JP2012224733A - Adhesive composition, production method of the same, cured material of the same, and electronic device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition capable of being stably coated even in a small but desired amount, and having high reliability.SOLUTION: The adhesive composition includes: a core-shell powdery polymer which is constituted of 20 to 80 wt.% of a core including (A) an epoxy resin having a melting point of ≤25°C, and a (meth)acrylate-based polymer having a weight-average particle size of 0.1 to 3.0 μm and a glass transition temperature of ≤-30°C, and 80 to 20 wt.% of a shell including a (meth)acrylate-based polymer having a glass transition temperature of ≥70°C, and which has a softening point of ≥70°C; and (C) a latent curing agent for the epoxy resin, wherein the content of the (B) component is in the range of 10 to 100 pts.wt to 100 pts.wt of the (A) component; and the composition has viscosity at 25°C and 2.5 rpm as measured by an E-type viscometer of 0.1 to 500 Pa s; and the composition generates no bubbles of ≥1 mm in diameter after being allowed to stand for 2 min at 25°C in a vacuum of 100 Pa.

Description

  The present invention relates to an adhesive composition, a production method thereof, a cured product thereof, and an electronic device using the same.

  In recent years, miniaturization of semiconductor devices has been demanded, and semiconductor elements have also been miniaturized. Accordingly, an adhesive composition used for fixing a semiconductor element is required to have a sufficient adhesive strength in a small amount. Application of such an adhesive composition is usually performed by a dispenser or the like, and the application amount is controlled.

  Here, the adhesive composition used for bonding semiconductor elements includes powder components such as various fillers and rubbers for the purpose of improving impact resistance and adjusting the viscosity. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 05-65391

  However, when the powder component is included, air is easily taken into the adhesive composition during the kneading, and bubbles are included in the adhesive composition after the kneading. When air bubbles are included in the adhesive composition, air is discharged together with the adhesive composition at the time of dispensing, and the application amount of the adhesive composition cannot be precisely controlled. Thereby, there exists a problem that the application quantity of the apply | coated adhesive composition may be insufficient and the desired adhesive strength may not be obtained.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a highly reliable adhesive composition that can stably apply a desired amount even in a small amount.

As described above, in order to supply the adhesive in a stable coating amount, it is important that there are few bubbles in the adhesive.
The present inventors have studied the defoaming method of the adhesive composition and the amount of bubbles encapsulated in the adhesive composition. If the adhesive composition does not generate bubbles under a predetermined condition, the dispenser The later application amount became uniform, and it was found that an adhesive composition with high reliability could be obtained, and the present invention was achieved.

The first of the present invention relates to an adhesive composition.
[1] From (A) an epoxy resin having a melting point of 25 ° C. or less, and (B) a (meth) acrylate polymer having a weight average particle diameter of 0.1 to 3.0 μm and a glass transition temperature of −30 ° C. or less. A core-shell type powdery polymer having a softening point of 70 ° C. or higher, and a core composed of 20 to 80% by weight of a core and a shell of 80 to 20% by weight of a (meth) acrylate polymer having a glass transition temperature of 70 ° C. or higher. And (C) a latent curing agent for epoxy resin, the content of the component (B) is in the range of 10 to 100 parts by weight per 100 parts by weight of the component (A), and measured with an E-type viscometer The adhesive composition has a viscosity of 0.1 to 500 Pa · s at 25 ° C. and 2.5 rpm, and does not generate bubbles having a diameter of 1 mm or more after being left for 2 minutes under a vacuum degree of 25 ° C. and 100 Pa.
[2] The component (B) is made of a (meth) acrylate polymer having a glass transition temperature of −30 ° C. or lower obtained by polymerizing a (meth) acrylate monomer and a crosslinkable monomer. A glass transition temperature of 70 ° C. or higher obtained by graft copolymerization of a core, a (meth) acrylate monomer, a crosslinkable monomer, and, if necessary, a monomer copolymerizable therewith [1] The adhesive composition according to [1], comprising a (meth) acrylate copolymer and a shell having an average thickness of 50 mm or more.
[3] The adhesive composition according to [1] or [2], wherein the component (C) is an imidazole curing accelerator or an aminourea curing accelerator.
[4] The adhesive composition according to [3], wherein the imidazole curing accelerator is a microcapsule type.
[5] The adhesive composition according to any one of [1] to [4], wherein the shear adhesive strength after heat curing at 205 ° C. for 5 seconds is 2 × 10 ⁶ Pa or more.
[6] The adhesive composition according to any one of [1] to [5], which is used for bonding a semiconductor chip.
[7] A method for producing an adhesive composition according to any one of [1] to [6], wherein the epoxy resin, the core-shell powdered polymer, and the latent curing agent for epoxy resin, And then defoaming with a rotation and revolution type stirrer.
[8] A cured product of the adhesive composition obtained by curing the adhesive composition according to any one of [1] to [6].
[9] An electronic device including a semiconductor element bonded with the adhesive composition according to any one of [1] to [6].

