JPH0234623A - Resin composition for semiconductor sealing - Google Patents

Abstract

PURPOSE:To make it possible to form a resin composition for semiconductor sealing, having a low stress, excellent thermal shock resistance, soldering-heat resistance, etc., and markedly reduced in mold staining by mixing a specified modified epoxy resin with a reaction product of a bismaleimide with a polyphenol compound and an inorganic filler as essential components. CONSTITUTION:This composition essentially consists of a modified epoxy resin (a) consisting of a vinyl-modified silicone polymer-based flexible vinyl polymer dispersed in the form particles of 1.0mum or below in a graft polymer of an epoxy resin with a vinyl polymer, a reaction product (b) of a bismaleimide of formula I (wherein R1 is a 2C or higher bivalent organic group) with a polyphenol compound having at least two phenolic hydroxyl groups and an inorganic filler (c). It is desirable that component (b) is used desirably in such an amount that 30-80wt.% maleimide compound is contained in the resin composition, and that component (c) is used in an amount of 100-600 pts.wt. per 100 pts.wt. total of components (a) and (b).

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention has a low modulus of elasticity and a low coefficient of thermal expansion, and also has excellent thermal shock resistance and soldering heat resistance without impairing heat resistance. The present invention relates to a resin composition for semiconductor encapsulation, which has excellent moldability and is suitable for encapsulation of 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 its economic advantages such as low raw material requirements 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.

[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 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, and this has led to defects that were not seen with conventional sealing resins. 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 the thinning of the resin layer, causing thermal shock that causes damage to the crank of the vancivation film, aluminum wiring slide, or the sealing resin. 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 damage to the package and reducing the moisture resistance of the semiconductor. This causes a decrease in the reliability of the chain. Therefore, it is desired to develop a sealing resin that has less stress and excellent solder heat resistance.

One possible way to reduce the 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 it is necessary to reduce this. To do this, a large amount of inorganic filler with a low coefficient of thermal expansion must be used in the resin, but currently a considerable amount of inorganic filler is already being used, and further increasing this amount will cause deterioration of moldability. becomes. On the other hand, attempts have been made to add plasticizers to lower the elastic modulus of the resin and reduce stress, or to use flexible epoxy resins or phenolic resins, 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.

One way to improve the impact resistance at high temperatures is to increase the heat resistance temperature (glass transition temperature). The use of maleimide resins is considered to be an effective means for this purpose. In particular, bismaleimide is often used due to its low softening point and low viscosity.
Since it has a relatively low molecular weight, it has a problem in that it bleeds onto the surface of the mold during curing, significantly contaminating the mold.

The present invention solves problems such as low stress, thermal shock resistance, and soldering heat resistance, which are required for resins for sealing semiconductors that require high reliability such as highly integrated circuits, and furthermore, An object of the present invention is to provide a resin composition for semiconductor encapsulation that has significantly improved staining.

[Means to solve problems]

As a result of various studies, the inventors of the present invention found that it is possible to uniformly disperse fine particles of a soft vinyl polymer, mainly a vinyl-modified silicone polymer, in a resin composition, and that a reaction product of a specific bismaleimide and a polyphenol compound can reduce stress. The present invention was achieved by finding that it is effective in reducing the size, improving thermal shock resistance and soldering heat resistance, and that mold staining is significantly improved.

That is, the present invention provides (a) a modified epoxy resin in which a soft vinyl polymer mainly composed of a vinyl-modified 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; Resin, (b) -11 Bismaleimide represented by formula (1) and at least 2 phenolic hydroxyl groups
(c) an inorganic filler; (R represents a divalent organic group having at least 2 carbon atoms); (c) an inorganic filler; It is a resin composition for

