JPH0588864B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is suitable for encapsulating electronic components such as semiconductors that require high reliability with low elastic modulus and low thermal expansion coefficient and excellent thermal shock resistance without impairing heat resistance. The present invention relates to a resin composition suitable for semiconductor encapsulation. [Prior art] In recent years, so-called plastic encapsulation, which uses thermosetting resins such as epoxy resins, has become widely used as a method for encapsulating semiconductors, taking advantage of its economic advantages such as low raw materials and suitability for mass production. It has been put into practical use. In particular, resin compositions containing polyfunctional epoxy resins, novolac type phenolic resins, and inorganic fillers as main components have become mainstream as sealing resins because of their excellent heat resistance, moldability, and electrical properties. [Problems to be Solved by the Invention] On the other hand, the integration of semiconductor chips has progressed, and the chip size has accordingly increased. In addition, the shape of packages is becoming smaller and thinner, as seen in flat packages, in contrast to the increase in chip size due to higher density mounting on boards. This has led to the occurrence of defective phenomena that were not seen with conventional sealing resins. In other words, as the chip becomes larger and the resin layer becomes thinner, stress in the resin due to the difference in coefficient of thermal expansion between the sealing resin and the chip can lead to cracks in the packaging film or the sealing resin due to thermal shock. This causes destruction phenomena, lowers the moisture resistance of semiconductors, and ultimately lowers reliability. Therefore, it is desired to develop a sealing resin that has less stress. One possible way to reduce stress is to reduce the coefficient of thermal expansion of the resin to reduce the difference between it and that of the chip, but the difference between the coefficient of thermal expansion of the resin and that of the chip is large, and in order to reduce this, requires the use of a large amount of inorganic filler with a low coefficient of thermal expansion in the resin, but currently a considerable amount of inorganic filler is already being used, and further increasing this amount may cause deterioration of moldability. Become. On the other hand, attempts have been made to add plasticizers or to use flexible epoxy resins or phenolic resins in order to lower the elastic modulus of the resin and reduce stress; The cured product had a problem in terms of heat resistance. Furthermore, as exemplified by JP-A-58-108220, methods have been invented in which rubber particles are dispersed in a sealing resin to provide crack resistance while maintaining heat resistance. There were several problems, such as mold contamination and poor impact resistance at high temperatures exceeding the glass transition temperature of the sealing resin, such as in a solder bath. If the mold is heavily contaminated, the mold must be cleaned in a complicated manner, which reduces productivity, which is extremely inconvenient. In addition, if the thermal shock resistance at high temperatures is poor, the reliability after soldering will decrease, but this is a fatal defect in encapsulating materials such as ICs. The present invention is a semiconductor encapsulation resin that has low stress, excellent thermal shock resistance, etc., and does not cause mold contamination during molding, which is required for encapsulation resin for semiconductors that require high reliability such as highly integrated circuits. The purpose of the present invention is to provide a resin composition for stopping use. [Means for solving the problem] As a result of various studies, the present inventors have found that it is effective to uniformly disperse fine particles of a soft vinyl polymer containing acrylic acid esters as a main component in a resin composition. As a result of this discovery, and further studies on the vinyl polymer composition, particle size, etc., the present invention was achieved. That is, the present invention provides: (a) A soft vinyl polymer mainly composed of alkyl acrylate having an alkyl group having 4 or more carbon atoms is uniformly dispersed in a graft polymer of an epoxy resin and a vinyl polymer with a particle size of 0.5 μ or less. A resin composition for semiconductor encapsulation characterized by containing as main components a modified epoxy resin, (b) a curing agent, (c) an inorganic filler, and, if necessary, (d) an epoxy resin. As the epoxy resin used in a) of the present invention, commonly used epoxy resins can be used as long as they are polyhydric epoxy resins, and glycidylated compounds such as phenol novolak and cresol novolak can be used because of their heat resistance and electrical properties. Preferred are novolak epoxy resins such as, but other compounds having two or more active hydrogens in one molecule, such as bisphenol A,
