JP2002012841A - Acrylic thermoset adhesive composition and adhesive sheets - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic thermoset adhesive excellent in adhesive strength to a polyimide film, having heat resistance bearing the heat of the solder reflow at the time of mounting, and hardly causing abnormal appearance caused by flowing-out or the like of the resin at the time of adhesion, and further to provide adhesive sheets having adhesive layers formed out of the adhesive. SOLUTION: This acrylic thermoset adhesive composition comprises an acrylic polymer obtained by copolymerizing a monomer mixture comprising (A) an imide group-containing (meth)acrylate, (B) an alkyl (meth)acrylate, and (C) a functional group-containing monomer having reactivity with an epoxy group, and an epoxy resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an acrylic thermosetting adhesive composition and an adhesive sheet. The acrylic thermosetting adhesive composition and the adhesive sheet of the present invention are, in particular, a reinforcing material such as a metal constituting an electronic component such as an IC, and a heat-resistant film used for a flexible printed wiring board such as a polyimide film. It can be advantageously used for bonding.

[0002]

2. Description of the Related Art Various adhesives have been used for fixing reliability of electronic parts and the like for the purpose of improving reliability. In particular, it is used for structural bonding applications such as fixing a flexible printed wiring board to a reinforcing material, fixing a circuit board used for a semiconductor device such as a ball grid array to a reinforcing plate or a heat sink, and manufacturing a temporary fixing during parts transport. Adhesives are increasingly used in process bonding applications.

In such applications, a polyimide film is used for a flexible circuit board, and a metal material or a glass epoxy plate is used for a reinforcing material. Good adhesiveness is required. In such an application, since solder bonding is performed at the time of component mounting, the adhesive is required to have high heat resistance that does not cause softening or flow during solder reflow. In addition, with the miniaturization of electronic devices, the bonding area has tended to be reduced.
It is very important to control the fluidity of the adhesive (glue protrusion).

[0004] Conventionally, a thermosetting adhesive sheet that can be cured by heat treatment for bonding electronic components and the like has been proposed for bonding electronic components and the like. For example, Japanese Patent Publication No. 3-44592 and Japanese Patent Publication No. 7-115090 disclose that an acrylic monomer is polymerized by irradiating ultraviolet light to a photopolymerizable composition obtained by adding an epoxy resin and a curing agent to a monofunctional acrylic monomer. Thermosetting adhesive compositions have been proposed. However, such a thermosetting adhesive composition has excellent adhesion to a metal plate or a glass epoxy plate, but has insufficient adhesion to a polyimide film.

In any of the above proposals, the photopolymerizable composition contains a curing agent such as imidazole, dicyandiamide, or polyamine, and the curing agent causes a curing reaction with an epoxy group. is there. in this case,
During the storage before or after the photopolymerization, the above-mentioned curing reaction gradually progresses, and there is a possibility that the adhesive properties and the like may be reduced accordingly. As described above, the thermosetting adhesive composition proposed above has been difficult in terms of storage stability. Furthermore, since the acrylic polymer and the epoxy resin formed by photopolymerization were not cross-linked even after curing, the heat resistance was insufficient.

Further, in Japanese Patent Publication No. 44592/1991, since a large amount of epoxy resin is used as a curing component, unreacted low-molecular-weight epoxy resin flows out during gluing by press (glue runs out) and appearance is abnormal. There was also a problem of causing such troubles.

In addition, as an acrylic polymer, a (meth) acrylic acid alkyl ester having an average of 2 to 14 carbon atoms in an alkyl group generally used in a pressure-sensitive adhesive sheet is used as a main monomer to impart heat resistance thereto. In a system in which various high Tg monomers were copolymerized and an epoxy resin was added, it was possible to create an adhesive sheet excellent in adhesiveness to metal materials and heat resistance. The adhesion was insufficient.

[0008]

DISCLOSURE OF THE INVENTION The present invention relates to an acrylic heat-resistant adhesive having excellent adhesive strength to a polyimide film, heat resistance enough to withstand solder reflow during mounting, and no appearance abnormality due to resin flowing out during bonding. It is an object of the present invention to provide an adhesive sheet having a curable adhesive and an adhesive layer formed from the adhesive.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies to explain the above problems, and as a result, have found that the above object can be achieved by the acrylic thermosetting adhesive composition shown below. The present invention has been completed.

That is, the present invention provides a monomer mixture containing an imide group-containing (meth) acrylate (A), an alkyl (meth) acrylate (B), and a functional group-containing monomer (C) reactive with an epoxy group. The present invention relates to an acrylic polymer obtained by polymerization and an acrylic thermosetting adhesive composition containing an epoxy resin.

