JPH0995525A - Epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition which shows excellent cracking resistance when subjected to thermal stress resulting from an abrupt temperature change in a soldering step. SOLUTION: This resin composition essentially consists of an epoxy resin, a phenolic resin curing agent, a cure accelerator and fused silica, and is an epoxy resin composition for semiconductor sealing in which the fused silica comprises 5-40wt.% broken fused silica of a mean particle diameter of 10-30μm and 95-60wt.% spherical fused silica of a mean particle diameter of 10-30μm and is contained in an amount of 80-93wt.% based on the entire composition.

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 heat resistance 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 a thermosetting resin. Especially in integrated circuits, an O-cresol novolac type epoxy resin excellent in heat resistance and moisture resistance is used. An epoxy resin cured with a novolac type phenolic resin is used. 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 flat package that is surface-mounted from the conventional DIP type.
P, TSOP, SOJ, QFP, TQFP, etc. That is, a large chip is to be enclosed in a small and thin package, and cracks due to stress and a decrease in moisture resistance due to these cracks have been 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. It has been desired to develop a highly reliable encapsulating resin composition suitable for encapsulating these large chips.

In order to solve these problems, the addition of a thermoplastic oligomer (Japanese Patent Laid-Open No. 62-15849) and various silicone compounds (Japanese Patent Laid-Open No. 62- 11585, 62-
No. 116654, 62-128162), and further silicone modification (Japanese Patent Laid-Open No. 62-136860), but the resin strength is reduced, so that thermal stress in the soldering process is applied. On the contrary, resin cracks were always generated. On the other hand, in order to obtain an epoxy resin composition for semiconductor encapsulation which is excellent in heat stress resistance during soldering, that is, solder heat resistance, use of a biphenyl type epoxy resin as a resin system (Japanese Patent Laid-Open No. 64-65).
No. 116) has been studied, but the use of a biphenyl type epoxy resin improves the adhesion to the lead frame and the low water absorption, and improves the solder heat resistance, in particular, the occurrence of cracks is reduced. At high temperatures, the solder heat resistance was insufficient, and it was not possible to obtain a highly reliable epoxy resin composition for semiconductor encapsulation. In addition, a large amount of spherical fused silica with excellent fluidity is blended as a filler,
A method of achieving low water absorption and low thermal expansion was also studied, but the resin strength was lowered because of the spherical shape, and the solder heat resistance was insufficient.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention adjusts the shape, particle size and filling amount of fused silica as a filler to lower water absorption, lower thermal expansion and higher strength. The present invention provides an epoxy resin composition for semiconductor encapsulation, in which solder heat resistance of a semiconductor package during mounting on a substrate is remarkably improved.

[0005]

The present invention is an epoxy resin composition containing (A) an epoxy resin, (B) a phenol resin curing agent, (C) a curing accelerator, and (D) fused silica as essential components. And the fused silica has an average particle size of 3 to 8 μm.
Crushed fused silica 5 to 40% by weight, average particle size 10 to 30
An epoxy resin composition for semiconductor encapsulation, comprising 95 to 60% by weight of spherical fused silica having a particle size of 80 μm, and 80 to 93% by weight in the total composition.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin used in the present invention is
It has two or more epoxy groups in one molecule. Examples thereof include bisphenol type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, triphenol methane type epoxy resin and biphenyl type epoxy resin. In particular, equation (1)
When a biphenyl type epoxy resin represented by, for example, a relatively low molecular weight compound such as 3,3 ′, 5,5′-tetramethylbiphenol diglycidyl ether in which R is a methyl group is used, the adhesiveness and melt viscosity are It is preferable in terms of settings. These resins may be used alone or as a mixture.

The phenol resin curing agent used in the present invention is
It refers to all polymers having a phenolic hydroxyl group. Examples thereof include phenol novolac resin, cresol novolac resin, phenol aralkyl resin, dicyclopentadiene modified phenol resin, and terpene modified phenol resin. These resins may be used alone or as a mixture.

The curing accelerator used in the present invention may be any one as long as it accelerates the reaction between the epoxy group and the phenolic hydroxyl group, and those generally used for sealing materials can be widely used. , Diazabicycloundecene, triphenylphosphine, benzyldimethylamine, 2-methylimidazole and the like, and these may be used alone or in combination of two or more kinds.

