JP2002265913A - Method for bonding by 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

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precision bonding method using an epoxy bonding film and capable of temporary bonding.

[0002]

2. Description of the Related Art In recent years, electronic devices have become lighter and thinner and smaller, and a heat-resistant adhesive film has been used as an adhesive for mounting printed circuit boards, semiconductor chips, and the like. Conventionally, printed circuit boards have been thermocompression bonded using a prepreg-type adhesive in which a glass cloth is impregnated with a resin. However, there is a limit in using prepreg to reduce the interlayer thickness. Therefore, when a heat-resistant adhesive film is used, the printed circuit board is formed thinner because it does not pass through a glass cloth. The adhesive which has protruded from the bonding surface at the time of bonding must be removed when dimensional accuracy is required as described above, and is not preferable in appearance. For example, JP-A-11-35892 discloses that
There has been proposed a bonding method using a film adhesive that removes, by using a heat-resistant tape, the protrusion of the adhesive from a bonding surface generated by bonding the film-shaped adhesive by applying heat and pressure.

On the other hand, a tacky adhesive generally used for temporary bonding is called a pressure-sensitive adhesive. These are blended with relatively low molecular weight rubber, resin and plasticizer, etc.
Many exhibit stickiness at room temperature. JP-A-6-15799
No. 5, JP-A-6-329999 and JP-A-10-204396 disclose a thermosetting pressure-sensitive adhesive sheet which exhibits tackiness at the time of joining, but which is cured by heating and can be temporarily bonded and adhered. ing. Since such a thermosetting pressure-sensitive adhesive sheet is bonded by heating, it is impossible to temporarily bond a portion requiring heating.

Japanese Patent Laid-Open No. 2000-2000 discloses a pressure-sensitive adhesive film which solves this drawback and can be peeled off without increasing the adhesive force by heating.
No. 44896. Also, Special 2000
-265131 discloses a heat-resistant pressure-sensitive adhesive sheet in which a release sheet is laminated. However, pressure-sensitive adhesive tapes and sheets can be used for temporary bonding, but are soft because they contain low molecular weight rubber, resin and plasticizer.
It is difficult to perform fine processing according to the bonding surface shape of the adherend,
And poor solvent resistance.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a bonding method in which a bonding surface having a fine shape can be bonded precisely and the bonding agent has excellent heat resistance and solvent resistance. Therefore, an object of the present invention is to provide a bonding method that can be applied as temporary bonding.

[0006]

According to the present invention, there is provided a heating step of sandwiching an epoxy adhesive film between two bonding surfaces of an adherend, heating or heating and pressing, and after the heating step,
A removing step of etching at least one of a portion of the epoxy adhesive film that does not need to be bonded and a portion that has melted and protruded from the bonding surface. By removing the unnecessary portion of the epoxy adhesive film or the protruding portion of the epoxy adhesive film by etching, precise bonding can be performed even with a complicated and fine bonding surface shape.

[0007] Preferably, a weight average molecular weight obtained by polymerizing a bifunctional epoxy resin and a bifunctional phenol is 70,00.
An epoxy adhesive film having a high molecular weight epoxy polymer of 0 or more as a main component 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. Also solvent resistance,
Good heat resistance and adhesion.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
First, a heating step of sandwiching the epoxy adhesive film between the two adhesive surfaces of the adherend and heating or heating and applying pressure 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 60 to 300 ° C.
Is preferred. If the temperature is lower than 60 ° C., the epoxy adhesive film may not melt, and if it exceeds 300 ° C., the epoxy adhesive film may be decomposed. Pressing may be performed as needed, but is preferably 0 to 20 MPa. If it exceeds 20 MPa, the adherend may be broken.

The adherend may be any material such as plastic, ceramics and metal. Plastics include polyester, polypropylene, polystyrene,
Examples include 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, enamel, and the like. Metals are boron, carbon, magnesium, aluminum, silicon, titanium, chromium, iron,
Examples include nickel, copper, zirconium, silver, platinum, gold, lead, and alloys thereof.