  According to the present invention, it is possible to obtain a highly reliable adhesive composition capable of stably applying a desired amount even in a small amount.

1. Adhesive Composition The adhesive composition of the present invention contains (A) an epoxy resin, (B) a core-shell type powdered polymer, and (C) a latent curing agent for epoxy resin, as necessary. For example, it contains fillers, thermoplastic polymer fine particles, various additives, and the like.

  The viscosity of the adhesive composition of the present invention at 25 ° C. and 2.5 rpm measured with an E-type viscometer is 0.1 to 500 Pa · s, preferably 5 to 200 Pa · s. If it is less than a lower limit, it will flow easily when apply | coating an adhesive composition, and it will become difficult to apply | coat an adhesive composition only to a desired range. On the other hand, when the upper limit is exceeded, bubbles are difficult to escape during the defoaming treatment of the adhesive composition, which is not preferable from the viewpoint of manufacturing efficiency.

  In addition, the adhesive composition of the present invention does not generate bubbles having a diameter of 1 mm or more after being left for 2 minutes at 25 ° C. under a vacuum of 100 Pa. If the adhesive composition does not generate bubbles under such conditions, the adhesive composition contains almost no bubbles, and even when the adhesive composition is applied little by little, the amount applied Can be stabilized. The generation of bubbles is observed visually.

Further, the adhesive composition of the present invention preferably has a shear bond strength of 2 × 10 ⁶ Pa or more after being heat-cured at 205 ° C. for 5 seconds, more preferably 2.5 × 10 ⁶ Pa or more. preferable. By setting the shear adhesive strength to 2 × 10 ⁶ Pa or more, the adhesive composition of the present invention can be used for various applications. The shear bond strength is measured by a tensile tester according to JIS K6850.

1-1. (A) Epoxy Resin The epoxy resin in the adhesive composition of the present invention is a resin having a melting point of 25 ° C. or lower, that is, a liquid at room temperature, and cures by reacting with the latent curing agent for epoxy resin by heating.

  Such an epoxy resin is not particularly limited as long as it is an epoxy resin having one or more epoxy groups in one molecule. For example, aromatic diols typified by bisphenol A, bisphenol S, bisphenol F, bisphenol AD, and the like, and diols obtained by modifying ethylene glycol, propylene glycol, and alkylene glycol with diols and epichlorohydrin are obtained. Divalent glycidyl ether compound (hereinafter referred to as “bisphenol A type epoxy resin”, for example, using bisphenol A as a raw material); novolak resin derived from phenol or cresol and formaldehyde; polyalkenylphenol and its copolymer Novolak type polyvalent glycidyl ether compounds obtained by reaction of polyphenols typified by, etc. and epichlorohydrin; glycidyl ether compounds of xylylene phenol resin, etc. Murrell. These epoxy resins may be used alone or in combination of two or more.

Of these, cresol novolac type epoxy resin, phenol novolac type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, triphenolmethane type epoxy resin, triphenolethane type epoxy resin, trisphenol type epoxy resin, Examples include dicyclopentadiene type epoxy resin, diphenyl ether type epoxy resin, and biphenyl type epoxy resin.
An epoxy resin having a melting point of 25 ° C. or higher can be used in combination for adjusting various properties as long as the adhesive composition after blending is liquid and does not hinder handling.

  The epoxy resin is preferably contained in an amount of 30 to 90 parts by weight, more preferably 40 to 80 parts by weight per 100 parts by weight of the adhesive composition. When the epoxy resin is contained in the above range, the adhesive strength of the adhesive composition becomes sufficient.

1-2. (B) Core-shell type powdery polymer The core-shell type powdery polymer is added for the purpose of improving the impact resistance of the cured product of the adhesive composition and the shape retention during heat curing. Since the adhesive composition of the present invention contains a core-shell type powdery polymer, it has a property of solidifying in a non-adhesive state or an adhesive state at a temperature lower than the temperature at which the adhesive composition is thermally cured (main curing) ( (Pseudo-curability).

  Depending on the type of adherend to which the adhesive composition is applied, various processing treatments such as bending, cutting, degreasing, acid treatment, etc. of the adherend may be performed after the adhesive composition is applied and before the adhesive composition is fully cured. Necessary. However, when the above processing is performed in a state where the adhesive composition is uncured, there are problems such that the adhesive composition is dropped and scattered during the processing, and the adhesive composition is eluted in the processing liquid. .

  On the other hand, in the adhesive composition of the present invention, since the adhesive composition has pseudo-curability, the adhesive composition is simulated by applying the adhesive composition to the adherend and then heating for a short time. It can be cured (solidified), and the adhesive composition does not fall off, scatter or dissolve during processing. Moreover, removal of an excess adhesive composition also becomes easy by carrying out pseudo-curing of the adhesive composition.

