JPH0530862B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an epoxy resin composition for semiconductor encapsulation. More specifically, it is an epoxy resin composition for semiconductor encapsulation that uses a preliminary reaction product of epoxy-modified hydrogenated polybutadiene resin and phenol novolak resin as a flexibilizing agent, and maintains the heat resistance and moisture resistance of the epoxy resin. The present invention relates to an epoxy resin composition for semiconductor encapsulation which provides a cured product having a low elastic modulus and a low expansion coefficient. [Problems to be solved by conventional technology/inventions] In recent years, semiconductor devices have become larger and more highly integrated, and when semiconductors are encapsulated with conventional epoxy resin compositions, chips and lead frames Thermal stress caused by the difference in coefficient of linear expansion with the sealing resin causes problems such as cracks in the chip and breakage of bonding lines, reducing the reliability of semiconductor components. This is because conventional epoxy resin compositions for semiconductor encapsulation have been developed from the viewpoint of heat resistance and water resistance, and the cured product is extremely hard and has poor flexibility, which increases the stress applied to the device. be. This stress can be reduced by lowering the elastic modulus, expansion coefficient, and glass transition point, but from the viewpoint of maintaining moisture resistance and heat resistance, the higher the glass transition point is, the better. One way to reduce stress is to add a flexibilizing agent, but the conventional method of lowering the elastic modulus with a flexibilizing agent greatly lowers the glass transition point of the cured product.
Deterioration of electrical properties and moisture resistance occurs at high temperatures,
It is unsuitable as a resin composition for semiconductor encapsulation. In order to improve electrical properties at high temperatures, there is a method of blending silicone resin with a low elastic modulus, which is a heat-resistant flexibilizing agent, but using silicone resin has poor adhesion to metals and poor moisture permeability. Because of this, there is a problem of lack of reliability in terms of moisture resistance. As a flexibilizing agent that has moisture resistance and does not lower the glass transition point, it is obtained by reacting polybutadiene having carboxyl groups at both ends or a copolymer of polybutadiene and acrylonitrile having carboxyl groups at both ends with an epoxy resin. Rubber-modified epoxy flexibilizing agents have also been proposed, but there is a problem in that unsaturated bonds in the polybutadiene structure are oxidized and degraded when kept at high temperatures, resulting in loss of flexibility. [Means for solving the problem] In order to improve the problem, the present inventors have conducted intensive research to obtain a semiconductor encapsulating material that has heat resistance, moisture resistance, and a low elastic modulus. , a flexibilizing agent which is a preliminary reaction product of an epoxy-modified hydrogenated polybutadiene resin and a phenol novolac resin, a novolac-type epoxy resin, a hardening agent, a curing accelerator, a filler, a mold release agent, and a semiconductor encapsulation containing a surface treatment agent. The inventors discovered an epoxy resin composition for use as a stopper and completed the present invention. [Example] Examples of the novolak type epoxy resin used in the present invention include cresol novolak type epoxy resin, phenol novolak type epoxy resin, alkylbenzene-modified phenol novolak type epoxy resin, and brominated phenol novolak type epoxy resin. However, it is not limited to these. These may be used alone, or 2
More than one species may be used in combination. Examples of the curing agent used in the present invention include, but are not limited to, phenol novolak resins, cresol novolak resins, alkyl-modified phenol novolak resins, and the like. These may be used alone or in combination of two or more. The curing accelerator used in the present invention can be used without particular limitation as long as it is a common catalyst, and specific examples thereof include phosphorus compounds such as triphenylphosphine and triphenyl phosphite;
-Imidazoles such as methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecyl imidazole, 2-ethyl, -4-methylimidazole, 2-(dimethylaminomethyl)phenol, 2,4,6 - Tertiary amines such as tris(dimethylaminomethyl)phenol, benzyldimethylamine, α-methylbenzylmethylamine, and organic acid salts such as 1,8-diazabicyclo(5,4,0)undecene-7; The amount added is in the sealing resin composition,
It may be 0.02 to 1.0% (weight%, the same applies hereinafter). Examples of the filler used in the present invention include crystalline silica powder and quartz glass powder. The amount of filler added to the sealing resin composition is preferably 50 to 80%; if it exceeds 80%, the fluidity of the composition will decrease and molding will become difficult, and if it is less than 50%, the coefficient of linear expansion will increase. Problems such as problems tend to occur. Examples of the mold release agent include natural waxes, synthetic waxes, higher fatty acids or metal salts thereof, and paraffins. The surface treatment agent refers to a surface treatment agent for the filler, and a known silane coupling agent is used. In the present invention, a pre-reaction product of an epoxy-modified hydrogenated polybutadiene resin and a phenolic novolak resin is used as a flexibilizing agent. The epoxy-modified hydrogenated polybutadiene resin is, for example, a hydrogenated polybutadiene resin having a carboxyl group at the end, or a mixture of a hydrogenated polybutadiene resin having a hydroxyl group at the end, a bisphenol epoxy resin, or an alicyclic epoxy resin. Add catalyst and heat to 130-150℃,
It refers to a resin such as an epoxy-modified hydrogenated polybutadiene resin having epoxy groups at both ends, which is obtained by reaction in a nitrogen atmosphere for about 2 to 30 hours. As the hydrogenated polybutadiene resin having a carboxyl group at the terminal, for example, Nippon Soda
Examples include CI1000 manufactured by Co., Ltd. Examples of hydrogenated polybutadiene resins having hydroxyl groups at the terminals include GI1000 and GI2000 manufactured by Nippon Soda Co., Ltd.