The shape of the adherend may be any shape such as a film, a plate, a bar, and a sphere, and the adhesion surface may be finely processed.

Next, the removing step will be described. After the above-described heating step using the epoxy adhesive film, at least one of an unnecessary portion of the epoxy adhesive film and a portion that is melted and protrudes from the adhesive surface is removed by etching. For example, when bonding an adhesive surface that has been subjected to microfabrication in the shape, after bonding in a heating step with an adhesive film cut into a shape larger than the adhesive surface, remove the unnecessary parts that have protruded from the adhesive surface in advance. Since it can be removed with an etchant, precise bonding is possible. Further, the present invention may be applied as a temporary bonding method by removing all the epoxy adhesive film between bonding surfaces, which are unnecessary portions after bonding in a heating step, and peeling off the bonding surfaces between the bonding surfaces. Can be.

In the removing step in the present invention, etching is preferably performed using an etching solution containing an alkali metal compound and an organic solvent, and the organic solvent further preferably includes at least one of an amide solvent and an alcohol solvent. In addition to these components, a compound may be appropriately added as necessary.

The alkali metal compound used in the etching solution of the present invention may be any alkali metal compound such as lithium, sodium, potassium, rubidium, cesium, etc., which can be dissolved in an alcohol solvent. , Lithium, sodium, potassium, rubidium, cesium and other metals, hydrides, hydroxides, borohydrides, amides, fluorides, chlorides, bromides, iodides, borates, phosphates, carbonates, sulfates Salts, nitrates, organic acid salts, alcoholates, phenolates and the like. Examples of the amide solvent 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 esters 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 cured epoxy resin, and the solubility of the decomposed product is particularly good. preferable. These solvents can be used in combination, and can also be used in combination with other solvents typified by ketone solvents, ether solvents and the like.

The alcohol solvent used in the etching solution of the present invention includes, for example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, iso-butanol, and te.
rt-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-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, triethylene glycol monoethyl ether, tetraethylene glycol, polyethylene glycol (molecular weight 200 to 40)
0), 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentane Diol, glycerin, dipropylene glycol and the like. 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 preferred because of their high solubility of alkali metal compounds. Some of these solvents can be used in combination.

[0015] Ketone solvents which can be used together include, for example, acetone, methyl ethyl ketone, 2-pentanone,
Examples include 3-pentanone, 2-hexanone, methyl isobutyl ketone, 2-heptanone, 4-heptanone, diisobutyl ketone, and cyclohexanone.

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

The etchant used in the present invention can be mixed with an amide-based solvent in an optional composition with an alcohol-based solvent.
The composition is 1 to 50% by weight of the alcohol solvent with respect to 9% by weight. If the concentration of the amide solvent is lower than 50% by weight, the swelling property of the epoxy cured product and the solubility of the decomposition product decrease, which is not preferable. If the concentration is higher than 99% by weight, the concentration of the alkali metal compound decreases. It 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 is preferably 0.5% by weight or less.
The range of 40% by weight is preferable, and if it is less than 0.5% by weight, the decomposition rate of the cured epoxy resin is lowered, which is not preferable. It is not preferable.

The thus obtained etching solution can be used by appropriately adding a surfactant and the like, if necessary.

In order to adjust the etching rate at the time of etching, the etching solution is used at a temperature higher than the freezing point of the solvent.
It can be used at any temperature below the boiling point.

As an etching method, the adherend adhered by the adhesive film is immersed in an etching solution. The etching rate can be increased depending on the temperature, or vibration can be given by ultrasonic waves. Further, spraying or the like, or high pressure can be applied. Further, a portion to be etched of the epoxy adhesive film can be selected and etched.

By such a removing step, the portion protruding from the adhesive surface of the epoxy adhesive film can be removed without damaging the adherend and the portion necessary for bonding the epoxy adhesive film. Here, after the removing step, the width of the protrusion of the epoxy adhesive film from the adhesive surface is set to 10
It is preferable to control the progress of the etching so as to be 0 μm or less. Furthermore, when the present invention is applied as a temporary bonding method, the etching proceeds further than the removal of the portion protruding from the bonding surface described above, and the epoxy bonding film between the bonding surfaces, which is a portion where bonding is unnecessary, is etched. All of them can be removed to separate the bonding surfaces.

