JP3302259B2 - Epoxy resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for semiconductor encapsulation having excellent solder stress resistance in the surface mounting of semiconductor devices.

[0002]

2. Description of the Related Art Conventionally, electronic components such as diodes, transistors, and integrated circuits are sealed with a thermosetting resin. Particularly, in an integrated circuit, an O-cresol novolac epoxy resin having excellent heat resistance and moisture resistance is used. An epoxy resin composition is used which is cured with a novolak-type phenol resin. However, in recent years, chips have been gradually increased in size with the increase in integration of integrated circuits, and small and thin QFPs and SOs that have been surface-mounted from conventional DIP types have been packaged.
P, SOJ, TSOP, TQFP, PLCC have been changed. That is, since a large chip is sealed in a small and thin package, cracks are likely to occur due to stress, and problems such as a decrease in moisture resistance due to the cracks have been greatly highlighted. In particular, abrupt exposure to a high temperature of 200 ° C. or more in the soldering step causes a problem that the package is cracked and the moisture resistance is deteriorated due to the separation between the resin and the chip. Suitable for sealing these large chips,
The development of a highly reliable encapsulating resin composition is strongly desired. To solve these problems, an epoxy resin (e.g., JP 64 65116 and JP-Hei 6-184272 discloses) having crystallinity study of is performed, the low thermal expansion after molding of the composition and Solder stress resistance was improved by reducing moisture absorption. However, since the epoxy resin having crystallinity has a low molecular weight, there are many unreacted substances remaining after curing, and there are many problems in mold releasability and mold contamination during molding. In particular, in many cases, insufficient hardness of the cured product at the time of mold release and breakage of an IC chip inside the package (hereinafter referred to as chip crack) caused by a decrease in mold releasability often become problems.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an epoxy resin composition for semiconductor encapsulation which is excellent in workability during molding and soldering resistance against such problems.

[0004]

According to the present invention, there is provided (A) a bife
Nyl type epoxy resin, (B) phenol resin curing agent,
(C) The weight ratio (c1 / c2) of the organic tertiary phosphine compound (c1) to the imidazole derivative (c2) is 49/1.
(C1 + c2) is 0.05 to 5 parts by weight with respect to 100 parts by weight of the total epoxy resin, and (D) 80 to 92% by weight is contained in the total resin composition.
That it consists of an inorganic filler is a semiconductor encapsulating epoxy resin composition characterized, and has excellent solder stress resistance compared with the conventional epoxy resin composition.

The biphenyl type epoxy resin used in the present invention has an endothermic peak of 70 (differential scanning calorimeter) by DSC.
It is an epoxy resin having a temperature of up to 150 ° C. and in which a crystal peak by X-ray diffraction can be confirmed. When the endothermic peak is less than 70 ° C., the blocking property of the resin composition itself increases,
On the other hand, when the temperature exceeds 150 ° C., workability becomes extremely poor. The biphenyl type epoxy resin of the present invention can be used in combination with other epoxy resins, but the epoxy resin used in combination is preferably 50% by weight or less based on the total amount of the epoxy resin. Examples of the epoxy resin that can be used in combination include bisphenol A type epoxy resin, phenol novolak type epoxy resin, and ordinary glycidyl type epoxy resin. The phenolic resin curing agent used in the present invention is not particularly limited in its molecular weight and molecular structure. Triphenolmethane compounds and the like are mentioned, and phenol novolak resins, dicyclopentadiene-modified phenol resins, paraxylylene-modified phenol resins, terpene-modified phenol resins and the like are preferable, and they may be used alone or in combination. As for the amount of these curing agents, the ratio of the number of epoxy groups of the epoxy resin to the number of hydroxyl groups of the phenol resin curing agent is preferably 0.8 to 1.2.

It is important to use a mixture of an organic tertiary phosphine compound and an imidazole derivative as the main component of the curing accelerator used in the present invention. Examples of the organic tertiary phosphine compound include triphenylphosphine, tricyclohexylphosphine, 1,2-bis (agephenylphosphino) ethane, bis (diphenylphosphino) methane, and the like, with preference given to triphenylphosphine. . These compounds can be used alone or in combination. Examples of the imidazole derivative include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-undecylimidazole, and the like, and preferred is 2-methylimidazole. Imidazole and 2-phenylimidazole. These compounds can be used alone or in combination. The use of the organic tertiary phosphine compound of the present invention, triphenylphosphine, and the imidazole derivative, 2-methylimidazole or 2-phenylimidazole, is already known, but can be obtained independently by incorporating the respective advantages. The effect that was not found was found in the case of a specific blending ratio. The mixing ratio of the organic tertiary phosphine compound to the imidazole derivative is 49/1 to 1 by weight ratio of the organic tertiary phosphine compound / imidazole derivative.
/ 1, preferably 30/1 to 4/1.
The total amount of the organic tertiary phosphine compound and the imidazole derivative is 0.05 to 100 parts by weight of the total epoxy resin.
5 parts by weight. If the weight ratio of the organic phosphine compound to the imidazole derivative is less than 1/1, the heat resistance of the cured composition will be poor. On the other hand, if the weight ratio exceeds 49/1, the curing properties deteriorate, and problems such as mold release failure and mold contamination during molding occur. Furthermore, when the total amount of the organic phosphine compound and the imidazole derivative is less than 0.05 part by weight based on 100 parts by weight of the total epoxy resin, the curing properties are deteriorated,
If it exceeds 5 parts by weight, the electrical properties of the cured product will deteriorate.

