JP5271467B2 - Temporary bonding method using epoxy adhesive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bonding method which enables the precise bonding of a fine-shape adhesive surface with the adhesive excellent in heat resistance and solvent resistance and is further applicable for temporary bonding allowing the adhesive surface to be easily peeled off without damage. SOLUTION: The method for bonding by an epoxy adhesive film includes a heating process wherein the film is sandwiched between the two bondable surfaces of object bodies and then subjected to heating or heating and pressing and a subsequent removing process wherein the part of the film not requiring bonding and/or the part of the film melted and forced out of the bonded surfaces are subjected to etching.

Description

  The present invention relates to a precise bonding method using an epoxy adhesive film and capable of temporary bonding.

In recent years, electronic devices have become lighter, thinner, and smaller, and heat-resistant adhesive films are used as adhesives for mounting printed boards and semiconductor chips. Conventionally, a printed circuit board has been thermocompression bonded using a prepreg type adhesive in which a glass cloth is impregnated with a resin. However, when prepreg is used, there is a limit to reducing the interlayer thickness. Therefore, when a heat-resistant adhesive film is used, the printed board is formed thinner because no glass cloth is interposed.
The adhesive that protrudes from the adhesive surface at the time of bonding needs to be removed when dimensional accuracy is required as described above, which is not preferable in terms of appearance. For example, Japanese Patent Laid-Open No. 11-35892 discloses an adhesive method using a film adhesive that removes protrusion of an adhesive from an adhesive surface generated by heating and pressurizing a film-like adhesive using a heat-resistant tape. Has been proposed.

On the other hand, the adhesive adhesive generally used for temporary adhesion is called an adhesive. These are blended with relatively low molecular weight rubbers, resins, plasticizers, and the like, and often exhibit adhesiveness at room temperature.
JP-A-6-157959, JP-A-6-329999, and JP-A-10-204396 show adhesiveness at the time of bonding, but are cured by heating, and can be temporarily bonded and bonded. A sheet is disclosed. Since such a thermosetting pressure-sensitive adhesive sheet is bonded by heating, temporary bonding of a portion requiring heating is impossible.

Japanese Unexamined Patent Publication No. 2000-44896 discloses a pressure-sensitive adhesive film that eliminates this drawback and can be re-peeled without increasing the adhesive force by heating. Japanese Patent Publication No. 2000-265131 discloses a heat-resistant adhesive sheet in which release sheets are laminated.
However, although pressure-sensitive adhesive tapes and pressure-sensitive adhesive sheets can be used for temporary bonding, they are soft because they contain low molecular weight rubber, resin, and plasticizer, and it is difficult to perform microfabrication that matches the shape of the adhesion surface of the adherend. In addition, the solvent resistance is poor.

Problems to be solved by the invention

  An object of the present invention is to provide a bonding method in which a fine-shaped bonding surface can be precisely bonded, and the adhesive is excellent in heat resistance and solvent resistance. Further, the bonding method can be applied as temporary bonding because the bonding surface easily peels without damage. Is to provide.

Means for solving the problem

In the present invention, an epoxy adhesive film is sandwiched between two adhesion surfaces of an adherend, and a heating step of heating or heating and pressurizing, and after the heating step, a portion of the epoxy adhesive film that does not require adhesion and a melt are melted. And a removing step of etching at least one of the portions protruding from the bonding surface.
By removing a portion where the epoxy adhesive film does not need to be bonded or a protruding portion by etching, precise bonding can be performed even with a complicated and fine bonding surface shape.

  Preferably, an epoxy adhesive film mainly composed of a high molecular weight epoxy polymer having a weight average molecular weight of 70,000 or more obtained by polymerizing a bifunctional epoxy resin and a bifunctional phenol is used. This epoxy adhesive film has high strength and elongation, and is rich in flexibility, so that it can be processed into the same shape as an adhesive surface having a complicated and fine shape. Moreover, solvent resistance, heat resistance and adhesiveness are good.

Hereinafter, the present invention will be described in detail.
First, a heating process in which the epoxy adhesive film in the present invention is sandwiched between two adhesive surfaces of an adherend and heated or heated and pressurized will be described below.
The conditions for bonding using an epoxy adhesive film in the heating step may be any conditions suitable for bonding, and the heating temperature is preferably 60 to 300 ° C. If the temperature is lower than 60 ° C, the epoxy adhesive film may not be melted. If the temperature exceeds 300 ° C, the epoxy adhesive film may be decomposed. Moreover, although what is necessary is just to pressurize as needed, 0-20 Mpa is preferable. If it exceeds 20 MPa, the adherend may be destroyed.

