JPH0588887B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is applicable to semiconductors and other electronic components that require high reliability, low stress, low coefficient of thermal expansion, and excellent thermal shock resistance and soldering heat resistance without impairing heat resistance. The present invention relates to a semiconductor encapsulation resin composition suitable for 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, as opposed to larger chips due to higher density mounting on substrates and surface mounting. This has led to the occurrence of defective phenomena that were not seen with conventional sealing resins. In other words, stress in the resin due to the difference in thermal expansion coefficient between the sealing resin and the chip increases as the chip becomes larger and the resin layer becomes thinner.
Thermal shock causes breakdown phenomena such as cracks in the packaging film, aluminum wiring slides, or cracks in the sealing resin.Also, with surface mounting, the package itself is exposed to the solder bath temperature, so the moisture inside the package expands rapidly. This causes damage to the package, causing cracks and damage to the package.
This is a cause of reducing the moisture resistance of semiconductors and, in turn, reducing reliability. Therefore, it is desired to develop a sealing resin that has less stress and excellent solder heat resistance. 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, but these methods have not produced results. The cured product had problems in terms of heat resistance. In addition, as exemplified by JP-A-58-108220, methods have been invented to provide crack resistance while maintaining heat resistance by dispersing rubber particles in a sealing resin. There were several problems such as poor impact resistance at high temperatures exceeding the glass transition temperature of the sealing resin. The present invention is a semiconductor encapsulation resin that has low stress, thermal shock resistance, and excellent soldering heat resistance, which is required for semiconductor encapsulation resins that require high reliability such as highly integrated circuits. The purpose is to provide a composition. [Means for Solving the Problem] As a result of various studies, the present inventor has developed a modified epoxy resin in which silicone polymer fine particles are dispersed in a graft polymer of an epoxy resin and a vinyl polymer, a maleimide resin, and an active OH group that reacts with the same. A resin that is cured with an aralkyl resin that has two or more of the following and contains a phenyl group as a repeating unit in its molecular structure reduces stress, is effective in thermal shock resistance, and has excellent soldering heat resistance. As a result of the discovery that the present invention is provided, the present invention has been achieved. That is, the present invention provides (a) a modified epoxy resin in which a silicone polymer is uniformly dispersed in a graft polymer of an epoxy resin and a vinyl polymer with a particle size of 1.0 μ or less, (b) a bismaleimide compound, and (c) a phenol aralkyl compound. A resin composition for semiconductor encapsulation, characterized in that the main components thereof are a resin and/or a resorcinol aralkyl resin, and (d) an inorganic filler. 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 glycidyl resins such as phenol novolak and cresol novolak can be used because of their heat resistance and electrical properties. Novolac epoxy resins such as compounds are preferred, but other compounds having two or more active hydrogens in one molecule, such as bisphenol A, bishydroxydiphenylmethane, resorcinol, bishydroxydiphenyl ether, tetrabromobisphenol A Polyhydric phenols such as ethylene glycol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, diethylene glycol, polypropylene glycol, bisphenol A-ethylene oxide adduct, polyhydric alcohols such as trishydroxyethyl isocyanurate, ethylene diamine,
Glycidyl-type epoxy resin, dicyclopentadiene diepoxide, butadiene dimer diepoxide obtained by reacting epichlorohydrin or 2-methylepichlorohydrin with polyamino compounds such as aniline, polyhydric alkoxy compounds such as adipic acid, phthalic acid, isophthalic acid, etc. It is possible to use one or more epoxy resins selected from aliphatic (including alicyclic) epoxy resins such as the following. The graft polymer of an epoxy resin and a vinyl polymer in (a) of the present invention is typically produced by polymerizing a vinyl monomer to produce 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 styrene, alkenyl aromatics such as vinyltoluene, methyl methacrylate, dodecyl methacrylate, butoxyethyl methacrylate, glycidyl methacrylate, methyl acrylate, butyl acrylate, - acrylic esters such as ethylhexyl acrylate, hydroxyethyl acrylate, trimethylolpropane triacrylate, etc., acrylic compounds without ester groups such as acrylonitrile, acrylic acid, butoxymethylacrylamide, methacrylamide, etc., vinyl acetate, vinyl laurate, Typical examples