JPH0940748A - Epoxy resin composition for semiconductor sealing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin compsn. for semiconductor sealing excellent in resistance to soldering stress by compounding an epoxy resin contg. a specified amt. of an epoxy resin represented by a specific formula with a phenol resin curative and a cure accelerator. SOLUTION: A xylene compd. and cresol are copolymerized and the resulting product is converted into a glycidyl ether by reacting with epichlorohydrin, giving an epoxy resin represented by formula I (n is 0-20). Pref. o-cresol is used in place of cresol in the above process, giving an epoxy resin represented by formula II. An epoxy resin contg. 30-100wt.% epoxy resin represented by formula I or II is compounded with a phenol resin curative contg. 30-100wt.% phenol resin curative represented by fomrula III R1 and R2 are each H, halogen, or alkyl), pref. by formula IV, an inorg. filler (e. g. a fused silica powder) in an amt. of about 80-90wt.% of the objective compsn., a cure accelerator (e.g. triphenylphosphine), and if necessary other additives, then kneaded at about 70-100 deg.C on a hot roll, etc., cooled, and ground, giving an epoxy resin compsn. for seinconductor sealing.

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 solder stress resistance in 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 epoxy resin composition obtained by curing an ortho-cresol novolak type epoxy resin having excellent heat resistance and moisture resistance with a phenol novolak resin and blending an inorganic filler such as fused silica or crystalline silica as a filler is used. ing. However, in recent years, chips have become larger and larger due to the higher integration of integrated circuits, and packages have been
Small and thin QFP surface mounted from IP type,
SOP, SOJ, TSOP, TQFP and PLCC have been changed. That is, since a large chip is enclosed in a small and thin package, thermal stress causes cracking, 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 or peeling of the resin and the chip. Therefore, development of a highly reliable epoxy resin composition for semiconductor encapsulation suitable for encapsulating these large chips is desired.

[0003]

The present invention addresses these problems by using the epoxy resin represented by formula (1) as the epoxy resin and the phenol represented by formula (3) as the phenol resin curing agent. It is an object of the present invention to provide an epoxy resin composition for semiconductor encapsulation, in which the solder stress resistance of a semiconductor package during mounting is remarkably improved by using a resin curing agent.

[0004]

The present invention provides an epoxy resin containing (A) the epoxy resin represented by the formula (1) in an amount of 30 to 100% by weight based on the total amount of the epoxy resin,

[0005]

Embedded image (N = 0 to 20)

An epoxy resin composition for semiconductor encapsulation which contains (B) a phenol resin curing agent, (C) an inorganic filler, and (D) a curing accelerator as essential components, and is superior to conventional epoxy resin compositions. It also has resistance to soldering stress and moisture resistance after soldering.

The epoxy resin represented by the molecular structure of the formula (1) is obtained by polymerizing xylenes and cresol by Friedel-Crafts alkylation reaction and glycidyl etherification with epichlorohydrin. Compared with the conventional cresol novolac type epoxy resin, it has a lower elastic modulus in the rubber region of the cured product, low hygroscopicity, and excellent adhesiveness to metals such as lead frame (42 alloy, copper alloy). Further, an epoxy resin obtained by polymerizing paraxylene represented by the molecular structure of the formula (5) and phenol by Friedel-Crafts alkylation reaction and glycidyl etherified with epichlorohydrin (Japanese Patent Publication No. 62-28165, JP-A-3-28165). 14819, JP-A-6-2282
76), the epoxy resin of the formula (1) of the present invention uses cresol for the phenol part,
Since it has a lower hygroscopicity than the resin of the formula (5), it has an excellent solder stress resistance. Among the cresols, the epoxy resin of the formula (2) using orthocresol is preferable.