Bishydroxydiphenylmethane, resorcinol,
Bishydroxydiphenyl ether, polyhydric phenols such as tetrabromobisphenol A, ethylene glycol, neopentyl glycose, glycerin, trimethylolpropane, pentaerythritol, diethylene glycol, polypropylene glucose, bisphenol A-ethylene oxide adduct, trishydroxy Glycidyl-type epoxy resin obtained by reacting epichlorohydrin or 2-methylepichlorohydrin with polyhydric alcohols such as ethyl isocyanurate, polyamino compounds such as ethylenediamine, aniline, polycarboxylic compounds such as adipic acid, phthalic acid, isophthalic acid, etc. One or more epoxy resins selected from aliphatic (including alicyclic) epoxy resins such as , dicyclopentadiene diepoxide, butadiene dimer diepoxide, etc. can be used. The graft polymer of an epoxy resin and a vinyl polymer in step (a) of the present invention is typically produced by polymerizing a vinyl monomer to form the vinyl polymer in the presence of an epoxy resin. The term graft polymer herein includes what is commonly called a block polymer. Vinyl monomers used to make the vinyl polymer include alkenyl aromatics such as styrene and vinyltoluene, methyl methacrylate, dodecyl methacrylate, butoxyethyl methacrylate, glycidyl methacrylate, methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate,
Acrylic esters such as trimethylolpropane triacrylate, acrylic compounds without ester groups such as acrylonitrile, acrylic acid, butoxymethylacrylamide, methacrylamide, etc., vinyl acetate, vinyl laurate, vinyl versatate, vinyl chloride, vinyl Representative examples include non-conjugated vinyl compounds such as denchloride, ethylene, and acrylic acetate, and conjugated diene compounds such as butadiene, isoprene, and chloroprene.In addition, polymerizable vinyl compounds such as dibutyl fumarate, monomethyl maleate, diethyl itaconate, etc. Compounds can also be used. In order to polymerize the vinyl monomers described above to obtain a vinyl polymer, a radical initiator such as lauroyl peroxide, benzoyl peroxide, tertiary butyl perbenzoate, dimethyl dibenzoyl peroxyhexane, tertiary butyl perpivalate, dimethyl dibenzoyl peroxide, etc. is usually used. tertiary butyl peroxide, 1,1-bisterciabutyl peroxy 3,3,5-trimethylcyclohexane, dimethyl ditertiary butyl peroxyhexane, tertiary butyl cumyl peroxide,
Methyl ethyl ketone peroxide, cyclohexanone peroxide, kyumene hydroperoxide, tertiary butyl peroxyallyl carbonate, dioctyl peroxydicarbonate, tertiary butyl peroxymaleic acid, succinic acid peroxide, tertiary butyl peroxyisopropyl carbonate, peroxide Peroxides such as hydrogen oxide, azobisisobutyronitrile,
Typically, radical polymerization is carried out using an azo compound such as azobisdimethylvaleronitrile. Further, if necessary, a reducing agent may be used in combination to carry out so-called redox polymerization, and a polymerization inhibitor such as hydroquinone or a chain transfer agent such as dodecyl mercaptan may be used. Furthermore, in order to promote grafting, it is effective to introduce a polymerizable double bond or a chemical bond that can be grafted into the epoxy resin. Examples of methods for introducing polymerizable double bonds include acrylic acid, acrylamide,
Methylol acrylamide, butoxymethyl acrylamide, hydroxyethyl methacrylate, glycidyl methacrylate, maleic anhydride, monoethyl itaconate, monobutyl fumarate, chloromethylstyrene, phosphoxyethyl methacrylate, chlorohydroxypropyl methacrylate, parahydroxystyrene, dimethyl A typical method is to react a compound having a functional group and a polymerizable double bond, such as aminoethyl methacrylate, with an epoxy resin in advance. In the present invention, the epoxy resin or the vinyl polymer may remain free in the graft polymer without being grafted. The modified epoxy resin a) can be obtained by polymerizing a monomer that forms a flexible vinyl polymer in the presence of the above-mentioned graft polymer of an epoxy resin and a vinyl polymer by a conventional method. The flexible vinyl polymer used in the present invention must be a polymer mainly composed of acrylate having an alkyl group having 4 or more carbon atoms, preferably 20 or less carbon atoms. In the case of a polymer mainly composed of alkyl acrylate having less than 4 carbon atoms, the particle size of the obtained soft vinyl polymer exceeds 0.5 μm, and the low stress that is the objective of the present invention cannot be achieved, and the thermal shock resistance cannot be improved. . Carbon number 4
