JPH0535175B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to epoxy resin compositions. More specifically, the present invention provides an epoxy resin composition particularly useful for semiconductor encapsulation, which has a glass transition point at least equivalent to that of conventional epoxy cured products, while having a low elastic modulus and low internal stress. The present invention relates to an epoxy resin composition that provides the following properties. Generally, when a semiconductor element is sealed with a thermosetting resin, internal stress is generated due to curing shrinkage during curing and thermal shrinkage during cooling, causing problems such as cracks in the semiconductor element and breakage of bonding wires. Therefore, it is desired to reduce the internal stress. The internal stress of the cured epoxy product is determined by the formula below. F=K∫ ^T _Tg (α ₁ − α ₂ ) EdT, where F: Internal stress of the cured product α ₁ : Coefficient of thermal expansion of the sealing member α ₂ : Coefficient of thermal expansion of the semiconductor element E: Modulus of elasticity of the cured product Tg : Glass transition point of cured product Therefore, in order to reduce internal stress,
(1) Decrease the elastic modulus. (2) Decrease the coefficient of thermal expansion of the cured product. (3) Lower the glass transition point. However, from the viewpoint of heat resistance and moisture resistance, the higher the glass transition point, the better, and a temperature of at least 150°C or higher is required. For example, in method (1) above, when conventional flexibility imparting agents such as polyester elastomer or silicone rubber are used, it has the effect of lowering the elastic modulus, but the glass transition point decreases significantly and at high temperatures. There are problems with electrical properties and moisture resistance. Furthermore, when a silicone resin is used, its adhesion to metal is poor and there is a problem in moisture resistance. Next, as for method (2), when a large amount of inorganic filler is used, there are problems such as damage to the surface of the semiconductor element and increase in the viscosity of the sealing material, resulting in poor workability. As a result of extensive research by the present inventors to solve the above-mentioned problems, a composition containing a low epoxy equivalent O-cresol novolak type epoxy resin modified with a specific liquid rubber has been developed. It was discovered that a cured product having a high glass transition point, low elastic modulus, and low internal stress can be obtained, leading to the present invention. That is, the present invention has an epoxy equivalent of 180 to 205 g/
O-cresol novolak type epoxy resin of eq.
A liquid rubber-modified novolac type epoxy resin obtained by reacting 100 parts of a butadiene-acrylonitrile copolymer having a carboxyl group, an amino group, or a hydroxyl group at the end, or 5 to 50 parts of a carboxyl group-containing polybutadiene, a curing agent, and a curing agent. accelerator,
An epoxy resin composition containing a filler is provided. The O-cresol novolak type epoxy resin used in the present invention is a glycidyl etherified O-cresol novolak containing two or more phenolic hydroxyl groups per molecule, and has an epoxy equivalent of
It is 180-205g/eq. The epoxy equivalent is
If it is less than 180 g/eq., it is difficult to synthesize it industrially, and if it is more than 205 g/eq., the glass transition point will be significantly lowered. In particular, in the case of conventional novolac type epoxy resins having an epoxy equivalent of 210 to 230 g/eq., there are problems such as a decrease in the glass transition point and an increase in the coefficient of thermal expansion. As the butadiene-acrylonitrile copolymer having a carboxyl group, amino group, or hydroxyl group at the end, or the carboxyl group-containing polybutadiene used as a modifier in the present invention, any conventionally known one can be used, and the former is a commercially available product. For example, Hycar manufactured by Gutstoritsi
-CTBN, ATBN, HTBN, etc. Commercially available products of the latter include PB-C-1000 manufactured by Nippon Soda Co., Ltd.
Examples include PB-C-2000. The reaction between the O-gresol novolak type epoxy resin and the butadiene-acrylonitrile copolymer or polybutadiene is carried out by a conventionally known method, for example at 120°C to 200°C.
It can be obtained by adding a catalyst such as triphenylphosphine or tertiary amine and allowing the reaction to occur until there is no change in the epoxy equivalent. In addition, the ratio of butadiene-acrylonitrile copolymer or polybutadiene to be reacted is 5 to 50 parts by weight based on 100 parts by weight of O-cresol novolak type epoxy resin.