include non-conjugated vinyl compounds such as vinyl versatate, vinyl chloride, vinylidene chloride, ethylene, and allyl acetate, and conjugated diene compounds such as butadiene, isoprene, and chloroprene.Other examples include vinyl silicone, dibutyl fumarate, and monomethyl maleate. Polymerizable vinyl compounds such as fluorine compounds of acrylic acid, methacrylic acid such as diethyl itaconate, trifluoroethyl methacrylate, and tetrafluoropropyl methacrylate 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, chlormethylstyrene, phosphoxyethyl methacrylate, chlorohydroxypropyl methacrylate, para A typical method is to react a compound having a functional group and a polymerizable double bond, such as hydroxystyrene or dimethylaminoethyl 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 addition-reacting an addition-reactive silicone polymer in the presence of the above-mentioned graft polymer of an epoxy resin and a vinyl polymer, or by adding a monomer that forms a soft vinyl polymer by a conventional method. It can be obtained by polymerization according to the method. In other words, addition reaction type silicone rubber is a rubber produced by the addition reaction of a vinyl-modified silicone polymer having a vinyl group in the molecule and a hydrogen-modified silicone polymer having an active hydrogen in the molecule through a silylation reaction, and its particle size is 1.0μ or less, preferably 0.5μ or less, more preferably 0.01μ
0.2μ or less. The particle size of silicone rubber
If it exceeds 1.0μ, the purpose of the present invention, which is to reduce stress, cannot be achieved and thermal shock resistance cannot be improved. A vinyl-modified silicone polymer is a polysiloxane that has at least one Si-CH=CH ₂ bond at the end or inside the molecule, and a hydrogen-modified silicone polymer has a Si-H bond at the end or inside the molecule. Refers to polysiloxane having at least two or more. Both are usually commercially available in combination, and examples of these include SE-1821 from Toray Silicone Co., Ltd. and KE-1204 from Shin-Etsu Chemical Co., Ltd. The particle size of silicone rubber obtained by addition reaction can also be controlled by the amount of double bonds introduced into the epoxy resin. Further, the soft vinyl polymer can be obtained by polymerizing monomers that form a soft vinyl polymer by a conventional method. The flexible vinyl polymer used in the present invention must be a polymer mainly composed of vinyl-modified silicone. The polymer mainly composed of vinyl-modified silicone refers to a homopolymer or copolymer of vinyl-modified silicone, or a copolymer of vinyl-modified silicone and another vinyl monomer. Examples of vinyl-modified silicones include methacryloxypropylsiloxane, methacryloklopropylalkoxysilane, and vinylalkoxysilane. Furthermore, as other vinyl monomers, all the monomers used in preparing the graft polymers mentioned above can be used. The proportion of other vinyl monomers to be used is such that the copolymer obtained is soft, that is, liquid or rubbery, and its particle size is 1.0μ or less. 80% by weight or less. In order to achieve the object of the present invention of reducing stress and improving impact resistance, the particle size of the soft vinyl polymer is 1.0μ or less, preferably 0.5μ or less, and more preferably 0.01μ or more and 0.2μ or less. . If the particle size of the soft vinyl polymer exceeds 1.0μ, it will not be possible to reduce stress.
Thermal shock resistance is also not improved. The particle size of the soft vinyl polymer can be controlled by selecting the type and amount of the vinyl polymer that forms the graft polymer with the epoxy resin, and the composition of the monomers that form the soft vinyl polymer. It can also be controlled by the amount of double bonds. The amount of the modified epoxy resin used is in the range of 0.1 to 10, preferably in the range of 0.5 to 2.0, in terms of equivalent ratio to (c) the phenolic alkyl resin and/or the resorcin alkyl resin described below. The compositions of the present invention may optionally contain unmodified epoxy resins. As the unmodified epoxy resin, all the epoxy resins used in (a) of the present invention can be used, and both may be the same or different. In addition, the amount of silicone polymer (the amount of silicone rubber and/or soft vinyl polymer obtained by addition reaction) is 5% relative to the total of the modified epoxy resin in (a) and the epoxy resin used if desired.
It is required to be at least 10% by weight, particularly preferably 10 to 50% by weight. If it is less than 5% by weight, low stress cannot be achieved. To adjust the amount of silicone polymer to a desired amount, the amount of vinyl monomer used in producing the modified epoxy resin (a) may be adjusted, but by changing the amount of unmodified epoxy resin, It is easier to carry out, and from this point of view as well, it is preferable to use an unmodified epoxy resin. The bismaleimide compound (b) used in the present invention is represented by the general formula ().

