JPH02209916A - Resin composition for semiconductor sealing use - 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] [Industrial Application Field] The present invention has excellent moldability and adhesion to lead frames,
The present invention also relates to a resin composition for semiconductor encapsulation that is suitable for encapsulating electronic components such as semiconductors that require high reliability with excellent low stress properties.

[Conventional technology]

In recent years, as a method for encapsulating semiconductors, so-called plastic encapsulation using thermosetting resins such as epoxy resins has become widespread (practical), taking advantage of its economic advantages such as low raw materials 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 of their excellent heat resistance, moldability, and electrical properties.

On the other hand, as semiconductor chips have become more highly integrated, the size of elements has become larger. Therefore, stress in the resin due to the difference in thermal expansion between the sealing resin and the element causes destructive phenomena such as cracks in the passivation film, misalignment of the aluminum wiring, and cranking of the sealing resin. To solve this problem, efforts have been made to lower the stress of the sealing resin by lowering its elastic modulus or thermal expansion coefficient.

The present inventors first discovered that a silicone polymer of 1.0 μm was added to a graft polymer of an epoxy resin and a vinyl polymer.
We have invented a modified epoxy resin that is uniformly dispersed with the following average particle diameter, and have been working to reduce stress in sealing resin.

(Unexamined Japanese Patent Publication) [Problem to be solved by the invention] However, the innovation in semiconductor technology is remarkable, and devices are becoming more highly integrated and multi-functional, and the size of devices is becoming larger and the width of aluminum wiring is becoming thinner. be. Therefore, attempts have been made to further reduce the stress of the sealing resin, but in order to further reduce the stress, 1. either increase the amount of flexible component to further lower the elastic modulus, or reduce the amount of filler. It is necessary to increase the thermal expansion further to lower the thermal expansion. However, increasing the flexible component causes problems such as deterioration of mechanical strength, and increasing the amount of filler causes problems such as a decrease in fluidity.To prevent the above-mentioned fracture phenomenon, conventional low stress levels alone cannot be used. Therefore, there is a demand for further improvement in the fluidity of the sealing resin and its adhesion to the device.

[Means to solve problems]

As a result of various studies, the present inventors discovered a modified epoxy resin (Japanese Patent Application Laid-Open No. 2003-100002) in which fine particles of a previously invented silicone polymer having an average particle size of 1 μm or less are uniformly dispersed in a resin composition.
) with specific combinations of curing accelerators and/or
Alternatively, the present inventors have discovered that it is effective to use a combination of spherical silica and crushed silica having a specific particle size distribution, and have arrived at the present invention. That is, the present invention consists of: (1) essentially (a) a modified epoxy resin in which a silicone polymer is uniformly dispersed in a graft polymer of an epoxy resin and a vinyl polymer with an average particle diameter of 1.0 μ or less; (referred to as a modified epoxy resin) (b) a curing agent having at least two phenolic hydroxyl groups in one molecule (hereinafter referred to as a phenolic curing agent); (c) a combination of spherical silica and crushed silica; 1. A resin composition for semiconductor encapsulation, comprising a curing accelerator consisting of trialkylphosphine and triethylammonium tetraphenylporate.

(2) The silica according to claim (1) has a particle size of 20 to 65
From 20 to 95% by weight of spherical silica containing 30 to 70% by weight of μ particles and 5 to 80% by weight of crushed silica containing 50% by weight or more of particles with a particle size of 1 to 5μ. The resin composition for semiconductor encapsulation according to claim 1, characterized in that the silica is used.

(3) Claim (1) wherein the silicone polymer is a silicone rubber obtained by reaction with an addition reaction type silicone polymer and/or a soft vinyl polymer mainly composed of a vinyl-modified silicone polymer. ) is the resin composition for semiconductor encapsulation as described above.

As the epoxy resin used in (a) of the present invention, commonly used epoxy resins can be used as long as they are polyhydric epoxy resins, and glycidyl resins such as phenol novolak and talesol novolak can be used because of their heat resistance and electrical properties. Preferred are novolak epoxy resins such as compounds, but other compounds having two or more active hydrogens in one molecule, such as polyhydric phenols such as bisphenol A, &-hydroxydiphenylmethane, resorcinol, bishydroxydiphenyl ether, and tetrabromobisphenol A. polyhydric alcohols such as ethylene glycol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, diethylene glycol, polypropylene glycol, bisphenol A-ethylene oxide adduct, trishydroxyethyl isocyanurate, polyamino compounds such as ethylenediamine and aniline, Ebichlorohydrin is a glycidyl-type epoxy resin obtained by reacting polycarboxylic compounds such as adipic acid, phthalic acid, and isophthalic acid with 2-methylepichlorohydrin.
One or more epoxy resins selected from aliphatic (including alicyclic) epoxy resins such as dicyclopentadiene dieboxide, butadiene dimer diepoxide, etc. can be used.