  The adherend may be any material such as plastic, ceramics, or metal. Examples of the plastic include polyester, polypropylene, polystyrene, polyvinyl chloride, polymethyl methacrylate, polycarbonate, polyimide, nylon, epoxy resin, phenol resin, unsaturated polyester resin, and polyurethane. Examples of the ceramic include alumina, zirconia, boron nitride, silicon nitride, silicon carbide, cement, soda-lime glass, quartz glass, borosilicate glass, cement, and enamel. Metals include boron, carbon, magnesium, aluminum, silicon, titanium, chromium, iron, nickel, copper, zirconium, silver, platinum, gold, lead, and alloys thereof.

  The shape of the adherend may be any shape such as a film shape, a plate shape, a rod shape, or a spherical shape, and the bonding surface may be finely processed.

Next, the removal process will be described. After the heating step using the epoxy adhesive film described above, at least one of an unnecessary part of the epoxy adhesive film and a part that melts and protrudes from the adhesive surface is removed by etching. For example, when adhering an adhesive surface that has been finely processed in shape, after bonding with a heating process with an adhesive film cut to a shape larger than the adhesive surface, a portion that does not need to stick out in advance from the adhesive surface is removed. Since it can be removed by an etching solution, precise bonding becomes possible.
In addition, the present invention can be applied as a temporary bonding method by removing all of the epoxy adhesive film between the bonding surfaces, which are unnecessary bonding, by etching and peeling the bonding surfaces after bonding in the heating step. Can do.

  In the removing step in the present invention, etching is preferably performed with an etching solution containing an alkali metal compound and an organic solvent, and the organic solvent more preferably contains at least one of an amide solvent and an alcohol solvent. Moreover, you may add a compound suitably other than these components as needed.

As the alkali metal compound used in the etching solution in the present invention, any alkali metal compound such as lithium, sodium, potassium, rubidium, and cesium that dissolves in an alcohol solvent may be used. For example, lithium, Metals such as sodium, potassium, rubidium, cesium, hydride, hydroxide, borohydride, amide, fluoride, chloride, bromide, iodide, borate, phosphate, carbonate, sulfate, nitrate , Organic acid salts, alcoholates, phenolates and the like.
Examples of amide solvents include formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N, N, N ′, N′-tetramethylurea, 2-pyrrolidone, N-methyl-2-pyrrolidone, carbamic acid ester and the like can be used. Of these, the use of N, N-dimethylformamide, N, N-dimethylacetamide, and N-methyl-2-pyrrolidone has the effect of swelling the epoxy resin cured product, and the solubility of the decomposition product is particularly good. preferable. These solvents can be used in combination, and can also be used in combination with other solvents represented by ketone solvents, ether solvents and the like.

  Examples of the alcohol solvent used for the etching solution in the present invention include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, iso-butanol, tert-butanol, 1-pentanol, 2 -Pentanol, 3-pentanol, 2-methyl-1-butanol, iso-pentyl alcohol, tert-pentyl alcohol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pen Tanol, 4-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclo Hexanol, -Methylcyclohexanol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, Triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol, polyethylene glycol (molecular weight 200 to 400), 1,2-propanediol, 1,3-propanediol, 1,2-butanediol 1,3-butanedio , 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, glycerin, and dipropylene glycol. Of these, methanol, ethanol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol, diethylene glycol monomethyl ether, triethylene glycol, tetraethylene glycol, and polyethylene glycol are particularly preferable because of high solubility of alkali metal compounds. Several types of these solvents can be used in combination.

  Examples of the ketone solvent that can be used in combination here include acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-hexanone, methyl isobutyl ketone, 2-heptanone, 4-heptanone, diisobutyl ketone, and cyclohexanone.

  Examples of ether solvents that can be used in combination include dipropyl ether, diisopropyl ether, dibutyl ether, anisole, phenetole, dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether.

  The etching solution used in the present invention can be blended in an arbitrary composition with respect to the amide solvent, and the alcohol solvent is preferably 1 to 50 with respect to 50 to 99% by weight of the amide solvent. It is a composition by weight. If the concentration of the amide solvent is lower than 50% by weight, it is not preferable because the swellability of the epoxy cured product and the solubility of the decomposition product are reduced. This is not preferable because the decomposition rate of the cured epoxy resin decreases.

  The concentration of the alkali metal compound in the etching solution may be any concentration, but it is preferably in the range of 0.5 wt% to 40 wt%, and if it is less than 0.5 wt%, the decomposition rate of the cured epoxy resin product Is not preferable, and if it exceeds 40% by weight, the alkali metal compound is not completely dissolved in the alcohol solvent, which is not preferable.