Next, the epoxy adhesive film of the present invention will be described. The epoxy adhesive film in the present invention preferably contains, as a main component, 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 a temperature of 200 ° C. or less is possible, and it is excellent in adhesive strength, heat resistance and solvent resistance, and can be punched out in the same shape as the adhesive surface, so that fine processing is possible. The epoxy adhesive film optionally contains a polyfunctional epoxy resin, a curing agent, a cross-linking agent, and the like, as necessary, in addition to the high molecular weight epoxy polymer as a main component.

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

As the bifunctional epoxy resin used as a raw material of the high molecular weight epoxy polymer, any compound having two epoxy groups in the molecule can be used without any limitation. 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 bifunctional phenol,
Alternatively, diglycidyl ethers of bifunctional alcohols and their halides, hydrogenated products and the like can be mentioned. Two or more of these compounds can be used in combination. Further, as the bifunctional phenol used in the present invention, any compound having two phenolic hydroxyl groups in a molecule can be used without limitation, and a halogenated bifunctional phenol makes the film flame retardant. It is preferable. For example, monocyclic bifunctional phenols such as hydroquinone, resorcinol, catechol, and polycyclic bifunctional phenols such as bisphenol A, bisphenol F, naphthalene diols, biphenols and halides such as alkyl-substituted products thereof, alkyl-substituted products, etc. No. Two or more of these compounds can be used in combination.

The equivalent ratio of the bifunctional epoxy resin to the bifunctional phenol is as follows: epoxy group / phenolic hydroxyl group = 1 / 0.9 to 1 /
It is preferred to be in the range of 1.1. When the phenolic hydroxyl group is less than 0.9, the polymer does not linearly increase in molecular weight but causes a side reaction to crosslink and become insoluble in a solvent.

As the catalyst used for the polymerization of the high molecular weight epoxy polymer, an alkali metal compound or a compound containing no alkali metal element can be used alone or in combination. Examples of alkali metal compounds include sodium, lithium and potassium hydroxides, 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 removal by an adsorbent after synthesis is easy.

Examples of the compound containing no alkali metal element include:
The compound is not limited as long as it does not contain an alkali metal element and has a catalytic ability to promote an etherification reaction between an epoxy group and a phenolic hydroxyl group, and examples thereof include imidazoles, amines, and organic phosphorus compounds. Examples of imidazoles include imidazole, 2-imidazole, 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, and 2-imidazole.
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-
And cyanoethylimidazole.

Examples of the amines include aliphatic or aromatic primary amines, secondary amines, tertiary amines, quaternary ammonium salts, and aliphatic cyclic amines. , 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, diisobutylamine,
Di-N-butylamine, diphenylamine, N-methylaniline, tri-N-propylamine, tri-N-octylamine, tri-N-butylamine, triphenylamine, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium Iodide and the like.

The organic phosphorus compound is not limited as long as it is a phosphorus compound having an organic group. For example, hexamethylphosphoric triamide, tri (dichloropropyl) phosphate, tri (chloropropyl) phosphate, phosphorous acid Triphenyl, trimethyl phosphate, phenylphosphonic acid,
Triphenylphosphine, tri-N-butylphosphine, diphenylphosphine and the like.

When these catalysts are used in combination,
With respect to 1 mol of the bifunctional epoxy resin, the alkali metal compound is in the range of 0.005 to 0.20 mol, the alkali metal-free compound is in the range of 0.005 to 0.20 mol, and 1 mol of the bifunctional epoxy resin. Of 0.01 to 0.
The range is 30 moles. 0.01 ~
Preferably it is in the range of 0.30 mol. If the amount is less than 0.01 mol, the reaction for increasing the molecular weight is remarkably slow, and if it exceeds 0.30 mol, the molecular weight may not be increased linearly.