Examples of soft vinyl polymers mainly composed of alkyl acrylates having the above alkyl groups include butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate, lauryl acrylate, tridecyl acrylate, myristyl acrylate, and cetyl acrylate. It is a polymer mainly composed of the above, and it is also possible to copolymerize monomers that can be copolymerized with these acrylates, but the proportion used depends on whether the resulting copolymer is soft, that is, on liquid or rubber. and its particle size is 0.5μ or less, and although it depends on the type of monomer, it is usually 80% by weight or less of the total monomers. These monomers are not particularly limited, but include, for example, acrylates such as methyl acrylate, ethyl acrylate, and propyl acrylate, alkyl methacrylates having an alkyl group having 1 to 24 carbon atoms, cyclohexyl acrylate, benzyl acrylate, and phenoxyethyl acrylate. , phenoxydiethylene glycol acrylate, tetrahydrofurfuryl alcohol acrylate, isobornyl acrylate, dicyclopentadienyl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, glycidyl methacrylate, 1,6-hexane glycol diacrylate, neo Various acrylic acids such as pentyl glycol diacrylate, polypropylene glycol diacrylate, and trimethylolpropane triacrylate, methacrylic acid, ester acids, acrylonitrile, acrylic acid, butoxymethylacrylamide, methacrylamide, and other acrylic compounds without ester groups. , vinyl acetate, vinyl laurate,
Representative examples include non-conjugated vinyl compounds such as vinyl versatate, vinyl chloride, vinyldene chloride, ethylene and allyl acetate, and conjugated diene compounds such as butadiene, isoprene and chloroprene.Other examples include dibutyl fumarate, monoethyl maleate, Polymerizable vinyl compounds such as diethyl itaconate and the like can be used. As mentioned above, the modified epoxy resin is produced by polymerizing monomers that form a soft vinyl polymer in the presence of a graft polymer of an epoxy resin and a vinyl polymer by a conventional method, so that the soft vinyl polymer is dispersed in an approximately spherical shape. Although it is obtained as a composition, the particle size varies depending on the type of vinyl polymer and the type of soft vinyl polymer, but if the particle size exceeds 0.5μ, the purpose of the present invention cannot be achieved. In order to achieve the purpose of the present invention of low stress and improve impact resistance, 0.5μ or less, preferably 0.2μ or less 0.01μ
The particle size must be greater than or equal to Particle size control of the soft vinyl polymer depends on the type of vinyl polymer that forms the graft polymer with the epoxy resin and the monomer composition that forms the soft vinyl polymer, but it also depends on the amount of double bonds introduced into the epoxy resin. It can also be controlled by The composition of the invention may optionally contain an epoxy resin as d). As the epoxy resin in d), all the epoxy resins used in a) above can be used, and the two may be the same or different. Further, the amount of the soft vinyl polymer is required to be 5% by weight or more, and preferably 10 to 20% by weight, based on the total amount of the epoxy resins used in a) and d). If it is less than 5% by weight, low stress cannot be achieved. Moreover, if it exceeds 20% by weight, the strength will drop significantly and it will be difficult to put it into practical use. In order to adjust the above-mentioned soft vinyl polymer to the desired amount, the amount of the vinyl monomer used in producing the modified epoxy resin in a) may be adjusted, but the amount of the epoxy resin in d) may be adjusted. It is easier to carry out the process by making the epoxy resin d), and from this point of view, it is preferable to use the epoxy resin d) in combination. The curing agent b) used in the present invention is generally a novolac type phenolic resin obtained by reacting phenols such as phenol and alkylphenol with formaldehyde or paraformaldehyde, but modified novolac type phenolic resins are also available. , aralkyl-based phenolic resins, commonly used amine-based curing agents, acid anhydrides, and the like can be used alone or in combination. Although there is no particular restriction on the amount to be added, a stoichiometric amount of the epoxy group of the epoxy resin and the functional group of the curing agent is preferred. Examples of the inorganic filler c) used in the present invention include crystalline silica, fused silica, alumina,
Examples include powder-resistant materials such as talc, calcium silicate, calcium carbonate, mica, clay, and titanium white, as well as glass fibers and carbon fibers alone or in combination, but crystalline materials are usually used in terms of thermal expansion coefficient, thermal conductivity, etc. , meltable silica powder, etc. are used.
