JPH02302422A - Resin composition for semiconductor sealing - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention has a low elastic modulus, a low coefficient of thermal expansion, and has excellent heat resistance, especially low stress and excellent soldering heat resistance after moisture absorption, and is required to have high reliability. The present invention relates to a semiconductor encapsulating resin composition suitable for encapsulating electronic components such as semiconductors.

[Prior Art] In recent years, so-called plastic encapsulation, which uses thermosetting resins such as epoxy resins, has become a popular method for encapsulating semiconductors, taking advantage of its economic advantages such as inexpensive raw materials and mass productivity. It has been widely 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] As semiconductor chips become more highly integrated, their chip sizes have become larger. On the other hand, with the trend toward higher density mounting on substrates and surface mounting, the shape of packages is becoming smaller and thinner, as seen in flat packages, contrary to the trend toward larger semiconductor chips. 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 thermal expansion coefficient between the sealing resin and the chip, as the chip becomes larger and the resin layer becomes thinner, causes cracks in the passivation film as a thermal shock.
This causes destructive phenomena such as misalignment of aluminum wiring and cracks in sealing resin. In addition, with surface mounting, the package itself is exposed to the solder bath temperature, so the moisture inside the package expands rapidly, causing damage to the package such as cracks, and reducing the moisture content of the semiconductor lii'. This in turn causes a decrease in reliability. Therefore, it is desired to develop a sealing resin that has low stress and excellent soldering heat resistance after absorbing moisture.

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 in reality, the difference between the coefficient of thermal expansion of the resin and that of the chip is large (, In order to shrink this, it is necessary to use a large amount of inorganic filler with a low coefficient of thermal expansion in the resin. However, currently a considerable amount of inorganic filler is already being used, and further increasing this amount is difficult for molding. On the other hand, attempts have been made to add plasticizers or use flexible epoxy resins or phenolic resins to lower the elastic modulus of the resin and reduce stress. However, the cured product obtained by this method had a problem in terms of heat resistance.

JP-A-62-270617 and JP-A-62-2
No. 73222 discloses that 1.0μ of silicone polymer is added to a graft polymer of epoxy resin and vinyl polymer.
A method of reducing stress while maintaining heat resistance by uniformly dispersing particles with the following average particle diameter is disclosed. These methods are effective in reducing stress, but when a package that has absorbed moisture is exposed to high temperatures that exceed the glass transition temperature of the resin, such as in a solder bath, cracks occur in the package, resulting in poor solder heat resistance after moisture absorption. There was still a problem with that.

The present invention is suitable for encapsulating semiconductors that require high reliability such as highly integrated circuits, and has low stress, excellent thermal shock resistance, and excellent soldering heat resistance after moisture absorption. The purpose is to provide a resin composition.

[Means for Solving the Problem] As a result of various studies, the present inventors discovered that the above object can be achieved by uniformly dispersing silicone polymer particles in an epoxy resin having a specific structure, The present invention has been achieved.

That is, the present invention provides a modified epoxy resin υ in which a silicone polymer is uniformly dispersed with an average particle diameter of 1.0 μ or less in a graft polymer of a vinyl polymer and a vinyl polymer (where n is an integer from 3 to 16). ) (b) a curing agent;
and (C) an inorganic filler.

This is an acid used in the production of component (a) in the present invention.

General formula (
The epoxy compound represented by I) is obtained by the following general formula ■■ obtained by reacting a dialdehyde compound represented by the following general formula II with phenol in the presence of an acidic catalyst.
It is obtained by reacting a phenol compound represented by the following with epichlorohydrin.

■ O=C-(CLI--C=0
(11) (wherein n represents an integer of 3 to 16) As the epoxy compound of general formula I, those in which n is 3 to 16 can be used, preferably 5 to 12. If n is less than 3, flexibility will be impaired, and if n exceeds 16, no increase in Tg can be expected.