Examples include GI3000. Further, as bisphenol type epoxy resins, for example, Epicoat 807, 827, 828 manufactured by Yuka Ciel Epoxy Co., Ltd.
Ciba Geigy's Araldite, such as 834.
Examples include GY250, GY255, GY260, GY280, and Dow Chemical's DER-330, GY331, and GY337. Examples of alicyclic epoxy resins include Araldite CY175, Araldite CY179, and Ciba Geigy.
Examples include 180 and RD-4. A preliminary reaction product of an epoxy-modified hydrogenated polybutadiene resin and a phenol novolak resin is prepared by adding a phosphorus-based compound or an imidazole-based compound as a catalyst to a mixture of an epoxy-modified hydrogenated polybutadiene resin and a phenol novolak resin, and then reacting the mixture under a nitrogen atmosphere. It can be obtained by reaction at 120-150°C for about 5-20 hours. The phenol novolac resin has a softening point of 60
~110℃ is preferable. Examples of phosphorus compounds used as catalysts include phosphines such as triphenylphosphine, and imidazole compounds include 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-undecylimidazole, and 2-heptadecyl. Imidazole is preferred. The compounding ratio of the epoxy-modified hydrogenated polybutadiene resin and the phenolic novolac resin is such that the equivalent ratio of the epoxy group in the epoxy-modified hydrogenated polybutadiene resin to the hydroxyl group in the phenolic novolac resin (epoxy group/phenolic hydroxyl group) is 0.02/1 to 1. 0.3/1
It is preferable that the ratio is as follows. If the equivalent ratio of the epoxy groups in the epoxy-modified hydrogenated polybutadiene resin to the hydroxyl groups in the phenol novolac resin is less than 0.02, the proportion of the hydrogenated polybutadiene component in the flexibilizing agent decreases, and the semiconductor encapsulation material Even if used for
If the equivalence ratio is greater than 0.3, gelation tends to occur during the preliminary reaction between the epoxy-modified hydrogenated polybutadiene resin and the phenol novolac resin, or a stable flexibilizing agent may not be obtained. be. The amount of catalyst added is 0.1 to 100 parts (parts by weight, same hereinafter) of epoxy-modified hydrogenated polybutadiene resin.
2.0 parts is preferred. The amount [s] of the flexibilizing agent, which is a preliminary reaction product between the epoxy-modified hydrogenated polybutadiene resin and the phenol novolac resin produced in this way, is determined by [s]/( [b]+[s]) is preferably in the range of 5 to 70%, and 10 to 60%
It is more preferable that If the proportion is less than 5%, the elastic modulus of the obtained composition may not be reduced sufficiently, and the flexibility effect may not be sufficient, and if it exceeds 70%, the glass transition point may be lowered. Problems such as heating, a decrease in mechanical strength, and a significant decrease in electrical properties at high temperatures tend to occur. The equivalent ratio (epoxy group/phenolic hydroxyl group) between the epoxy group of the novolak type epoxy resin and the total of the phenolic hydroxyl groups in the curing agent and the flexibilizing agent in the composition of the present invention is preferably in the range of 0.7 to 1.3. A coloring agent such as carbon, a flame retardant such as antimony trioxide, antimony pentoxide, phosphate, etc. may be added to the composition of the present invention, if necessary. Hereinafter, the composition of the present invention will be specifically explained based on Examples. Examples 1 to 8 100 parts of hydrogenated polybutadiene resin (CI1000) having a carboxyl group at the terminal, 64 parts of bisphenol type epoxy resin (Epicote 828) and 0.5 part of 2-ethyl-4-methylimidazole were mixed at 150 parts while blowing nitrogen. The reaction was carried out at ℃ for 6 hours, and an epoxy-modified hydrogenated polybutadiene resin having epoxy groups at both terminals and an epoxy equivalent of 900 was synthesized. 100 parts of phenol novolac resin (PSF-4261, manufactured by Gunei Chemical Co., Ltd.), 85 parts of the above epoxy-modified hydrogenated polybutadiene resin (equivalent ratio of epoxy group/phenolic hydroxyl group = 0.1), and 2-ethyl-4-methyl 0.3 parts of imidazole while blowing nitrogen.
