JPH02624A - Resin composition for semiconductor sealing - Google Patents

Abstract

PURPOSE:To obtain the present composition decreased in modulus and a coefficient of thermal expansion and improved in thermal shock resistance and soldering-heat resistance without detriment to its heat resistance by mixing a modified epoxy resin, a reaction product of a specified bismaleimide with a diamine, and an inorganic filler together. CONSTITUTION:An addition reaction of an addition reaction type silicone polymer (b) is performed in the presence of a graft polymer (a) obtained by polymerizing a vinyl monomer (ii) in the presence of an epoxy resin (i) to obtain a modified epoxy resin (A) in which a silicone rubber of a particle diameter <=1.0mum is dispersed. Separately, a bismaleimide (c) of formula I (wherein R1 is a 2C or higher bivalent organic group) is reacted with a diamine (d) of formula II (wherein R2 is R1) in a molar ratio of (c) to (d) of (10-1):(1-3) at 70-220 deg.C for 5-240min to obtain a reaction product (B). A mixture of component A with component B is mixed with 200-80 pts.wt., per 100 pts.wt. component A, inorganic filler (C) (e.g., silica).

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a heat-resistant town that has a low modulus of elasticity, a low coefficient of thermal expansion, and is heat resistant. Excellent heat resistance and soldering heat resistance.
The present invention relates to a semiconductor encapsulating resin composition suitable for encapsulating electronic components such as semiconductors that require high reliability.

[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 material content and suitability for mass production. has been made into 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 that the invention seeks to solve]

On the other hand, as semiconductor chips have become more highly integrated, their chip sizes have become larger. In addition, the shape of the pan cage 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. For this reason, defective phenomena that were not observed with conventional sealing resins have been introduced. That is,
Stress in the resin due to the difference in thermal expansion coefficient between the sealing resin and the chip increases the size of the chip and thins the resin layer, causing cracks in the bancivation film, sliding of aluminum wiring, or cracks in the sealing resin due to thermal shock. In addition, as the pan cage itself is exposed to the solder bath temperature due to surface mounting, the moisture inside the package expands suddenly and violently, causing a crack phenomenon in the package and reducing the moisture resistance of the semiconductor. This results in a decrease in 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, so 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 a problem in heat resistance.

In addition, as typified by JP-A No. 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 such as a solder bath.

The present invention is suitable for semiconductor encapsulation, which has a small resistance to heat shock and excellent soldering heat resistance, which is required for encapsulation resins for semiconductors that require high reliability such as highly integrated circuits. The purpose is to provide a resin composition.

[Means for solving problems]

As a result of various studies, the present inventors discovered that silicone rubber fine particles formed by reaction of an addition-reactive silicone polymer can be uniformly dispersed in a resin composition, and that a reaction product of a specific bismaleimide and diamine can reduce stress. The present invention was achieved based on the discovery that it is effective in reducing the size and improving thermal shock resistance and soldering heat resistance.

That is, the present invention provides: (a) a modified epoxy in which silicone rubber obtained by reacting an addition-reactive silicone polymer with a particle size of 1.0 μm or less is uniformly dispersed in a graft polymer of an epoxy resin and a vinyl polymer; The resin, (b) a reaction product R9 of bismaleimide represented by general formula (I) and diamine represented by general formula (II), represents a divalent organic group having at least 2 carbon atoms. ) 'zN R2Nil□
(U) (+12 represents a divalent organic group having at least 2 carbon atoms) (c) A resin composition for semiconductor encapsulation characterized by containing 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 novolank and cresol crucible rank can be used because of their heat resistance and electrical properties. Preferred are novolazoqueboxy resins such as compounds, 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. polyhydric alcohols such as ethylene glycol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, diethylene glycol, polypropylene glycol, bisphenol 8-ethylene oxide adduct, trishydroxyethyl isocyanurate, polyamino compounds such as ethylenediamine and aniline, Adipic acid,
Glycidyl-type epoxy resins obtained by reacting polyhydric carboxy compounds such as fucuric acid and isophthalic acid with epichlorohydrin or 2-methylepichlorohydrin; 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 produced by producing the vinyl polymer in the presence of an epoxy resin (a typical method is to produce it by polymerizing a vinyl monomer). The term graft polymer as used herein includes what is commonly called a block polymer. Vinyl monomers used to make vinyl polymers include alkenyl aromatics such as styrene, vinyltoluene, etc., 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, Typical examples include non-conjugated vinyl compounds such as vinyl chloride, vinyldene 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 itaco. It is also possible to use polymerizable vinyl compounds such as fluorine compounds of methacrylic acid, acrylic acid, etc., trifluoroethyl methacrylate, and tetrafluoropropyl methacrylate. 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 perhenzoate, dimethyldibenzoyl peroxyhexane, tert-butyl perpivalate, etc. is usually used. ditertiary butyl peroxide, ■, 1- and tertiary butyl peroxide 33.5
-) Limethyl cyclohexane, dimethyl ditert-butyl peroxyhexane, tert-butyl cumyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, cumene hydroperoxide, tert-butyl peroxyallyl carbonate, dioctyl peroxy dicarbonate, tert-butyl peroxide Using peroxides such as butyl peroxymaleic acid, succinic peroxide, tert-butyl peroxyisopropyl carbonate, hydrogen peroxide, and azo compounds such as abisisobutyronitrile and azobisdimethylvaleronitrile, radical Polymerization is typical.

