JPH0867739A - Epoxy resin composition - Google Patents

Abstract

PURPOSE: To obtain an epoxy resin composition for semiconductor sealing markedly improved in soldering stress resistance by mixing epoxy resins based on an epoxy resin represented by a specified formula with a specified curing agent, an inorganic filler and a cure accelerator. CONSTITUTION: This resin composition essentially consists of epoxy resins containing 30-100wt.%, based on the total amount thereof, epoxy resin of the formula (wherein (m) is an integer of 1 or greater; (n) is an integer of 0 or greater; m+n=1-20; and R is H, a halogen or an alkyl), a phenolic resin curing agent having at least two hydroxyl groups, an inorganic filler and a cure accelerator. By using the epoxy resin of the above formula, it is possible to markedly improve the soldering stress resistance of a semiconductor package in mounting on the substrate of the package.

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 which is excellent in resistance to solder stress in surface mounting semiconductor devices.

[0002]

2. Description of the Related Art Conventionally, electronic parts such as diodes, transistors, and integrated circuits have been sealed with thermosetting resin. Particularly in integrated circuits, orthocresol novolac type epoxy resin excellent in heat resistance and moisture resistance is used as a phenol resin. An epoxy resin composition is used which is hardened with a novolac resin and mixed with an inorganic filler such as fused silica or crystalline silica as a filler. However, in recent years, as the integration of integrated circuits has increased, the size of chips has gradually increased, and the package is a small and thin QFP, SOP, which is surface-mounted from the conventional DIP type.
It is changing to SOJ, TSOP, TQFP, PLCC. That is, a large chip is enclosed in a small and thin package, and cracks are generated due to thermal stress, and problems such as deterioration of moisture resistance due to these cracks are greatly highlighted. In particular, in the soldering process, when exposed to a high temperature of 200 ° C. or more, the moisture resistance is deteriorated due to cracking of the package and peeling of the resin and the chip. Therefore, development of a highly reliable resin composition for semiconductor encapsulation suitable for encapsulating these large chips is desired.

[0003]

The present invention addresses the above problems by using the epoxy resin represented by the formula (1) to prevent solder stress of the package during mounting on the substrate of the semiconductor package. Another object of the present invention is to provide an epoxy resin composition for encapsulating a semiconductor, which has remarkably improved properties.

[0004]

The present invention provides (A) an epoxy resin containing 30 to 100% by weight of an epoxy resin represented by the following formula (1) with respect to the total amount of epoxy resin:

[0005]

Embedded image (The value of m is an integer of 1 or more, the value of n is 0 or an integer of 1 or more, m + n = 1 to 20, R in the formula is hydrogen, halogens,
Same or different atom or group selected from alkyl groups)

An epoxy resin composition for semiconductor encapsulation comprising (B) a phenolic resin curing agent having two or more hydroxyl groups, (C) an inorganic filler, and (D) a curing accelerator as essential components. It has excellent solder crack resistance and moisture resistance after soldering as superior reliability compared to the epoxy resin composition.

The epoxy resin represented by the molecular structure of the formula (1) is prepared by polymerizing orthoxylene and paraxylene, or orthoxylene and phenols by Friedel-Crafts alkylation reaction and glycidyl etherification with epichlorohydrin. Is obtained by Compared with the conventional cresol novolac type epoxy resin, the elastic modulus of the cured product is low in the rubber region, low hygroscopicity, and excellent adhesion to metals such as lead frames (42 alloy, copper alloy) and silicon chips. Further, by introducing orthocresol into the paraxylylene-modified epoxy resin represented by the following formula (2) (Japanese Patent Publication No. 62-28165),

[0008]

[Chemical 3] (N = 0 to 20)

As the epoxy resin composition, it is possible to obtain an epoxy resin composition which has high strength at high temperature in the rubber region and is obviously excellent in solder crack resistance. The epoxy resin represented by the structural formula (1) may of course be modified with ortho-xylene alone, and the copolymer with para-xylene may be either random copolymer or block copolymer. In the structural formula (1), the ratio of ortho-xylene to the total xylene-modified component is preferably 30% or more in order to exert the effect of ortho-xylene. By adjusting the amount of the epoxy resin used, solder crack resistance can be maximized. In order to bring out the effect of solder crack resistance, it is desirable to use the epoxy resin represented by the formula (1) in an amount of 30% by weight or more, preferably 50% by weight or more, based on the total amount of epoxy resin. If it is less than 30% by weight, the target solder crack resistance is insufficient. Further, R in the formula is preferably a hydrogen atom.