The imide group-containing (meth) acrylate (A) has excellent cohesive strength, can impart high heat resistance to the obtained acrylic polymer, and has a strong adhesiveness to the polyimide film for the acrylic polymer. Can be granted. The alkyl (meth) acrylate (B) is used for imparting tackiness to the acrylic polymer, and the flexibility / flexibility of the acrylic polymer depends on the proportion of the alkyl (meth) acrylate (B) used.
The cohesion can be adjusted. The functional group-containing monomer (C) having a reactivity with an epoxy group can introduce a functional group having a reactivity with an epoxy group of an epoxy resin which is a thermosetting component into an acrylic polymer. The crosslinking reaction of the system resin proceeds, and the heat resistance can be further improved. In the adhesive composition of the present invention, since a curing agent is not particularly required for the reaction of the epoxy group, storage stability is also good. Such an adhesive composition is
Has excellent workability that can be cured in a relatively short time.

The acrylic thermosetting adhesive composition comprises:
It is preferable that the epoxy resin is prepared so as to contain 5 to 30 parts by weight of the epoxy resin based on 100 parts by weight of the acrylic polymer.

In order to promote the crosslinking reaction with the epoxy resin and sufficiently improve the heat resistance, the epoxy resin is preferably used in an amount of 5 parts by weight or more. On the other hand, when the amount of the epoxy resin increases, at the time of press bonding, the resin may flow out and cause an abnormal appearance, and the cured product may be excessively cross-linked to cause a peeling phenomenon on the adherend surface and storage stability to be reduced. Therefore, the content of the epoxy resin is preferably 30 parts by weight or less, more preferably 20 parts by weight or less.

In the acrylic thermosetting adhesive composition, the monomer mixture contains 5 to 60% by weight of an imide group-containing (meth) acrylate (A), 15 to 94% by weight of an alkyl (meth) acrylate (B), Those containing 1 to 25% by weight of a functional group-containing monomer (C) reactive with an epoxy group are preferred.

At the above ratio, an acrylic polymer obtained by copolymerizing a monomer mixture containing an imide group-containing (meth) acrylate (A), an alkyl (meth) acrylate (B) and a functional group-containing monomer (C) is obtained. A good balance between heat resistance and adhesiveness is preferred. In particular, 15 to 45% by weight of the imide group-containing (meth) acrylate (A),
50 to 65% by weight of the alkyl (meth) acrylate (B) and 5 to 20% by weight of the functional group-containing monomer (C)
Is preferable.

In the acrylic thermosetting adhesive composition, the imide group-containing (meth) acrylate (A) is represented by the following general formula (1), general formula (2), general formula (3), Formula (4) and general formula (5):

Embedded image (Wherein, R ¹ , R ² and R ³ are each independently a hydrogen atom or a methyl group, R ⁴ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. It is preferably at least one selected from compounds represented by the following formula: The imide group-containing (meth) acrylate (A) having such a structure is preferable for imparting high heat resistance to the acrylic polymer.

In the acrylic thermosetting adhesive composition, the functional group reactive with the epoxy group is preferably at least one selected from a carboxyl group, a hydroxyl group and an epoxy group.

Among the functional groups reactive with the epoxy group, the functional group has good reactivity with the epoxy group. In addition, a primary or secondary amino group-containing monomer is difficult to use because it has high reactivity with an epoxy group and can greatly reduce storage stability.

In the acrylic thermosetting adhesive composition, the acrylic polymer is preferably obtained by copolymerizing a monomer mixture by irradiation with radiation.

The acrylic polymer can be obtained by copolymerizing the above monomer mixture by various polymerization methods. Among them, irradiation with radiation such as ultraviolet rays or electron beams enables bulk polymerization and requires a solvent and an emulsifier. And not. That is, according to the radiation irradiation, corrosion of electronic components due to the residual organic solvent, swelling due to vaporization and expansion at high temperatures, peeling, there is no deviation, and contamination by bleeding of the emulsifier,
There is no need to worry about poor adhesion and reduced moisture resistance. In addition, the monomer mixture can be copolymerized by irradiating ultraviolet light with relatively low intensity, so that the resulting acrylic polymer can be easily made to have a high molecular weight and a high degree of cross-linking, and the heat resistance due to the improvement in cohesive strength can be improved. Particularly favorable preparation (production) of an acrylic thermosetting adhesive composition (adhesive layer) is possible.

The acrylic polymer obtained by copolymerizing the monomer mixture by irradiation with radiation is preferably one obtained by copolymerizing a crosslinking agent together with the monomer mixture.

Further, the acrylic thermosetting adhesive composition preferably contains a crosslinking agent in addition to the acrylic polymer as the base polymer.

By containing a cross-linking component in the acrylic polymer or the acrylic thermosetting adhesive composition, the adhesive holding properties can be improved.

It is preferable that the acrylic thermosetting adhesive composition of the present invention further contains an inorganic filler.