The modified epoxy resin in (a) of the present invention can be produced by the method disclosed in JP-A-Sho by the present applicant.

That is, a graft polymer of an epoxy resin and a vinyl polymer is typically produced by polymerizing a vinyl polymer in the presence of an epoxy resin to produce the vinyl monomer. Vinyl monomers used to form this cotechnyl polymer include styrene, alkenyl aromatics such as vinyltoluene, methyl methacrylate, dodecyl methacrylate, butoxyethyl methacrylate, glycidyl methacrylate, methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate,
Acrylic esters such as trimethylolpropane triacrylate, acrylonitrile, acrylic acid, butoxymethylacrylamide, acrylic compounds without ester groups such as methacrylamide, vinyl acetate, vinyl laurate, vinyl persatate, vinyl chloride, vinylidene chloride, Non-conjugated vinyl compounds such as ethylene, allyl acetate, etc.,
Typical examples are conjugated diene compounds such as isoprene and chloroprene, and fluorine in methacrylic acid and acrylic acid such as vinyl silicone, dibutyl fumarate, monomethyl maleate, diethyl itaconate, trifluoroethyl methacrylate, and tetrafluoropropyl methacrylate. It is also possible to use polymerizable vinyl compounds such as compounds.

In order to polymerize the above-mentioned monomers to produce vinyl polymers, radical initiators such as lauroyl peroxide, benzoyl peroxide, tert-butyl perbenzoate, dimethyl dibenzoyl peroxyhexane, tert-butyl perpivalate, diter Chaributyl peroxide, 1.1- and tertiary butyl peroxide, 3.3.5-) dimethylcyclohexane, dimethyl ditertiary butyl peroxyhexane,
Tert-butyl cumyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, cumene hydroperoxide, tert-butyl peroxyallyl carbonate, dioctyl peroxydicarbonate, tert-butyl peroxymaleic acid, succinic acid peroxide, kusha butyl Typically, radical polymerization is carried out using peroxides such as peroxyisopropyl carbonate and hydrogen peroxide, and azo compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile.

In addition, so-called redox polymerization may be carried out by using a reducing agent in combination as necessary (a polymerization inhibitor such as hydroquinone,
A chain transfer agent such as dodecyl mercaptan may also be used.

In addition, it is effective to introduce a graftable chemical bond such as a polymerizable double bond into the epoxy resin in order to promote grafting.9 For example, acrylic acid, acrylamide, , methylol acrylamide,
Butoxymethylacrylamide, hydroxyethyl methacrylate, glycidyl methacrylate, maleic anhydride, monoethyl itaconate, monobutyl fumarate, chloromethylstyrene, phosphoxyethyl mequaacrylate, 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 addition-reacting an addition-reactive silicone polymer in the presence of the above-mentioned graft polymer of an epoxy resin and a vinyl polymer, or by adding a monomer that forms a soft vinyl polymer by a conventional method. It can be obtained by polymerization according to the method. (Unexamined Japanese Patent Publication No. 62-270617
In other words, the addition reaction type silicone rubber is an addition reaction between 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. A vinyl-modified silicone polymer is a polysiloxane having at least one St-CIl-CH bond at the end or inside the molecule, and a hydrogen-modified silicone polymer is a rubber produced at the end or inside the molecule. 5i
Referring to polysiloxanes having at least two -H bonds, both are usually commercially available in combination; examples of these include, for example, Toray Silicone Co., Ltd. +7)
Examples include SR-1821 and KE-1204 manufactured by Shin-Etsu Chemical Co., Ltd.

Further, the soft vinyl polymer can be obtained by polymerizing monomers forming the soft vinyl polymer by a conventional method.

The flexible vinyl polymer used in the present invention must be a polymer mainly composed of vinyl-modified silicone.The polymer mainly composed of vinyl-modified silicone refers to a homopolymer or copolymer of vinyl-modified silicone. Examples of the vinyl-modified silicone, which refers to a copolymer of a vinyl-modified silicone and another vinyl monomer, include methacryloxypropylsiloxane, methacryloxypropylalkoxysilane, and vinylalkoxysilane. Furthermore, as other 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 rubbery, and has a particle size of 1.0μ or less, and although it depends on the type of monomer, usually all monomers are used. 80% by weight or less.

