixed solvent of 713 parts by mass. Next, an adhesive laminate was prepared by the following method, and various tests were performed by the following methods. The results are shown in Table 2.

Abbreviations in Tables 2 and 3 indicate the following. The unit of the blending amount in the table is part by mass. The structure of the novolak resin used in the examples is shown in the general formula (2).
-Epoxy resin A: manufactured by DIC, trade name “Epicron N-655” [o-cresol novolac type epoxy resin, epoxy equivalent = 210 g / equivalent]
-Novolak resin A: DIC Corporation trade name "Phenolite LA-1356" [melamine structure-containing phenol novolak resin represented by formula (2), nitrogen content 16%, hydroxyl group equivalent = 146 g / equivalent]
-Novolak resin B: DIC Corporation product name "Phenolite LA-3018" [melamine structure-containing cresol novolak resin shown in Formula (2), nitrogen content 18%, hydroxyl group equivalent = 151 g / equivalent]
-Novolak resin C: product name "YLH-969" manufactured by Japan Epoxy Resin Co., Ltd. [melamine structure-containing phenol novolak resin represented by formula (2), nitrogen content 15%, hydroxyl group equivalent = 148 g / equivalent]
-Phenol resin A: Product name "Phenolite TD-2106" manufactured by DIC (hydroxyl equivalent = 104 g / equivalent)
Curing accelerator A: N, N-dimethylbenzylamine (pKa = 8.9)
Curing accelerator B: 1,8-diazabicyclo [5,4,0] undecane (pKa = 12.5)
Curing accelerator C: 2-ethyl-4-methylimidazole (pKa = 8.3)
Curing accelerator D: 2-undecylimidazole (pKa = 7.8)
Curing accelerator E: 1,8-diazabicyclo [5,4,0] undecane phenol salt

［式（２）におけるＹは水素原子又はメチル基であり、ｎは１〜１０の整数である。］

[Y in Formula (2) is a hydrogen atom or a methyl group, and n is an integer of 1-10. ]

(Examples 2 to 10)
Adhesive compositions were obtained in the same manner as in Example 1 using the compositions described in Examples 2 to 10 in Table 2. Next, an adhesive laminate was prepared in the same manner as in Example 1, and various tests were performed in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Examples 1-7)
Adhesive compositions were obtained in the same manner as in Example 1 using the compositions described in Comparative Examples 1 to 7 in Table 3. Next, an adhesive laminate was prepared in the same manner as in Example 1, and various tests were performed in the same manner as in Example 1. The results are shown in Table 3.

○ Preparation of Adhesive Sample Film thickness after drying on a polyimide film having a thickness of 25 μm (trade name “Kapton 100H”, manufactured by Toray Industries, Inc.) using the adhesive solutions obtained in Examples 1 to 10 and Comparative Examples 1 to 7. Was applied to a thickness of 20 μm, dried at 50 ° C. for 2 minutes, and further dried at 150 ° C. for 5 minutes. Next, a rolled copper foil having a thickness of 35 μm was bonded and laminated under the conditions of 80 ° C., 0.3 MPa, and 1 m / min. Further, this polyimide film / adhesive layer / copper foil laminate was heat-pressed for 2 minutes at 150 ° C. and 3 MPa, and then heat-treated in an oven at 150 ° C. for 2 hours to cure the adhesive layer to prepare an adhesive sample. Each was produced.

○ Measurement of peel adhesion strength The adhesion sample produced by the above method was cut into a width of 10 mm, and the peel adhesion strength when peeling the copper foil from the polyimide film was measured with a tensile tester under a temperature condition of 23 ° C. (Unit: N / mm). At this time, the tensile speed was 50 mm / min.

○ Solder heat resistance The adhesive sample prepared by the above method was cut to 20 mm width, floated in a solder bath melted at 260 ° C. for 60 seconds with the polyimide film face up, and the foamed state on the surface of the test piece was observed. did.
○: No change from the state before the test ×: Swelling (peeling of the adhesive layer) occurs on the entire test piece surface

○ Hygroscopic solder heat resistance The adhesive sample prepared by the above method was cut to a width of 20 mm, and left in a constant temperature and humidity machine at 40 ° C. and 85% humidity for 3 days. The sample was floated for 60 seconds in the solder bath melted in the above, and the foamed state on the surface of the test piece was observed.
○: No change from the state before the test ×: Swelling (peeling of the adhesive layer) occurs on the entire test piece surface

○ Preparation of “resin flow-out property during heat bonding” confirmation sample Using the adhesive solutions obtained in Examples 1 to 10 and Comparative Examples 1 to 7, a polyimide film having a thickness of 25 μm (made by Toray Industries, trade name “ Kapton 100H ") was applied so that the film thickness after drying was 20 µm, dried at 50 ° C for 2 minutes, and further dried at 150 ° C for 3 minutes. Two holes with a diameter of 6 mm were formed in the film-formed polyimide film, and then a rolled copper foil with a thickness of 35 μm was bonded together and laminated under the conditions of 80 ° C., 0.3 MPa, and 1 m / min. Further, this polyimide film / adhesive layer / copper foil laminate was thermocompression bonded at 150 ° C. and 3 MPa for 2 minutes.

O Resin flow-out property at the time of heat bonding The two holes of the obtained adhesion sample were observed with a microscope, the length of the adhesive flowing out from the hole end line was measured, and the average flow-out length was obtained. The resin flow length at this time was determined to be acceptable if it was 0.20 mm or less, and the resin flow length exceeding 0.20 mm was determined to be unacceptable. The determination criterion is based on the fact that the resin flow-out length needs to be 0.20 mm or less from the resin flow-out property at the time of heat bonding and the circuit groove embedding property.

  The adhesive composition of the present invention can be used for bonding resin films such as polyimide films and PET films, and metal foils such as copper and aluminum. In particular, it is useful for bonding an FPC or a flexible flat cable.

Claims (5)

Contains a nylon resin solid at 25 ° C. that dissolves in an alcohol solvent, an epoxy resin, a novolak resin having a structure represented by the following general formula (1), and a curing accelerator having an acid dissociation constant exceeding 8.3 An adhesive composition comprising:
When the total amount of diamine components is 100 mol%, the nylon resin contains piperazine in an amount of 20 mol% or more, and the amine value is 1 to 6 (mgKOH / g) .
The content of the epoxy resin is 25 to 150 parts by mass with respect to 100 parts by mass of the nylon resin,
Content of the said novolak resin is the range shown by the following formula, The adhesive composition characterized by the above-mentioned.
Hydroxyl equivalent / epoxy equivalent =
{(Content of novolak resin) ÷ (hydroxyl equivalent of novolak resin)} ÷
{(Epoxy resin content) / (epoxy group equivalent of epoxy resin)}
= 0.2 to 1.5

[X in Formula (1) is a melamine structure or a guanamine structure, and Y is a hydrogen atom or a methyl group. Moreover, n is an integer of 1-10. ]   The adhesive composition according to claim 1, wherein the nylon resin has an acid value of 4 to 10 (mg KOH / g).   The adhesive composition according to claim 1 or 2, wherein the epoxy resin has two or more epoxy groups in one molecule. The coverlay film, wherein the adhesive composition according to any one of claims 1 to 3 is applied to one side of a polyimide film. A flexible copper-clad laminate comprising the adhesive composition according to any one of claims 1 to 3 , wherein a copper foil is bonded to at least one surface of a polyimide film.