The blending amount is preferably 200 to 800 parts by weight per 100 parts by weight of the epoxy resin, and if it is less than 200 parts by weight, the coefficient of thermal expansion will be large and good impact resistance will not be obtained. Moreover, if it exceeds 800 parts by weight, the fluidity of the resin decreases and moldability deteriorates, making it difficult to put it into practical use. The resin composition for semiconductor encapsulation of the present invention includes a) particles of 0.5μ or less of a soft vinyl polymer mainly composed of an alkyl acrylate having an alkyl group having 4 or more carbon atoms in a graft polymer of an epoxy resin and a vinyl polymer; Modified epoxy resin uniformly distributed in diameter,
The main components are b) a curing agent, c) an inorganic filler, and optionally d) an epoxy resin, but in practical use imidazoles, tertiary amines, phenols, organometallic compounds, organic phosphines, etc. It is also possible to appropriately blend curing accelerators, fatty acid amides, fatty acid salts, mold release agents such as wax, flame retardants such as prom compounds, antimony, phosphorus, coloring agents such as carbon black, silane coupling agents, etc. . The resin composition for semiconductor encapsulation of the present invention is sufficiently premixed using a mixer or the like, and then heated and rolled.
Alternatively, it can be easily obtained as a molding material by kneading with a melt mixer such as a kneader, followed by cooling and pulverization. The resin composition for semiconductor encapsulation of the present invention thus obtained has a low elastic modulus, a low coefficient of thermal expansion,
Since this resin composition exhibits excellent thermal shock resistance, excellent reliability can be obtained when this resin composition is used for encapsulating highly integrated semiconductors or small and thin semiconductors such as flat packages. Also,
There is no mold contamination during molding, making it suitable for long-term continuous production. [Example] The present invention will be specifically explained using examples.
The invention is not limited to the examples. In the following, parts mean parts by weight unless otherwise specified. Example 1 100 parts of orthocresol novolac epoxy resin (epoxy equivalent: 217), 10 parts of toluene, and 1 part of methacrylic acid were mixed at 120-125°C in the presence of a tertiary amine.
After reacting for an hour, 3.6 parts of butyl acrylate,
0.1 part of glycidyl methacrylate, 0.05 part of t-butylperoxy 2-ethylhexanoate to 100%
Incubate at ℃ for 1 hour. Additionally, 30 parts of butyl acrylate, neopentyl glycol diacrylate
0.6 parts, 1,1-bis(t-butylperoxy)
After reacting for 4 hours while continuously adding 0.15 part of 3,3,5-tricyclohexane dropwise and then for another 4 hours, the solvent was removed under reduced pressure to obtain a modified epoxy resin (A) (epoxy equivalent: 285). Orthocresol novolac epoxy resin (epoxy equivalent: 217) 56 parts, modified epoxy resin (A) 44 parts,
Novolac type phenolic resin (phenol equivalent
106) Mix 41 parts of triphenylphosphine, 0.85 parts of triphenylphosphine, 400 parts of fused silica previously treated with a silane coupling agent, 2 parts of carbon black, and 2.5 parts of carnauba wax, and then heat to 80 to 90°C.
After melting and mixing for 3 minutes with a hot roll, cool and grind.
A molding resin composition was obtained. Using this composition, transfer molding (175℃,
30Kg/cm ² for 3 minutes) to obtain a test piece for physical property testing and a 16-pin DIP (equipped with a 4×8 m/m element) for thermal shock testing. These specimens were molded at 175°C.
After post-curing for 4 hours, various tests were conducted. Example 2 100 parts of orthocresol novolac epoxy resin (epoxy equivalent: 217), 10 parts of toluene, and 0.6 parts of methacrylic acid were mixed at 120 to 125°C in the presence of a tertiary amine.