[Formula] (R represents a divalent organic group having at least 2 carbon atoms) Examples of such bismaleimide compounds include N,N'-ethylene bismaleimide, N,
N'-hexamethylene bismaleimide, N,N'-
m-phenylene bismaleimide, N,N'-p-
Phenylene bismaleimide, N,N'-4,4'-diphenylmethane bismaleimide, N,N'-4,
4'-diphenyl ether bismaleimide, N,
N'-methylenebis(3-chloro-p-phenylene)bismaleimide, N,N'-4,4'-diphenylsulfone bismaleimide, N,N'-4,4'-
Dicyclohexylmethane bismaleimide, N,
Examples include N'-α,α'-4,4'-diethylenecyclohexane bismaleimide, N,N'-m-methaxylene bismaleimide, and N,N'-4,4'-diphenylcyclohexane bismaleimide. In the present invention, one or more of the above bismaleimide compounds can be used. Moreover, maleimide compounds other than those mentioned above can be used in combination as necessary. The amount of the bismaleimide compound used in the composition of the present invention is usually 30 to 80% by weight. The aralkyl resin used in the present invention has two or more active OH groups and has

〔Example〕

(Production of modified epoxy resin) Production 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 to 125°C in the presence of a tertiary amine for 2 hours.
After reacting for an hour, 5 parts of butyl acrylate, 10 parts of methacryloxypropyl silicone oligomer (manufactured by Shin-Etsu Chemical Co., Ltd.), 0.4 parts of azobisisovaleronitrile, and 100 parts of ethyl acetate are reacted at 75°C for 4 hours. Furthermore, 10 parts of vinyl-modified polysiloxane and 10 parts of hydrogen-modified polysiloxane (both KE-1204, manufactured by Shin-Etsu Chemical Co., Ltd.) were added as addition reaction type silicone polymers, and the mixture was stirred vigorously and reacted for 2 hours. Thereafter, the mixture was further heated to 130°C. Modified epoxy resin (a-1) in which silicone rubber with a particle size of 0.2 to 0.5μ is dispersed by removing the solvent under reduced pressure.
(epoxy equivalent: 295) was obtained. Production Example 2 The amount of methacrylic acid used in Production Example 1 was
Modified epoxy in which silicone rubber with a particle size of 0.2 to 0.5μ is dispersed was prepared in the same manner as in Production Example 1, except that the amount of vinyl-modified polysiloxane and the amount of hydrogen-modified polysiloxane were 30 parts each. Resin (a-2) (epoxy equivalent
320). Production Example 3 100 parts of orthocresol novolac epoxy resin (epoxy equivalent: 217), 10 parts of toluene, and 1 part 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 butyl acrylate,
100 parts of glycidyl methacrylate, 0.05 parts of t-butyl peroxy 2-ethylhexanoate
Incubate at ℃ for 1 hour. Additionally, 30 parts of methacryloxypropylsiloxane, 0.6 parts of neopentyl glycol diacrylate, 1,1-bis(t-butylperoxy)3,3,5-tricyclohexane
Continuously drop 0.15 parts for 4 hours, then for an additional 4 hours.
After reacting for an hour, the solvent was removed under reduced pressure and the particle size was 0.2.
A modified epoxy resin (a-3) (epoxy equivalent: 295) in which a soft vinyl polymer of ~0.5μ was dispersed was obtained. Production Example 4 The amount of methacrylic acid used in Production Example 3 was
1.2 parts, the amount of butyl acrylate was 5.0 parts, the amount of methacryloxypropylsiloxane was 55 parts, and the amount of neopentyl glycol diacrylate was 1.0 parts, except that the particle size was 0.2 parts.