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 products such as phenol novolak and cresol novolak can be used in view of their heat resistance and electrical properties. Novolak epoxy resin 4 <Preferably, other compounds having two or more active hydrogens in one molecule, such as polyhydric phenols such as bisphenol A, bishydroxydiphenylmethane, resorcinol, bishydroxydiphenyl ether, and tetrabromobisphenol A, and 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 icthalic 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 with epoxy 4M abutinyl polymer in (a) of the present invention is typically produced by polymerizing vinyl monomers to produce the vinyl polymer in the presence of an epoxy resin. The term graft polymer as used herein includes what is commonly referred to as block polymers; the vinyl monomers used to make the vinyl polymer include alkenyl aromatics such as styrene, vinyltoluene, etc., methyl methacrylate, dodecyl methacrylate, etc. Acrylate, butoxyethyl methacrylate, glycidyl methacrylate, methyl acrylate,
Acrylic esters such as butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, trimethylolpropane triacrylate, etc., acrylic compounds without ester groups such as acrylonitrile, acrylic acid, butoxymethylacrylamide, methacrylamide, etc., vinyl Representative examples include non-conjugated vinyl compounds such as acetate, vinyl laurate, vinyl persatate, vinyl chloride, vinylidene chloride, ethylene, allyl acetate, etc., and conjugated diene compounds such as bucdiene, isoprene, and chloroprene.
Polymerizable vinyl compounds such as fluorine compounds of methacrylic acid and acrylic acid such as vinyl silicone, dibutyl fumarate, monomethyl maleate, 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, tert-butyl perbenzoate, etc. is usually used.
Dimethyldibenzoyl peroxyhexane, tert-butyl perbivalate, di-tert-butyl peroxide, 1.1-bi-tert-butyl peroxy 3゜3
．． 5- Trimethylcyclohexane, dimethyl ditertiarybutyl peroxyhexane, tert-butyl cumyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, cumene hydroperoxide, tert-butyl peroxyallyl carbonate, dioctyl peroxydicarbonate, tert-butyl Radical polymerization using peroxides such as peroxymaleic acid, succinic peroxide, tert-butylperoxyisopropyl carbonate, hydrogen peroxide, and azo compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile Representative.

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.

In addition, 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. acrylamide, methylol acrylamide,
Butoxymethylacrylamide, hydroxyethyl methacrylate, glycidyl methacrylate, maleic anhydride, monoethyl itaconate, monobutyl fumarate, chloromethylstyrene, phosphoxyethyl methacrylate, chlorohydroxypropyl methacrylate, rose hydroxystyrene, 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 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 particle size of the resulting soft vinyl polymer is 1
．． It is 0μ or less, preferably 0.5μ or less, more preferably 0.01μ or more and 0.2μ or less. If the particle diameter of the soft vinyl polymer exceeds 1°θμ, the object of the present invention, which is to reduce stress, cannot be achieved and thermal shock resistance cannot be improved.

The soft 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 is a homopolymer or copolymer of vinyl-modified silicone. The vinyl-modified silicone, which refers to a copolymer of a vinyl-modified silicone and another vinyl monomer, includes, for example, methacryloxypropylsiloxane, methacryloxypropylalkoxysilane, vinylalkoxysilane, and the like. 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 obtained copolymer is soft, that is, liquid or rubber-like, and has a particle size of 1.0μ or less, and the proportion of the other vinyl monomers is usually within the range of 1.0 μm or less, depending on the type of monomer. -80% by weight or less.

The particle size of the soft vinyl polymer obtained by polymerization can be controlled by selecting the type and amount of the vinyl polymer that forms the graft polymer with the epoxy resin, and the monomer composition that forms the soft vinyl polymer. It can also be controlled by the amount of double bonds introduced.

It is difficult to disperse a vinyl-modified silicone polymer in an epoxy resin other than a graft polymer of an epoxy resin and a vinyl polymer, even if the silane coupling rule, modified silicone oil, etc. are used, for example.

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

In addition, the amount of the soft vinyl polymer is required to be 5% by weight or more based on the total amount of epoxy resin used.1. 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 bismaleimide used in the present invention is the above-mentioned maximum (1)
This is shown in . Such bismaleimides include, for example, 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-)emshin)bismaleimide,
N,N',4,4'-diphenylsulfone bismaleimide, N,N',4,4°-dicyclohexylmethane bismaleimide, N,N'-α.