  The etching solution thus obtained can be used by appropriately adding a surfactant or the like as necessary.

  In the etching, the etching solution can be used at an arbitrary temperature not lower than the freezing point of the solvent and not higher than the boiling point in order to adjust the etching rate.

  An etching method includes immersing an adherend adhered by an adhesive film in an etching solution. The etching rate can be increased by temperature, or vibration can be applied by ultrasonic waves. Also, spraying or the like, or high pressure can be applied. Furthermore, it is possible to select and etch the portion to be etched in the epoxy adhesive film.

By such a removal process, the part which protruded from the adhesion surface of the epoxy adhesive film can be removed without damaging the part necessary for adhesion of the adherend or the epoxy adhesive film. Here, after the removing step, it is preferable to adjust the progress of etching so that the width of the protrusion of the epoxy adhesive film from the adhesive surface is 100 μm or less.
Further, when the present invention is applied as a temporary bonding method, the etching is further advanced than the removal of the portion protruding from the above-described bonding surface, and the epoxy adhesive film between the bonding surfaces which is not necessary to be bonded is etched. All can be removed and the adhesive surfaces can be separated.

Next, the epoxy adhesive film in the present invention will be described.
The epoxy adhesive film in the present invention is preferably mainly composed of a high molecular weight epoxy polymer having a weight average molecular weight of 70,000 or more obtained by polymerizing a bifunctional epoxy resin and a bifunctional phenol, Thermocompression bonding at 200 ° C. or lower is possible, and it is excellent in adhesive strength, heat resistance and solvent resistance, and can be punched in the same shape as the adhesive surface, so that fine processing is possible. The epoxy adhesive film appropriately contains a polyfunctional epoxy resin, a curing agent, a crosslinking agent and the like as necessary in addition to the high molecular weight epoxy polymer as a main component.

  The preferable high molecular weight epoxy polymer as described above will be described below. For example, the mixing ratio of a bifunctional epoxy resin and a bifunctional phenol is set to epoxy group / phenol hydroxyl group = 1: 0.9 to 1.1 in a solvent in the presence of a catalyst. It is obtained by heating and polymerizing.

The bifunctional epoxy resin used as a raw material for the high molecular weight epoxy polymer can be used without limitation as long as it is a compound having two epoxy groups in the molecule. For example, bisphenol A type epoxy resin, bisphenol F type Epoxy resin, bisphenol S-type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, diglycidyl etherified product of bifunctional phenols, diglycidyl etherified product of difunctional alcohols and their halides, hydrogenation Such as things. Two or more of these compounds can be used in combination.
In addition, as the bifunctional phenols used in the present invention, any compound having two phenolic hydroxyl groups in the molecule can be used without limitation. Further, when the halogenated bifunctional phenols are used, the film becomes flame retardant. This is preferable. For example, hydroquinone, resorcinol, catechol, which are monocyclic bifunctional phenols, bisphenol A, bisphenol F, naphthalenediols, biphenols, which are polycyclic bifunctional phenols, halides such as alkyl substitutions thereof, alkyl substitutions, and the like Can be mentioned. Two or more of these compounds can be used in combination.

The equivalent ratio of bifunctional epoxy resin and difunctional phenols is
Epoxy group / phenolic hydroxyl group = 1 / 0.9 to 1 / 1.1
It is preferable to set it as the range. When the phenolic hydroxyl group is less than 0.9, a high molecular weight is not formed in a straight chain, but a side reaction occurs and crosslinks and it does not dissolve in a solvent.

As a catalyst used for the polymerization of the high molecular weight epoxy polymer, an alkali metal compound or an alkali metal element-free compound can be used alone or in combination.
Examples of alkali metal compounds include sodium, lithium, potassium hydroxide, halides, organic acid salts, alcoholates, phenolates, hydrides, borohydrides, amides, and the like. Among these, it is preferable that the alkali metal compound catalyst is a lithium compound catalyst because it can be easily removed by the adsorbent after completion of the synthesis.

The alkali metal element-free compound is not limited as long as it is a compound that does not contain an alkali metal element and has a catalytic ability to promote the etherification reaction of an epoxy group and a phenolic hydroxyl group. For example, imidazoles, amines, organic phosphorus Compound etc. are mentioned.
Examples of imidazoles include imidazole, 2-imidazole, 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole. 4,5-diphenylimidazole, 2-methylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2-heptadecylimidazoline, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-phenyl-4-methylimidazole 2-ethylimidazoline, 2-phenyl-4-methylimidazoline, benzimidazole, 1-cyanoethylimidazole and the like.