The inorganic filler used in the present invention includes fused silica powder, spherical silica powder, crystalline silica powder, secondary aggregated silica powder, porous silica powder, secondary aggregated silica powder or silica obtained by pulverizing porous silica powder. Examples thereof include powder, alumina, and the like, and particularly preferred are fused silica powder, spherical silica powder, and a mixture of fused silica powder and spherical silica powder. The amount of the inorganic filler is preferably 80 to 92% by weight in the whole resin composition in view of the balance between solder stress resistance and moldability. The epoxy resin composition for encapsulation of the present invention contains an epoxy resin, a phenol resin curing agent, a curing accelerator and an inorganic filler as essential components, but if necessary, a silane coupling agent, a brominated epoxy resin, Various additives such as flame retardants such as antimony oxide and hexabromobenzene, coloring agents such as carbon black and red iron oxide, release agents such as natural wax and synthetic wax, and low stress additives such as silicone oil and rubber are appropriately mixed. No problem. In addition, in order to manufacture the epoxy resin composition for sealing of the present invention as a molding material, an epoxy resin, a curing agent, a curing accelerator, an inorganic filler, and other additives are sufficiently uniformly mixed by a mixer or the like. Alternatively, the mixture may be melt-kneaded with a hot roll or a kneader, cooled, and pulverized to obtain a molding material. These molding materials can be applied to sealing, coating, insulating and the like of electronic parts or electric parts.

Hereinafter, the present invention will be described specifically with reference to examples. Example 1 YX4000H (manufactured by Yuka Shell Co., Ltd.) (melting point 110 ° C., epoxy equivalent 190 g / eq) (hereinafter referred to as E1) 6.3 parts by weight ortho-cresol novolak type epoxy resin (softening point 65 ° C., epoxy equivalent) 200 g / eq) (hereinafter referred to as E2) 2.7 parts by weight Phenol novolak resin curing agent (softening point 90 ° C., hydroxyl equivalent 105 g / eq) (hereinafter referred to as P1) 5.0 parts by weight triphenylphosphine 0.2 Parts by weight 2-phenylimidazole 0.05 parts by weight Fused silica powder 85 parts by weight Carbon black 0.2 parts by weight Carnauba wax 0.5 parts by weight is mixed at room temperature with a mixer, and kneaded at 70-100 ° C with a biaxial roll. Then, after cooling, it was pulverized to obtain a molding material. The obtained molding material was tableted, and a 6 × 6 mm chip was used for a solder crack test at 175 ° C., 70 kg / cm ² and 120 seconds by a low-pressure transfer molding machine.
Sealed in 2p package, and 3 for solder moisture resistance test
A 6 mm chip was sealed in a 16 pSOP package. The sealed test element was subjected to the following solder crack test and solder moisture resistance test.

Evaluation method of mold releasability: The number of molded products remaining at the mold gate when molding was performed at 175 ° C., 70 kg / cm ² and 120 seconds using a mold for 80 pQFP was evaluated. n = 20. Solder crack test: Sealed test element at 85 ° C, 8
After treating for 72 hours in an environment of 5% RH, and then immersing in a solder bath at 260 ° C. for 10 seconds, external cracks were observed with a microscope. Solder moisture resistance test: Sealed test element at 85 ° C, 85
% RH environment for 72 hours, and then immersed in a solder bath at 260 ° C. for 10 seconds, followed by a pressure cooker test (1
(25 ° C., 100% RH) to determine the oven failure of the circuit. Table 1 shows the test results. Continuous moldability: The mold contamination of the continuous moldability with the auto mold (80pQFP) and the appearance of the molded package were observed, and the limit molding number was evaluated. Examples 2 to 4 Compounded according to the formulation shown in Table 1 and obtained a molding material in the same manner as in Example 1. A molded product sealed with the molding material for a test was obtained, and the molded product was evaluated in the same manner as in Example 1. Table 1 shows the test results. Comparative Examples 1 to 5 Compounded according to the formulation in Table 2, and a molding material was obtained in the same manner as in Example 1. A molded product sealed with the molding material for a test was obtained, and the molded product was evaluated in the same manner as in Example 1. Table 2 shows the test results.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

The resin composition of the present invention has excellent hardness and releasability of a cured product at the time of molding, and has excellent crack resistance when subjected to thermal stress due to a rapid temperature change in a soldering process. High reliability and excellent moisture resistance make it highly reliable when used for encapsulation, coating and insulation of electronic and electrical components, especially for highly integrated large chip ICs mounted on surface mount packages. It is suitable for products that require properties.

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Claims (3)

(57) [Claims] (A) a biphenyl type epoxy resin,
(B) a phenolic resin curing agent, (C) a weight ratio (c1 / c2) between the organic tertiary phosphine compound (c1) and the imidazole derivative (c2) is 49/1 to 1/1, and the total epoxy resin 100 (C1 + c2) 0.05 to 5 parts by weight with respect to parts by weight, (D) all resin group
An epoxy resin composition for semiconductor encapsulation, comprising an inorganic filler contained in the composition in an amount of 80 to 92% by weight . 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the organic tertiary phosphine compound is triphenylphosphine. 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the imidazole derivative is 2-methylimidazole or 2-phenylimidazole.