JPH0236219A - Resin composition for semiconductor encapsulation - Google Patents

Abstract

PURPOSE:To provide the subject composition containing a specific modified epoxy resin, a maleimide resin, a specific polyphenol resin and an inorganic filler and having low elastic modulus, small thermal expantion coefficient, low residual stress and excellent heat-resistance and moldability. CONSTITUTION:The objective composition contains (A) a modified epoxy resin containing uniformly dispersed silicone rubber particles having particle dismeter of <=1.0mum and produced by reacting an addition reaction-type silicone polymer to a graft polymer of an epoxy resin and vinyl polymer (e.g., polystyrene), (B) a maleimide resin, (C) a polyphenol resin of formula I and/or formula II and (D) an inorganic filler (e.g., crystalline silica, alumina or clay).

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention has low stress, excellent heat resistance, and excellent moldability.
The present invention relates to a resin composition for semiconductor encapsulation that is suitable for encapsulating electronic components such as semiconductors that require high reliability.

[Conventional technology]

In recent years, so-called plastic encapsulation using thermosetting resins such as epoxy resins has been widely put into practical use as a method for encapsulating semiconductors, taking advantage of economic advantages such as low raw material costs and suitability for mass production. 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 they have excellent heat resistance, moldability, and electrical properties.

[Problem to be solved by the invention]

On the other hand, as semiconductor chips have become more highly integrated, their chip sizes have become larger. In addition, the shape of pan cages has become smaller and smaller as seen in flat packages, as opposed to larger chips due to higher density mounting on substrates and surface mounting.
There is a trend toward thinner products. For this reason, defective phenomena that were not observed with conventional sealing resins have been introduced. In other words, stress in the resin due to the difference in coefficient of thermal expansion between the sealing resin and the chip increases the size of the chip and thins the resin layer, causing thermal shock that can cause the passivation film to crank, the aluminum wiring to slide, or the sealing resin to crack. Also, as the package itself is exposed to the solder bath temperature due to surface mounting, the moisture inside the pan cage expands rapidly, causing cracks and other destructive phenomena in the pan cage, reducing the moisture resistance of the semiconductor. , which in turn causes a decline in credibility. Therefore, it is desired to develop a sealing resin that has less stress and excellent solder heat resistance.

Specifically, one way is to reduce the thermal expansion coefficient of the resin and increase the heat resistance temperature (glass transition temperature) of the resin, and for this purpose, it is possible to combine a maleimide resin and a phenol resin.

However, molded products cured only with maleimide resin and phenolic resin have a high glass transition temperature, a low coefficient of thermal expansion, and excellent crack resistance when immersed in a solder bath, but the elastic modulus increases, making it difficult for aluminum wiring to slide. However, there was a problem in reducing the stress of the passivation film on the crank.

Furthermore, the phenolic resins used in imperial palaces, such as novolac resins, have poor fluidity during molding and require high pressure. For this reason, especially in the case of thin pan cages, gaps (voids) may occur in the molded product.
The problem was the flow of gold wire.

The present invention is a semiconductor encapsulation resin that has low stress, excellent solder heat resistance, and excellent moldability, which is required for semiconductor encapsulation resins that require high reliability such as highly integrated circuits. A composition is provided.

[Means to solve problems]

As a result of various studies, the present inventors found that they were cured using a combination of a modified epoxy resin in which fine particles of silicone rubber made by reacting an addition-reactive silicone polymer with an epoxy resin were uniformly dispersed, a maleimide resin, and a polyphenol resin with a specific structure. The present invention was achieved as a result of the discovery that a molded product has low stress, excellent soldering heat resistance, and excellent moldability.

That is, the present invention provides (a) a modified epoxy resin in which silicone rubber is uniformly dispersed with a particle size of 1.0 μ or less, which is obtained by reacting an addition reaction type silicone polymer in a graft polymer with an epoxy resin and a vinyl polymer; (b) a maleimide resin; (c) a polyphenol resin represented by the structural formula (n); and (II) (d) an inorganic filler. This is a stopper resin composition.