The core-shell type powdery polymer is in the form of powder and is used by being dispersed in the adhesive composition.
The core-shell type powdery polymer in the adhesive composition of the present invention comprises a (meth) acrylate polymer having a weight average particle diameter in the range of 0.1 to 3.0 μm and a glass transition temperature of −30 ° C. or lower. The core is composed of 20 to 80% by weight and a shell made of a (meth) acrylate polymer having a glass transition temperature of 70 ° C. or higher.

  The core-shell type powdery polymer has a softening point of 70 ° C or higher, preferably 80 ° C to 150 ° C. When the softening point is less than 70 ° C., the storage stability in the adhesive composition is insufficient, and there is a possibility that nozzle clogging or the like may occur when the adhesive composition is applied.

  The core of the core-shell type powdery polymer is composed of a (meth) acrylate polymer having a glass transition temperature of −30 ° C. or lower. By having a core composed of a (meth) acrylate-based polymer having a glass transition temperature of −30 ° C. or lower, the core-shell type powdery polymer functions to absorb external stress, and the adhesive composition is cured. The impact strength of objects is greatly improved.

The (meth) acrylate polymer constituting the core is preferably obtained by copolymerizing a (meth) acrylate monomer and a crosslinkable monomer.
The (meth) acrylate monomer is preferably a (meth) acrylate monomer having an alkyl group having 2 to 8 carbon atoms, such as ethyl acrylate, propyl acrylate, n-butyl acrylate, cyclohexyl acrylate, 2 -Ethylhexyl acrylate, ethyl methacrylate, butyl methacrylate and the like are used. These may be used alone or in combination of two or more.

  In addition, examples of the crosslinkable monomer include monomers having two or more double bonds having substantially the same reactivity. Examples include ethylene glycol diacrylate, ethylene glycol dimethacrylate, butylene glycol diacrylate, butylene glycol dimethacrylate, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, hexanediol Examples thereof include aromatic divinyl monomers such as acrylate, hexanediol methacrylate, oligoethylene diacrylate, oligoethylene dimethacrylate, and divinylbenzene, triallylic acid triallyl, triallyl isocyanurate, and the like. These crosslinkable monomers may be used alone or in combination of two or more. The amount used is usually 0.01 to 5% by weight, preferably 0.1 to 2% by weight, based on the total weight of the monomers used to form the core.

  In the (meth) acrylate polymer constituting the core, the (meth) acrylate monomer and the crosslinkable monomer, if necessary, together with the (meth) acrylate monomer and the crosslinkable monomer, It is also possible to use other monomers that can be copolymerized. The amount of the other monomer is usually 50% by weight or less based on the total weight of the monomers used in the core.

  The weight average particle diameter of the core is in the range of 0.1 to 3.0 μm. When the particle diameter of the core particles is less than 0.1 μm, the surface area becomes large at the same weight, so that the dispersibility in the adhesive composition is reduced, and the pressure-sensitive adhesive composition containing the core-shell type powdery polymer is reduced. The storage stability and the mechanical strength of the cured product of the adhesive composition are significantly reduced. On the other hand, when the particle diameter of the core particles exceeds 3.0 μm, the shear adhesive strength and peel strength of the cured product of the adhesive composition may be lowered. The weight average particle diameter is specified by a light scattering measurement method.

  The shell of the core-shell type powder polymer is made of a (meth) acrylate polymer having a glass transition temperature of 70 ° C. or higher. When the glass transition temperature of the shell is less than 70 ° C., the storage stability may be insufficient when an adhesive composition is obtained.

  The (meth) acrylate polymer constituting the shell is obtained by graft copolymerization of a (meth) acrylate monomer, a crosslinkable monomer, and a monomer copolymerizable therewith if necessary. What is obtained is preferred. As the (meth) acrylate monomer, a (meth) acrylate monomer having 1 to 4 carbon atoms can be used alone or in combination of two or more. Examples of the (meth) acrylate monomer having 1 to 4 carbon atoms in the alkyl group include ethyl acrylate, n-butyl acrylate, methyl methacrylate, butyl methacrylate, and the like. You may use combining more than a seed. Of these, methyl methacrylate is particularly preferred.

The crosslinkable monomer and other monomers used as necessary can be the same as those used for the core.
The amount of the crosslinkable monomer used is usually 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the total weight of the monomers contained in the shell. Moreover, the usage-amount of another monomer shall normally be 50 weight% or less.

  The average thickness of the shell is 50 mm or more. If the thickness of the shell is less than 50 mm, the core is not sufficiently covered with the shell, the core is exposed, and the storage stability of the adhesive composition may be lowered.

  The core-shell type powdery polymer can be produced by a two-stage continuous multi-stage seed emulsion polymerization method. It is also possible to form a shell by partially aggregating the seed latex prepared in the first stage by solvent coagulation or the like and then graft-polymerizing the seed latex.

