JPH10279663A - Epoxy resin composition for semiconductor sealing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition used for low-warpage ball grid arrays and giving sealed semiconductor devices excellent in reliability by mixing an epoxy resin having a specified structure with a phenolic resin curing agent having a specified structure, a cure accelerator and an inorganic filler. SOLUTION: The epoxy resin is represented by formula I (wherein R1 and R2 are each H, methyl, ethyl or t-butyl; and n is 1 or greater). The glycidyl ether group bonded to the benzene ring bonded to the -CH is ortho in position. The phenolic resin curing agent is represented by formula II (wherein n is 1 or greater), and the phenolic hydroxyl group bonded to the benzene ring bonded to the -CH- is ortho in position. The cure accelerator may be anything that can accelerate the reaction of the epoxy groups with the phenolic hydroxyl groups and is exemplified by 1,8-diazabicyclo[5.4.0]undecene-7. The inorganic filler is desirably spherical fused silica.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly reliable epoxy resin composition for a ball grid array having a small package warpage.

[0002]

2. Description of the Related Art Semiconductor packages have come to take various forms in order to make electronic products lighter and thinner, smaller, denser, more functional, and less expensive. In recent years, as a special package developed, there is a ball grid array (hereinafter, referred to as BGA). This BGA has a structure in which a semiconductor element is directly mounted on a circuit board, and the semiconductor element is sealed with an epoxy resin composition (hereinafter, referred to as a resin composition). It is mounted on a motherboard via solder balls on the back surface of a circuit board on which semiconductor elements are mounted. The production volume of this package is increasing significantly because an element having a large number of pins can be easily mounted on a motherboard. This package has a so-called bimetal structure, and large warpage is likely to occur. Various resin compositions for reducing this warpage have been studied, but none of them has completely solved the warpage. For example, it has been found that a resin system having a high glass transition temperature (hereinafter, referred to as Tg) is effective for reducing the warpage of BGA.
No. 8755. However, even if a resin system having a high Tg disclosed in this publication is used, it is still insufficient to reduce warpage.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a highly reliable resin composition for a BGA having a small package warpage.

[0004]

The present invention provides (A) an epoxy resin represented by the formula (1), (B) a phenol resin curing agent represented by the formula (2), (C) a curing accelerator, and D) An epoxy resin composition for semiconductor encapsulation comprising an inorganic filler.

Embedded image (R ₁ and R _{2 in} the formula (1) are selected from hydrogen, methyl group, ethyl group and tertiary butyl group, and may be the same or different.)

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
As shown in the formula (1), the epoxy resin used in the present invention has a glycidyl ether group bonded to a benzene ring linked to —CH— at the ortho position, and thus has the above-mentioned structure. Curing shrinkage of the cured product is slightly smaller than that of the resin disclosed in
Was found to be less warped. Although the reason is not clear, it is estimated that the skeleton of the epoxy resin is greatly restricted in the degree of freedom and becomes rigid due to the steric hindrance due to the presence of the glycidyl ether group at the ortho position, and the curing shrinkage ratio decreases. Is done. Although there is a difference in the curing shrinkage of the cured product, Tg is almost the same.

The epoxy resin represented by the formula (1) includes various structures, and these may be used alone or as a mixture. Further, another epoxy resin may be used in combination as long as the properties of the epoxy resin represented by the formula (1) are not impaired. As the epoxy resin used in combination, for example, ortho-cresol novolak type epoxy resin, phenol novolak type epoxy resin, triazine nucleus containing epoxy resin, dicyclopentadiene modified epoxy resin,
Examples include a biphenyl type epoxy compound, an alkyl-modified triphenol methane type epoxy resin other than the formula (1), a stilbene type epoxy compound, and a bisphenol type epoxy compound. It is desirable that the epoxy resin used in the present invention has as little ionic impurities as possible, such as chlorine ions and sodium ions, in order to improve moisture resistance reliability.

The phenolic resin curing agent used in the present invention has, as shown by the formula (2), a phenolic hydroxyl group bonded to a benzene ring linked to -CH- at the ortho position. As a result, the curing shrinkage of the cured product is reduced and the warpage of the BGA is reduced as compared with the resin disclosed in the above-mentioned publication. The phenol resin represented by the formula (2) may be used in combination with another phenol resin as long as the properties of the phenol resin are not impaired. Examples of the phenol resin used in combination include phenol novolak resin, cresol novolak resin, dicyclopentadiene-modified phenol resin, and xylylene-modified phenol resin. The phenolic resin curing agent used in the present invention,
It is desirable that the amount of ionic impurities such as chlorine ions and sodium ions be as small as possible to improve the humidity resistance reliability.

The curing accelerator used in the present invention includes:
Any material that promotes the reaction between the epoxy group and the phenolic hydroxyl group may be used, and those generally used for a sealing material can be widely used. More preferred are 1,8-diazabicyclo (5,4,0) undecene-7 and formula (3)
Is a tetraphenylphosphonium-tetranaphthoic acid borate represented by

Embedded image 1,8-diazabicyclo (5,4,0) undecene-7
Is effective for improving the adhesion to various substrates, and the curing accelerator of the formula (3) has the effect of significantly improving the room temperature storage characteristics of the resin composition. These curing accelerators may be used alone or as a mixture. Further, if necessary, it may be used in combination with another curing accelerator. Examples of the curing accelerator used in combination include triphenylphosphine, dimethylbenzylamine, tetraphenylphosphonium / tetraphenylborate, and the like.