The fused silica used in the present invention has an average particle size of 3
~ 8 μm crushed fused silica and average particle size 10-30 μm
Of spherical fused silica. Here, the average particle size means a particle size at which the cumulative weight becomes 50%. When the average particle diameter of the crushed fused silica is less than 3 μm, the resin strength is lowered and the solder heat resistance is insufficient, and when it exceeds 8 μm, the fluidity is lowered and the moldability is deteriorated. Further, if the average particle diameter of the spherical fused silica is less than 10 μm, the fluidity is lowered and the formability is deteriorated, and if it exceeds 30 μm, the passivation film on the semiconductor surface, the aluminum wiring and the like are damaged. In the fused silica used in the present invention, the blending ratio of the crushed fused silica and the spherical fused silica is 5 to 40% by weight of the crushed fused silica,
The spherical fused silica is 95-60% by weight. If the content of the crushed fused silica is less than 5% by weight, the resin strength is lowered and the solder heat resistance is insufficient. If it exceeds 40% by weight, the fluidity is lowered and the moldability is deteriorated. Also, spherical fused silica is 95
If the content exceeds 10% by weight, the resin strength decreases and the solder heat resistance is insufficient. If it is less than 60% by weight, the fluidity is lowered and the moldability is deteriorated. The amount of fused silica used in the present invention is 80 to 93% by weight based on the total composition. If it is less than 80% by weight, water absorption and thermal expansion are increased and the solder heat resistance is insufficient, and if it exceeds 93% by weight, fluidity is lowered and moldability is deteriorated.

The encapsulating epoxy resin composition of the present invention contains an epoxy resin, a phenol resin curing agent, a curing accelerator, and fused silica as essential components. In addition to these, a silane coupling agent and bromine may be added if necessary. Flame retardants such as epoxidized epoxy resin, antimony trioxide and hexabromene, coloring agents 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. There is no problem even if additives are properly mixed. Further, in order to produce the encapsulating epoxy resin composition of the present invention as a molding material, an epoxy resin, a phenol resin curing agent, a curing accelerator, fused silica, 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 molding material. These molding materials can be applied to sealing, coating, insulating, etc. of electronic parts or electric parts.

Hereinafter, the present invention will be described specifically with reference to examples. Example 1 Crushed fused silica (average particle size 5 μm) 10.00 parts by weight Spherical fused silica (average particle size 15 μm) 75.00 parts by weight 3,3 ′, 5,5′-tetramethylbiphenol diglycidyl ether (melting point 104 C, epoxy equivalent 194) 9.07 parts by weight Phenol novolac resin curing agent (softening point 85 ° C., hydroxyl equivalent 105) 4.88 parts by weight 1,8-diazabicyclo (5,4,0) undecene-7 (DBU) 0 0.25 parts by weight Carnauba wax 0.50 parts by weight Carbon black 0.30 parts by weight was mixed with a mixer at room temperature, kneaded with a biaxial roll at 80 to 100 ° C., cooled and pulverized to obtain a molding material. Spiral flow, solder crack resistance and solder moisture resistance tests of the obtained molding material were carried out. Table 1 shows the evaluation results.

Evaluation method Spiral flow: A mold for spiral flow measurement according to EMMI-I-66 was used, and the mold temperature was 175 ° C., the injection pressure was 70 kg / cm ² , and the curing time was 2 minutes. Deformation of gold wire: 52pQFP with a chip size of 6 × 6 mm and a gold wire length of 3 mm, mold temperature 175 ° C., injection pressure 70 kg /
It was molded at cm ² and a curing time of 2 minutes, and the gold wire deformation was observed by an X-ray fluoroscope. Solder cracking property: 52pQF with chip size 6x6mm
P was molded at a mold temperature of 175 ° C., an injection pressure of 70 kg / cm ² and a curing time of 2 minutes, and the obtained molded product was post-cured at 175 ° C. for 8 hours. This molded product was treated in an environment of 85 ° C. and 85% RH for 48 hours, 72 hours, and 120 hours, then immersed in a solder bath at 260 ° C. for 10 seconds, and external cracks were observed with a microscope. Solder moisture resistance: 52 pQFP with a chip size of 6 × 6 mm was molded at a mold temperature of 175 ° C., an injection pressure of 70 kg / cm ² and a curing time of 2 minutes, and the obtained molded product was post-cured at 175 ° C. for 8 hours. This molded product was treated in an environment of 85 ° C. and 85% RH for 72 hours, then immersed in a solder bath at 260 ° C. for 10 seconds, and then subjected to a pressure cooker test (125 ° C., 100 ° C.).
% RH) to measure the open circuit failure of the circuit. Examples 2 to 5, Comparative Examples 1 to 7 According to the formulations in Tables 1 and 2, molding materials were obtained in the same manner as in Example 1 and evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.
It shows in Table 2.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

According to the present invention, the resistance to cracking when subjected to thermal stress due to a rapid temperature change in the soldering process is very excellent, and the reliability of the surface mounting package is improved, so that it has an industrial value. It is tremendous.

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

Claims (2)

[Claims] 1. An epoxy resin composition containing (A) an epoxy resin, (B) a phenol resin curing agent, (C) a curing accelerator, and (D) fused silica as essential components, the fused silica being an average. Crushed fused silica 5-40 with particle size 3-8 μm
95% by weight, spherical fused silica 95 having an average particle size of 10 to 30 μm
An epoxy resin composition for semiconductor encapsulation, which comprises 60 to 60% by weight, and 80 to 93% by weight in the total composition. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the epoxy resin is a biphenyl type epoxy resin represented by the formula (1). (Here, R in the formula is hydrogen or a methyl group, and may be the same or different.)