  The content of the core-shell type powdery polymer is in the range of 10 to 100 parts by weight, preferably 10 to 50 parts by weight, per 100 parts by weight of the (A) epoxy resin. If the content of the core-shell type powdery polymer is less than the lower limit, the impact resistance of the cured product of the adhesive composition may not be sufficient. On the other hand, when the upper limit is exceeded, the viscosity of the adhesive composition is remarkably increased, and the handleability is lowered.

1-3. (C) Latent type curing agent for epoxy resin The latent type curing agent for epoxy resin in the present invention is (A) epoxy at room temperature where the adhesive composition is usually stored even when mixed with (A) epoxy resin. It means a curing agent that hardly reacts with the epoxy group of the resin but exhibits the reaction activity of the epoxy group when heated.

  In the present invention, the latent curing agent for epoxy resin is preferably a curing agent exhibiting an epoxy group reaction activity at 70 ° C. or higher, more preferably 80 to 120 ° C. By using a latent curing agent for epoxy resin that exhibits reaction activity at such a temperature, the storage stability of the adhesive composition can be improved. Moreover, even if it is a case where the temperature of an adhesive composition rises at the time of the defoaming process of an adhesive composition, it can prevent that an adhesive composition solidifies.

(C) Although the latent thermosetting agent for epoxy resins is not particularly limited, it is preferable to use an imidazole type curing accelerator or an aminourea type curing accelerator.
Examples of imidazole-type curing accelerators include 2-phenylimidazole (manufactured by Shikoku Kasei Co., Ltd., trade name “Cureazole 2PZ”), 2,4-diamino-6- [2′-ethylimidazolyl- (1 ′)]-ethyltriazine (Shikoku Kasei Co., Ltd., trade name “CURESOL 2E4MZ-A”) and the like.
As amino urea type curing accelerators, amines such as PTI Japan, trade name “Omicure 94”, trade name “Omicure 52”, Fuji Kasei • trade name “Fujicure FXE-1030”, and urea and isocyanate are reacted. Examples thereof include aminourea compounds having a urea bond.

  More preferably, the latent thermosetting agent for (C) epoxy resin includes a microcapsule type curing accelerator. In the microcapsule type curing accelerator, the curing accelerator is encapsulated in the microcapsule, the microcapsule is destroyed by heating, and the curing accelerator diffuses into the adhesive composition to cause the epoxy resin (A). It exhibits the reaction activity of

  Examples of the curing accelerator encapsulated in the microcapsule include amine-based curing agents, acid anhydride-based curing agents, phenol-based curing agents, mercaptan-based curing agents, boron halide salt-based curing agents, and quaternary ammonium salt systems. Examples thereof include a curing agent, a urea curing agent, and a phosphine curing agent. In the present invention, an amine curing agent is particularly preferable, and an imidazole curing agent is particularly preferable.

  The average particle size defined by the median diameter of the curing accelerator to be enclosed is preferably more than 0.3 μm and 12 μm or less. More preferably, it is 1-10 micrometers, More preferably, it is 1.5-5 micrometers. When the particle diameter exceeds 12 μm, the amount of the curing accelerator encapsulated in each microcapsule increases, and it becomes difficult to uniformly cure the epoxy resin in the adhesive composition. On the other hand, when the particle size is smaller than 0.3 μm, it is difficult to form a capsule film, the storage stability of the adhesive composition is lowered, and the solvent resistance of the microcapsule type curing accelerator may be impaired.

  The microcapsules for encapsulating the curing accelerator are preferably those made of a polymer compound from the viewpoint of the balance between stability in the adhesive composition during storage and the expression of activity by heating. Examples of the polymer compound used in the microcapsule include polymer compounds obtained from polyurethane compounds, polyurethane urea compounds, polyurea compounds, polyvinyl compounds, melamine compounds, epoxy resins, and phenol resins.

  The microcapsule type curing accelerator is usually provided as a paste dispersed in an epoxy resin.

  The latent curing agent for epoxy resin is preferably in the range of 1 to 50 parts by weight, more preferably 10 to 40 parts by weight per 100 parts by weight of the (A) epoxy resin. By setting the amount of the latent curing agent for the epoxy resin in such a range, it becomes possible to sufficiently accelerate the curing of the (A) epoxy resin, and the strength of the cured product of the adhesive composition is sufficient. can do.

1-4. Filler The adhesive composition of the present invention may contain a filler for the purpose of controlling the viscosity of the adhesive composition, improving the strength of the cured product of the adhesive composition, controlling the linear expansion, and the like.
There are no particular restrictions on the type of filler, such as calcium carbonate, magnesium carbonate, barium sulfate, magnesium sulfate, aluminum silicate, zirconium silicate, iron oxide, titanium oxide, aluminum oxide (alumina), zinc oxide, silicon dioxide, potassium titanate. Inorganic fillers such as kaolin, talc, glass beads, sericite activated clay, bentonite, aluminum nitride, and silicon nitride can be used.