By adding an inorganic filler to the thermosetting adhesive composition, it is possible to reduce the water absorption of the adhesive composition bulk,
It is possible to control the coefficient of linear expansion, shorten the bonding time and curing time by increasing the thermal conductivity, and improve the workability and the like.

In the acrylic thermosetting adhesive composition containing the inorganic filler, the inorganic filler is an organic adhesive component (acrylic polymer, epoxy resin, crosslinking agent) in the acrylic thermosetting adhesive composition. ) Total 100
It is preferable to contain 10 to 200 parts by weight with respect to parts by weight.

In order to more effectively exert the control of the water absorption rate and the linear expansion coefficient by the inorganic filler, the amount of the inorganic filler is preferably at least 10 parts by weight, more preferably at least 30 parts by weight. More preferred. In addition, when the amount of the inorganic filler is increased, the adhesion is hindered, and particularly, the adhesive force at a high temperature is greatly reduced, and the adhesive fixing force may be poor.
It is more preferably at most 00 parts by weight, more preferably at most 100 parts by weight.

Further, the present invention relates to an adhesive sheet having an adhesive layer formed on one or both sides of a base material from the acrylic thermosetting adhesive composition.

Adhesive sheets having the acrylic thermosetting adhesive composition of the present invention as an adhesive layer have good adhesive strength to a polyimide film and have heat resistance to withstand solder reflow. It is useful as an adhesive sheet for electronic parts and the like.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION The imide group-containing (meth) acrylate (A) is as shown by the above-mentioned general formulas (1) to (5), and specific examples thereof include, for example, N-acryloyloxyethyl-1. , 2,3,6-tetrahydrophthalimide (manufactured by Toagosei Co., Ltd., trade name: ARONIX TO
-1428), N-acryloyloxyethyl hexahydrophthalimide (manufactured by Toagosei Co., Ltd., trade name: Aronix TO-1429), N-acryloyloxyethyl-3,4,5,6-tetrahydrophthalimide (Toagosei Co., Ltd. Product name: Aronix TO-1534)
Are available as commercial products. One or more imide group-containing (meth) acrylates (A) can be used. In the present invention, (meth) acrylate refers to acrylate and / or methacrylate, and hereinafter, (meth) has the same meaning.

The alkyl (meth) acrylate (B) includes, for example, an alkyl group having 1 to 1 carbon atoms.
About 4 alkyl (meth) acrylates can be mentioned.
Further, the alkyl group may be linear or branched. Specific examples of the alkyl (meth) acrylate (B) include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate,
Representative examples thereof include isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, and the like. As One or more of these can be used.

Examples of the functional group-containing monomer (C) having reactivity with the epoxy group include a carboxyl group-containing monomer, a hydroxyl group-containing monomer, and an epoxy group-containing monomer.

Representative examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, and caprolactone-modified (meth) acrylate. Examples of the hydroxyl group-containing monomer include 2-hydroxy-3-phenoxypropyl ( Representative examples thereof include meth) acrylate, 2-hydroxyethyl (meth) acrylate, and N-methylol (meth) acrylamide. Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate and alicyclic epoxy group. Containing (meth) acrylates are typical examples.

In addition, the acrylic polymer as a base polymer contains, as a copolymerization component, a monomer (D) copolymerizable therewith, in addition to the monomers (A), (B) and (C). be able to. By using, as the monomer (D), those having various functional groups or polar groups not reactive with the epoxy group,
Acrylic polymer can be modified, and heat resistance and adhesiveness can be improved. Examples of the optional monomer (D) include vinyl acetate, styrene, (meth) acrylonitrile, isobornyl (meth) acrylate, (meth) acryloylmorpholine, (meth) acrylamides and the like. However, if the proportion of the monomer (D) in the monomer mixture is not large, the object of the present invention may be impaired. Therefore, the proportion of the monomer (D) should be 30% by weight or less, further 20% by weight or less. Is preferred.
The monomer (D) can be used by substituting a part of the monomer (B).

The acrylic polymer can be obtained by copolymerizing the monomers (A), (B) and (C) and, if necessary, the monomer mixture containing the monomer (D). As the polymerization method, a solution polymerization method, an emulsion polymerization method, a photopolymerization method using a radiation such as an electron beam or an ultraviolet ray, which can advance the addition polymerization of the monomer mixture, and a combination method of these methods can be arbitrarily adopted. The acrylic polymer only needs to be contained in the adhesive, and the polymerization need not be completed before application to the substrate.
When the photopolymerization method is adopted, the acrylic polymer can be directly formed on the substrate by coating and curing the monomer mixture on the substrate, thereby improving coating properties on the substrate. For this purpose, it is also possible to apply a polymer obtained by partially polymerizing and polymerizing the monomer mixture to increase the viscosity on a base material, and further subject this to photopolymerization.