  Examples of amines include aliphatic or aromatic primary amines, secondary amines, tertiary amines, quaternary ammonium salts, and aliphatic cyclic amines. As these compounds, N, N— Benzyldimethylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, tetramethylguanidine, triethanolamine, N, N′-dimethylpiperazine, 1,4-diazabicyclo [2 , 2,2] octane, 1,8-diazabicyclo [5,4,0] -7-undecene, 1,5-diazabicyclo [4,4,0] -5-nonene, hexamethylenetetramine, pyridine, picoline, piperidine Pyrrolidine, dimethylcyclohexylamine, dimethylhexylamine, cyclohexylamine, diisobuty Amine, di-N-butylamine, diphenylamine, N-methylaniline, tri-N-propylamine, tri-N-octylamine, tri-N-butylamine, triphenylamine, tetramethylammonium chloride, tetramethylammonium bromide, tetra Examples include methylammonium iodide.

  The organic phosphorus compound is not limited as long as it is a phosphorus compound having an organic group, and examples include hexamethyl phosphate triamide, tri (dichloropropyl) phosphate, tri (chloropropyl) phosphate, triphenyl phosphite, Examples thereof include trimethyl phosphate, phenylphosphonic acid, triphenylphosphine, tri-N-butylphosphine, diphenylphosphine and the like.

  The compounding amount of these catalysts, when used in combination, is in the range of 0.005 to 0.20 mol of an alkali metal compound and 0.005 to 0.20 mol of an alkali metal-free compound with respect to 1 mol of the bifunctional epoxy resin. And with respect to 1 mol of bifunctional epoxy resins, those sum total is the range of 0.01-0.30 mol. When used alone, it is preferably in the range of 0.01 to 0.30 mol. If it is less than 0.01 mol, the high molecular weight reaction is remarkably slow, and if it exceeds 0.30 mol, there is a possibility that it will not be linearized.

As a polymerization reaction solvent for the bifunctional epoxy resin and the bifunctional phenol, any solvent that can dissolve the bifunctional epoxy resin and the bifunctional phenol may be used. Amide type, ketone type, ether type, alcohol type, ester There are solvents such as systems. These solvents can be used in combination.
For example, examples of amide solvents include formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N, N, N ′, N′-tetramethylurea. and so on.

Examples of the ketone solvent include 2-pentanone, 3-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, phorone, methylcyclohexanone, 2-pyrrolidone, N-methylpyrrolidone, carbamic acid ester, cyclohexanone, acetylacetone, diisobutyl. Such as ketones.
Examples of ether solvents include dipropyl ether, diisopropyl ether, dibutyl ether, anisole, phenetole, dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether.

Examples of alcohol solvents include 2-propanol, 1-butanol, 2-butanol, iso-butanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, and 2-methyl-1-butanol. , Iso-pentyl alcohol, tert-pentyl alcohol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 4-methyl-2-pentanol, 2-ethyl-1 -Butanol, 1-heptanol, 2-heptanol, 3-heptanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 4-methylcyclohexanol, ethylene glycol, ethylene glycol monomethyl Ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, tri Ethylene glycol monoethyl ether, tetraethylene glycol, polyethylene glycol (molecular weight 200-400), 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4 -Butanediol, 2,3-butanediol, 1,5-pentanediol, Glycerin, and the like dipropylene glycol. Among these, there are methanol, ethanol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol, diethylene glycol monomethyl ether, triethylene glycol, tetraethylene glycol, polyethylene glycol and the like.

  Examples of the ester solvent include butyl formate, isobutyl formate, pentyl formate, propyl acetate, butyl acetate, pentyl acetate, 3-methoxybutyl acetate, sec-hexyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, Examples include cyclohexyl acetate, benzyl acetate, ethyl propionate, and butyl propionate.

  The solid content concentration in the polymerization reaction using a solvent is preferably in the range of 10 to 50% by weight, and if it is less than 10% by weight, the solution viscosity at the time of application is remarkably lowered, and the thickness accuracy is deteriorated. This may cause repelling or the like, resulting in poor coatability. If it exceeds 50% by weight, side reactions will increase and it will be difficult to achieve a high molecular weight in a straight chain. The tendency for this side reaction to increase is more likely to occur as the solid content concentration increases, and therefore it is preferably 40% by weight or less, and more preferably 30% by weight or less.

  The polymerization reaction temperature is preferably 60 to 150 ° C., and if it is less than 60 ° C., the high molecular weight reaction is extremely slow, and if it exceeds 150 ° C., side reactions increase and it is difficult to increase the molecular weight linearly. The obtained high molecular weight epoxy polymer has a styrene equivalent weight average molecular weight of 70,000 or more, and the reduced viscosity of the dilute solution of the high molecular weight epoxy polymer is 0.60 dl / g or more (N, N-dimethyl). Acetamide (25 ° C.) is more preferable. If it is less than 0.60 dl / g, the film-forming ability decreases.