The modified epoxy of the fal component in the present invention is disclosed in Japanese Unexamined Patent Publication No. 6
Publication No. 2-270617 and JP-A-62-27322
It can be manufactured by the method disclosed in Publication No. 2. That is, a graft polymer of an epoxy compound represented by the general formula (I) and a vinyl polymer is typically produced by producing the vinyl polymer in the presence of the epoxy compound represented by the general formula (I). (Manufactured by polymerizing vinyl monomers. Vinyl monomers used to produce vinyl polymers include alkenyl aromatics such as styrene, vinyl toluene, etc.; methyl methacrylate, dodecyl methacrylate, butoxyethyl methacrylate; Acrylate, glycidyl methacrylate, methyl acrylate, butyl acrylate, 2
- 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 , vinyl persatate, vinyl chloride, hnylidene chloride, ethylene, allyl acetate, etc.:
Typical examples are conjugated diene compounds such as butadiene, isoprene, and chlorobrene, and other examples include vinyl silicone,
Polymerizable vinyl compounds such as fluorine compounds of methacrylic acid and acrylic acid such as dibutyl fumarate, monomethyl maleate, diethyl itaconate, trifluoroethyl methacrylate, and tetrafluoropropyl methacrylate can also be used. The amount of vinyl monomer used at this time is not particularly limited, but generally epoxy resin 10
The amount is 1 to 50 parts by weight relative to 0 parts by weight. 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-bistarcharybutylperoxy-3,3,5-trimethylcyclohexane, dimethyl ditertiarybutylperoxyhexane, tertiarybutylcumyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, cumene hydroper Peroxides such as oxide, tert-butyl peroxyallyl carbonate, dioctyl peroxydicarbonate, tert-butyl peroxymaleic acid, succinic acid peroxide, tert-butyl peroxyisopropyl carbonate, hydrogen peroxide,
Typically, radical polymerization is carried out using an azo compound such as azobisisobutyronitrile or azobisdimethylvaleronitrile. The amount of these radical initiators used is usually 0.1-10% by weight based on the vinyl monomer.

Furthermore, so-called redox polymerization may be carried out by using a reducing agent in combination as necessary, 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 graftable chemical bond such as a polymerizable double bond into the epoxy resin. Examples of methods for introducing polymerizable double bonds include acrylic acid, methacrylic acid, acrylamide, methylol acrylamide, butoxymethyl acrylamide, hydroxyethyl methacrylate, glycidyl methacrylate, maleic anhydride, monoethyl itaconate, and monobutyl fumarate. , chloromethylstyrene,
Phosphoxyethyl methacrylate, chlorohydroxypropyl methacrylate, parahydroxystyrene,
A typical method is to react a compound having a functional group and a polymerizable double bond, such as dimethylaminoethyl methacrylate, with an epoxy resin in advance. When using a compound having a functional group and a polymerizable double bond.

The amount used is usually 0 per 100 parts by weight of epoxy resin.
．． It is 1 to 10 parts by weight.

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 used as component (a) in the present invention is prepared by adding an addition reaction type silicone polymer in the presence of the above-mentioned graft polymer of an epoxy resin and a vinyl polymer by a conventional method (addition reaction type (silicone rubber) or by polymerizing monomers that form a soft vinyl polymer by a conventional method (soft vinyl polymer).

That is, the addition reaction type silicone rubber 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. Vinyl-modified silicone polymers have at least one Si-CH=CH* bond at the end or inside of the molecule.
A hydrogen-modified silicone polymer is a polysiloxane having 5i at the end or inside the molecule.
A polysiloxane having at least two -H bonds. Both are usually commercially available in combination; examples of these include Toshi Silicone SE-1821;
Shin-Etsu Chemical Co., Ltd.'s E-1204 and the like are listed.

Further, the soft vinyl polymer can be obtained by polymerizing a polymer that forms a soft vinyl polymer by a conventional method. 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 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, methacryloxypropylalkoxysilane, and vinylalkoxysilane. Moreover, as other vinyl monomers, all the monomers used in preparing the above-mentioned graft polymers can be used. The proportion of other vinyl monomers to be used is such that the resulting copolymer is soft, ie liquid or rubbery, and has an average particle size of 1.0μ or less.Although it depends on the type of monomer, usually all the monomers are 80% by weight or less.