α'-4,4°-dimethylenecyclohexane bismaleimide, N,N'-m-methaxylene bismaleimide,
N, N'', 4,4°-diphenylcyclohexane bismaleimide, etc., and one or more of these can be used.

At least 2 phenolic hydroxyl groups used in the present invention
Examples of compounds in which more than one compound exists are bisphenols such as bisphenol A, bisphenol F, and bisphenol S, and condensation products of these with aldehydes, and condensation products of phenols such as phenol, cresol, xylenol, and resorcinol with aldehydes or alkyl ethers. There are condensation reaction products, etc., and a small number of these products (one kind or a mixture can be used).

In order to obtain the reaction product of bismaleimide and a polyphenol compound represented by the general formula (I) used in the present invention, a prepolymer is obtained by heat-treating a pulverized mixture of bismaleimide and a polyphenol compound in a solid state. However, preferably, the bismaleimide and borphenol compounds are dissolved in an organic solvent, partially cured to the prepolymer stage by heat treatment, and then discharged into a poor solvent, and the precipitated crystals are filtered and dried to form pellets. form or powder;
The heat treatment conditions in this case are generally 5 to 240 minutes at a temperature of 70 to 220°C, preferably 10 to 180 minutes at a temperature of 80 to 200°C.

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 the re-reacted 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-
Examples include aprotic polar solvents such as 2-pyrrolidone and 13-dimethyl-2-imidazolinone.

It is also possible to use a catalyst in producing a prepolymer by reacting bismaleimide and polyphenol. Examples of catalysts include phosphines such as tributylphosphine, trioctylphosphine, tricyclohexylphosphine, triphenylphosphine, tribenzylphosphine, tritolylphosphine, and ρ-styryldiphenylphosphine, 1.2-bis(diphenylphosphino)ethane, 1. 4-bis (diphenylphosphino)
Diphenylphosphinoalkanes such as butane, boron compounds such as triphenylphosphine/triphenylborane, tetraphenylphosphonium/tetraphenylborate, triethylammonium/tetraphenylborate, 1,8-diaza-bicyclo(5,40)undecene-
7 and derivatives thereof, tris(polyoxaalkyl)amines represented by tris(3,6-dioxahebutyl)amine, and the like. Other tertiary amines and imidazoles can also be used, but tris(polyoxaalkyl)amines are most preferred from the viewpoint of reactivity.

The amount of catalyst used is 0.1 to 10 parts by weight based on 100 parts of the total amount of bismaleimide and polyphenol compound.

The ratio of bismaleimide and polyphenol compound to be used is at least 1 part per 10 parts by weight of bismaleimide per 100 parts by weight of the polyphenol compound, preferably in the range of 200 parts by weight to 1000 parts by weight. 1001i
If the amount is less than 1 part, sufficient solder heat properties cannot be obtained.

The prepolymer is preferably used in an amount such that the maleimide compound is contained in the resin composition in an amount of 30 to 80% by weight.

Examples of the H-free 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. Examples include carbon fibers alone or in mixtures, but from the viewpoint of thermal expansion coefficient, thermal conductivity, etc., crystalline, meltable, etc. silica powder is usually used. The total amount of (a) and (b) is 100
! It is preferably 100 to 600 parts by weight, and 1
If the amount is less than 0.00 parts by weight, the coefficient of thermal expansion will be large and good impact resistance will not 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.

The resin composition for semiconductor encapsulation of the present invention includes the above (a) and (b).
, (c) as essential components, but in practical use, curing accelerators such as imidazoles, tertiary amines, quaternary ammonium salts, organometallic compounds, organic phosphines, fatty acid amides, fatty acid salts, waxes, etc. mold release agents such as
It is also possible to appropriately incorporate flame retardants such as bromine compounds, antimony, and phosphorus, colorants such as carbon black, silane coupling agents, amines, phenols, etc. The resin composition for semiconductor encapsulation of the present invention It can be easily obtained as a molding material by sufficiently premixing using a mixer or the like, kneading with a hot roll or a melt mixer such as a Nigu, and then cooling and pulverizing.