The polyfunctional epoxy resin used for the epoxy adhesive film in the present invention is a compound having two or more epoxy groups in the molecule. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol Novolac epoxy resin, cresol novolac epoxy resin, bisphenol A novolac epoxy resin, bisphenol F novolac epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, Hydantoin type epoxy resins, isocyanurate type epoxy resins, diglycidyl etherified products of polyfunctional phenols, diglycidyl etherified products of polyfunctional alcohols, and their halides, water Such additives can be used.
A plurality of these compounds can be used in combination. The blending amount of the polyfunctional epoxy resin with respect to the high molecular weight epoxy polymer is preferably in the range of 1 to 200 parts by weight with respect to 100 parts by weight of the high molecular weight epoxy polymer.

Examples of the curing agent used for the epoxy adhesive film in the present invention include polyfunctional phenols, amines, imidazole compounds, acid anhydrides, and the like.
Polyfunctional phenols include monocyclic bifunctional phenols hydroquinone, resorcinol, catechol, polycyclic bifunctional phenols bislaenol A, bisphenol F, naphthalenediols, bisphenols and their halides, alkyl-substituted products, Novolak resins and resol resins that are polycondensates of phenols and aldehydes can be used.
Amines include aliphatic primary amines, secondary amines, tertiary amines, aromatic primary amines, secondary amines, tertiary amines, guanidines, urea derivatives, etc., specifically, triethylenetetramine, Examples include diaminodiphenylmethane, diaminodiphenyl ether, dicyandiamide, tolylbiguanide, guanylurea, and dimethylurea.
As the imidazole compound, alkyl-substituted imidazole, benzimidazole and the like can be used.
Examples of the acid anhydride include phthalic anhydride, hexahydrophthalic anhydride, pyromellitic dianhydride, and bayzophenone tetracarboxylic dianhydride.
The compounding amount of the curing agent is preferably 1 to 70 parts by weight with respect to 100 parts by weight of the polyfunctional epoxy resin.

  In the synthesis of the high molecular weight epoxy polymer used in the present invention, a curing accelerator can be used as necessary, and for example, tertiary amine, imidazole, quaternary ammonium salt and the like can be used.

In the present invention, mask isocyanates may be used as the crosslinking agent. This is because if an isocyanate group having an isocyanate group is used as a crosslinking agent as it is, the reactivity with the alcoholic hydroxyl group is very high, so that the crosslinking reaction proceeds at room temperature and gelation of the epoxy resin solution may occur. The isocyanate group is used as a mask (block).
The isocyanates preferably used in the present invention have two or more isocyanate groups in the molecule. For example, as the diisocyanates, hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, isophorone diisocyanate, phenylene diisocyanate, tolylene diisocyanate, trimethyl. Hexamethylene diisocyanate, naphthalene diisocyanate, diphenyl ether diisocyanate, diphenylpropane diisocyanate, biphenyl diisocyanate and their isomers, alkyl-substituted products, halides, hydrogenated products to the benzene ring, and the like.
Furthermore, triisocyanates having three isocyanate groups, tetraisocyanates having four isocyanate groups, and the like can be used, and these can be used in combination.

The isocyanate group blocking (masking) agent is not limited as long as it is a compound having active hydrogen that reacts with an isocyanate group, and examples thereof include ketone oximes, alcohols, phenols, and amines.
Examples of ketone oximes include acetone oxime, methyl ethyl ketone oxime, methyl isobutyl ketone oxime, and cyclohexanone oxime.
Examples of alcohols include monofunctional alcohols such as methyl alcohol, ethyl alcohol, N-propyl alcohol, isopropyl alcohol, N-butyl alcohol, isobutyl alcohol, pentanol, hexanol, and cyclohexanol, ethylene glycol, propylene glycol, butylene glycol, etc. Bifunctional alcohols.
Phenols include monofunctional phenols such as phenol, cresol, xylenol, trimethylphenol, butylphenol, phenylphenol, naphthol, hydroquinone, resorcinol, catechol, bisphenol A, bisphenol F, biphenol, naphthalene diol, dihydroxydiphenyl ether, dihydroxydiphenylsulfone And polyfunctional phenols such as pyrogallol, hydroxyhydroquinone, phloroglucin, phenol novolak, cresol novolak, bisphenol A novolak, naphthol novolak, and resole.
Examples of amines include N-propylamine, isopropylamine, N-butylamine, isobutylamine, benzylamine, and triethylenediamine.

