JPH10147628A - Epoxy resin composition for sealing semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition for sealing a semiconductor, excellent in solder stress resistance and solder moisture resistance. SOLUTION: This composition comprises (A) a crystalline epoxy compound having 50-150 deg.C melting point, (B) a resin curing agent composed of 30-100wt.% of a dihydroxybenzene/alkylaldehyde resin curing agent of the formula ((m) is 2-7: (n) is 0-10; Xs are each hydrogen or hydroxyl group and may be different or the same, and at least one of X is hydroxyl group) in the whole resin curing agent, (C) an inorganic filler and (D) a curing promoter as essential components.

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 having excellent resistance to soldering stress in surface mounting of a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, electronic components such as diodes, transistors, and integrated circuits have been sealed with a thermosetting resin composition. In particular, in an integrated circuit, an ortho-cresol novolac type excellent in heat resistance and moisture resistance is used. Epoxy resin with phenol
An epoxy resin composition (hereinafter, referred to as a resin composition) which is cured with a formaldehyde resin and blended with an inorganic filler such as fused silica or crystalline silica as a filler is used. However, in recent years, chips have been gradually increased in size with the increase in integration of integrated circuits, and small and thin QFPs, SOPs, SOPs, and SPSs that have been surface-mounted from conventional DIP types have been packaged.
OJ, TSOP, TQFP, PLCC have been changed. That is, a large chip is sealed in a small and thin package, cracks are generated by thermal stress, and problems such as a decrease in moisture resistance due to the cracks have been greatly highlighted. Particularly, in the soldering process, there is a problem in that the device is suddenly exposed to a high temperature of 200 ° C. or more, and the moisture resistance is deteriorated due to cracking of the package or separation of the chip from the resin composition. Therefore, development of a highly reliable resin composition suitable for sealing these large chips is desired.

[0003]

SUMMARY OF THE INVENTION The present invention solves such a problem by using a dihydroxybenzene / alkylaldehyde resin curing agent represented by the formula (1) as a resin curing agent. An 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 is improved.

[0004]

According to the present invention, (A) a melting point of 5
A crystalline epoxy compound at 0 to 150 ° C., (B) a resin curing agent containing 30 to 100 wt% of a dihydroxybenzene / alkyl aldehyde resin curing agent represented by the following formula (1) in all resin curing agents, (C) An epoxy resin composition for semiconductor encapsulation containing an inorganic filler and (D) a curing accelerator as essential components.

Embedded image (However, m = 2 to 7, n = 0 to 10, X is hydrogen or a hydroxyl group, and may be the same or different,
At least one of them is a hydroxyl group. )

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The melting point used in the present invention is 50 to 150.
The molecular structure of the crystalline epoxy compound at ℃ is low molecular, has a planar structure and is a solid that crystallizes at room temperature, but melts rapidly in the temperature range above the melting point and has a low viscosity. It changes to a liquid. The melting point of the crystalline epoxy compound is preferably from 50 to 150 ° C., and if it is lower than 50 ° C., the crystalline epoxy compound is melted at room temperature, and there is a concern about workability and a decrease in room temperature storage property of a resin composition using the same. Is done. Fifteen
If the temperature exceeds 0 ° C., the composition does not melt sufficiently during kneading and cannot be uniformly dispersed, so that the curability and moldability are reduced. Further, the molded product becomes non-uniform, and the strength differs depending on each part, so that the performance of the semiconductor package is reduced. Examples of the crystalline epoxy compound satisfying these conditions include a biphenyl type epoxy compound of the formula (2), a bisphenol type epoxy compound of the formula (3), a stilbene type epoxy compound of the formula (4),
Examples include naphthalene type epoxy compounds, which may be used alone or as a mixture. Particularly, the epoxy compounds of the formulas (2), (3) and (4) are preferable, and these may be used as a mixture. Further, in order to improve the moisture resistance reliability, it is desirable that the amount of chlorine ions, sodium ions and other free ions contained in these crystalline epoxy compounds is as small as possible.

Embedded image (R ₁ in the formula is an atom or a group selected from hydrogen, an alkyl group, and a halogen, and they may be the same or different from each other.)

[0006]

Embedded image (R ₂ in the formula is an atom or group selected from hydrogen, an alkyl group, and a halogen, and they may be the same or different from each other.)

[0007]

Embedded image (R ₃ in the formula is an atom or a group selected from hydrogen, an alkyl group, and a halogen, and they may be the same or different.)