As the epoxy resin used in (a) of the present invention, any polyhydric epoxy resin can be used, and from the viewpoint of heat resistance and electrical properties, glycidylated compounds such as phenol novolac and cresol novolac can be used. Preferred are novolanque epoxy resins such as, but other compounds having two or more active hydrogens in one molecule, such as polyhydric phenols such as bisphenol A, bishydroxydiphenylmethane, redulucin, bishydroxydiphenyl ether, and tetrabromobisphenol A, Ethylene glycol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, diethylene glycol, polypropylene glycol, bisphenol A-ethylene oxide adduct, polyhydric alcohols such as trishydroxyethyl isocyanurate, ethylenediamine, polyamino compounds such as aniline, adipic acid , glycidyl-type epoxy resins obtained by reacting polyhydric carboxy compounds such as phthalic acid and isophthalic acid with epichlorohydrin or 2-methylepichlorohydrin, aliphatic (alicyclic It is possible to use one or more epoxy resins selected from epoxy resins of the following groups.

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 form the vinyl polymer in the presence of an epoxy resin. The term graft polymer herein includes what is commonly referred to as a bronch 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, 2-ethylhexyl acrylate,
Acrylic esters such as hydroxyethyl acrylate, trimethylolpropane triacrylate, etc., acrylic compounds without ester groups such as acrylonitrile, acrylic acid, butoxymethylacrylamide, methacrylamide, etc., vinyl acetate, vinyl laurate, vinyl persatate, Representative examples include non-conjugated vinyl compounds such as 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, monomethyl maleate, and diethyl itaconate. Polymerizable vinyl compounds such as methacrylic acid such as trifluoroethyl methacrylate and tetrafluoropropyl methacrylate, and fluorine compounds of acrylic acid 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, tert-butyl perbenzoate, dimethyl dibenzoyl perboxyhexane, tert-butyl perbivalate, diter Chaributyl peroxide, 1.1-bister Chaributyl peroxide 33.5
-) Limethylcyclohexane, dimethyl ditert-butyl peroxyhexane, tert-butyl cumyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, cumene hydroperoxide, tert-butyl peroxyallyl carbonate, dioctyl peroxydicarbonate , tertiary butyl peroxymaleic acid, succinic peroxide, tertiary butyl peroxyisobrobyl carbonate, peroxides such as hydrogen peroxide, and azo compounds such as azobisisobutyronitrile, azobisdimethylvaleronitrile. A typical example is radical polymerization.

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. Methods for introducing polymerizable double bonds include, for example, acrylic acid, acrylamide, methylolacrylamide,
Butoxymethylacrylamide, hydroxyethyl methacrylate, glycidyl methacrylate, maleic anhydride, monoethyl itaconate, motuptyl fumarate, chloromethylstyrene, phosphoxyethyl methacrylate, chlorohydroxypropyl methacrylate, parahydroxystyrene, dimethylaminoethyl A typical method is to react a compound having a functional group and a polymerizable double bond, such as 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 subjecting an addition-reactive silicone polymer to an addition reaction in the presence of the above-mentioned graft polymer of an epoxy resin and a vinyl polymer by a conventional method. That is, the silicone rubber in (a) is a rubber produced by an addition reaction through a silylation reaction between a vinyl-modified silicone polymer having a vinyl group in the molecule and a hydrodiene-modified silicone polymer having active hydrogen in the molecule, and the particles thereof The diameter is 1.0μ or less, preferably 0.5μ or less, more preferably 0.5μ or less. O1μ or more 0.
It is 2μ or less. If the particle size of the silicone rubber exceeds 10 μm, the object 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 polysoloxane having at least one 5i-CIl=C11□ bond at the end or inside the molecule, and a hydrogen-modified silicone polymer is a polysoloxane having at least one S i -II bond at the end or inside the molecule. A polysoloxane having two or more elements. Both are usually commercially available in combination, examples of which include 5E4821 from Toren Ricoh 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.