When an epoxy resin other than the epoxy resin represented by the formula (1) is used in combination, it means a compound or polymer having two or more epoxy groups in general. For example, a biphenyl type epoxy compound, a bisphenol type epoxy compound, a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, a triphenol methane type epoxy compound, an alkyl modified triphenol methane type epoxy compound and the like are referred to. The phenolic resin curing agent having two or more hydroxyl groups used in the present invention includes phenol novolac resin, cresol novolac resin,
Dicyclopentadiene modified phenolic resin, paraxylylene modified phenolic resin, terpene modified phenolic resin, triphenol methane compound and the like, particularly phenol novolak resin, dicyclopentadiene modified phenolic resin, paraxylylene modified phenolic resin, terpene modified phenolic resin and these Mixtures are preferred. The amount of these curing agents to be added is preferably such that the number of epoxy groups in the epoxy resin matches the number of hydroxyl groups in the curing agent.

Examples of the inorganic filler used in the present invention include fused silica powder, spherical silica powder, crystalline silica powder, secondary agglomerated silica powder, porous silica powder, alumina, and the like. In particular, spherical silica powder or fused silica. A mixture of powder and spherical silica powder is preferred. Further, the blending amount of the inorganic filler is preferably 70 to 90% by weight with respect to the total amount of the epoxy resin composition from the viewpoint of solder crack resistance. When the amount of the inorganic filler is less than 70% by weight, low thermal expansion and low water absorption cannot be obtained, and the solder crack resistance is insufficient. On the other hand, if the amount of the inorganic filler exceeds 90% by weight, problems such as displacement of the die pad and the gold wire in the semiconductor package due to high viscosity may occur. The curing accelerator used in the present invention may be any one as long as it accelerates the curing reaction between the epoxy group and the hydroxyl group, and those generally used for sealing materials can be widely used. For example, 1,8-diazabicycloundecene, triphenylphosphine, benzyldimethylamine and 2-
Methylimidazole and the like can be mentioned, and they can be used alone or in combination of two or more.

The epoxy resin composition of the present invention contains an epoxy resin, a phenol resin curing agent, an inorganic filler, and a curing accelerator as essential components. In addition to these, a silane coupling agent, a brominated epoxy resin, and Flame retardants such as antimony trioxide and hexabromobenzene, coloring agents such as carbon black and red iron oxide, mold release agents such as natural wax and synthetic wax, and various additives such as low stress additives such as silicone oil and rubber. There is no problem even if mixed.
Further, in order to produce the encapsulating epoxy resin composition of the present invention as a molding material, the epoxy resin, the phenol resin curing agent, the curing accelerator, the inorganic filler, and the other additives are sufficiently uniformly mixed with a mixer or the like. After that, the mixture can be further melt-kneaded with a hot roll or a kneader, cooled and pulverized to obtain a sealing material. These molding materials are coatings for transistors, integrated circuits, etc., which are electric or electronic parts,
It can be applied to insulation, sealing, and the like.

The present invention will be specifically described below with reference to examples. Example 1 The following composition Epoxy resin represented by the following formula (3) (softening point 55 ° C., epoxy equivalent 250 g / eq 4.64 parts by weight)

[0014]

[Chemical 4] (The value of n is a mixture showing 0 to 3, and the weight ratio thereof is 1 for n = 0, 0.70 for n = 1, 0.38 for n = 2, and 0.22 for n = 3. It is.)