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, hydroquine ethyl methacrylate, glycidyl methacrylate, maleic anhydride, monoethyl itaconate, motuptyl fumarate, chloromethylstyrene, phosphoxyethyl methacrylate, chlorohydroxypropyl methacrylate, rose hydroxystyrene, dimethylamino A typical method is to react a compound having a functional group and a polymerizable double bond, such as ethyl methacrylate, with an epoxy resin in advance.

In the present invention, the epoxy resin and 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 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. is 1.0μ or less, preferably 0.5μ or less, more preferably 0.01μ or more and 0.
It is 2μ or less. If the particle size of the silicone rubber exceeds 1.0 microns, 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 polysiloxane having at least one 5i-CH=CHz bond at the end or inside the molecule.
The hydrogen-modified silicone polymer is a polysiloxane having at least two 5t-H bonds at the end or inside the molecule. Both are usually commercially available in combination; examples of these include 5E-1821 from Toray Silicone Co., Ltd. and KE from Shin-Etsu Chemical Co., Ltd.
-1204 etc. are mentioned.

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 one 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,
Particularly preferred is 10 to 50% by weight. If it is less than 5% by weight, low stress cannot be achieved.

The bismaleimide used in the present invention has the general formula (+)
This is shown in . Such bismaleimides include, for example, N,N'-ethylene bismaleimide, N
, N-hexamethylene bismaleimide, NN'-m
-Phenylene bismaleimide, N, N' -p-Phenylene bismaleimide, N, N', 4.4 -Diphenylmethane bismaleimide, N, N, 4.4' -
diphenyl ether bismaleimide, NN"-methylenebis(3-chloro-p-phenylene)bismaleimide,
N, N, 4.4°-diphenylsulfone bismaleimide, N, N', 4.4°-dicyclohexylmethane bismaleimide, NN' -αα-4,4-dimethylenecyclohexane bismaleimide, N, N' -m-Meta-xylene bismaleimide, N, N'', 4.4'-diphenylcyclohexane bismaleimide, etc., and at least one of these is used.
Maleimide compounds other than those represented by 1) can also be used in combination.

The diamine used in the present invention is represented by the general formula (■).

Examples of such diamines include 4.4-diaminodicyclohexylmethane, 1.4-diaminodicyclohexane, 26-diamitupyridine, m-phenylenediamine, p-phenylenediamine, 4.4'-diaminodiphenylmethane, 2. 2゛-bis(4-aminophenyl)
Propane, benzidine, 44°-diaminophenyl oquindo, 4,4-diaminodiphenylsulfone, bis(4
-aminophenyl)methylphosphine oxide, bis(
4-aminophenyl) phenylphosphine oxide, bis(4-aminophenyl) methylamine, 1,5-diaminonaphthalene, m-xylylene diamine, 1,1-bis(p-aminophenyl) flat, p-xylylene diamine Hexamethylene diamine, 66-diamine 2,2-
dipyridyl, 4.4”-diaminohenduphenone, 4
4'-diaminoazubenzene, bis(4-aminophenyl)phenylmethane, 1,1-bis(4-aminophenyl)cyclohexane, 1,1-bis(4-amino-3
-methylphenyl)cyclohexane, 2,5-bis(m
-7minophenyl)-1,3,4-oxadiazole,
25-bis(p-aminophenyl)-1,34-oxadiazole, 2,5-bis(m-aminophenyl)thiazolo(4,5-d)thiazole, 55'-di(m-aminophenyl)- (22')-bis(1,3,4-oxadiadur), 4,4-diaminodiphenyl ether, 4
゜4''-bis(p-aminophenyl)-2,2 dithiadur, m-bis(4-p-aminophenyl-2-thiazolyl)benzene, 4,4-diaminobenzanilide, 4
, 4-diaminophenylbenzoate, N N'-bis(4-aminohensyl)-p-phenylenediamine,
Examples include 4,4 methylenebis(2-chloroaniline), and at least one kind or a mixture of these can be used.