  These blocking (masking) agents may be used alone or in combination of two or more. This mask (block) agent is preferably used so that the active hydrogen of the mask (block) agent is 0.5 to 3.0 equivalents relative to 1.0 equivalent of isocyanate groups of the isocyanates. If it is less than 0.5 equivalent, the mask (block) becomes incomplete, and the possibility that the high molecular weight epoxy polymer gels increases. If it exceeds 3.0 equivalent, the mask (block) agent becomes excessive, There is a risk that the mask (block) agent remains on the formed film and the heat resistance and chemical resistance are lowered.

  It is preferable that the compounding quantity of isocyanate with respect to high molecular weight epoxy polymer is the range of isocyanate group equivalent 0.1-2 with respect to alcoholic hydroxyl group equivalent 1 of high molecular weight epoxy polymer. If it is less than 0.1, crosslinking is difficult, and if it exceeds 2, isocyanates remain in the film, which may reduce heat resistance and chemical resistance.

  The epoxy adhesive film of the present invention can be blended with a flame retardant as necessary, and the flame retardant includes bromine compounds such as tetrabromobisphenol A, decabromodiphenyl ether, brominated epoxy resin, brominated phenol resin, and the like. Can be used. Further, phosphorus-containing compounds such as phosphate esters and nitrogen-containing compounds such as melamines can also be used.

  A component of the above epoxy adhesive film, a high molecular weight epoxy polymer, a polyfunctional epoxy resin, a curing agent, a crosslinking agent, and the like are dissolved or dispersed in a solvent to obtain a varnish. The mixing method is not particularly limited as long as the varnish is uniformly mixed and dispersed. For example, equipment such as a raking machine, a bead mill, a pearl mill, a ball mill, a homomixer, and a mechanical stirrer can be used. The mixing and dispersing temperature may be a temperature range not lower than the freezing point of the solvent used and not higher than the boiling point. The order of adding the materials to be mixed and dispersed may be any order.

As the support on which the varnish is applied, one that does not dissolve in the solvent used for the varnish is preferable. For example, a plastic film such as a polyimide film, a polyester film, a polyethylene film, or a polypropylene film can be used. The surface to be coated can be a roughened surface.
After applying this varnish, the solvent is removed. Various methods such as solvent extraction, vacuum drying, and heat drying can be used to remove the solvent, but drying by heating is preferable. The temperature is lower than the composition of the varnish used or the decomposition temperature of the support. By this solvent removal, the varnish applied on the support is formed in a B-stage (semi-cured) state, and the epoxy adhesive film in the present invention is obtained. In general, the thickness is preferably 200 μm or less.

An epoxy adhesive film mainly composed of a high molecular weight epoxy polymer having a weight average molecular weight of 70,000 or more obtained by polymerizing the above bifunctional epoxy resin and a bifunctional phenol is precisely matched to the shape of a complicated adhesive surface. Can be stamped. Thereby, inadequate contact with a to-be-adhered body by processing an adhesive film smaller than an adhesive surface in order to prevent a protrusion can be avoided.
In addition, the epoxy adhesive film can be cut roughly in accordance with the shape of the adhesive surface, and the protruding part and unnecessary part can be removed by etching after the heating process. Film can also be used.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to this.
Example 1
Bisphenol A type epoxy resin (epoxy equivalent: 172) is used as the bifunctional epoxy resin, bisphenol A (hydroxyl group equivalent: 114) is used as the bifunctional phenol, and epoxy group / phenolic hydroxyl group = 1 / 1.02. In the presence of 0.05 mol of lithium hydroxide as a catalyst with respect to 1 mol of epoxy resin and N, N-dimethylacetamide as a solvent, the solid content concentration of the solution becomes 30% by weight. The weight average molecular weight in terms of styrene by gel permeation chromatography (GPC) method having a film-forming ability obtained by polymerizing by heating at 120 ° C. for 10 hours in the solvent was as high as 200,000. A molecular weight epoxy polymer was obtained.

  In this high molecular weight epoxy polymer, isophorone diisocyanate is used as an isocyanate having two or more isocyanate groups, and 2.5 equivalents of phenol novolac resin is used as a masking agent for 1.0 equivalent of the isocyanate groups. It mix | blended so that it might become 0.5 equivalent of isocyanate groups with respect to 1 equivalent of alcoholic hydroxyl groups of a molecular weight epoxy polymer.

  60 parts by weight of cresol novolac type epoxy resin (epoxy equivalent: 195) as a polyfunctional epoxy resin and 20 parts by weight of phenol novolac resin (hydroxyl equivalent: 106) as a curing agent are added to 100 parts by weight of a high molecular weight epoxy polymer. did.