  Moreover, you may mix | blend the polymer particle in which the softening point temperature by a ring and ball method (JACT test method: RS-2) exceeds 120 degreeC as an organic filler. Examples thereof include copolymers obtained by copolymerizing polystyrene and monomers copolymerizable therewith, polyester fine particles, polyurethane fine particles, rubber fine particles and the like.

The shape of the filler is not particularly limited, and may be a regular shape such as a spherical shape, a plate shape, or a needle shape, or an irregular shape. The filler preferably has an average primary particle size of 1.5 μm or less. The specific surface area ^is preferably 1m ² / g~500m 2 / g.
The average primary particle diameter of the filler can be measured by a laser diffraction method described in JIS Z8825-1. The specific surface area can be measured by the BET method described in JIS Z8830.

  When a filler is blended, it is preferable to blend 30% by weight or less in the adhesive composition. If the filler content exceeds the upper limit, not only will the amount of air bubbles taken in during the production of the adhesive composition increase, but the viscosity of the adhesive composition will increase, and the defoaming efficiency of the adhesive composition will increase. Decreases.

1-5. Thermoplastic polymer fine particles The adhesive composition of the present invention contains a thermoplastic polymer having a softening point temperature measured by a ring and ball method of 50 to 120 ° C., preferably 70 to 100 ° C., if necessary. You may mix | blend the thermoplastic polymer microparticles | fine-particles whose average particle diameter is 0.05-5 micrometers, Preferably it is 0.1-3 micrometers. By containing thermoplastic polymer fine particles in the adhesive composition, the impact resistance of the cured product of the adhesive composition can be improved. Moreover, it can prevent that the viscosity of an adhesive composition raises with a thermoplastic polymer microparticle by making a number average particle diameter below an upper limit. The measuring method of the number average particle diameter can be specified by a dry particle size distribution meter.

  Examples of the thermoplastic polymer fine particles include fine particles obtained by suspension polymerization of a resin containing an epoxy group and a double bond group with a monomer capable of radical polymerization. Examples of the resin containing an epoxy group and a double bond group include a resin obtained by reacting a bisphenol F type epoxy resin and methacrylic acid in the presence of a tertiary amine. Examples of radically polymerizable monomers include butyl acrylate, glycidyl methacrylate, and divinylbenzene.

  1-30 weight part is preferable with respect to 100 mass parts of adhesive composition, and, as for the compounding quantity of a thermoplastic polymer microparticle, 5-20 weight part is more preferable. By setting it as such a range, a thermoplastic polymer microparticle can improve the impact resistance of the hardened | cured material of adhesive composition.

1-6. Other Additives The adhesive composition of the present invention may further comprise a coupling agent such as a silane coupling agent, an ion trapping agent, an ion exchange agent, a leveling agent, a pigment, a dye, a plasticizer, and an antifoaming agent as necessary. Etc. may be contained.

1-7. Method for Producing Adhesive Composition The adhesive composition of the present invention comprises (A) an epoxy resin, (B) a core-shell type powdered polymer, and (C) a latent curing agent for epoxy resin, as necessary. After mixing a filler, thermoplastic polymer fine particles, various additives, etc., it is obtained by performing a defoaming treatment.

  All the above components may be mixed all at once, or may be mixed in several times. The mixing method is not particularly limited, and for example, it can be performed using a known kneading machine such as a double-arm stirrer, a roll kneader, a twin screw extruder, a ball mill kneader, or a planetary stirrer. In order to knead the adhesive composition uniformly without gelling, the kneading temperature is preferably set to 25 to 35 ° C.

  After each component is uniformly mixed, defoaming treatment is performed. In conventional adhesive compositions, defoaming is also performed by performing vacuum depressurization treatment or vibration treatment, but these methods require time for defoaming and ensure defoaming. It may not be possible. Therefore, it is preferable that the defoaming treatment of the adhesive composition of the present invention is stirred with a rotation / revolution type stirrer under reduced pressure conditions. When using a rotation and revolution type stirrer, the temperature of the adhesive composition rises due to mechanical frictional heat, heat storage by stirring, and the like, and the viscosity of the adhesive composition is lowered, so that defoaming is easy. However, it is preferable to perform the defoaming treatment at a temperature lower than the temperature at which the latent curing agent for epoxy resin (C) exhibits the epoxy group reaction activity. Specifically, it is preferable to perform the defoaming treatment while controlling the temperature so that the temperature of the adhesive composition is less than 50 ° C.

  When the defoaming treatment is performed with a rotation and revolution type stirrer, the degree of reduced pressure is preferably −0.1 MPa or less. By setting it as such a range, a defoaming process can be performed efficiently.

  As for the stirring speed when the defoaming treatment is performed by the rotation / revolution type stirrer, the revolution speed is preferably 600 to 3000 rpm, and the rotation speed is preferably 200 rpm to 1000 rpm. If the revolution speed and the rotational speed are less than the lower limit values, it takes time for the defoaming process, which is not preferable from the viewpoint of production efficiency. On the other hand, when the upper limit is exceeded, the temperature rise of the adhesive composition due to mechanical frictional heat and heat storage by stirring may increase, and the adhesive composition may be cured.