In the present invention, bismaleimide represented by general formula (1) and diamine represented by (II) are used as reactants. If it is not used as a reactant, good kneading properties cannot be obtained due to the high softening point of bismaleimide, resulting in a non-uniform resin composition, which poses a problem in terms of moldability. By using it as a reactant, the softening point of bismaleimide can be lowered and good kneading properties can be obtained.

The reaction product of bismaleimide represented by general formula (1) and diamine represented by (II) can be obtained by the method shown below.

(1) Bismaleimide and diamine are pulverized and mixed in solid form, heat treated to form a prepolymer, and then pulverized to form pellets or powder. The heating conditions in this case are preferably those that partially cure the prepolymer stage, and for -S, the temperature is 70 to 220°C for 5 to 240 minutes, preferably 8
Suitably, the heating time is 10 to 180 minutes at a temperature of 0 to 200°C.

(2) Bismaleimide and diamine are dissolved in an organic solvent, then discharged into a poor solvent, and the precipitated crystals are
! Either by over-drying it into a pellet or powder form, or by dissolving it in an organic solvent and partially curing it to the prepolymer stage by heat treatment, then discharging it into a poor solvent, and filtering and drying the precipitated crystals. Shape into pellets or powder. The conditions in this case also conform to (1). The organic solvent that can be used is limited in that it does not substantially react with both components, but it is also desirable that it be a good solvent for both reaction components. The reaction solvents usually used are halogenated hydrocarbons such as methylene chloride, dichloroethane, and trichlorothylene, ketones such as acetone, methyl ethyl ketone, cyclohexanone, and diisopropyl ketone, ethers such as tetrahydrofuran, dioxane, and methyl cellosolve, benzene, toluene, and chlorobenzene. Aromatic compounds such as acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, N-methyl-2-pyrrolidone, aprotic polar solvents such as 1,3-dimethyl-2-imidabrinone, etc. It is.

The usage ratio of (I) and (II) is usually in molar ratio (■)
: (II) is in the range of 10:1-1-3.

Further, the blending amount of the bismaleimide and diamine reactant is preferably 10% or more and 80% or less based on the total amount of the epoxy resin and the reactant. If it is less than 10%, good soldering heat resistance cannot be obtained, and if it is more than 80%, the elastic modulus becomes high and stress cannot be sufficiently reduced.

Examples of the amorphous filler (c) 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 is preferably 200 to 800 parts by weight per 100 parts by weight of the above epoxy resin, and 200 m
! If it is less than 1 part, 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 the above (a) and (b).
, (c) as an essential component, but in practical use, it is used for phenols such as novolac type phenol resins and aralkyl phenol resins, and maleimide resins such as diallyl phthalate, triallyl isocyanurate, and 00''-diallyl bisphenol A. Commonly used reaction diluents, imidazoles, tertiary amines, quaternary ammonium salts, metal compounds, hardening accelerators such as phosphines, fatty acid amides, fatty acid salts, mold release agents such as waxes, etc. It is also possible to appropriately blend a flame retardant such as a bromine compound, antimony, or phosphorus, a coloring agent such as carbon black, a silane coupling agent, etc. The resin composition for semiconductor encapsulation of the present invention can be mixed with a mixer or the like. After sufficiently premixing, the mixture is kneaded with a hot roll or a melt mixer such as a Ni-Goo, and then cooled and pulverized to easily obtain a molding material.