[0008]

[Chemical 6]

By adjusting the amount of the epoxy resin used, solder stress resistance can be maximized. In order to bring out the effect of resistance to solder stress, the epoxy resin represented by the formula (1) is used in an amount of 30% by weight or more, preferably 50% by weight, based on the total amount of epoxy resin.
The above use is desirable. If it is less than 30% by weight, the intended solder stress resistance is insufficient. When other epoxy resin is used in combination with the epoxy resin represented by the formula (1), compounds or polymers having two or more epoxy groups may be used in general. For example, biphenyl type epoxy compound, phenol novolac type epoxy resin,
Examples include cresol novolac type epoxy resin, triphenol methane type epoxy resin, and alkyl modified triphenol methane type epoxy resin.

As the phenol resin curing agent of the present invention,
Any compound or polymer having two or more phenolic hydroxyl groups may be used. Examples thereof include phenol novolac resin, cresol novolac resin, dicyclopentadiene modified phenol resin, terpene modified phenol resin, triphenol methane compound, and phenol resin represented by the above formula (3), which may be used alone or in combination. Good. Among these, the phenol resin represented by the molecular structure of the formula (3) is preferable. That is, as compared with the conventional phenol novolac resin, the elastic modulus of the cured product is low in the rubber region, low hygroscopicity, and excellent adhesion to metals such as lead frame (42 alloy, copper alloy). . Further, in the formula (3), the phenol resin of the above formula (4) using meta-xylene whose strength at the time of heating is improved due to the influence of the distance between the crosslinking points is preferable. The phenol resin of the formula (4) can be obtained by polymerizing metaxylene and phenol by Friedel-Crafts alkylation reaction. By adjusting the amount of the phenol resin used, solder stress resistance can be maximized. In order to bring out the effect of resistance to soldering stress, it is desirable to use the phenol resin represented by the formula (3) in an amount of 30% by weight or more, preferably 50% by weight or more based on the total amount of the curing agent for the phenol resin. Further, it is desirable that the amount of these phenol resin curing agents is such that the number of epoxy groups of the epoxy compound and the number of hydroxyl groups of the curing agent are matched.

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 and fused silica are used. A mixture of powder and spherical silica powder is preferred. Further, the compounding amount of the inorganic filler is preferably 80 to 90% by weight based on the total amount of the epoxy resin composition in view of resistance to solder stress. When the amount of the inorganic filler is less than 80% by weight, low thermal expansion and low water absorption cannot be obtained, and the solder stress resistance is insufficient. Further, if the amount of the inorganic filler exceeds 90% by weight, there arises inconveniences such as die pad in the semiconductor package and displacement of the gold wire wire due to high viscosity. 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 encapsulating materials can be widely used. For example, diazabicycloundecene, triphenylphosphine, dimethylbenzylamine, 2-methylimidazole and the like may be used alone or in combination.

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, but in addition to this, a silane coupling agent, a brominated epoxy resin may be added if necessary. Various additives such as flame retardants such as antimony oxide and hexabromobenzene, colorants such as carbon black and red iron oxide, mold release agents such as natural wax and synthetic wax, and low stress additives such as silicone oil and rubber. It doesn't matter. In order to produce the encapsulating epoxy resin composition of the present invention as a molding material, the epoxy resin, the curing agent, the curing accelerator, the filler, and other additives are sufficiently uniformly mixed with a mixer or the like, and then, It can be melt-kneaded with a hot roll or a kneader, cooled, and then pulverized to obtain a sealing material. These molding materials can be applied to coating, insulation, sealing, etc. of transistors, integrated circuits, etc., which are electric or electronic parts.

The present invention will be specifically described with reference to examples. Example 1 Epoxy resin of the formula (2) (softening point 57 ° C., epoxy equivalent 254 g / eq) (n is a mixture showing a value of 0 to 3, and the weight ratio is n = 0 when 1 is n = 1 is 0.71, n = 2 is 0.44, and n = 3 is 0.27.) 6.80 parts by weight Orthocresol novolac type epoxy resin (softening point 58 ° C., epoxy equivalent 200 g / eq) 1 70 parts by weight Phenolic resin curing agent represented by the formula (4) (softening point 65 ° C., hydroxyl group equivalent 170 g / eq) (a value of n is a mixture of 0 to 3, and a weight ratio thereof is n = 0. N = 1 is 0.65, n = 2 is 0.41 and n = 3 is 0.28 with respect to 1. 4.24 parts by weight Phenol novolac resin curing agent (softening point 65 ° C., hydroxyl equivalent 105 g) / Eq) 1.06 parts by weight Fused silica powder (average particle size 10μ A specific surface area of 2.0m ² / g) 35 parts by weight of spherical silica powder (average particle size 30 [mu] m, a specific surface area of 2.5m ² / g) 50 parts by weight of triphenylphosphine 0.2 part by weight of carbon black 0.5 parts by weight of carnauba Mix 0.5 parts by weight of wax with a mixer at room temperature and mix at 70-100 ° C for 2
The mixture was kneaded by a shaft roll, cooled and pulverized to obtain a molding material.