〔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 1 100 parts of orthocresol novolak epoxy resin (1217 epoxy resin), 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, 3.6 parts of butyl acrylate, 0.1 part of glycidyl nucleate, 2 parts of t-butylperoxy
- 0.05 part of ethylhexanoate is reacted at 100°C for 1 hour. Furthermore, 30 parts of methacryloxypropyl siloxane, 0 parts of neopentyl glycol diacrylate
．． 6 parts, 1,1-bis(t-butylperoxy)3,3
．． 5- After reacting for 4 hours while continuously adding 0.15 parts of tricyclohexane dropwise, and then reacting for another 4 hours, the solvent was removed under reduced pressure to form a modified product in which a soft vinyl polymer with a particle size of 0.2 to 0.5μ was dispersed. Epoxy resin (a-1) (epoxy equivalent 2
95) was obtained.

Production Example 2 In Production Example 1, the amount of methacrylic acid 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. Modified epoxy resin (a-2) in which a soft vinyl polymer with a particle size of 0.2 to 0.5 μm was dispersed (epoxy equivalent weight 3
15) was obtained.

(Production of reaction product of bismaleimide and polyphenol compound) Production example 3 100 parts of N,N'-4,4'-diphenylmethane bismaleimide (manufactured by Mitsui Toatsu Chemical Co., Ltd.), phenol novolac resin (Japanese Gunpowder type, softening point 85°C), 185 parts of N-methyl-2-pyrrolidone, and 1.2 parts of tris(3,6-thioxaheptyl)amine were placed in a flask equipped with a reflux device, and kept at 120°C and reacted for 3 hours. 10 drops of liquid
00 parts of ion-exchanged water, the resulting suspension was filtered, vacuum-dried at 50°C for 24 hours, and the prepolymer (b
-1) was obtained. When comparing the infrared absorption spectrum of the obtained reaction product with before and after the reaction, a decrease in the characteristic absorption derived from the double bond at a wave number of 3100 clI-1 and a characteristic absorption derived from the ether bond at 1200 cm-' were confirmed, both before and after the reaction. The infrared absorption spectra of this material are shown in Figures 1 and 2.

Examples 1 to 2 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 heated roll at 20'C, a resin composition for molding was obtained by cooling, crushing, and tableting.

Using this composition, transfer molding (185°C1
30kg/d for 3 minutes) to test a 100-pin flat package (20m x 30a x 2.5mm, i
oam×1OIl111 test element diameter 13I),
A test piece for measuring physical properties was molded and post-cured at 180°C for 6 hours.

The test results are shown in Table-2.

[Effects of the Invention] As explained in the Examples and Comparative Examples, the resin composition for semiconductor encapsulation according to the present invention has low stress and excellent soldering heat resistance,
Furthermore, since there is less mold staining, it has an excellent effect on productivity. Therefore, when the resin composition of the present invention is used for encapsulating highly integrated semiconductors or small and thin semiconductors such as flat packages, excellent reliability and high productivity can be obtained, and it is industrially beneficial. It can be said that this is a great invention.

[Brief explanation of the drawing]

FIG. 1 shows an infrared absorption spectrum of a reaction product of bismaleimide and phenol novolank, and FIG. 2 shows an infrared absorption spectrum before the reaction.

Claims (1)

[Scope of Claims] (a) A modified structure in which a soft vinyl polymer mainly composed of a vinyl-modified silicone polymer is uniformly dispersed in a graft polymer of an epoxy resin and a vinyl polymer with a particle size of 1.0μ or less. Epoxy resin, (b) Reaction product of bismaleimide represented by the general formula (I) and a polyphenol compound having at least two or more phenolic hydroxyl groups, ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (R_1 is at least 2 A resin composition for semiconductor encapsulation, characterized in that it contains (c) an inorganic filler representing a divalent organic group having a carbon number of .