In order to achieve low stress in the sealing resin, which is one of the objectives of the present invention, and to improve the IW resistance, the average particle diameter of the addition reaction type silicone rubber and the soft vinyl polymer should be 1.0μ or less, preferably 0.0μ or less. .5μ or less. If the average particle size of the addition reaction silicone rubber and soft vinyl polymer exceeds 1.0μ, it will not be possible to reduce the stress and the impact resistance will not be improved. When a graft polymer is formed with an epoxy resin, the blade part of the Coniﾾ÷roll is determined by the type and amount of the polymer, addition reaction type silicone rubber, and the polymer or monomer composition that forms the soft vinyl polymer. τ can be controlled by the number of double bonds introduced.

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

The amount of the polymer or monomer used to form the addition reaction type silicone rubber and the soft vinyl polymer is 1 to 100 parts by weight per 100 parts by weight of the epoxy resin.

The composition of the present invention contains the modified epoxy resin (a) as an essential component, but may contain an unmodified polyfunctional epoxy in order to adjust the addition reaction type silicone rubber and/or soft vinyl polymer to a desired amount. As the unmodified polyfunctional epoxy, all of the above-mentioned epoxy resins can be used, and the two may be the same or different.

The amount of modified epoxy resin to be used is the desired amount of addition reaction type silicone rubber and/or soft vinyl polymer, and the addition reaction type silicone rubber and/or contained in the modified epoxy resin.
Alternatively, it can be determined by the amount of soft vinyl polymer.

In addition, the amount of silicone rubber and/or soft vinyl polymer obtained by the addition reaction is the modified epoxy resin of (a),
0.5% by weight or more is required, particularly preferably 1 to 30% by weight, based on the total of the phenolic curing agent (b) and the epoxy resin used if desired.
If it is less than that, low stress cannot be achieved.

As the curing agent having at least two phenolic water a groups in one molecule used in the present invention, a novolac type phenol resin obtained by reacting phenols such as phenol and alkylphenol with formaldehyde or paraformaldehyde is generally used. However, in addition to these, polyhydric phenols such as modified novolac type phenolic resin, phenol aralkyl resin, resorcin aralkyl resin, triphenol methane, and tetraphenol ethane can be used alone or in combination. In addition,
From the viewpoint of heat resistance, novolac phenol or phenol aralkyl resin is preferably used.

There is no particular restriction on the amount of the phenolic curing agent, but the equivalent ratio to the epoxy used is in the range of 0.1 to 10, preferably 0.5 to 2.0.

In the present invention, as a curing accelerator for epoxy resin,
It is characterized by using a combination of trialkylphosphine and triethylammonium tetraphenylporate. Trialkylphosphine has an excellent curing accelerator effect, while triethylammonium tetraphenylporate has latent curing properties and exhibits excellent wettability in the initial stage of curing. By combining these types of curing accelerators, , the adhesion between the element and the lead frame is improved while maintaining the initial fluidity. When the adhesion is improved, the stress of the resin on the element is dispersed, which effectively reduces the stress and allows a good cured state to be obtained. The weight ratio of the combination is preferably 1.0 of triethylammonium tetraphenylporate to 0.05 to 5 of trialkylphosphine. If this ratio is less than 0.05, the curing speed will be slow and a good cured state cannot be obtained, and if it exceeds 5, the initial fluidity will be impaired and good adhesion will not be obtained.

Examples of trialkylphosphines include tributylphosphine, trioctylphosphine, tricyclohexylphosphine, triphenylphosphine, methyldiphenylphosphine, tribenzylphosphine, tritolylphosphine, etc., and one or more of these may be used. Can be done. Note that, in the present invention, tritolylphosphine is preferably used among these. Further, the blending amount of the curing accelerator is the modified epoxy resin (a),
0.5 to 5 parts by weight based on a total of 100 parts by weight of the phenolic curing agent (b) and the epoxy resin used if desired.
．． 0 parts by weight is preferred.

Furthermore, in order to achieve the object of the present invention, by using crushed silica and spherical silica together, which develop a specific particle size distribution, it is possible to minimize (suppress) the decrease in fluidity even when the amount of silica is increased. We have discovered that maintaining good fluidity maintains adhesion with lead frames and elements, and is effective in reducing stress.

The crushed silica that can be used in the present invention has a particle size of 1 to 5.
It is a product containing 50% by weight or more of μ particles, and if the content is less than 50% by weight, the fluidity is greatly reduced. Further, spherical silica contains 30 to 70% by weight of particles having a particle size of 20 to 65#, and if the content is less than 30% by weight or exceeds 70111%, the fluidity will be greatly reduced. In order to achieve excellent effects using these silicas, it is preferable to use 20 to 95% by weight of the above-mentioned spherical silica in the total silica.

In addition, the amount of total silica is (a) modified epoxy resin,
150 to 9 parts by weight, based on a total of 100 parts by weight of the phenolic hardener (b) and the epoxy resin used if desired.
If the amount is less than 150 parts by weight, the coefficient of thermal expansion will be large (an excellent low stress will not be achieved), and if it exceeds 900 parts by weight, the fluidity of the resin will be significantly reduced and the moldability will deteriorate.