Parts by weight are preferred, and 10 to 40 parts by weight is particularly preferred since heat resistance and mechanical properties are good. In addition, if it is less than 5 parts by weight, the effect of lowering the elastic modulus is low, and if it exceeds 50 parts by weight, the glass transition temperature is lowered and
This is not preferable because workability decreases due to the increase in viscosity. Known curing agents can be used, such as novolak resins such as phenol novolak and cresol novolak, aromatic polyamines such as diaminodiphenylmethane and diaminodiphenyl sulfone, pyromellitic anhydride and benzophenonetetracarboxylic anhydride. Examples include acid anhydrides such as, but are not limited to. The amount of curing agent used is preferably 0.7 to 1.2 of the theoretical amount. A curing accelerator may be added as necessary, but 2.
Tertiary amines such as 4,6-tris(dimethylaminomethyl)phenol and benzyldimethylamine, 2-ethyl-4-methylimidazole and 2-
imidazoles such as phenyl-4-methylimidazole, 1,8-diaza-bicyclo(5,4,
0) Undecene-7 is exemplified, and the amount added is preferably 0.3 to 3 parts by weight per 100 parts by weight of the epoxy resin. Examples of fillers that may be added as desired include silica powder, quartz glass powder, and alumina powder, and the amount added is preferably 50 to 90% by weight of the composition. In the present invention, if necessary, natural waxes, synthetic waxes, higher fatty acids and their metal salts, or release agents such as paraffin, coloring agents such as carbon black, and coupling agents may be added. Additionally, flame retardants such as antimony trioxide, phosphorus compounds, and brominated epoxy resins may be added. Below, examples will be given and concretely explained. Examples and Comparative Examples Using the following materials, blends with the compositions shown in Table 1 were melt-kneaded using heated rolls at 50°C to 100°C for 5 minutes, cooled, and then crushed to obtain the respective resin compositions. I got something. Next, these compositions were mixed at 175℃×70Kg/
Transfer molded at cm ² × 10 minutes at 180°C.
After post-curing for ×5 hours, physical properties were evaluated. The results are shown in Table-2. Epoxy resin A: O-cresol novolak type epoxy resin (Sumi Epoxy ESCN-195XL manufactured by Sumitomo Chemical Co., Ltd.,
(epoxy equivalent: 195 g/eq.) B: O-cresol novolak type epoxy resin (epoxy equivalent: 190 g/eq.) C: O-cresol novolak type epoxy resin (Sumi Epoxy ESCN220L manufactured by Sumitomo Chemical Co., Ltd., epoxy equivalent: 217 g/eq.) Modifier A: CTBN-1300×8 (terminal carboxylic acid butadiene-acrylonitrile copolymer manufactured by Gutstoritsi, molecular weight 3500) B: ATBN-1300×16 (terminal amino group butadiene-acrylonitrile copolymer manufactured by Gutstoritsi, molecular weight 3,400) C: PB-C-2000 (Carboxyl group-containing polybutadiene manufactured by Nippon Soda Co., Ltd., molecular weight 2000) Curing agent Phenol novolac resin (Tamanol 754 manufactured by Arakawa Chemical Co., Ltd. OH equivalent 110 g/eq) Curing accelerator 1,8-diaza-bicyclo ( 5,4,0) Undecene-7 Filler Crystalline silica powder (Hisilex No. manufactured by Hayashi Kasei Co., Ltd.)
3. Average particle size: 10μ) In addition, carnauba wax was used as a mold release agent, and a silane coupling agent (SH-6040 manufactured by Toray Silicon Co., Ltd.) was used as a coupling agent. When the modifier is A or C, the reaction between the O-cresol novolak type epoxy resin and the modifier involves the epoxy resin, the modifier, and the epoxy resin.
The test is carried out by charging 0.5 parts of triphenylphosphine per 100 parts into a flask and stirring at 130°C for 3 hours under a nitrogen atmosphere. The mixture was heated and stirred at 130° C. for 3 hours without a catalyst.

【table】

[Table] Tables 1 and 2 show that low epoxy equivalent O-cresol novolac type epoxy resin modified with 5 to 50 parts by weight of liquid rubber per 100 parts of the O-cresol novolak type epoxy resin has a high epoxy equivalent content. Compared to those using resins, if we compare them at the same glass transition point, more rubber modification is possible and the elastic modulus is lower; conversely, if we have the same elastic modulus, we can obtain a composition that exhibits much higher heat resistance. I know that it will happen.

Claims (1)

[Claims] 1 Obtained by reacting an O-cresol novolak type epoxy resin with an epoxy equivalent of 180 to 205 g/eq. and a butadiene-acrylonitrile copolymer having a carboxyl group, an amino group, or a hydroxyl group at the end, or a carboxyl group-containing polybutadiene. An epoxy resin composition comprising a liquid rubber-modified novolak type epoxy resin and a curing agent as essential components.