The reaction was carried out at 140°C for 10 hours to obtain a flexibilizing agent (A) in which the epoxy-modified hydrogenated polybutadiene resin and the phenol novolac resin were pre-reacted. Cresol novolac type epoxy resin (EOCN102S, manufactured by Nippon Kayaku Co., Ltd.), brominated phenol novolac type epoxy resin (BREN-S, manufactured by Nippon Kayaku Co., Ltd.), phenol novolac type epoxy resin (PSF, which is a curing agent) -4261), curing accelerator, flexibilizing agent (A),
Fused silica as a filler (RD-8, Ryumori Co., Ltd.)
After mixing 2 parts of silane coupling agent, 6 parts of antimony trioxide, 2 parts of wax, and 5 parts of colorant in the proportions shown in Table 1,
After kneading with heating rolls, the mixture was cooled and pulverized to prepare an epoxy resin composition for molding. The obtained composition was molded at 175°C/3 minutes,
Post-curing was performed at 180°C for 6 hours to prepare a cured test piece. Flexural modulus of the molded product obtained in this way (JIS
K6911), glass transition temperature and 121℃, 2 atm.
The volume resistivity was measured before and after a 500 hour pressure test. The results are shown in Table 1. Example 9 Phenol novolac resin (PSF-4261) 100
42 parts of the epoxy-modified hydrogenated polybutadiene resin used in Example 1 (equivalent ratio of epoxy group/phenolic hydroxyl group = 0.05) and 0.2 part of 2-ethyl-4-methylimidazole were mixed, and the same as in Example 1 was prepared. A composition was prepared and evaluated in the same manner as in Example 1, except that the resulting flexibilizing agent (B) was used. The results are shown in Table 1. Example 10 Triphenylphosphine was used as a catalyst for the synthesis of epoxy-modified hydrogenated polybutadiene resin and the preliminary reaction of epoxy-modified hydrogenated polybutadiene resin and phenol novolac resin, and the resulting flexibilizing agent (C) was used. Otherwise, a composition was prepared and evaluated in the same manner as in Example 6. The results are shown in Table 1. Comparative Example 1 An epoxy resin composition for sealing having the formulation shown in Table 1 was prepared using DER736 manufactured by Dow Chemical Company as a flexibilizing agent, and evaluated. The results are shown in Table 1. Comparative Example 2 Using Araldite GY298 manufactured by Ciba Geigy as a flexibilizing agent, an epoxy resin composition for sealing having the formulation shown in Table 1 was prepared and evaluated. The results are shown in Table 1. Comparative Example 3 An epoxy resin composition for sealing having the formulation shown in Table 1 was prepared without using a flexibilizing agent and evaluated. The results are shown in Table 1.

[Table] [Effects of the Invention] As is clear from the above description, the epoxy resin composition for sealing uses the preliminary reaction product of the epoxy-modified hydrogenated polybutadiene resin of the present invention and the phenol novolac resin as a flexibilizing agent. The material maintains heat resistance and moisture resistance, has a low elastic modulus, and is suitable as an epoxy resin composition for semiconductor encapsulation.

Claims (1)

[Claims] 1. A flexibilizing agent which is a preliminary reaction product of an epoxy-modified hydrogenated polybutadiene resin and a phenol novolak resin, a novolak-type epoxy resin, a curing agent, a curing accelerator, a filler, a mold release agent, and a surface. An epoxy resin composition for semiconductor encapsulation containing a processing agent. 2 Equivalence ratio of the epoxy group of the epoxy-modified hydrogenated polybutadiene resin and the hydroxyl group of the phenolic novolac resin (epoxy group/phenolic hydroxyl group)
The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the ratio is in the range of 0.02/1 to 0.3/1.