In the above-mentioned copolymerization, an appropriate initiator according to the type of polymerization is used. For example, in a solution polymerization method and an emulsion polymerization method, a thermal polymerization initiator, potassium persulfate,
Redox-based initiators, such as ammonium persulfate and hydrogen peroxide, which are used in combination with them, are used. Specific examples of the thermal polymerization initiator include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropylperoxydicarbonate, di-n-propylperoxydicarbonate, and di (2-ethoxyethyl) peroxide. Oxydicarbonate, t-butyl peroxy neodecanoate, t-butyl peroxy pivalate,
Organic peroxides such as (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methyl Butyronitrile), 1,1-azobis (cyclohexane 1-carbonitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethyl-4-methoxy) Valeronitrile), dimethyl 2,2
'-Azobis (2-methylpropionate), 4,4'
-Azobis (4-cyanoparecic acid), 2,2'-azobis (2-hydroxymethylpropionitrile), 2,
2'-azobis [2- (2-imidazolin-2-yl)
Azo compounds such as [propane].

In the photopolymerization method, an initiator is not particularly required when an electron beam is used, but when an ultraviolet ray or the like is used, a benzoin-based, benzophenone-based, anthraquinone-based, xanthone-based, thioxanthone-based, or ketal-based compound is used. Various photopolymerization initiators such as a system are used. Specific examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α′-dimethylacetophenone, methoxyacetophenone, 2,2-dimethoxy -2-phenylacetophenone, 2,2-diethoxyacetophenone,
Acetophenone-based compounds such as 1-hydroxycyclohexylenyl ketone, 2-methyl-1- [4- (methylthio) -phenyl] -2-morpholinopropane-1, benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; Benzoin ether compounds, α-ketol compounds such as 2-methyl-2-hydroxypropiophenone, ketal compounds such as benzyldimethyl ketal, aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride, 1-phenone- 1,1-propanedione-2- (o
-Ethoxycarbonyl) oximes and other photoactive oxime compounds, benzophenone, benzoylbenzoic acid, 3,
3'-dimethyl-4-methoxybenzophenone, 3,3
And benzophenone-based compounds such as', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone.

When the acrylic polymer is prepared by photopolymerization, a reactive diluent having at least two ethylenically unsaturated double bonds can be used as a crosslinking agent. Examples of the crosslinking agent (reactive diluent) include trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, 1,2-ethylene glycol di (meth) acrylate, and 1,6-hexanediol. Examples include polyfunctional (meth) acrylates such as di (meth) acrylate, and polyfunctional vinyl ethers. Such a crosslinking agent (reactive diluent) can be contained in the monomer mixture or a partially polymerized product thereof.

The acrylic thermosetting adhesive composition of the present invention may contain a crosslinking agent in addition to the base polymer comprising the acrylic polymer. Examples of the crosslinking agent include known crosslinking agents such as isocyanate compounds, epoxy compounds, and aziridine compounds.

The amount of the cross-linking agent used is not particularly limited. However, when the amount of the cross-linking agent is large, the elasticity of the adhesive layer formed on the adhesive sheet tends to be high, and the adhesive property such as poor adhesion is poor. The amount of the crosslinking agent used is 5 parts by weight based on 100 parts by weight of the acrylic polymer (in the case of photopolymerization, the monomer mixture or the partial polymer thereof is included) because of the possibility of causing a decrease. Parts or less, more preferably 3 parts by weight or less. on the other hand,
In order to obtain the effect of improving the retention properties by the cross-linking agent, the amount of the cross-linking agent to be used is 0.05 parts by weight or more, and more preferably 0.1 parts by weight or more based on 100 parts by weight of the acrylic polymer. Is preferred.

Examples of the epoxy resin include various compounds having two or more epoxy groups in the molecule. For example, bisphenol type epoxy resin, aliphatic epoxy resin, phenolic epoxy resin, halogenated bisphenol type epoxy resin, biphenyl type epoxy resin and the like can be mentioned. The epoxy resin can be appropriately determined according to the epoxy equivalent and the number of functional groups,
Those having an epoxy equivalent of 500 or less are preferably used from the viewpoint of heat resistance.

An inorganic filler may be added to the acrylic thermosetting adhesive composition. Although the kind of the inorganic filler is not particularly limited, examples thereof include silica powder, alumina, calcium carbonate, antimony trioxide, and titanium oxide. Such an inorganic filler is 0.5 to 250 μm, preferably 1 to 100 μm.
m, more preferably 5 to 30 μm. The particle shape is not particularly limited, and may be any shape such as a sphere, a needle, a flake, or a star. The choice of shape is determined appropriately by the rheological properties of the final adhesive composition.