In order to achieve the purpose of the present invention of reducing stress and improving thermal shock resistance, the average particle diameter of the addition reaction silicone rubber or soft vinyl polymer is 1.0μ or less, preferably 0.5μ or less, More preferably the mouth, old μ or more 0.2
It is less than μ. If the average particle diameter of the addition reaction type silicone rubber or soft vinyl polymer exceeds 1.0 μm, stress reduction cannot be achieved and thermal shock resistance cannot be improved. The particle size of the addition reaction type silicone rubber or soft vinyl polymer can be controlled by controlling the type and amount of the vinyl polymer that forms the graft polymer with the epoxy resin, and the above-mentioned characteristics that form the addition reaction type silicone rubber or soft vinyl polymer. This is possible by selecting the polymer or monomer composition, but it can also be controlled by the amount of double bonds introduced into the epoxy resin. Further, the amount of the above-mentioned specific polymer or monomer used to form the addition reaction type silicone rubber and the soft vinyl polymer is not particularly limited, but in terms of -M, it is 1 to 100 parts by weight per 100 parts by weight of the epoxy resin. Parts by weight.

Although it is easy to disperse a vinyl-modified silicone polymer in a graft polymer of an epoxy resin and a vinyl polymer, it is difficult to disperse a vinyl-modified silicone polymer in other epoxy resins, such as using a silane coupling agent. , even if modified silicone oil or the like is used.

The composition of the present invention has the modified epoxy resin as component (a) as an essential component, but the proportion of the addition reaction type silicone rubber and/or soft vinyl polymer in the entire resin composition is adjusted to a desired value. In order to
Examples of unmodified polyfunctional epoxy resins that may contain more than one type of unmodified polyfunctional epoxy resin include compounds having two or more active hydrogens in one molecule, such as bisphenol A, bishydroxydiphenylmethane, and resorcinol. , bishydroxydiphenyl ether, bishykyl, resorcinol aralkyl, brominated bisphenol A5, polyhydric phenols such as brominated phenol novolak, ethylene glycol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, diethylene glycol, polypropylene glycol, bisphenol. Ethylene oxide adducts, polyhydric alcohols such as trishydroxyethyl isocyanurate, polyamino compounds such as ethylenediamine, aniline, 4.4'-diaminodiphenylmethane, polycarboxylic compounds such as adipic acid, phthalic acid, isophthalic acid, etc., and epichlorohydrin. Alternatively, aliphatic (including alicyclic group) epoxy resins such as glycidyl-type epoxy resins obtained by reacting with 2-methylepichlorohydrin, dicyclopentadiene diepoxide, butadiene dimer diepoxide, etc. can be used. . Furthermore, an epoxy compound represented by the general formula (I) can also be used.

The amount of modified epoxy resin used as component (a) is:

What is the amount of modified epoxy resin used as the fat component?

A desired addition reaction type silicone rubber and/or soft vinyl polymer is added to the final sealing resin composition, and a desired addition reaction type silicone rubber and/or soft vinyl polymer is added to the modified epoxy resin. It can be easily determined by one skilled in the art based on the amount.

In addition, silicone rubber obtained by addition reaction and/or
Alternatively, the amount of the soft vinyl polymer is required to be 1 to 30% by weight, particularly preferably 2 to 12% by weight, in the total amount of the ta) component, the unmodified epoxy resin used if desired, and the bl component. If it is less than 30% by weight, low stress cannot be achieved, and if it exceeds 30% by weight, the fluidity of the resin will decrease.
Formability deteriorates.

The curing agent used in the present invention (bl component) is
Novolac-type phenolic resins obtained by reacting phenols such as phenol and alkylphenols with formaldehyde or paraformaldehyde are common, but there are also modified novolac-type phenolic resins, phenol aralkyl resins, resorcin aralkyl resins,
Polyhydric phenols such as triphenolmethane and tetraphenoleethane, the phenolic compound represented by the general formula m above, and commonly used amine curing agents and acid anhydrides can be used alone or in combination. can.

The amount of the curing agent to be blended is generally in the range of 1.0 to 1O, preferably 0.5 in terms of equivalent ratio to the modified epoxy resin of component (a) and the unmodified epoxy resin used if desired. ~2.0.

Examples of the inorganic filler as component (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., amorphous or spherical silica powder with crystallinity and meltability is usually used. Its compounding amount is (
10 parts by weight per 100 parts by weight of the total amount of components a), component (b), and unmodified epoxy resin used if desired.
The amount is preferably from 0 to 800 parts by weight, and if it is less than 100 parts by weight, the coefficient of thermal expansion will be large and good thermal shock resistance will not be obtained. Moreover, when it exceeds 800 parts by weight, the fluidity of the resin decreases and moldability deteriorates.