As the solvent for the polymerization reaction of the bifunctional epoxy resin and the bifunctional phenol, any solvent can be used as long as it can dissolve the bifunctional epoxy resin and the bifunctional phenol, such as amide, ketone, ether, and alcohol. There are solvents such as solvents and esters. These solvents can be used in combination. For example, amide solvents include, for example, formamide, N-methylformamide, N, N-
Dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N, N,
N ', N'-tetramethylurea and the like.

Examples of the ketone solvent include 2-pentanone, 3-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, holon, methylcyclohexanone, 2-pyrrolidone, N-methylpyrrolidone, carbamic acid ester, and cyclohexanone. , Acetylacetone,
Diisobutyl ketone, and the like. Examples of ether solvents include dipropyl ether, diisopropyl ether,
Examples include dibutyl ether, anisole, phenetole, dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and the like.

As the alcohol solvent, for example, 2-
Propanol, 1-butanol, 2-butanol, i
so-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-pentanol, 4-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, cyclohexanol, 1-methylcyclohexanol, 2-methyl Cyclohexanol, 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, Ethylene 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- Butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, glycerin, dipropylene glycol and the like.
Among them, 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, and 2-ethylhexyl. Examples include acetate, 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.
If the amount is less than 0% by weight, the solution viscosity at the time of application becomes extremely low, and the thickness accuracy is deteriorated, repelling or the like is caused, and the coatability is deteriorated. If it exceeds 50% by weight, side reactions increase and it is difficult to increase the molecular weight into a linear form. The tendency for the side reaction to increase is more likely to occur as the solid content concentration is higher, so the content is preferably 40% by weight or less, and more preferably 30% by weight or less.

The polymerization reaction temperature is preferably from 60 to 150 ° C., and if it is lower than 60 ° C., the reaction for increasing the molecular weight is extremely slow, and if it exceeds 150 ° C., side reactions increase and it is difficult to increase the molecular weight into a linear form. The weight average molecular weight in terms of styrene of the obtained high molecular weight epoxy polymer is 70,000 or more, and the reduced viscosity of a 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. 0.60
If it is less than 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 a molecule.
Epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolak epoxy resin, cresol novolak epoxy resin, bisphenol A novolak epoxy resin, bisphenol F novolak epoxy resin, alicyclic epoxy resin, aliphatic Chain epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, diglycidyl ether compound of polyfunctional phenol, diglycidyl ether compound of polyfunctional alcohol,
And their halides and hydrogenated products. These compounds can be used in combination of two or more. The compounding 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 based on 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, and these can be used. Polyfunctional phenols are monocyclic bifunctional phenol hydroquinone, resorcinol, catechol, polycyclic bifunctional phenol bisphenol A, bisphenol F, naphthalene diols, bisphenols and their halides, alkyl-substituted products,
Novolak resins and resole resins, which are polycondensates of these phenols and aldehydes, can be used. The amines include aliphatic primary amines, secondary amines, tertiary amines, aromatic primary amines, secondary amines, tertiary amines, guanidines, urea derivatives, and the like, specifically, triethylenetetramine, Examples thereof include diaminodiphenylmethane, diaminodiphenylether, dicyandiamide, tolylbiguanide, guanylurea, and dimethylurea. As the imidazole compound, alkyl-substituted imidazole, benzimidazole and the like can be used. As the acid anhydride, phthalic anhydride, hexahydrophthalic anhydride, pyromellitic dianhydride, bezophenone tetracarboxylic dianhydride and the like can be used. The amount of the curing agent is preferably 1 to 70 parts by weight based on 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 if necessary, and for example, tertiary amine, imidazole, quaternary ammonium salt and the like can be used.

In the present invention, a masking isocyanate may be used as a crosslinking agent. This is because if an isocyanate having an isocyanate group is used as it is as a crosslinking agent, the reactivity with an alcoholic hydroxyl group is extremely high, so that the crosslinking reaction proceeds at room temperature and gelation of the epoxy resin solution may occur. This isocyanate group is used as a mask (block). Isocyanates preferably used in the present invention are those having two or more isocyanate groups in the molecule. Examples include hexamethylene diisocyanate, naphthalene diisocyanate, diphenyl ether diisocyanate, diphenylpropane diisocyanate, biphenyl diisocyanate, and isomers, alkyl-substituted products, halides, and hydrogenated products of the benzene ring. Further, triisocyanates having three isocyanate groups, tetraisocyanates having four isocyanate groups, and the like can be used, and these can be used in combination.