The composition of the present invention contains the modified epoxy resin (a) as an essential component, but may contain an unmodified epoxy resin if desired. Examples of the unmodified epoxy resin include the epoxy resin used in (a), and 11 or more epoxy resins selected from these can be used.

In addition, the silicone rubber obtained by addition reaction is required to be at least 5% by weight based on the total amount of epoxy resin used,
In particular, 10 to 50% by weight is preferable, and if it is less than 5% by weight, stress reduction will not be achieved. The amount of silicone rubber in the resin composition is 1% by weight or more, preferably in the range of 2 to 12% by weight.

The bismaleimide used in the present invention has two or more maleimide groups in one molecule, such as N,
N'-ethylene bismaleimide, N, N'-hexamethylene bismaleimide, N.

N-m-phenylene bismaleimide, N N'p
-phenylene bismaleimide, NN, 44°-diphenylmethane bismaleimide, NN' 4 4' -diphenyl ether bismaleimide, NN -methylenebis (3-chloro-pphenylene) bismaleimide
, N, N″, 44′-diphenylsulfone bismaleimide, NN′4.4′-dicyclohexylmethane bismaleimide, NN-α,α-4,4 dimethylenechlorhexane bismaleimide, NN′-m-methaxylene bis Examples include maleimide, N, N4,4'-diphenylcyclohexane bismaleimide, and at least one of these can be used.

The amount of maleimide used is 30 to 80% by weight in the resin composition.
It is preferable to mix it so that it is included.

The amount of polyphenol resin represented by structural formula (I) and/or structural formula (n) used in the present invention is as follows:
Usually 10 to 500 parts by weight of maleimide resin
Parts by weight range. When used, the resin composition may be blended and kneaded in the usual manner, but it is preferable to dissolve the maleimide resin in the polyphenol resin in advance in terms of kneading and moldability. It is even more preferable to do so.

Furthermore, although the composition of the present invention contains a polyphenol resin represented by structural formula (1) (II) as an essential component, it may contain other phenol resins as desired. As other phenol resins, novolac phenol resins, aralkyl phenol resins, or modified versions thereof can be used alone or in combination.

Examples of the 8g-free filler (d) used in the present invention include powders such as crystalline silica, fused silica, alumina, talc, calcium silicate, calcium carbonate, mica, clay, and titanium white, or glass fibers. Carbon fibers may be used alone or in combination, but from the viewpoint of thermal expansion coefficient, thermal conductivity, etc., crystalline, meltable, etc. silica powder is usually used. The blending amount thereof is preferably 100 to 600 parts by weight per 100 parts by weight of the total amount of (a), (b), and (c); if it is less than 100 parts by weight, the coefficient of thermal expansion is large and good impact resistance cannot be obtained. Moreover, if it exceeds 600 parts by weight, the fluidity of the resin decreases and moldability deteriorates, making it difficult to put it into practical use.

In the present invention, when curing the resin composition, it is preferable to use a basic compound as a curing accelerator. For example, phosphines such as triphenylphosphine, tri-4-methylphenylphosphine, tri-4-methoxyphenylphosphine, tributylphosphine, trioctylphosphine, tri-2-cyanoethylphosphine, 1,
Examples include 8-diazabicyclo(5,4,0)undecene-7 and its salts, imidazoles, and tertiary ammonium salts. The amount of curing accelerator used is (a)
(b) 0.1 to 1100 parts by weight of total ff of (c)
10 parts by weight is preferred.

Moreover, an organic peroxide and an azo compound can be used in combination if necessary. Examples of organic peroxides include dialkyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 1.3bis-(L-butylperoxy-isopropyl)benzene, 1,1-di-butylperoxy 3.3.5-1-limethylcyclohexane,
Examples include dialkyl peroxides such as 1.1-di-t-butylperoxycyclohexane and alkyl peresters such as t-butylperbenzoate.

Ab compounds include azobisisobutyronitrile, azobisdimethylvaleronitrile, and the like.