  This varnish was applied to a polyethylene terephthalate film having a thickness of 50 μm and dried in a drier at 150 ° C. for 5 minutes to obtain an epoxy adhesive film having a thickness of 10 μm.

  [Heat Heating] This epoxy adhesive film was cut into 25 mm square and sandwiched between SUS304 (thickness 10 mm) as an adherend and Si wafer (thickness 2 mm). The shape of the bonding surface of SUS304 and Si wafer is 20 mm square, with two circles with a diameter of 3 mm in the center and a rectangular hole with a width of 1 mm and a length of 10 mm. After sandwiching the epoxy adhesive film, hot pressing was performed at 170 ° C. and 0.5 MPa for 15 minutes. The tensile bond strength of the sample after bonding by hot pressing was 53 MPa.

[Removal Step] A mixed solution of 4% by weight of sodium hydroxide and 96% by weight of N-methyl-2-pyrrolidone was prepared as an etching solution.
The sample after the heating step was immersed in the etching solution at 120 ° C. for 2 hours. The hole portion of the bonding surface, which is an unnecessary portion of bonding, and the epoxy adhesive film around the bonding surface were dissolved. The remaining width (the width of the epoxy adhesive film protruding from the edge of the bonding surface) after being melted by hot pressing and protruding from the edge of the bonding surface was 80 μm. The adhesion strength of the sample after the etching was the same value as before the etching.

This sample was immersed in N, N-dimethylacetamide for 24 hours, but there was no change in the appearance of the bonded site, and the tensile bond strength was the same value as before the immersion.
Further, when this sample was immersed in an etching solution at 120 ° C., the Si wafer was peeled from SUS304 after 10 hours. All the epoxy adhesive films on the bonding surface of SUS304 and Si wafer were dissolved.

(Example 2)
When synthesizing a high molecular weight epoxy polymer, sodium methoxide as a catalyst was added in an amount of 0.04 mol and 0.05 mol of imidazole with respect to 1 mol of the epoxy resin, and cyclohexanone was used as a solvent. Similarly, a high molecular weight epoxy polymer having a styrene conversion weight average molecular weight of 70,000 was obtained by gel permeation chromatography (GPC).

  This high molecular weight epoxy polymer was varnished in the same manner as in Example 1 and applied to a polyimide film having a thickness of 50 μm, and then dried in a dryer at 150 ° C. for 5 minutes to give an epoxy adhesive having a thickness of 20 μm. A film was obtained.

  Adhesion was performed in the same manner as in Example 1 except that the adherend was 42 alloy having a thickness of 30 mm and polyethylene terephthalate having a thickness of 20 mm. The tensile bond strength of the sample after bonding by hot pressing was 55 MPa. This sample was immersed in an etching solution having the same composition as in Example 1 at 120 ° C. for 2 hours. The hole in the adhesive surface and the epoxy adhesive film around the adhesive surface dissolved. The width of the epoxy adhesive film protruding from the edge of the adhesive surface was 60 μm. The adhesion strength of the sample after the etching was the same value as before the etching. This sample was immersed in N, N-dimethylacetamide for 24 hours, but there was no change in the appearance of the bonded site, and the tensile bond strength was the same value as before the immersion.

  Furthermore, when this sample was further immersed in an etching solution having the same composition as in Example 1 at 120 ° C., 42 alloys were peeled from polyethylene terephthalate after 10 hours. All of the epoxy adhesive films on the bonded surface of 42 alloy and polyethylene terephthalate were dissolved.

(Example 3)
Adhesion was performed in the same manner as in Example 1 except that the epoxy adhesive film obtained in Example 1 was replaced with a 35 μm thick copper foil and SUS304 as the adherend. The tensile bond strength of the sample after bonding by hot pressing was 61 MPa. This sample was immersed in an etching solution having the same composition as in Example 1 at 120 ° C. for 3 hours. The holes in the adhesive surface and the excess epoxy adhesive film around the adhesive surface dissolved. The width of the epoxy adhesive film protruding from the edge of the adhesive surface was 70 μm. The adhesion strength of the sample after the etching was the same value as before the etching. This sample was immersed in N, N-dimethylacetamide for 24 hours, but there was no change in the appearance of the bonded site, and the tensile bond strength was the same value as before the immersion.

  Furthermore, when this sample was further immersed in an etching solution having the same composition as in Example 1 at 120 ° C., the copper foil peeled off from SUS304 after 12 hours. All epoxy adhesive films on both adhesive surfaces were dissolved.