  In addition, in the conventional adhesive composition, when the defoaming treatment is performed with a rotation and revolution type stirrer, the temperature of the adhesive composition rises due to mechanical frictional heat generated during stirring, and the adhesive composition is solidified. There is. However, in the present invention, (C) the latent curing agent for epoxy resin is used. In particular, when the latent curing agent for epoxy resin of microcapsule type is used, the temperature of the adhesive composition increases during stirring. Even if it does, hardening of an epoxy resin is not accelerated | stimulated and sufficient defoaming can be performed.

1-8. Use of Adhesive Composition The adhesive composition of the present invention can be used for bonding various members as a one-component adhesive composition. In particular, since the adhesive composition of the present invention hardly contains bubbles, it can be applied to applications in which a small amount is applied for adhesion. Specifically, it is particularly suitable for applications in which 10 mg or less of an adhesive composition is applied and adhered. Examples of such include adhesion of semiconductor elements in electronic devices such as semiconductor devices.
The electronic device is suitable for bonding electronic / electrical components such as sensors, capacitors, switches, and relays.

<Synthesis Example 1>
Synthesis of thermoplastic polymer fine particles (acrylic rubber-modified epoxy resin) In a 2000 ml four-necked flask equipped with a stirrer, gas introduction tube, thermometer, and cooling tube, a liquid epoxy resin, bisphenol A type epoxy resin (Epomic R-) 140P; manufactured by Mitsui Chemicals, Inc.), 12 g of acrylic acid, 1 g of dimethylethanolamine and 50 g of toluene were added and reacted at 110 ° C. for 5 hours while introducing air to introduce double bonds.
Next, 350 g of butyl acrylate, 20 g of glycidyl methacrylate, 1 g of divinylbenzene, 1 g of azobisdimethylvaleronitrile, and 2 g of azobisisobutyronitrile were added and reacted at 70 ° C. for 3 hours while introducing nitrogen into the reaction system. The reaction was carried out at 90 ° C. for 1 hour.

  Next, toluene is removed under reduced pressure at 110 ° C., the composition is rapidly cured at low temperature in the presence of a photocuring catalyst, and the fracture surface morphology of the cured product is observed with an electron microscope to measure the dispersed rubber particle size. An acrylic rubber-modified epoxy resin in which finely crosslinked acrylic rubber fine particles having an average particle diameter of 0.05 μm obtained by the method were uniformly dispersed was obtained.

<Example 1>
30 parts by weight of liquid epoxy resin A (Mitsubishi Chemical Corporation: YL-983U) at 25 ° C., 20 parts by weight of epoxy resin B (Mitsui Chemicals: VG-3101L (diglycidyl ether type epoxy resin)) at 25 ° C. Parts, 10 parts by weight of a core-shell type powdered polymer (manufactured by Ganz Kasei Co., Ltd .: F351G), 9 parts by weight of the acrylic rubber-modified epoxy resin obtained in Synthesis Example 1, and a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-403) ) 1 part by weight was mixed and kneaded with a three-roll mill. Furthermore, 30 parts by weight of an epoxy resin latent curing agent A (manufactured by Asahi Kasei Co., Ltd .: Novacure HXA-4922 (microcapsule type imidazole curing accelerator)) was added to obtain an adhesive composition.

  The obtained adhesive composition was stirred with a rotation and revolution type stirrer under vacuum (100 Pa). After stirring for a predetermined time, the mixture was allowed to stand for 2 minutes under a vacuum of 25 ° C. and 100 Pa, and then defoamed until no bubbles with a diameter of 1 mm or more were generated. The generation of bubbles was confirmed visually. In addition, at the time of stirring with a stirrer, it managed so that the temperature of an adhesive composition did not rise to 50 degreeC or more by mechanical friction heat and the heat storage by stirring.

  The obtained adhesive composition was subjected to viscosity stability, elastic modulus, adhesive strength, and adhesion reliability test by the following methods. The results are shown in Table 1.

(Viscosity stability measurement method)
Using an E-type viscometer, the initial viscosity η1 (25 ° C.) of the adhesive composition at room temperature (25 ° C.) and 2.5 rpm was measured. The adhesive composition was stored in a thermostat at 23 ° C. for 24 hours, then taken out from the thermostat and measured for viscosity η2 (25 ° C.) after storage at room temperature (25 ° C.) and 1 rpm. These measured values were applied to the following formula (1) to determine the viscosity increase rate. The viscosity increase rate calculated by the formula (1) was 1 or more and less than 1.2, ◯, more than 1.2 and less than 1.5, and 1.5 or more, x.
Viscosity increase rate = viscosity after storage at 23 ° C. η2 (25 ° C.) / Initial viscosity η1 (25 ° C.) (1)

(Measurement method of elastic modulus)
The adhesive composition was applied to a release paper with a thickness of 100 μm using a special applicator. This adhesive composition is heated at 150 ° C. for 1 hour, cooled to room temperature, peeled off from the release paper, cut to a predetermined size, and measured for elastic modulus in a tensile mode using a DMS (Dynamic Mechanical Spectrometer). did.