The resin composition for semiconductor encapsulation of the present invention thus obtained has a low elastic modulus, a small coefficient of thermal expansion, and exhibits excellent thermal shock resistance and further excellent soldering heat resistance. When used to encapsulate highly integrated semiconductors or small and thin semiconductors such as flat packages, excellent reliability can be obtained.

[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 of modified epoxy resin) Production Example I 100 parts of orthocresol novolak 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. After that, 5 parts of butyl acrylate, 10 parts of methacryloxypropyl silicone oligomer (manufactured by Shin-Etsu Chemical Co., Ltd.), 0.4 parts of abbisisovaleronitrile,
100 parts of ethyl acetate is reacted at 75°C for 4 hours. Furthermore, as addition reaction type silicone polymers, 10 parts of vinyl-modified polysiloxane and 710 parts of hydrogen-modified polysiloxane (both KE-1204 manufactured by Shin-Etsu Chemical Co., Ltd.) were used.
) was added, stirred vigorously, and reacted for 2 hours. then on fire 1
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 amounts of vinyl-modified polysiloxane and hydrogen-modified polysiloxane were each 30 parts. , particle size 0.2~0,
Modified epoxy resin (a
-2) (epoxy equivalent: 320) was obtained.

Comparative Production Example 1 100 parts of orthocresol novolak epoxy resin (epoxy equivalent: 217), 100 parts of toluene, and 5 parts of a silane camping 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
Modified epoxy resin (a-3) in which silicone rubber with a particle size of 1 to 5 μm is dispersed by removing the solvent under reduced pressure at 0'C (
An epoxy equivalent of 295) was obtained.

(Production of reaction product of bismaleimide and diamine) Production example -
100 parts by weight of 3 N N -44-diphenylmethane bismaleimide powder and 30 parts by weight of 4.4"-diaminodiphenylmethane powder were reacted for 20 minutes with a heated roll at 150" C, cooled and further pulverized to give a softening point of 115. °C
A prepolymer (b-1) was obtained.

Production Example-4 100 parts by weight of N N -44-diphenylmethane bismaleimide, 30 parts by weight of 4.4°-diaminodiphenylmethane, and 200 parts by weight of methyl cellosolve were placed in a flask equipped with a reflux device and kept at 124°C in a nitrogen atmosphere for 5 hours. Made it react. The reaction solution was added dropwise to 1000 parts by weight of ethanol, and the resulting suspension was filtered and dried at 70°C for 24 hours to obtain a prepolymer (b-2) with a softening point of 140°C.

Examples 1 to 4 and Comparative Examples 1 to 5 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°C1
30kg/cIfl for 3 minutes)
Pin flat pack cage (20mm x 30mm x
2.5 aun, 10 + nm x 10 test elements) and a test piece for physical property measurement were molded and
Hardened after hours.

The test results are shown in Table-2.

Table (1) Aluminum slide 65°; : (3 imitation)) - 150°C (change) After 1000 cycles of heating and cooling, the deviation of the bonding panel (100μ x 100μ) at the corner of the test element ( 21V, P
, S test package was kept in a pre-heated car tester at 121°C and 12 atmospheres for 24 hours, and immediately placed in a Fluorinert (Limited 3M FC-70) at 215°C to count the number of cracks.

[Effects 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 low coefficient of thermal expansion, a low stress, and excellent soldering heat resistance. From the results shown, when this resin composition is used to encapsulate highly integrated semiconductors or small type 1 semiconductors such as flanto vano cages, excellent reliability can be obtained, making it suitable for industrial use. It can be said that this is a beneficial invention.

Claims (1)

[Claims] (a) A silicone rubber obtained by reacting an addition reaction type silicone polymer with a graft polymer of an epoxy resin and a vinyl polymer is uniformly dispersed with a particle size of 1.0μ or less. Modified epoxy resin, (b) Reactant of bismaleimide represented by general formula (I) and diamine represented by general formula (II)▲Mathical formula, chemical formula, table, etc. are available▼(I) R_1 is at least 2 carbons represents a divalent organic group having a number. ) H_2N-R_2-NH_2(II) (R_2 represents a divalent organic group having at least 2 carbon atoms.) (c) A resin for semiconductor encapsulation characterized by containing an inorganic filler. Composition.