The acrylic thermosetting adhesive composition of the present invention contains various known additives such as an organic filler such as silicone rubber particles, a plasticizer, a pigment, an antioxidant, and a silane coupling agent. Can be added as necessary. In particular, a silane coupling agent is useful for improving the internal cohesion of an adhesive such as an inorganic filler and an epoxy resin.

It is not necessary to add a general curing agent such as imidazole, dicyandiamide or polyamine known as a curing agent for epoxy resin as an optional component to the acrylic thermosetting adhesive composition of the present invention. The adhesive can also be used in a range in which the crosslinking between the acrylic polymer and the epoxy resin does not substantially proceed and the storage stability of the adhesive is not significantly impaired.

The adhesive sheets of the present invention can be obtained by applying the acrylic thermosetting adhesive composition of the present invention onto a base material by a method similar to a conventionally known method for forming a pressure-sensitive adhesive tape. , By forming an adhesive layer. That is, when the acrylic thermosetting adhesive composition is a solution, the solvent is removed by heating. In addition, if necessary, when an isocyanate-based compound is contained as a cross-linking agent, a method of performing a cross-linking treatment by heating or the like, and when a reactive diluent is used as a cross-linking agent, a curing treatment method by ultraviolet irradiation or the like. Will be applied. It is preferable that the thickness of the adhesive layer of the adhesive sheet manufactured in this way is usually about 20 to 100 μm.

As the base material, for example, base materials include polyethersulfone, polyimide, polyamideimide, polyetherimide, polysulfone, polyetheretherketone, polyester film, epoxy resin, acrylic resin, polyurethane resin and the like. In addition to a synthetic resin film or its porous film, a non-peelable substrate such as a nonwoven fabric, a resin such as steel wool and a metal fiber substrate, and a non-peelable substrate such as a release paper, it can be used. . When a releasable substrate is used as the substrate, the adhesive layer formed on the substrate can be transferred onto the non-releasable substrate.

In the adhesive sheets, an adhesive layer can be provided on one or both sides of the substrate. The obtained adhesive sheets can be used as a sheet or a tape.

[0048]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In each example, parts and% are based on weight unless otherwise specified.

Example 1 (Preparation of Acrylic Thermosetting Adhesive Composition) A reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer contained 300 parts of ethyl acetate as a solvent and contained an imide group as a monomer. 40 parts of acrylate (manufactured by Toagosei Co., Ltd., trade name: Aronix TO-1429), butyl acrylate 5
5 parts, 5 parts of acrylic acid, and 0.3 part of benzoyl peroxide as an initiator were added, and polymerized in a nitrogen stream.
An acrylic polymer solution having a solid content of about 30% was obtained. To 100 parts (solid content) of the above solution, 15 epoxy resin (trade name: Epikote 828, manufactured by Yuka Shell Epoxy Co., Ltd.)
Parts and a polyfunctional isocyanate-based cross-linking agent (manufactured by Nippon Polyurethane Co., trade name: Coronate L) were uniformly mixed to prepare a solution of an acrylic thermosetting adhesive composition.

(Preparation of Adhesive Sheet) Next, the adhesive solution was applied on a release substrate (silicone-treated polyethylene terephthalate film; hereinafter, the same release substrate was used). A drying treatment was performed for 5 minutes to form an adhesive layer having a thickness of 50 μm, thereby producing an adhesive sheet.

Example 2 (Preparation of Acrylic Thermosetting Adhesive Composition) As a monomer, 40 parts of imide group-containing acrylate (trade name: Aronix TO-1429, manufactured by Toagosei Co., Ltd.), 55 parts of butyl acrylate, and acrylic 5 parts of acid, 2,2-dimethoxy-2-phenylacetophenone 0.1 as an initiator.
One part was placed in a four-necked flask, and exposed to ultraviolet light under a nitrogen atmosphere to partially photopolymerize about 10% by weight of the monomer mixture to obtain a syrup having a viscosity of about 30 poise. To 100 parts of the partially polymerized syrup, 15 parts of an epoxy resin (trade name: Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.) and 0.3 part of 1,6-hexanediol diacrylate as a crosslinking agent were uniformly mixed. A photopolymerizable acrylic thermosetting adhesive composition was prepared.

(Preparation of Adhesive Sheet) Next, after applying the above-mentioned adhesive composition on a release substrate, 900 mJ / cm
By irradiating the ^second ultraviolet photopolymerized to form an adhesive layer having a thickness of 50 [mu] m, to produce an adhesive sheet.