The amount of the organic peroxide and azo compound added is preferably 0.1 to 5 parts by weight per 100 parts by weight of the maleimide resin.

In addition to the above-mentioned compositions, the composition of the present invention may optionally contain diallyl phthalate, triallylison annulate, 0.0''
- Blending reaction diluents, epoxy resins, amines, silicone oil, silane camping agents, mold release agents, coloring agents, M retardants, etc. commonly used for maleimide resins such as diallyl bisphenol A, Mix and knead to obtain molding material 4.

〔Example〕

The present invention will be specifically explained with reference to examples, but the present invention is not limited to the examples. In the following, parts mean parts by weight unless otherwise specified.

Production Example 1 100 parts of orthocresol novolak epoxy resin (1217 parts per epoxy), 1710 parts of tolu, 1 part of methacrylic acid
After reacting for 2 hours at 120 to 125°C in the presence of a tertiary amine, 5 parts of butyl acrylate, 10 parts of methacryloxypropyl silicone oligomer (manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.0 parts of azobisisovaleronitrile were added. 4 parts and 100 parts of ethyl acetate were reacted at 75°C for 4 hours. Furthermore, as addition reaction type silicone polymers, 10 parts of vinyl-modified polylinoxane and 10 parts of hydrogen-modified polysiloxane (both Kl!-1204 manufactured by Shin-Etsu Chemical Co., Ltd.) were added.
) was added, stirred vigorously, and reacted for 2 hours. Then 1 more
The solvent was removed under reduced pressure at 30°C, and the particle size was 0.2-0.
Modified epoxy resin (a
-1) (epoxy equivalent: 295) was obtained.

Production Example 2 Same as Production Example 1 except that the amount of methacrylic acid used in Production Example 1 was 1.2 parts, and the total amount of vinyl-modified polysiloxane and hydrogen-modified polysiloxane was 30 parts each. The particle size is 0.2 to 0.
Modified epoxy resin (a
-2) (i 320 per epoxy) 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 Toshi Silicone Co., Ltd.) were kept at 75°C. , addition reaction silicone polymer (manufactured by Toshi Silicone Co., Ltd.) 3
0 part was added, and the mixture was stirred vigorously and reacted for 2 hours. then 13
The solvent was removed under reduced pressure at 0'C to obtain a modified epoxy resin (a-3) (1295 epoxy resin) in which silicone rubber with a particle size of 1 to 5 μm was dispersed.

Examples 1 to 4 and Comparative Examples 1 to 6 The raw materials shown in Table 1 were mixed in a mixer, and further 110 to 1
After melt-mixing for 5 minutes using a hot roll at 20°C, a resin composition for molding was obtained by cooling, crushing, and tableting.

Using this composition, transfer molding (185°C,
30kg/cffl for 3 minutes)
0 pin flat package (20mm x 30mm x 2.5
A body, a 12 mm x 12 mm test element), and a test piece for measuring physical properties were molded and then cured at 180°C for 6 hours.

The test results are shown in Table-2.

C) Effects of the invention) As explained in the examples and comparative examples, according to the present invention,
The obtained resin composition has a low modulus of elasticity (low coefficient of thermal expansion, and is therefore excellent in boat stress, as well as exhibits excellent heat resistance and moldability. When used for sealing small and thin semiconductors such as cages, excellent reliability can be obtained, and it can be said that this invention is industrially useful.

Patent applicant: Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] (1) (a) A modified epoxy resin in which silicone rubber is uniformly dispersed with a particle size of 1.0μ or less, which is obtained by reacting an addition reaction type silicone polymer with a graft polymer of an epoxy resin and a vinyl polymer. , (b) Maleimide resin, (c) Polyphenol resin represented by structural formula (I) and/or structural formula (II), ▲There are mathematical formulas, chemical formulas, tables, etc.▼▲There are mathematical formulas, chemical formulas, tables, etc.▼ ( I) (II) (d) A resin composition for semiconductor encapsulation, comprising an inorganic filler.