The molding material obtained by crushing was EMMI-
Using a test mold according to I-66, 175 ° C, 70k
The spiral flow was measured under the conditions of g / cm ² and 120 seconds. Further, the obtained molding material is made into tablets, which are then subjected to a low pressure transfer molding machine at 175 ° C. and 70 kg / c.
m ² for 6 seconds for soldering stress test under the condition of 120 seconds
A 6 mm chip was encapsulated in 52 pQFP, and a 3 × 6 mm chip was encapsulated in 16 pSOP for a solder moisture resistance test. The sealed test element was subjected to the following solder stress test and solder moisture resistance test. Solder stress test: Sealed test element at 85 ° C
After treatment for 24 hours, 48 hours, 72 hours, and 120 hours in an environment of 85% RH, and after dipping in a solder bath at 260 ° C. for 10 seconds, external cracks were observed with a microscope. It was expressed by the number of cracks generated / total number. Solder moisture resistance test: Sealed test element at 85 ° C, 8
After being treated for 72 hours in an environment of 5% RH and then immersed in a solder bath at 260 ° C. for 10 seconds, a pressure cooker test was performed to measure open defects of the circuit (the number of test pieces is 16). Table 1 shows the test results.

Examples 2 to 7 Compounding was carried out according to the formulation shown in Table 1, and molding materials were obtained in the same manner as in Example 1. A sealed molded product for testing was obtained from this molding material, and a solder stress 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. Comparative Examples 1 to 5 Compounding was performed according to the formulation shown in Table 2, and a molding material was obtained in the same manner as in Example 1. The epoxy resin of the formula (5) used in Comparative Examples 4 and 5 has a softening point of 63 ° C. and an epoxy equivalent of 239 g / e.
The value of q and n is a mixture showing 0 to 3, and the weight ratio is such that n = 0 is 1, n = 1 is 0.75, n = 2 is 0.46, and n = 3 is 0. 22. Sealed molded products for testing were obtained from these molding materials, and solder stress tests and solder moisture resistance tests were conducted using the molded products in the same manner as in Example 1. The test results are shown in Table 2.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

According to the present invention, the semiconductor package is excellent in soldering stress resistance and moisture resistance during mounting.

Claims (5)

[Claims] 1. An epoxy resin containing (A) the epoxy resin represented by the formula (1) in an amount of 30 to 100% by weight based on the total amount of the epoxy resin, (N = 0 to 20) (B) Phenolic resin curing agent, (C)
An epoxy resin composition for semiconductor encapsulation, which comprises an inorganic filler and (D) a curing accelerator as essential components. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the epoxy resin of the formula (1) is the formula (2). Embedded image (N = 0 to 20) 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the phenol resin curing agent has the formula (3). Embedded image (Wherein R ₁ and R ₂ are the same or different atoms or groups selected from hydrogen, halogens and alkyl groups) (n = 0 to 20) 4. The epoxy resin for semiconductor encapsulation according to claim 1, 2 or 3, wherein the phenol resin curing agent of the formula (3) contains 30 to 100% by weight based on the total phenol resin curing agent. Composition. 5. The epoxy resin composition for semiconductor encapsulation according to claim 1, claim 2, claim 3, or claim 4, wherein the phenol resin curing agent of formula (3) is of formula (4). Embedded image (N = 0 to 20)