Example 3 (Preparation of Acrylic Thermosetting Adhesive Composition) 45 parts of imide group-containing acrylate (manufactured by Toagosei Co., Ltd., trade name: Aronix TO-1429), 45 parts of butyl acrylate and a fat as a monomer 10 parts of cyclic epoxy group-containing acrylate (manufactured by Daicel Chemical Co., Ltd., trade name: Cyclomer A200), 2,2-dimethoxy- as an initiator
0.1 part of 2-phenylacetophenone is charged into a four-necked flask and exposed to ultraviolet light under a nitrogen atmosphere to partially photopolymerize about 10% by weight of the monomer mixture, thereby obtaining a viscosity of about 30 poise. I got a syrup. To 100 parts of the partially polymerized syrup, 15 parts of an epoxy resin (trade name: Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.) and 0.3 part of 1,6-hexanediol diacrylate as a crosslinking agent were uniformly mixed. A photopolymerizable acrylic thermosetting adhesive composition was prepared.

(Preparation of Adhesive Sheet) Next, after applying the above-mentioned adhesive composition on a release substrate, the adhesive composition was applied at 900 mJ / cm.
By irradiating the ^second ultraviolet photopolymerized to form an adhesive layer having a thickness of 50 [mu] m, to produce an adhesive sheet.

Example 4 (Preparation of Acrylic Thermosetting Adhesive Composition) As a monomer, 25 parts of an imide group-containing acrylate (trade name: Aronix TO-1429, manufactured by Toagosei Co., Ltd.), 60 parts of ethyl acrylate and a fat 15 parts of cyclic epoxy group-containing acrylate (manufactured by Daicel Chemical Industries, Ltd., trade name: Cyclomer A100), 2,2-dimethoxy- as an initiator
0.1 part of 2-phenylacetophenone is charged into a four-necked flask and exposed to ultraviolet light in a nitrogen atmosphere to partially photopolymerize about 10% by weight of the monomer mixture, thereby obtaining a viscosity of about 30 poise. Syrup was obtained. To 100 parts of the partially polymerized syrup, 15 parts of an epoxy resin (trade name: Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.) and 0.3 part of 1,6-hexanediol diacrylate as a crosslinking agent were uniformly mixed. A photopolymerizable acrylic thermosetting adhesive composition was prepared.

(Preparation of Adhesive Sheet) Next, after applying the above-mentioned adhesive composition on a release substrate, 900 mJ / cm
By irradiating the ^second ultraviolet photopolymerized to form an adhesive layer having a thickness of 50 [mu] m, to produce an adhesive sheet.

Comparative Example 1 (Preparation of Acrylic Adhesive Composition) In a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer, 210 parts of ethyl acetate as a solvent, 60 parts of butyl acrylate as a monomer, and acryloyl 35 parts of morpholine, 5 parts of acrylic acid, and 0.3 part of benzoyl peroxide as an initiator were added, and polymerized in a nitrogen stream to obtain a solid content of about 3 parts.
A solution of 0% acrylic polymer was obtained. The above solution 10
To 0 part (solid content), 15 parts of an epoxy resin (trade name: Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.) and 1 part of a polyfunctional isocyanate cross-linking agent (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) The mixture was uniformly mixed to prepare an acrylic adhesive solution.

(Preparation of Adhesive Sheet) Next, after applying the adhesive solution on a release substrate, the adhesive solution was applied at 130 ° C. for 5 minutes.
A drying treatment was performed to form an adhesive layer having a thickness of 50 μm, thereby producing an adhesive sheet.

Comparative Example 2 (Preparation of Acrylic Adhesive Composition) As a monomer, 80 parts of isooctyl acrylate and 20 parts of acrylic acid were used.
0.05 parts of 2,2-dimethoxy-2-phenylacetophenone as an initiator is charged into a four-necked flask and exposed to ultraviolet light under a nitrogen atmosphere to partially photopolymerize about 10% by weight of the monomer mixture. As a result, a viscosity of about 30
I got a poise syrup. This partially polymerized syrup 1
In 00 parts, epoxy resin (Yuka Shell Epoxy Co., Ltd.)
(Trade name: Epicoat 828) and 10 parts of 1,6-hexanediol diacrylate as a crosslinking agent were uniformly mixed to prepare a photopolymerizable acrylic adhesive composition.

(Preparation of Adhesive Sheet) Next, after applying the above-mentioned adhesive on a release substrate, it was irradiated with 900 mJ / cm ² of ultraviolet light and photopolymerized to form an adhesive layer having a thickness of 50 μm. An adhesive sheet was produced.

Comparative Example 3 (Preparation of Acrylic Adhesive Composition) Ethyl acrylate as a monomer 80 parts, acryloyl morpholine 15
Parts, 5 parts of acrylic acid, and 0.05 parts of 2,2-dimethoxy-2-phenylacetophenone as an initiator were charged into a four-necked flask, and exposed to ultraviolet light under a nitrogen atmosphere to obtain about 10% by weight of the monomer mixture. Was partially photopolymerized to obtain a syrup having a viscosity of about 30 poise. 100 parts of the partially polymerized syrup is added to an epoxy resin (trade name: Epicoat 82, manufactured by Yuka Shell Epoxy Co., Ltd.).
8) 10 parts and 0.3 part of 1,6-hexanediol diacrylate as a crosslinking agent were uniformly mixed to prepare a photopolymerizable acrylic adhesive composition.