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

These block (mask) agents may be used alone or in combination of two or more. This mask
The (blocking) agent is preferably used such that the active hydrogen of the masking (blocking) agent is 0.5 to 3.0 equivalents with respect to 1.0 equivalent of the isocyanate group of the isocyanate. If the amount is less than 0.5 equivalent, the mask (block) becomes incomplete, and the possibility that the high molecular weight epoxy polymer gels becomes high. If the amount exceeds 3.0 equivalents, the mask (block) becomes incomplete.
Excessive agent, mask (block) on formed film
The agent may remain to reduce heat resistance and chemical resistance.

The amount of the isocyanate compounded with respect to the high molecular weight epoxy polymer is such that the isocyanate group equivalent is 0.1 with respect to the alcoholic hydroxyl group equivalent of 1 of the high molecular weight epoxy polymer.
It is preferably in the range of 1-2. If it is less than 0.1, crosslinking is difficult, and if it is more than 2, isocyanates remain in the film, which may lower heat resistance and chemical resistance.

The epoxy adhesive film of the present invention may optionally contain a flame retardant. Examples of the flame retardant include tetrabromobisphenol A, decabromodiphenyl ether, brominated epoxy resin, brominated phenol resin and the like. Can be used. Further, a phosphorus-containing compound such as a phosphate ester and a nitrogen-containing compound such as melamines can also be used.

A varnish is prepared by dissolving or dispersing the high-molecular-weight epoxy polymer, polyfunctional epoxy resin, curing agent, cross-linking agent, and the like, which are components of the above epoxy adhesive film, in a solvent. The mixing method is not particularly limited as long as the varnish is uniformly mixed and dispersed. For example, devices such as a grinder, 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 in a temperature range not lower than the freezing point of the solvent used and not higher than the boiling point. The order of charging the materials to be mixed and dispersed may be any order.

The support on which the varnish is applied is preferably a support that does not dissolve in the solvent used for the varnish. For example, a plastic film such as a polyimide film, a polyester film, a polyethylene film, or a polypropylene film can be used. May be used, and the surface to be applied may be a roughened surface. After applying the 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 preferred. The temperature is lower than the composition of the varnish to be 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 of the present invention is obtained. It is generally preferable that the thickness be 200 μm or less.

An epoxy adhesive film containing a high-molecular-weight epoxy polymer having a weight-average molecular weight of 70,000 or more obtained by polymerizing the above-mentioned bifunctional epoxy resin and a bifunctional phenol as a main component can be formed into a complicated adhesive surface. Can be precisely punched. Thereby, shortage of contact with the adherend can be avoided by processing the adhesive film smaller than the adhesive surface in order to prevent protrusion. In addition, the epoxy adhesive film is roughly cut into the shape of the adhesive surface and cut, and after the heating step, the protruding part and unnecessary parts can be removed by etching. Films can also be used.

[0049]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. (Example 1) Bisphenol A type epoxy resin (epoxy equivalent: 172) was used as a bifunctional epoxy resin, bisphenol A (hydroxyl equivalent: 114) was used as a bifunctional phenol, and epoxy group / phenolic hydroxyl group = 1. /1.02, using N, N-dimethylacetamide as a solvent in the presence of 0.05 mol of lithium hydroxide as a catalyst with respect to 1 mol of epoxy resin, and a solid content concentration of the solution. The composition was adjusted to 30% by weight, and the polymer was heated and polymerized at 120 ° C. for 10 hours in a solvent. The weight average molecular weight in terms of styrene by gel permeation chromatography (GPC) method having a film forming ability was obtained. A 200,000 high molecular weight epoxy polymer was obtained.