The inorganic filler used in the present invention is, for example, crushed fused silica powder, spherical silica powder, crystalline silica powder, secondary aggregated silica powder, porous silica powder, secondary aggregated silica powder or porous silica powder. Silica powder, alumina and the like. In addition, the shape of the inorganic filler may be crushed or spherical, but the flow characteristics,
Considering the balance between mechanical strength and thermal properties, spherical fused silica powder is preferred. These inorganic fillers may be used alone or as a mixture. Further, a material whose surface has been previously treated with a silane coupling agent or the like may be used.

The silane coupling agent used in the present invention is represented by the formulas (4) and (5) and has reactivity with both inorganic fillers and organic substances. These silane coupling agents act on the adhesive interface between the substrate on which the semiconductor is mounted and the resin composition, improve the adhesive strength, and have the effect of improving reliability such as solder resistance. These silane coupling agents may be used alone or as a mixture. Further, other coupling agents can be used in combination as needed. The method of addition is not particularly limited.

Embedded image (R in the formulas (4) and (5) is a methyl group or an ethyl group.)

The resin composition of the present invention comprises (A) to (D)
Alternatively, in addition to the components (A) to (E), a coloring agent such as carbon black, a flame retardant such as a brominated epoxy resin or antimony oxide, various release agents, and silicone oil may be appropriately compounded as necessary. . The resin composition of the present invention is, for example, after thoroughly and uniformly mixing all the compounding raw materials using a mixer or the like, and further melt-mixed with a hot roll or a kneader or the like,
It can be manufactured by pulverization after cooling. This resin composition can be particularly applied to the coating of BGA.

[0014]

The present invention will be described below by way of examples. The mixing ratio is by weight. Example 1 Epoxy resin (E-1) 11.5 parts by weight Phenol resin (H-1) 5.5 parts by weight 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) 2 parts by weight Spherical silica (average particle size: 15 μm) 80.0 parts by weight Carbon black 0.3 part by weight Brominated phenol novolak type epoxy resin 1.0 part by weight Antimony trioxide 1.0 part by weight Carnauba wax 0.5 part by weight Was mixed at room temperature using a mixer, kneaded at 50 to 130 ° C. using a biaxial roll, cooled, pulverized, and tableted to obtain a resin composition. This resin composition was evaluated by the following method. Table 1 shows the results.

Evaluation method BGA warpage: 2 using a low-pressure transfer molding machine
A 25-pin BGA was molded. Molded at a molding temperature of 175 ° C., a pressure of 70 kg / cm ² , and a curing time of 2 minutes.
Was carried out for 8 hours to obtain a sample for measurement. The BGA substrate used was a substrate using a bismaleimide triazine resin, and the size of the substrate was 27 × 27 × 0.
36mm, IC chip to mount is 9 × 9 × 0.35m
m, the size of the molded product of the measurement sample is 24 × 24 ×
1.18 mm. Warpage was measured using a molded product before solder ball mounting. The amount of warpage of the sample was measured at room temperature using a surface roughness meter (manufactured by Tokyo Seimitsu Co., Ltd.). The measurement position was on the diagonal line of the square package. Curing shrinkage: A disk having a diameter of 50 mm was molded, and the curing shrinkage was measured by the following method. Curing shrinkage (%) = {(r ₁ −r ₂ ) / r ₁ × 100} −
Cs r ₁ : Inner diameter (mm) of mold at 175 ° C. r ₂ : Outer diameter (mm) of disk when molded with the above mold, returned to room temperature after post-curing, and Cs: molded article of resin composition Was measured using a thermomechanical analyzer TMA120 manufactured by Seiko Electronics Co., Ltd.
Thermal expansion coefficient (%) in a temperature range of 75 ° C.

Examples 2 to 14, Comparative Examples 1 to 6 Resin compositions were prepared in the same manner as in Example 1 with the formulations shown in Tables 1 and 2, and evaluated in the same manner as in Example 1. The CA of the curing accelerator is a molten mixture of (DBU) / (phenol novolak resin of formula (H-2)) = 2/8 (weight ratio). The structural formulas of the epoxy resin, phenolic resin curing agent, and silane coupling agent used in Examples and Comparative Examples are shown below.

[Table 1]

[0017]

[Table 2]

[0018]

Embedded image

[0019]

Embedded image

[0020]

Embedded image

[0021]

According to the present invention, an epoxy resin composition for BGA having a small warpage can be obtained, and a semiconductor device encapsulated with the epoxy resin composition has excellent reliability.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 63/00 C08L 63/00 B H01L 23/29 H01L 23/30 R 23/31

Claims (3)

[Claims] (A) an epoxy resin represented by the formula (1),
(B) a phenolic resin curing agent represented by the formula (2),
An epoxy resin composition for semiconductor encapsulation, comprising (C) a curing accelerator and (D) an inorganic filler. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the curing accelerator is 1,8-diazabicyclo (5,4,0) undecene-7 or the formula (3). (A) an epoxy resin represented by the formula (1),
(B) a phenolic resin curing agent represented by the formula (2),
An epoxy resin composition for semiconductor encapsulation comprising (C) a curing accelerator, (D) an inorganic filler, and (E) a silane coupling agent represented by the formulas (4) and (5). Embedded image (R ₁ and R _{2 in} the formula (1) are selected from hydrogen, methyl group, ethyl group and tertiary butyl group, and may be the same or different.) Embedded image (R in the formulas (4) and (5) is a methyl group or an ethyl group.)