(Measurement method of adhesive strength)
The adhesive strength was measured according to JIS K6850. SUS304 was used for the adherend. A test piece (SUS304) coated with the obtained adhesive composition in a circle with a radius of 10 mm was bonded to the adherend, fixed with a jig, and then heated at 150 ° C. for 60 minutes to prepare an adhesive test piece. . Using this adhesion test piece, the shear bond strength was measured with a tensile tester (manufactured by Intesco). The adhesive strength of 20 MPa or more was evaluated as ◯ (good), the range of 10 MPa or more and less than 20 MPa was evaluated as Δ (somewhat inferior), and less than 10 MPa was evaluated as x (inferior).

(Shape retention after heating)
When measuring the adhesive strength, the shape retention of the adhesive layer in an adhesive test piece obtained by heating at 150 ° C. for 60 minutes was visually observed.
The case where there was no change in the shape before heating and after heating was evaluated as ◯ (good), and the case where the adhesive layer was spread × (inferior).

(Adhesion reliability test)
An adhesion test piece prepared in the same manner as in the above-described method for measuring the adhesive strength was stored at 85 ° C. and 85% Rh for 500 hours, and the shear adhesive strength was measured in the same manner as in the adhesion test.
In addition, a pressure cooker test was performed to evaluate an adhesion test piece prepared in the same manner as the above-described method for measuring adhesive strength. Specifically, it was stored for 100 hours under the conditions of 121 ° C., 2 atm, and humidity 100%, and the shear adhesive strength was measured in the same manner as in the adhesion test.
In each case, the adhesive strength of 20 MPa or more was evaluated as ◯ (good), the range of 10 MPa or more and less than 20 MPa was evaluated as Δ (somewhat inferior), and less than 10 MPa was evaluated as x (inferior).

<Example 2>
The amount of the epoxy resin A that is liquid at 25 ° C. is 40 parts by weight, the amount of the epoxy resin B that is liquid at 25 ° C. is 30 parts by weight, and the latent curing agent for epoxy resin B (Ajinomoto) An adhesive composition was obtained in the same manner as in Example 1 except that 10 parts by weight of Fine Techno Co., Amicure PN-40J) was used.

<Example 3>
The adhesive was the same as in Example 1 except that the amount of liquid epoxy resin A at 25 ° C. was 35 parts by weight, the amount of liquid epoxy resin B at 25 ° C. was 24 parts by weight, and no acrylic rubber-modified epoxy resin was used. A composition was obtained.

<Example 4>
An adhesive composition was obtained in the same manner as in Example 1 except that the amount of the liquid epoxy resin A at 25 ° C. was 50 parts by weight and the amount of the liquid epoxy resin B at 25 ° C. was 20 parts by weight.

<Comparative Example 1>
After stirring for a predetermined time, the adhesive composition was obtained in the same manner as in Example 1 except that the defoaming treatment was completed in a state where bubbles having a diameter of 1 mm or more were generated after being left for 2 minutes at 25 ° C. under a vacuum of 100 Pa. .

<Comparative example 2>
After stirring for a predetermined time, the adhesive composition was obtained in the same manner as in Example 2 except that after leaving for 2 minutes under a vacuum of 25 ° C. and 100 Pa, the defoaming treatment was completed in a state where bubbles with a diameter of 1 mm or more were generated. .

<Comparative Example 3>
After stirring for a predetermined time, the adhesive composition was obtained in the same manner as in Example 3 except that the defoaming treatment was completed in a state where bubbles having a diameter of 1 mm or more were generated after being allowed to stand at 25 ° C. under a vacuum of 100 Pa for 2 minutes. .

<Comparative example 4>
After stirring for a predetermined time, the adhesive composition was obtained in the same manner as in Example 4 except that the defoaming treatment was completed in a state where bubbles having a diameter of 1 mm or more were generated after being allowed to stand at 25 ° C. under a vacuum of 100 Pa for 2 minutes. .

<Comparative Example 5>
Adhesion was carried out in the same manner as in Example 1 except that the amount of liquid epoxy resin A at 25 ° C. was 35 parts by weight, the amount of liquid epoxy resin B at 25 ° C. was 25 parts by weight, and the core-shell powdered polymer was not used. An agent composition was obtained.

<Comparative Example 6>
The amount of the epoxy resin A that is liquid at 25 ° C. is 40 parts by weight, the amount of the epoxy resin B that is liquid at 25 ° C. is 30 parts by weight, and the curing agent for epoxy resin C (manufactured by Shikoku Kasei Co., Ltd., 2E4MZ) An adhesive composition was obtained in the same manner as in Example 1 except that 10 parts by weight were used.

