JPH07238139A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To provide an epoxy resin compsn. which gives a semiconductor package exhibiting improved resistance to soldering stress in mounting by compounding a specific epoxy compd. with a specific phenol resin curative. CONSTITUTION:This epoxy resin compsn. for semiconductor sealing contains an epoxy resin contg. 30-100 wt.% epoxy compd. of formula I (wherein R1 to R4 are each methyl; R5 to R8 are each H; R9 and R10 are each tert-butyl; and n is 0-20). a phenol resin curative contg. 30-100wt.% phenol resin of formula II (wherein R is II; and n is 0-20), an inorg. filler such as a spherical silica powder or its mixture with a fused silica powder in an amt. of 80-90wt.% of the compsn., and a curing accelerator.

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 the chips has gradually increased, and the package is the conventional DIP.
Small and thin type QFP and SO
It has changed to P, 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, when exposed to a high temperature of 200 ° C. or higher in the soldering process, moisture resistance is deteriorated due to cracking of the package and peeling of the chip from the resin. Therefore,
It is desired to develop a highly reliable resin composition for semiconductor encapsulation suitable for encapsulating these large chips.

[0003]

SUMMARY OF THE INVENTION The present invention addresses the above problems by using an epoxy compound represented by the formula (1) as an epoxy resin and a phenol resin represented by the formula (2) as a phenol resin curing agent. Another object of the present invention is 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 curing agent.

[0004]

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

[0005]

[Chemical 3] (In the formula, R _{1 to} R ₁₀ are hydrogen, halogens, carbon number 1 to 1
Same or different atom or group selected from the two alkyl groups)

(B) The phenol resin curing agent represented by the following formula (2) is added in an amount of 30 to 30 with respect to the total amount of the phenol resin curing agent.
Phenolic resin curing agent containing 100% by weight,

[0007]

[Chemical 4] (R in the formula is the same or different atom or group selected from hydrogen, halogens and alkyl groups having 1 to 5 carbon atoms)

An epoxy resin composition for semiconductor encapsulation containing (C) an inorganic filler and (D) a curing accelerator as essential components. The epoxy resin composition has excellent solder crack resistance and excellent reliability as compared with conventional epoxy resin compositions. It has moisture resistance after soldering.

The epoxy compound represented by the molecular structure of the formula (1) can be obtained by subjecting a bifunctional bisphenol type compound to glycidyl etherification with epichlorohydrin. Compared with the conventional cresol novolac type epoxy resin, low viscosity can be obtained at the time of melting, and it is possible to further increase the content of the inorganic filler. Therefore, as the cured product properties of the composition, low moisture absorption, low thermal expansion and high strength can be obtained. By adjusting the amount of the epoxy compound 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 compound 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 _{1 to} R ₁₀ in the formula are the same or different atoms or groups selected from hydrogen, halogens and alkyl groups having 1 to 12 carbon atoms,
It is preferable that R _{1 to} R ₄ are methyl groups and R _{5 to} R ₈ are hydrogen atoms. Further, considering the hydrophobicity of the resin, R ₉ and R ₁₀ are preferably tertiary butyl groups. If the alkyl group has more than 12 carbon atoms, the curability is poor. n is 0 to 20, but if it exceeds 20, the fluidity is poor. More preferable n is 0-10. 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, biphenyl type epoxy compound, bisphenol type epoxy compound, phenol novolac type epoxy resin,
It refers to cresol novolac type epoxy resin, triphenol methane type epoxy compound, alkyl modified triphenol methane type epoxy compound and the like.