After reacting for an hour, 3.6 parts of 2-ethylhexyl acrylate, 0.1 part of glycidyl methacrylate, t
-Butylperoxy 2-ethylhexanoate
0.05 part was reacted at 100°C for 1 hour. Further, 30 parts of 2-ethylhexyl acrylate, 0.4 parts of glycidyl methacrylate, 0.4 parts of neopentyl glycol acrylate, and 0.15 parts of 1,1-bis(t-butylperoxy)3,3,5-tricyclohexane were continuously added dropwise for 4 hours. After that, after reacting for another 4 hours, the solvent was removed under reduced pressure and the modified epoxy resin
(B)) (epoxy equivalent weight 297) was obtained. Various tests were conducted in the same manner as in Example 1 using the above modified epoxy resin. Example 3 100 parts of orthocresol novolac epoxy resin (epoxy equivalent: 217), 10 parts of toluene, and 1 part of methacrylic acid were reacted at 120 to 125°C for 2 hours in the presence of a tertiary amine, and then 3.6 parts of 2-ethylhexyl acrylate was added. , glycidyl methacrylate 0.1 part, t-
Butyl peroxy 2-ethylhexanoate 0.05
react at 100°C for 1 hour. Further, 30 parts of 2-ethylhexyl acrylate, 0.4 parts of glycidyl methacrylate, 0.4 parts of neopentyl glycol acrylate, and 0.15 parts of 1,1-bis(t-butylperoxy)3,3,5-tricyclohexane were continuously added dropwise for 4 hours. After that, after reacting for another 4 hours, the solvent was removed under reduced pressure and the modified epoxy resin (C)
(Epoxy equivalent: 296) was obtained. Various tests were conducted in the same manner as in Example 1 using the above modified epoxy resin. Example 4 100 parts of orthocresol novolac epoxy resin (epoxy equivalent: 217), 10 parts of toluene, and 0.9 parts of methacrylic acid were mixed at 120 to 125°C in the presence of a tertiary amine.
After reacting for an hour, 3.6 parts of lauryl acrylate;
100 parts of glycidyl methacrylate, 0.05 parts of t-butyl peroxy 2-ethylhexanoate
Incubate at ℃ for 1 hour. Furthermore, 30 parts of lauryl acrylate, 0.4 parts of glycidyl methacrylate, 0.6 parts of neopentyl glycol diacrylate, 1,
1-bis(t-butylperoxy)3,3,5-
4 while continuously dropping 0.15 part of tricyclohexane.
After reacting for another 4 hours, the solvent was removed under reduced pressure and the modified epoxy resin (D) (epoxy equivalent: 305)
I got it. Various tests were conducted in the same manner as in Example 1 using the above modified epoxy resin. Example 5 In producing the molding resin composition of Example 3, the same as Example 3 except that the amount of orthocresol novolak epoxy resin was changed to 13 parts and the amount of modified epoxy resin (B) was changed to 87 parts. I did it in the same way as 3. Example 6 100 parts of orthocresol novolac epoxy resin (epoxy equivalent: 217), 10 parts of toluene, and 0.4 part of methacrylic acid were reacted at 120 to 125°C for 2 hours in the presence of a tertiary amine, and then 1.3 parts of 2-ethylhexyl acrylate was reacted. 1 part and 0.02 part of t-butylperoxy 2-ethylxanoate were reacted at 100°C for 1 hour.
Furthermore, 11 parts of 2-ethylhexyl acrylate, 0.2 parts of neopentyl glycol diacrylate, 1,
1-bis(t-butylperoxy)3,3,5-
4 while continuously dropping 0.06 part of tricyclohexane.
After reacting for an additional 4 hours, the solvent was removed under reduced pressure to obtain a modified epoxy resin (G) (epoxy equivalent: 245). 100 parts of the above modified epoxy resin, 43 parts of novolak type phenolic resin (phenol equivalent: 106), 0.85 parts of triphenylphosphine, 400 parts of fused silica previously treated with a silane coupling agent, 2 parts of carbon black, and 2.5 parts of carnauba wax. Example 1
A molding resin composition was obtained in the same manner as above, and a test piece was also prepared. Each test was conducted. Comparative Example 1 100 parts of orthocresol novolak epoxy resin (epoxy equivalent: 217), 49 parts of novolak type phenolic resin (phenol equivalent: 106), 0.85 parts of tolphenylphosphine, 412 parts of fused silica previously treated with a silane cutting agent, carbon 2 parts of black and 2.5 parts of carnauba wax were mixed in a mixer, and then melted and mixed for 3 minutes with a heated roll at 80 to 90°C, cooled and ground to obtain a molding resin composition. Using this composition, transfer molding (175℃,
30 Kg/cm ² for 3 minutes) to obtain a test piece for physical property testing and a 16-pin DIP (equipped with a 4×8 m/m element) for thermal shock testing. After forming these test pieces,