The high molecular weight epoxy polymer is converted into isocyanates having two or more isocyanate groups as follows:
Using isophorone diisocyanate, 1.0 equivalent of the isocyanate group, 2.5 equivalents of phenol novolak resin as a masking agent, 0.5 equivalent of isocyanate group to 1 equivalent of alcoholic hydroxyl group of high molecular weight epoxy polymer. It was compounded so that it might become.

With respect to 100 parts by weight of the high molecular weight epoxy polymer, 60 parts by weight of a cresol novolac type epoxy resin (epoxy equivalent: 195) was used as a polyfunctional epoxy resin.
Phenol novolak resin (hydroxyl equivalent:
106) was blended in an amount of 20 parts by weight.

This varnish was applied to a polyethylene terephthalate film having a thickness of 50 μm, and dried in a dryer.
Drying was performed at 0 ° C. for 5 minutes to obtain an epoxy adhesive film having a thickness of 10 μm.

[Heating Step] This epoxy adhesive film was cut into a 25 mm square, and was sandwiched between an adherend SUS304 (thickness 10 mm) and a Si wafer (thickness 2 mm).
The shape of the bonding surface between the SUS304 and the Si wafer is 20 mm square, two circles having a diameter of 3 mm in the center, and a width of 1 mm and a length of 1
There is a 0 mm rectangular hole. After sandwiching the epoxy adhesive film, hot pressing was performed at 170 ° C. and 0.5 MPa for 15 minutes. The tensile adhesive strength of the sample after bonding by hot pressing was 53 MPa.

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

When this sample was immersed in N, N-dimethylacetamide for 24 hours, there was no change in the appearance of the bonded portion, and the tensile bond strength was the same as before immersion. Further, when this sample was immersed in an etching solution at 120 ° C., the Si wafer was separated from SUS304 after 10 hours. The epoxy adhesive film on the bonding surface between the SUS304 and the Si wafer was all dissolved.

Example 2 In synthesizing a high molecular weight epoxy polymer, 0.04 mol of sodium methoxide and 0.1 mol of imidazole were used as a catalyst per 1 mol of epoxy resin.
A high molecular weight epoxy polymer having a weight average molecular weight in terms of styrene of 70,000 as determined by gel permeation chromatography (GPC) was obtained in the same manner as in Example 1 except that 05 mol was added and cyclohexanone was used as a solvent.

This high molecular weight epoxy polymer was prepared in Example 1
A varnish was blended in the same manner as described above, applied to a polyimide film having a thickness of 50 μm, and then dried in a drier at 150 ° C. for 5 minutes to obtain an epoxy adhesive film having a thickness of 20 μm.

Bonding was performed in the same manner as in Example 1 except that the adherend was made of 42 alloy having a thickness of 30 mm and polyethylene terephthalate having a thickness of 20 mm. The tensile adhesive 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 holes 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 is 60μ.
m. The adhesive strength of the sample after etching was the same value as before etching. When this sample was immersed in N, N-dimethylacetamide for 24 hours, there was no change in the appearance of the bonding site, and the tensile bonding strength was the same value as before immersion.

When this sample was further immersed in an etching solution having the same composition as in Example 1 at 120 ° C.,
After 10 hours, 42 alloy had peeled off the polyethylene terephthalate. The epoxy adhesive film on the bonding surface of the 42 alloy and polyethylene terephthalate was all dissolved.

Example 3 The epoxy adhesive film obtained in Example 1 was used as an adherend with a copper foil having a thickness of 35 μm and SU.
Bonding was performed in the same manner as in Example 1 except that S304 was used. The tensile bonding 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 adhesive strength of the sample after etching was the same value as before etching. When this sample was immersed in N, N-dimethylacetamide for 24 hours, there was no change in the appearance of the bonding site, and the tensile bonding strength was the same value as before immersion.

When this sample was further immersed in an etching solution having the same composition as in Example 1 at 120 ° C.,
After 12 hours, the copper foil was separated from the SUS304. The epoxy adhesive films on both adhesive surfaces were all dissolved.