The resin composition for semiconductor encapsulation of the present invention has (a) general formula (I
) A modified epoxy resin in which a silicone polymer is uniformly dispersed with an average particle diameter of 1.0 μ or less in a graft polymer of an epoxy compound and a vinyl polymer shown in (b)
) A curing agent and (C)@tissue filler are essential components, but
In practical use, curing accelerators such as imidazoles, tertiary amines, quaternary ammonium salts, organometallic compounds, and organic phosphines, mold release agents such as fatty acid amides, fatty acid salts, and waxes, bromine compounds, antimony, phosphorus, etc. flame retardant,
Colorants such as carbon black, silane coupling agents,
It is also possible to appropriately blend a maleimide compound or the like.

The resin composition for semiconductor encapsulation of the present invention can be easily obtained as a molding material by sufficiently premixing with a mixer or the like, kneading with a hot roll or a melt mixer such as a Nigu, and then cooling and pulverizing. I can do it.

[Example] Synthesis Example 1 In a reactor equipped with a thermometer, a condenser, a dropping funnel, and a stirrer, 1.0 mol of phenol and 0 octanedial were added.
．． After adding 1 mole and heating to 40℃, add 0.2 m of concentrated hydrochloric acid.
1 was added. After the addition, the mixture was kept at 50°C for 30 minutes, and after the heat generation stopped, the temperature was raised to 90°C, and the reaction was carried out for 5 hours. Next, volatile components were removed at 5 mmHg and 150°C to obtain a phenol compound having a softening point of 98.9°C, free phenol of 0.5%, and hydroxyl equivalent of 122.

In a reactor equipped with a thermometer, a condenser, a dropping funnel and a stirrer, 1 mole of the phenolic compound obtained was dissolved in 10 moles of epichlorohydrin.

Next, the mixture was heated to 60° C., and 400 g of a 40% aqueous sodium hydroxide solution was continuously added dropwise over 2 hours. During this time, epichlorohydrin and water were azeotropically liquefied and separated into an organic layer and an aqueous layer in a separation tube, the aqueous layer was removed from the system and the organic layer was circulated into the system. After the reaction was completed, unreacted epichlorohydrin was removed at 5 mmHg and 150°C, and the reaction product was dissolved in methyl isobutyl ketone. Next, by-product salts were filtered off, and methyl isobutyl ketone was removed by evaporation to obtain an epoxy compound. This resin had a softening point of 74.9°C and an epoxy equivalent of 178.

Synthesis Example 2 A phenol compound having a softening point of 69.2°C, free phenol of 0.5%, and hydroxyl equivalent of 136 was obtained in the same manner as in Synthesis Example 1 except that octanedial was changed to dodecanedial. Using this, epoxy compound (2) was obtained in the same manner as in Synthesis Example 1. The softening point of this resin is 50℃,
The epoxy weight was 191.

Production example 1 Synthesis example! Epoxy resin (1) obtained in (epoxy equivalent: 17
8: 100 parts of Mitsui Toatsu Chemical Co., Ltd.), 10 parts of toluene, and 1 part of methacrylic acid in the presence of tetradecyldimethylbenzyl ammonium chloride at 120 to 125°C.
After reacting for hours, 5 parts of butyl acrylate, 10 parts of methacryloxypropyl silicone oligomer (manufactured by Shin-Etsu Chemical), 0.4 parts of azobisisovaleronitrile, and 100 parts of ethyl acetate were added and reacted at 75°C for 4 hours. I let it happen. Furthermore, as addition reaction type silicone polymers, 15 parts of vinyl-modified polysiloxane and 15 parts of hydrogen-modified polysiloxane (both manufactured by Shin-Etsu Chemical W, ε-120) were used.
4) was added and reacted for 2 hours with vigorous stirring. After that, the solvent was further removed under reduced pressure at 130°C, and the particle size was 0.2.
A modified epoxy resin (a-1) (epoxy equivalent: 271) in which silicone rubber of ~0.5μ was dispersed was obtained.