<Comparative Example 7>
An adhesive composition was obtained in the same manner as in Example 1 except that the defoaming method of the adhesive composition was a method in which the rotation and revolution type stirrer was not used and the mixture was allowed to stand for 1 hour under vacuum (100 Pa).

<Comparative Example 8>
An adhesive composition was obtained in the same manner as in Example 1 except that silicon rubber (E-601, manufactured by Toray Dow Corning Co., Ltd.) was used instead of the core-shell type powdery polymer.

  From the above results, when the defoaming treatment was allowed to stand for 2 minutes at 25 ° C. under a vacuum of 100 Pa with a rotation and revolution type stirrer until no bubbles with a diameter of 1 mm or more were generated, The adhesive strength after standing for time and after 100 hours of PCT was excellent (Examples 1 to 4). In particular, in the case of using a microcapsule type latent curing agent for epoxy resin (Examples 1, 3, and 4), after being left for 500 hours under viscosity stability, adhesive strength, and high temperature and high humidity, and for 100 hours of PCT. All of the subsequent adhesive strengths were excellent.

On the other hand, in the case where the defoaming treatment was not performed up to the above state, the adhesive strength decreased after being left for 500 hours under high temperature and high humidity and after 100 hours of PCT (Comparative Examples 1 to 4).
Further, when the core-shell type powdered polymer was not used, the defoaming treatment was allowed to stand for 2 minutes at 25 ° C. under a vacuum degree of 100 Pa. The shape retention after heating was further low (Comparative Example 5). Moreover, when silicon rubber was used instead of the core-shell type powdery polymer, the shape retention after heating was low (Comparative Example 8).

When a non-latent type curing agent for an epoxy resin was used (Comparative Example 6), the viscosity stability was low, and the adhesive strength after standing for 500 hours under high temperature and high humidity and after 100 hours of PCT was low. . This is presumably because the curing agent reacted with the epoxy resin due to the heat generated during the defoaming treatment of the adhesive composition.
Moreover, as a defoaming treatment method, the adhesive strength after being left under high temperature and high humidity for 500 hours and after PCT 100 hours was low only by leaving under vacuum (Comparative Example 7). This is presumably because the defoaming treatment was not sufficiently broken by leaving it alone under vacuum.

  The adhesive composition of the present invention contains almost no bubbles in the composition, and the amount applied does not change even when applied in small amounts. Therefore, the adhesive composition can be used for various applications such as bonding of semiconductor elements.

Claims (9)

(A) an epoxy resin having a melting point of 25 ° C. or lower;
(B) 20-80% by weight of a core composed of a (meth) acrylate polymer having a weight average particle diameter of 0.1 to 3.0 μm and a glass transition temperature of −30 ° C. or less, and a glass transition temperature of 70 ° C. or more. A core-shell type powdery polymer having a softening point of 70 ° C. or higher, comprising 80 to 20% by weight of a shell made of a (meth) acrylate polymer of
(C) containing a latent curing agent for epoxy resin,
The content of the component (B) is in the range of 10 to 100 parts by weight per 100 parts by weight of the component (A),
The viscosity at 25 ° C. and 2.5 rpm measured with an E-type viscometer is 0.1 to 500 Pa · s,
An adhesive composition in which bubbles having a diameter of 1 mm or more are not generated after being allowed to stand at 25 ° C. under a vacuum of 100 Pa for 2 minutes. The component (B) is
A core made of a (meth) acrylate polymer having a glass transition temperature of −30 ° C. or lower, obtained by polymerizing a (meth) acrylate monomer and a crosslinkable monomer;
A (meth) acrylate monomer, a crosslinkable monomer, and, if necessary, a monomer copolymerizable therewith, is obtained by graft copolymerization. The adhesive composition according to claim 1, comprising an acrylate copolymer and a shell having an average thickness of 50 mm or more.   The adhesive composition according to claim 1 or 2, wherein the component (C) is an imidazole curing accelerator or an aminourea curing accelerator.   The adhesive composition according to claim 3, wherein the imidazole curing accelerator is a microcapsule type. The adhesive composition according to any one of claims 1 to 4, wherein the shear adhesive strength after heat curing at 205 ° C for 5 seconds is 2 x 10 ⁶ Pa or more.   The adhesive composition according to any one of claims 1 to 5, which is used for bonding a semiconductor chip. A method for producing an adhesive composition according to any one of claims 1 to 6,
A method for producing an adhesive composition, wherein the epoxy resin, the core-shell powder polymer, and the latent curing agent for epoxy resin are mixed and then defoamed with a rotation and revolution type stirrer.   Hardened | cured material of the adhesive composition which hardened the adhesive composition as described in any one of Claims 1-6. The electronic device containing the semiconductor element adhere | attached with the adhesive composition as described in any one of Claims 1-6.