(Preparation of Adhesive Sheet) Next, after applying the above-mentioned adhesive on a release substrate, it was irradiated with 900 mJ / cm ² of ultraviolet rays to be photopolymerized to form an adhesive layer having a thickness of 50 μm. An adhesive sheet was produced.

Comparative Example 4 In Comparative Example 2, 20 parts of N-vinylpyrrolidone were used instead of 20 parts of acrylic acid, the amount of epoxy resin used was changed to 15 parts, and 3 parts of dicyandiamide was added as a curing agent for the epoxy resin. Other than the above, a photopolymerizable acrylic thermosetting adhesive composition was prepared in the same manner as in Comparative Example 2, and an adhesive sheet having an adhesive layer having a thickness of 50 μm was produced in the same manner as in Comparative Example 2. .

Comparative Example 5 (Preparation of Acrylic Thermosetting Adhesive Composition) 80 parts of ethyl acrylate, 15 parts of acryloylmorpholine and 5 parts of acrylic acid as monomers, 2,2 as an initiator
0.05 parts of dimethoxy-2-phenylacetophenone is charged into a four-necked flask, and exposed to ultraviolet light under a nitrogen atmosphere to partially photopolymerize about 10% by weight of the monomer mixture, thereby obtaining a viscosity of about 10%. 30 poise syrup was obtained. To 100 parts of the partially polymerized syrup, 100 parts of an epoxy resin (trade name: Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.) and a curing agent of the epoxy resin (trade name: ACR hardener, manufactured by A.R. X-361
5, modified polyamine ”) and 0.3 part of 1,6-hexanediol diacrylate as a crosslinking agent were uniformly mixed to prepare a photopolymerizable acrylic thermosetting adhesive composition.

(Preparation of Adhesive Sheet) Next, after applying the above-mentioned adhesive composition on a release base material, 900 mJ / cm
By irradiating the ^second ultraviolet photopolymerized to form an adhesive layer having a thickness of 100 [mu] m, to produce an adhesive sheet.

(Evaluation Test) The adhesive sheets obtained in Examples and Comparative Examples were subjected to the following evaluations. Table 1 shows the results.

<Peel adhesion strength> Width 10 mm, length 50 m
The adhesive sheet cut into m is laminated on a 75 μm-thick polyimide film (Ube Industries, Ltd .: trade name Upiplex 75S) with a laminator (temperature: 100 ° C., pressure: 5 k).
g / cm, speed: 2 m / min), and after removing the release substrate, the polyimide film having a thickness of 75 μm (Ube Industries, Ltd., trade name: Upirex 7)
5S) with a press (temperature: 200 ° C., time: 1 second, pressure: 5 kg / cm). This test piece was
After curing for 2 hours in a hot air oven at a temperature of 23 ° C,
After standing for 30 minutes in an atmosphere condition of a humidity of 65% RH, the film was pulled in a 90 ° direction at a pulling speed of 50 mm / min, and the center value was defined as the peeling adhesive strength (N / 10 mm).

<Heat resistance> The adhesive sheet is 75 μm thick.
After laminating (a temperature: 100 ° C., pressure: 5 kg / cm, speed: 2 m / min) on a polyimide film (Ube Industries, Ltd .: Iupilex 75S)
This was pressed into a 30 mm square SUS304 press machine (temperature: 1).
At 50 ° C., time: 1 second, pressure 5 kg / cm ² ). After heating this sample at 150 ° C for 1 hour,
60 in a state of floating in a solder bath molten at a temperature of 260 ° C.
Treated for seconds. The state of the surface of the adhesive layer after the treatment was visually observed, and the presence or absence of foaming of the adhesive layer and abnormal adhesion (lifting, wrinkling, peeling, displacement) were visually observed.
There was an abnormality, and the evaluation was made based on the following criteria.

<Glue Extrusion> A hole having a diameter of 2 cm was made at the center of the adhesive sheet cut into a square of 10 cm, and a temperature of 200 ° C.
After pressure bonding under a pressure of 10 kgf / cm ² and a pressing time of 1 second, the maximum value (mm) of the length of the glue protruding into the hole was measured.

[0070]

[Table 1] As can be seen from the results in Table 1 above, Example 1 of the present invention
The adhesive sheets Nos. To 4 have excellent adhesive strength to the polyimide film and good solder heat resistance.

In addition, there is almost no sticking out of glue at the time of heat bonding.