The composition of the present invention is mainly composed of a combination of the above-mentioned modified epoxy resin, an epoxy resin used as desired, a phenolic curing agent, and crushed and spherical silica. , a mold release agent such as wax, a bromine compound, a flame retardant such as antimony or phosphorus, a coloring agent such as carbon black, a silane coupling agent, etc. may be appropriately blended.

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〕

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 novolac epoxy resin (epoxy equivalent: 200), 10 parts of toluene, and 1.2 parts of methacrylic acid were heated at 120 to 125°C in the presence of a tertiary amine.
After reacting for 2 hours at 80'C, 10 parts of methacryloxypropyl silicone oligomer (manufactured by Shin-Etsu Chemical Co., Ltd.), 0.4 parts of azobisisovaleronitrile, and 50 parts of toluene were reacted at 80'C for 4 hours. Furthermore, as an addition reaction type silicone polymer, vinyl modified polysiloxane 27.5
1 part and 27.5 parts of hydrogen-modified polysiloxane (both Kl!-1204, manufactured by Shin-Etsu Chemical Co., Ltd.) were added, and the mixture was stirred vigorously and reacted for 2 hours. After that, another 130'
The solvent was removed under reduced pressure at C to obtain a modified epoxy resin (A) (epoxy equivalent: 337) containing silicone rubber with a particle size of 0.2 to 0.5 μm.

Production Example 2 100 parts of orthocresol novolac epoxy resin (1200 parts per epoxy), 100 parts of toluene, and 1.2 parts of methacrylic acid were mixed in the presence of a tertiary amine to 120 to 125 parts
After reacting for 2 hours at °C, 4 parts of butyl acrylate,
0.2 parts of glycidyl methacrylate and 0.05 parts of t-butylperoxy-2-ethylhexanoate were added
React at C for 1 hour. Furthermore, 50 parts of mexicloxypropylsiloxane, 1 part of neopentyl glycol diacrylate, 1.1-bis(t-butylperoxy) -
0.15 parts of 3,3,5-)licyclohexane was continuously added dropwise for 4 hours, and then reacted on fire for 4 hours, and the solvent was removed under reduced pressure to form soft vinyl with a particle size of 0.2 to 0.5μ. Modified epoxy resin (B) in which polymer is dispersed (epoxy 13
13) was obtained.

Examples 1 to 5 and Comparative Examples 1 to 6 After melt-mixing the formulations shown in Table 1 (the particle size distribution of silica in the formulations is shown in Table 2) with a heated roll at 80 to 100°C for 3 minutes. A resin composition for molding was obtained by cooling, pulverizing, and tableting.

Using this composition, transfer molding (180°C1
70kg/d for 3 minutes) for physical property testing and 16 pin DIP (4X
8 haze/+ element loading) was obtained. After molding, these test pieces were post-cured at 180'C for 6 hours and then subjected to each test.

The test results are shown in Table 3.6 [Effects of the Invention] The resin composition for semiconductor encapsulation according to the present invention can be produced by using a specific combination of curing accelerators and/or by using spherical silica having a specific particle size distribution. By using a combination of crushed silica in a specific proportion, it improves adhesion with semiconductor elements, maintains low elastic modulus and thermal expansion coefficient (and maintains excellent low stress, and improves the adhesiveness of the encapsulating resin. It also improves fluidity and exhibits good moldability.

When the resin composition of the present invention is applied to highly integrated semiconductor devices, excellent reliability can be obtained, making it an extremely useful invention industrially.

Patent applicant Mitsui Toatsu Chemical Co., Ltd.

Claims (3)

[Claims] (1) Essentially (a) a modified epoxy resin in which a silicone polymer is uniformly dispersed in a graft polymer of an epoxy resin and a vinyl polymer with an average particle size of 1.0 μ or less; (b) a modified epoxy resin in one molecule; A curing agent having at least two phenolic hydroxyl groups; (c) a combination of spherical silica and crushed silica; 1. A resin composition for semiconductor encapsulation, comprising: (2) The silica according to claim (1) has a particle size of 20 to 65
From 20 to 95% by weight of spherical silica containing 30 to 70% by weight of μ particles and 5 to 80% by weight of crushed silica containing 50% by weight or more of particles with a particle size of 1 to 5μ. The resin composition for semiconductor encapsulation according to claim 1, characterized in that the silica is used. (3) Claim (1) wherein the silicone polymer is a silicone rubber obtained by reaction with an addition reaction type silicone polymer and/or a soft vinyl polymer mainly composed of a vinyl-modified silicone polymer. ) The resin composition for semiconductor encapsulation described in .