A modified epoxy resin (a-4) (epoxy equivalent: 315) in which a soft vinyl polymer of ~0.5μ was dispersed was obtained. Comparative Production Example 1 100 parts of orthocresol novolac epoxy resin (epoxy equivalent: 217), 100 parts of toluene, and 5 parts of a silane coupling agent (γ-glycidoxypropyltrimethoxysilane, manufactured by Toray Silicone Co., Ltd.) were added to 75%
While maintaining the temperature at 0.degree. C., 30 parts of an addition reaction type silicone polymer (manufactured by Toray Silicone Co., Ltd.) was added, stirred vigorously, and reacted for 2 hours. Thereafter, the solvent was removed under reduced pressure at 130°C, and modified epoxy resin (a-5) in which silicone rubber with a particle size of 1 to 5μ was dispersed (epoxy equivalent: 295)
I got it. Examples 1 to 7 Modified epoxy resin, bismaleimide compound, phenol aralkyl resin,
A resorcinol aralkyl resin, a curing accelerator, an organic peroxide, a quaternary ammonium salt, a silica powder, a silane coupling agent, a wax, a coloring agent, and a flame retardant were blended and kneaded with rolls to obtain a molding material. Comparative Examples 1 to 5 Molding materials were obtained by blending and kneading different combinations of modified epoxy resin, bismaleimide compound, and phenol resin from those in the examples in the same manner as in the examples, using the formulations shown in Table 1. Comparative Example 6 A molding material was obtained by blending and kneading an epoxy resin and a novolac phenol resin in the same manner as in the example, according to the formulation shown in Table 1. Using each molding material, transfer molding (180
℃, 30Kg/ ^cm2 for 3 minutes) to test a 100-pin flat package (20mm x 30mm x 2.5mm, 12
mm x 12 mm test elements) and test pieces for measuring physical properties were molded and cured at 180°C for 6 hours. The test results are shown in Table-2.

【table】

【table】

【table】

〔Effect of the invention〕

As explained in the Examples and Comparative Examples, according to the present invention, the glass transition temperature is higher than that of the sealing resins mainly composed of polyfunctional epoxy resins and novolac phenol resins that have been mainly used in the past.
It has low thermal expansion. In addition, compared to sealing resins whose main components are bismaleimide compounds and phenolic resins other than the combination of the present invention, they have lower water absorption, greater flexibility, and lower stress. Only the examples of the present invention have excellent properties. When this resin composition is used for sealing a large-sized semiconductor device with a high degree of integration or a semiconductor device for surface mounting, excellent reliability can be obtained, and it can be said that this invention is industrially useful.

Claims (1)

[Scope of Claims] 1 (a) A modified epoxy resin in which a silicone polymer is uniformly dispersed in a graft polymer of an epoxy resin and a vinyl polymer with a particle size of 1.0 μ or less, (b) a bismaleimide compound (c) A resin composition for semiconductor encapsulation, characterized in that the main components thereof are a phenol aralkyl resin and/or a resorcin aralkyl resin, and (d) an inorganic filler. 2. The resin composition for semiconductor encapsulation according to claim 1, wherein the silicone polymer is a silicone rubber obtained by reaction of an addition reaction type silicone polymer and/or a soft vinyl polymer mainly composed of a vinyl-modified silicone polymer.