Epoxy resin represented by the formula (2) (softening point 55 ° C., epoxy equivalent 250 g / eq) 8.61 parts by weight

[0016]

[Chemical 5] (The value of n is a mixture showing 0 to 3. The weight ratio of n = 0 is 1 to n = 0.70, and n = 2 is 0.
45 and n = 3 is 0.30. )

Phenol novolac resin curing agent (softening point 65 ° C., hydroxyl group equivalent 105 g / eq) 5.55 parts by weight fused silica powder (average particle size 10 μm, specific surface area 2.0 m ² / g) 30 parts by weight spherical silica powder ( Average particle diameter 30 μm, specific surface area 2.5 m ² / g) 50 parts by weight triphenylphosphine 0.2 parts by weight carbon black 0.5 parts by weight Carnauba wax 0.5 parts by weight are mixed at room temperature with a mixer to give 70 to 100 parts. The mixture was kneaded with a biaxial roll at ℃, cooled and pulverized to obtain a molding material. The obtained molding material was tabletted, and a 6 × 6 mm chip was soldered for a solder crack test under conditions of 175 ° C., 70 kg / cm ² and 120 seconds with a low pressure transfer molding machine.
3x6 sealed in pQFP and used for solder moisture resistance test
The mm chip was encapsulated in 16 pSOP. The sealed test element was subjected to the following solder crack test and solder moisture resistance test. Solder crack test: sealed test element at 85 ° C, 8
It was treated for 24 hours and 72 hours in an environment of 5% RH and then immersed in a solder bath at 260 ° C. for 10 seconds, and then external cracks were observed with a microscope. Solder moisture resistance test: sealed test element at 85 ° C, 85
% RH for 24 hours, then immersed in a solder bath at 260 ° C for 10 seconds, and then subjected to a pressure cooker test (1
25 degreeC, 100% RH was performed, and the open defect of the circuit was measured. Bending strength: Measured at 240 ° C. according to JIS K6911. Boiling water absorption rate: Measured according to JIS K6911. The above test results are shown in Table 1.

Examples 2 to 5 Compounding was carried out according to the formulation shown in Table 1, and a molding material was obtained in the same manner as in Example 1. The epoxy resin of Example 5 has the following formula (4)
(Softening point 55 ° C., epoxy equivalent 250 g / e
q).

[0019]

[Chemical 6] (The value of m is an integer of 1 and 2, the value of n is an integer of 0, 1, 2.
The value of m + n is 1 to 4, and the weight ratio is 1 for m and 0 for n.
The structure of 1 is 0.7, the structure of m is 1 and the structure of n is 0.70, and the structure of m is 2 and the structure of n is 0.4.
0, m is 2, and n is 2 is 0.4. )

A molded product sealed with a test material was obtained from this molding material, and a solder crack test and a solder moisture resistance test were carried out in the same manner as in Example 1 using this molded product. Table 1 shows the test results. Comparative Examples 1 to 3 Compounding was performed according to the formulation shown in Table 1, and a molding material was obtained in the same manner as in Example 1. Using this molding material, a sealed molded product for testing was obtained, and a solder crack test and a solder moisture resistance test were conducted in the same manner as in Example 1 using this molded product. Table 1 shows the test results.

[0021]

[Table 1]

[0022]

According to the present invention, the solder crack resistance of the package at the time of mounting the semiconductor package on the substrate is significantly improved, and the moisture resistance is also improved.

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Claims (2)

[Claims] 1. An epoxy resin containing (A) an epoxy resin represented by the following formula (1) in an amount of 30 to 100% by weight based on the total amount of epoxy resin: (The value of m is an integer of 1 or more, the value of n is 0 or an integer of 1 or more, m + n = 1 to 20, R in the formula is hydrogen, halogens,
Same or different atom or group selected from alkyl groups) (B) Phenolic resin curing agent having two or more hydroxyl groups, (C) inorganic filler, and (D) curing accelerator as essential components An epoxy resin composition for semiconductor encapsulation, comprising: 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein R in the formula (1) is hydrogen.