After post-curing at 175°C for 4 hours, each test piece was tested. Comparative Example 2 100 parts of orthocresol novolac epoxy resin (epoxy equivalent: 217), 10 parts of toluene, and 0.9 parts of methacrylic acid were heated at 120 to 125°C in the presence of a tertiary amine at 2
After reacting for an hour, 3.6 parts of ethyl acrylate;
0.1 part of glycidyl methacrylate, 0.05 part of t-butylperoxy 2-ethylhexanoate to 100%
Incubate at ℃ for 1 hour. Furthermore, ethyl acrylate
30 parts, glycidyl methacrylate 0.4 parts, neopentyl glycol diacrylate 0.6 parts, 1,1
-Bis(t-butylperoxy)3,3,5-tricyclohexane (0.15 parts) was continuously added dropwise for 4 hours, and then the reaction was continued for another 4 hours.The solvent was removed under reduced pressure and the modified epoxy resin (E) (epoxy equivalent weight 298)
I got it. Various tests were conducted in the same manner as in Example 1 using the above modified epoxy resin. Comparative Example 3 100 parts of orthocresol novolac epoxy resin (epoxy equivalent: 217), 10 parts of toluene, and 0.5 part of methacrylic acid were heated at 120 to 125°C in the presence of a tertiary amine at 2
After reacting for an hour, 3.6 parts of butyl acrylate,
0.1 part of glycidyl methacrylate, 0.05 part of t-butylperoxy 2-ethylhexanoate to 100%
Incubate at ℃ for 1 hour. Furthermore, butyl acrylate
30 parts, glycidyl methacrylate 0.4 parts, neopentyl glycol diacrylate 0.6 parts, 1,1
-Bis(t-butylperoxy)3,3,5-tricyclohexane (0.15 parts) was continuously added dropwise for 4 hours, and then the reaction was continued for another 4 hours.The solvent was removed under reduced pressure and the modified epoxy resin (F) (epoxy equivalent weight 306)
I got it. Various tests were conducted in the same manner as in Example 1 using the above modified epoxy resin. Comparative Example 4 90 parts of orthocresol novolak epoxy resin (epoxy equivalent: 217), 10 parts of bisphenol A diglycidyl ether (epoxy equivalent: 190), novolak type phenolic resin (phenol equivalent: 106)
49 parts, 0.85 parts of triphenylphosphine, 412 parts of fused silica previously treated with a coupling agent,
A molding resin composition was obtained using 2 parts of carbon black and 2.5 parts of carnauba wax in the same manner as in Example 1.
Furthermore, test pieces were prepared and various tests were conducted. Comparative Example 5 90 parts of orthocresol novolac epoxy resin (epoxy equivalent: 217), styrene-butadiene rubber
10 parts, novolac type phenolic resin (phenol equivalent 106) 44 parts, triphenylphosphine 0.85 parts,
400 parts of fused silica, previously treated with a coupling agent;
A molding resin composition was obtained using 2 parts of carbon black and 2.5 parts of carnauba wax in the same manner as in Example 1.
Furthermore, test pieces were prepared and various tests were conducted. The contents of the above examples and comparative examples are shown in Table 1, and the test results are shown in Table 2.

【table】

【table】

〔Effect of the invention〕

As explained in the Examples and Comparative Examples, the resin composition for semiconductor encapsulation according to the present invention has a low elastic modulus, a small coefficient of thermal expansion, and exhibits excellent impact resistance. When used for encapsulating small and thin semiconductors such as highly integrated semiconductors or flat packages, it can achieve excellent reliability, and is suitable for long-term continuous production without mold contamination, making it an industrial choice. It can be said that this invention is useful in terms of

Claims (1)

[Claims] 1a A soft vinyl polymer mainly composed of an alkyl acrylate having an alkyl group having 4 or more carbon atoms is uniformly dispersed in a graft polymer of an epoxy resin and a vinyl polymer with a particle size of 0.5μ or less 1. A resin composition for semiconductor encapsulation, characterized in that the main components thereof are: (b) a curing agent; and (c) an inorganic filler. 2a A modified epoxy resin in which a soft vinyl polymer mainly composed of an alkyl acrylate having an alkyl group having 4 or more carbon atoms is uniformly dispersed in a graft polymer of an epoxy resin and a vinyl polymer with a particle size of 0.5 μ or less, 1. A resin composition for encapsulating a semiconductor, comprising: (b) a curing agent, (c) an inorganic filler, and (d) an epoxy resin.