The phenol resin curing agent represented by the formula (2) can be obtained by polymerizing paraxylene and phenols by the Friedel-Crafts alkylation reaction similarly to the epoxy resin. 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 frames (42 alloy, copper alloy). By adjusting the amount of the phenol resin curing agent used, solder crack resistance can be maximized. In order to bring out the effect of solder crack resistance, it is desirable to use the phenol resin curing agent represented by the formula (2) in an amount of 30% by weight or more, preferably 50% by weight or more based on the total amount of the phenol resin curing agent. Thirty
If it is less than wt%, the target solder crack resistance is insufficient. Further, R in the formula is hydrogen, halogens, carbon number 1 to 5
Are the same or different atoms or groups selected from among the alkyl groups, and among these, a hydrogen atom is preferable. If the alkyl group has more than 5 carbon atoms, the curability is poor.
n is 0 to 20, but if it exceeds 20, the fluidity is poor. Preferred n is 0-10. When other phenol resin curing agent is used in combination with the phenol resin curing agent represented by the formula (1), it means all polymers having a phenolic hydroxyl group. For example, phenol novolac resin, cresol novolac resin, dicyclopentadiene modified phenol resin, terpene modified phenol resin, triphenol methane compound and the like, particularly phenol novolac resin, dicyclopentadiene modified phenol resin, terpene modified phenol resin and these Mixtures are preferred.
Moreover, it is preferable to mix these curing agents so 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 powder. 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 solder crack resistance. When the amount of the inorganic filler is less than 80% by weight, low thermal expansion and low water absorption cannot be obtained, and solder crack resistance is insufficient. Further, when the amount of the inorganic filler exceeds 90% by weight, there is a problem such as displacement of the die pad and the gold wire in the semiconductor package due to the 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 sealing materials can be widely used. For example, 1,8-diazabicycloundecene, triphenylphosphine, dimethylbenzylamine, 2-methylimidazole and the like are 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, but in addition to this, a silane coupling agent, a brominated epoxy resin, 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 inorganic filler, the curing accelerator, and 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 compound represented by the formula (3) (melting point: 85 ° C., epoxy equivalent: 240) 6.68 parts by weight

[0015]

[Chemical 5]

Orthocresol novolac type epoxy resin (softening point 58 ° C., epoxy equivalent 200 g / eq) 1.67 parts by weight Phenolic resin curing agent represented by the formula (4) (softening point 63 ° C., hydroxyl equivalent 170 g / eq) ) 4.36 parts by weight

[0017]

[Chemical 6] (The value of n is a mixture showing 0 to 3, and the weight ratio thereof is 1 for n = 0 and 0.60 for n = 1 and 0.
42 and n = 3 is 0.22. )

Phenol novolac resin curing agent (softening point 65 ° C., hydroxyl equivalent 105 g / eq) 1.09 parts by weight fused silica powder (average particle size 10 μm, specific surface area 2.0 m ² / g) 35 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 molding material obtained by crushing was measured for spiral flow under the conditions of 175 ° C., 70 kg / cm ² , and 120 seconds using a mold according to EMMI-I-66. Further, the obtained molding material was tabletted, and a 6 × 6 mm chip was soldered with a low pressure transfer molding machine under the conditions of 175 ° C., 70 kg / cm ² , and 120 seconds for a solder crack test with 52 pQFP.
And a 3 × 6 mm chip was sealed in 16 pSOP for the solder moisture resistance test. The following solder crack test and solder moisture resistance test were performed on the sealed test element.

Solder crack test: The sealed test element was subjected to an environment of 85 ° C. and 85% RH for 24 hours, 48 hours,
It was treated for 72 hours and 120 hours 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 72 hours, then immersed in a solder bath at 260 ° C for 10 seconds, and then pressure cooker test (1
25 degreeC, 100% RH was performed, and the open defect of the circuit was measured. The test results are shown in Table 1. Examples 2 to 6 Compounding was performed according to the formulation shown in Table 1, and molding materials were obtained in the same manner as in Example 1. Using this molding material, a molded product sealed for testing was obtained, 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. The test results are shown in Table 1.

Comparative Examples 1 to 4 Compounding was carried out according to the formulation shown in Table 2, and molding materials were obtained in the same manner as in Example 1. Using this molding material, a molded product sealed for testing was obtained, 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. The test results are shown in Table 2.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

The present invention is excellent in solder crack resistance and moisture resistance after soldering.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 23/31

Claims (3)

[Claims] 1. (A) An epoxy compound represented by the following formula (1) is contained in an amount of 30 to 100% by weight based on the total amount of epoxy resin.
Epoxy resin containing, (In the formula, R _{1 to} R ₁₀ are hydrogen, halogens, carbon number 1 to 1
Same or different atom or group selected from 2 alkyl groups) (B) Phenolic resin curing agent represented by the following formula (2) is 30 to 100% by weight based on the total amount of the phenolic resin curing agent.
Phenolic resin curing agent containing, (R in the formula is the same or different atom or group selected from hydrogen, halogens and alkyl groups having 1 to 5 carbon atoms) (C) Inorganic filler, (D) Curing accelerator as essential components Epoxy resin composition for semiconductor encapsulation. 2. R _{1 to} R ₄ of the formula (1) are methyl groups, and R ₅ to
The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein R ₈ is a hydrogen atom, and R ₉ and R ₁₀ are tertiary butyl groups. 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein R in the formula (2) is hydrogen.