Production Example 2 100 parts of the epoxy compound used in Production Example 1, 10 parts of toluene, and 1 part of methacrylic acid were mixed in the presence of tetradecyldimethylpentylammonium chlorite to 120 to 12
After reacting at 5°C for 2 hours, butyl acrylate 3.
6 parts, glycidyl, 0.1 part of methacrylate and t-
Butyl peroxy-2-ethylhexanoate 0.05
100° C. and reacted at 100° C. for 1 hour. Furthermore, 30 parts of methacryloxypropylsiloxane, 0.6 parts of neopentyl glycol diacrylate, and 0.15 parts of 1,1-bis(t-butylperoxy)-3,3,5-tricyclohexane were continuously added dropwise for 4 hours. After further reaction for 4 hours, the solvent was removed under reduced pressure to reduce the particle size to 0.
A modified epoxy resin (a-2) (epoxy equivalent: 252) in which a 2-0.5 μm soft vinyl polymer was dispersed was obtained.

Production Example 3 100 parts of the epoxy resin (2) obtained in Synthesis Example 2, 10 parts of toluene, and 1 part of methacrylic acid were mixed in the presence of tetradecyldimethylbenzyl ammonium chloride to 120 to 12
After reacting at 5°C for 2 hours, 5 parts of butyl acrylate,
10 parts of methacryloxypropyl silicone oligomer (manufactured by Shin-Etsu Chemical), 0.4 parts of azobisisovaleronitrile
100 parts of ethyl acetate were added thereto, and the mixture was reacted at 75°C for 4 hours. As addition-reactive silicone polymers, 15 parts of vinyl-modified polysiloxane and 15 parts of hydrogen-modified polysiloxane (both manufactured by Shin-Etsu Chemical and E
-1204) and reacted for 2 hours with vigorous stirring. Thereafter, the solvent was removed under reduced pressure at 130° C. to obtain a modified epoxy resin (a-3) (epoxy equivalent: 292) in which silicone rubber with a particle size of 0.2 to 0.5 μm was dispersed.

Comparative Production Example 1 100 parts of orthocresol novolak epoxy resin (epoxy equivalent: 200), 10 parts of toluene, and 1 part of methacrylic acid in the presence of tetradecyldimethylbenzylammonium 120~! After reacting at 25°C for 2 hours, 5 parts of butyl acrylate, 10 parts of methacryloxypropyl silicone oligomer (manufactured by Shin-Etsu Chemical), 0.4 parts of azobisisovaleronitrile, and 100 parts of ethyl acetate were added, and the mixture was heated at 75°C. The mixture was allowed to react for 4 hours. Furthermore, 15 parts of vinyl-modified polysiloxane and 15 parts of hydrogen-modified polysiloxane (both manufactured by Shin-Etsu Chemical, E-1204) were added as addition-reactive silicone polymers, and the mixture was allowed to react for 2 hours with vigorous stirring. Thereafter, the solvent was further removed at 130° C. under reduced pressure to obtain a modified epoxy resin (a-4) (epoxy weight [290]) in which silicone rubber with a particle size of 0.2 to 0.5 μm was dispersed.

Examples 1 to 3 and Comparative Examples 1 to 3 Blends with the compositions (mold part) shown in Table 1 were mixed at 110 to 130
After melting and mixing for 3 minutes with a hot roll at ℃, cooling and pulverizing.
A resin composition for molding was obtained by tabletting.

Transfer molding (180℃) using the Kowara composition
, 30 kg/cm' for 3 minutes), the test 10
0 pin flat package (20mm x 30mm x 2.
5 mm, 10 mm x l Omm test elements) and test pieces for measuring physical properties were molded and heated at 180°C for 6 hours.
After curing for an hour.

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 excellent low stress and also exhibits excellent soldering heat resistance even after absorbing moisture. When the resin composition is used to encapsulate large-sized highly integrated semiconductor devices or small, thin semiconductors such as flat packages, excellent reliability can be obtained, and the invention is industrially useful.

Claims (2)

[Claims] (1) (a) A modified epoxy resin in which a silicone polymer is uniformly dispersed with an average particle diameter of 1.0μ or less in a graft polymer of an epoxy compound represented by the following general formula (I) and a vinyl polymer▲ There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, n represents an integer from 3 to 16.) (In the formula, n represents an integer from 3 to 16.) (b) Curing agent, and ( c) A resin composition for semiconductor encapsulation characterized by containing an inorganic filler. (2) The resin composition for semiconductor encapsulation according to claim 1, wherein the silicone polymer is a silicone rubber obtained by reacting an addition reaction type silicone polymer and/or a soft vinyl polymer mainly composed of a vinyl-modified silicone polymer. .