Example 4 The procedure of Example 1 was repeated except that tetrabromophenol A (equivalent hydroxyl group: 227) was used as a bifunctional phenol as a raw material of the high molecular weight epoxy polymer of Example 1. Styrene equivalent weight average molecular weight by gel permeation chromatography (GPC) method is 2
A high molecular weight epoxy polymer of 000 was obtained. A varnish was blended with this high molecular weight epoxy polymer in the same manner as in Example 1, and an epoxy adhesive film was obtained in the same manner as in Example 1. Bonding was performed in the same manner as in Example 1 using this epoxy adhesive film. The tensile adhesive strength of the sample after bonding by hot pressing was 45 MPa. This sample was added to an etching solution of the same composition as in Example 1 at 120 ° C. for 1 hour.
Soaked for hours. 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 etching was the same value as before etching. When this sample was immersed in N, N-dimethylacetamide for 24 hours, there was no change in the appearance of the bonding site, and the tensile bonding strength was the same value as before immersion.

When this sample was further immersed in an etching solution having the same composition as in Example 1 at 120 ° C.,
Six hours later, the Si wafer was separated from the SUS304. S
The epoxy adhesive film on the bonding surface between the i-wafer and the SUS 304 was all dissolved.

The details of the evaluation method in the above embodiment are shown below. The column used for gel permeation chromatography (GPC) is TSK gel G6000 + G5000 + G4000 + G3000 + G200
0 (product name of Tosoh Corporation) and N, N-
Dimethylacetamide was used and the sample concentration was 2% by weight. The styrene-equivalent weight average molecular weight was obtained by previously calculating the relationship between the molecular weight and the elution time using styrene having various molecular weights, and calculating the molecular weight from the elution time of the sample to obtain the styrene-equivalent weight average molecular weight. Measurement of tensile strength
Tensilon made by Toyo Baldwin, with a pulling speed of 5
mm / min. The width of the epoxy adhesive film protruding from the edge of the adhesive surface was read from a cross-sectional photograph.

[0065]

According to the method for bonding with an epoxy adhesive film of the present invention, the epoxy adhesive film has excellent heat resistance and solvent resistance, so that it is possible to precisely bond an adhesive surface having a fine shape. In addition, by contacting with an etching solution for a long time, the adhesive surfaces can be easily peeled off without damage, so that it can be applied as a temporary adhesive.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ayako Matsuo 1500 Oji Ogawa, Shimodate-shi, Ibaraki F-term in Hitachi Chemical Co., Ltd. Research Laboratory 4J004 AA13 AB05 CA04 CA06 CA08 CC02 FA05 4J036 AA01 DB06 DB07 JA06 4J040 EC021 EC061 EC081 EC261 EC311 GA05 JA09 JB02 LA01 MA02 MA04 MA10 NA20 PA23 PA30 PA33 PA37 PA42

Claims (8)

[Claims] 1. A heating step in which an epoxy adhesive film is sandwiched between two adhesive surfaces of an adherend and heating or heating and pressurizing is performed; A step of etching at least one of the portions protruding from the adhesive surface. 2. The bonding method using an epoxy adhesive film according to claim 1, wherein the portion where the bonding is unnecessary is between the bonding surfaces, and the bonding surfaces are separated by etching. 3. The bonding method using an epoxy adhesive film according to claim 1, wherein in the removing step, etching is performed using an etchant containing an alkali metal compound and an organic solvent. 4. The bonding method according to claim 3, wherein the organic solvent in the etching solution contains at least one of an amide type and an alcohol type. 5. The method according to claim 1, wherein after the removing step, the width of the protrusion of the epoxy adhesive film from the adhesive surface is 100 μm or less. 6. The epoxy adhesive according to claim 1, wherein the epoxy adhesive film contains, as a main component, 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. Adhesion method using an adhesive film. 7. A bifunctional epoxy resin and a bifunctional phenol are prepared by mixing epoxy group / phenolic hydroxyl group = 1 / 0.9-
7. The bonding method using the epoxy adhesive film according to claim 6, wherein the polymerization is performed at an equivalent ratio of 1 / 1.1. 8. The bonding method using an epoxy adhesive film according to claim 6, wherein the bifunctional phenols include halogenated bifunctional phenols.