Example 4
Gel permeation chromatography (GPC) in the same manner as in Example 1 except that tetrabromophenol A (hydroxyl equivalent: 227) was used as a bifunctional phenol as a raw material for the high molecular weight epoxy polymer of Example 1. A high molecular weight epoxy polymer having a styrene-converted weight average molecular weight of 200,000 was obtained. This high molecular weight epoxy polymer was varnished in the same manner as in Example 1, and an epoxy adhesive film was obtained in the same manner as in Example 1. Using this epoxy adhesive film, adhesion was performed in the same manner as in Example 1.
The tensile bond strength of the sample after bonding by hot pressing was 45 MPa. This sample was immersed in an etching solution having the same composition as in Example 1 at 120 ° C. for 1 hour. The portion of the hole in the adhesive surface and the excess epoxy adhesive film around the adhesive surface dissolved. The width of the epoxy adhesive film protruding from the edge of the adhesive surface was 50 μm. The tensile bond strength of the sample after the etching was the same value as before the etching. This sample was immersed in N, N-dimethylacetamide for 24 hours, but there was no change in the appearance of the bonded site, and the tensile bond strength was the same value as before the immersion.

  Furthermore, when this sample was further immersed in an etching solution having the same composition as in Example 1 at 120 ° C., the Si wafer was peeled off from SUS304 after 6 hours. All the epoxy adhesive films on the bonding surface of the Si wafer and SUS304 were dissolved.

Details of the evaluation methods in the above examples are shown below.
The column used for gel permeation chromatography (GPC) is TSK gel G6000 + G5000 + G4000 + G3000 + G2000 (product name of Tosoh Corporation), and N, N-dimethylacetamide is used as the eluent. The concentration was 2% by weight.
The styrene-converted weight average molecular weight was obtained by calculating the molecular weight from the elution time of the sample after obtaining the relationship between the molecular weight and elution time in advance using styrene of various molecular weights.
The tensile strength was measured using Tensilon manufactured by Toyo Baldwin Co., Ltd., and the tensile speed was 5 mm / min.
Moreover, the width | variety of the epoxy adhesive film protruded from the edge of the adhesive surface was read from the cross-sectional photograph.

Effect of the invention

  According to the bonding method using the epoxy adhesive film of the present invention, since the epoxy adhesive film is excellent in heat resistance and solvent resistance, it becomes possible to precisely bond the adhesive surface having a fine shape. In addition, by contacting with the etching solution for a long time, the bonding surfaces can be easily separated without being damaged, and thus can be applied as temporary bonding.

Claims (6)

Sandwiching the epoxy adhesive film between two bonded surfaces of the adherend, and bonding step of applying heat or heat and pressure, to separate between the adhesive surface of the epoxy adhesive film between the two adhesive surfaces and all the etching removal A removal step,
The epoxy adhesive film is mainly composed of a high molecular weight epoxy polymer having a weight average molecular weight of 70,000 or more obtained by polymerizing a bifunctional epoxy resin and a bifunctional phenol using sodium methoxide and imidazole as a catalyst, and a crosslinking agent. An epoxy adhesive film comprising a polyfunctional epoxy resin and a curing agent, wherein the bifunctional epoxy resin is a bisphenol A type epoxy resin, the bifunctional phenols are bisphenol A, and the crosslinking agent is a phenol novolac resin having an isocyanate group. masked isophorone diisocyanate, the multifunctional epoxy resin is a cresol novolak type epoxy resin, the temporary bonding method according epoxy adhesive film, wherein the curing agent is a phenolic novolak resin.
Between the bonding step and the removing step, at least one of the portion of the epoxy adhesive film that does not require temporary bonding and the portion that melts and protrudes from the bonding surface is necessary for temporary bonding of the adherend or the epoxy bonding film. The temporary adhesion method using an epoxy adhesive film according to claim 1, further comprising a protrusion removal step of etching without damaging the portion.
The temporary adhesion method using an epoxy adhesive film according to claim 1 or 2 , wherein in the removing step, etching is performed with an etching solution containing an alkali metal compound and an organic solvent.
The temporary adhesion method using an epoxy adhesive film according to claim 3 , wherein the organic solvent in the etching solution contains at least one of an amide type and an alcohol type.
OverhangThe width of the protrusion of the epoxy adhesive film from the adhesive surface after the removing step is 100 μm or less.2According to the described epoxy adhesive filmProvisionalBonding method.
The epoxy adhesive film according to any one of claims 1 to 5, wherein a bifunctional epoxy resin and a bifunctional phenol are polymerized at an equivalent ratio of epoxy group / phenolic hydroxyl group = 1 / 0.9 to 1 / 1.1. Temporary bonding method.