On the other hand, the adhesive sheets shown in Comparative Examples 1 to 5 which use an acrylic polymer obtained by copolymerizing a high Tg monomer with a (meth) acrylic acid alkyl ester, which can be generally used, are as follows: The adhesive strength to the polyimide film is low, and Comparative Examples 1 and 2 do not satisfy the heat resistance. Further, as shown in Comparative Example 4, when the acrylic polymer has no reactive functional group with an epoxy group and the epoxy resin is cured with a curing agent, the acrylic polymer and the epoxy resin are cross-linked even after curing. , Heat resistance is insufficient. In addition, as shown in Comparative Example 5, in the case of an epoxy adhesive composition in which the majority of the composition is occupied by the epoxy resin, the composition has excellent heat resistance, but has many unreacted low molecular components before curing. When gluing, glue sticks out.

Next, Examples 1 to 4 and Comparative Examples 4 and 5
Each of the adhesive sheets was subjected to a storage stability test. In the storage stability test, the temperature of each adhesive sheet was 23 ° C and the humidity was 65%
After being stored for 90 days under the RH atmosphere condition, it was subjected to the peel adhesion strength and heat resistance tests in the same manner as above, and evaluated.
As a result, each of the adhesive sheets of Examples 1 to 4 was almost the same in both properties as before storage. In contrast, Comparative Example 4,
In the adhesive sheet of No. 5, both properties were greatly reduced.

[0074]

The acrylic thermosetting adhesives and adhesive sheets of the present invention have excellent workability that can be cured in a relatively short time. In addition, the adhesive strength to polyimide film is excellent, and 200 ° C for solder reflow process during mounting etc.
It has heat resistance to withstand the above high temperature range, and does not cause adhesion abnormality such as peeling. When the amount of the epoxy resin used is less than a certain amount, the amount of glue exuded at the time of bonding can be reduced, and the storage stability is also good because it contains substantially no curing agent. As described above, according to the present invention, it is possible to provide a thermosetting adhesive sheet for fixing electronic components, which is excellent in reliability.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshimitsu Okuno 1-2-1 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation F-term (reference) 4J004 AA10 AA13 AB05 AB06 CA04 CA06 CA08 CC02 DB01 DB02 EA01 EA04 FA05 FA08 4J040 DF041 DF051 DF061 EC032 EC062 EC082 GA05 GA07 GA11 GA22 HA136 HA196 HA306 JA03 JA12 JB02 KA16 KA23 KA42 LA06 LA08 MA02 MA10 NA20

Claims (11)

[Claims] 1. A monomer mixture containing an imide group-containing (meth) acrylate (A), an alkyl (meth) acrylate (B) and a functional group-containing monomer (C) reactive with an epoxy group. Acrylic thermosetting adhesive composition containing an acrylic polymer to be obtained and an epoxy resin. 2. The acrylic thermosetting adhesive composition according to claim 1, comprising 5 to 30 parts by weight of an epoxy resin based on 100 parts by weight of the acrylic polymer. 3. A monomer mixture comprising a functional group-containing monomer having a reactivity with an imide group-containing (meth) acrylate (A) 5 to 60% by weight, an alkyl (meth) acrylate (B) 15 to 94% by weight and an epoxy group. (C) 1-2
The acrylic thermosetting adhesive composition according to claim 1, comprising 5% by weight. 4. An imide group-containing (meth) acrylate (A) is represented by the following general formula (1), general formula (2), general formula (3), general formula (4) and general formula (5): 1) (Wherein, R ¹ , R ² and R ³ are each independently a hydrogen atom or a methyl group, R ⁴ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. The acrylic thermosetting adhesive composition according to any one of claims 1 to 3, which is at least one selected from compounds represented by the following formula: 5. A functional group reactive with an epoxy group,
The acrylic thermosetting adhesive composition according to any one of claims 1 to 4, wherein the acrylic thermosetting adhesive composition is at least one selected from a carboxyl group, a hydroxyl group, and an epoxy group. 6. The acrylic thermosetting adhesive composition according to claim 1, wherein the acrylic polymer is obtained by copolymerizing a monomer mixture by irradiation with radiation. 7. The acrylic thermosetting adhesive composition according to claim 6, wherein the acrylic polymer is obtained by copolymerizing a crosslinking agent together with the monomer mixture. 8. The acrylic thermosetting adhesive composition according to claim 1, further comprising a crosslinking agent in addition to the acrylic polymer. 9. The acrylic thermosetting adhesive composition according to claim 1, further comprising an inorganic filler. 10. The acrylic thermosetting adhesive composition according to claim 9, comprising 10 to 200 parts by weight of an inorganic filler based on 100 parts by weight of a total of the organic adhesive component. 11. The method according to claim 1, wherein one or both sides of the substrate are provided.
10. An adhesive sheet having an adhesive layer formed from the acrylic thermosetting adhesive composition according to any one of 10.