Further, other epoxy resins may be used in combination as long as the properties of the crystalline epoxy compound are not impaired. Examples of the epoxy resin used in combination include an orthocresol novolak type epoxy resin and a triphenolmethane type epoxy compound.

The dihydroxybenzene / alkyl aldehyde resin curing agent of the formula (1) used in the present invention is dihydroxybenzene or a resin obtained by polycondensation of dihydroxybenzene and phenol with an alkyl aldehyde in the presence of an acid catalyst. Unlike a conventional phenol-formaldehyde resin, the resin contains a hydrophobic alkyl group, so that the amount of moisture absorption is relatively suppressed, and the adhesion to metals such as lead frames and silicon chips is excellent. Further, the strength of the rubber region at a high temperature is improved by the effect of dihydroxybenzene. N in the equation (1) is
A dihydroxybenzene-alkyl aldehyde resin containing 0 to 10 and containing at least 50% by weight of n = 0 to 2 is preferable. If n = 3 or more, the melt viscosity at the time of molding becomes high, so that the fluidity decreases, which is not preferable. M in the formula (1) is 2 to 7, and if it is 1, the effect of the hydrophobic alkyl group is so small that sufficient low hygroscopicity cannot be obtained. Also, 8
As described above, the steric hindrance is large, and the curing reaction between the epoxy group and the hydroxyl group is inhibited, so that the curability of the resin composition may be lowered or the glass transition temperature of the cured product may be lowered. By adjusting the compounding amount of the dihydroxybenzene / alkyl aldehyde resin curing agent, the solder stress resistance can be maximized. In order to bring out the effect of the solder stress resistance, the dihydroxybenzene / alkyl aldehyde resin curing agent represented by the formula (1) should be blended in all the resin curing agents in an amount of 30% by weight or more, preferably 50% by weight or more. desirable. If it is less than 30% by weight, the target solder stress resistance is insufficient, which is not preferable. When used in combination with the dihydroxybenzene-alkyl aldehyde resin represented by the formula (1), as the other resin, any polymer having a phenolic hydroxyl group may be used.
For example, phenol-formaldehyde resin, cresol novolak resin, dicyclopentadiene-modified phenolic resin, xylylene-modified phenolic resin, terpene-modified phenolic resin, triphenolmethane compound and the like, and particularly preferred are dicyclopentadiene-modified phenolic resin Xylylene-modified phenolic resins and the like may be mentioned, and these may be used as a mixture. Further, it is preferable to mix them in such a manner that the number of epoxy groups and the number of phenolic 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 aggregated silica powder, porous silica powder, and alumina. And a mixture of fused silica powder and spherical silica powder is preferred. The compounding amount is 70 to 70% in all resin compositions from the viewpoint of solder stress resistance.
90% by weight is preferred. If it is less than 70% by weight, low thermal expansion properties and low moisture absorption properties cannot be obtained, and solder stress resistance becomes insufficient. If the content exceeds 90% by weight, inconveniences such as displacement of a die pad and a gold wire in a semiconductor package due to an increase in viscosity occur.

As the curing accelerator used in the present invention, any one can be used as long as it accelerates the curing reaction between the epoxy group and the phenolic hydroxyl group, and those generally used in sealing materials can be widely used. For example, 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, benzyldimethylamine, 2-methylimidazole and the like can be mentioned, and these may be used alone or as a mixture.

The resin composition of the present invention comprises, in addition to the components (A) to (D), if necessary, a silane coupling agent, a brominated epoxy resin, a flame retardant such as antimony trioxide and hexabromobenzene, and carbon black. , Colorants such as bengalara,
Various additives such as release agents such as natural wax and synthetic wax, and low stress additives such as silicone oil and rubber may be appropriately compounded.

In order to produce the resin composition of the present invention,
After sufficiently mixing the components (A) to (D) and other additives and the like using a mixer or the like, the mixture is further melt-kneaded with a hot roll or a kneader, and then cooled and ground to form a sealing material. can do. These resin compositions are used for coating electrical or electronic components such as transistors and integrated circuits,
It can be applied to insulation, sealing, and the like.

[0014]

The present invention will be specifically described below with reference to examples. Example 1 YX4000H (manufactured by Yuka Shell Epoxy Co., Ltd., melting point 105 ° C., epoxy equivalent 195 g / eq) 8.68 parts by weight Dihydroxybenzene alkyl aldehyde resin represented by the formula (5) (softening point 80 ° C., Hydroxyl equivalent 72 g / eq) 1.51 parts by weight

[0015]

Embedded image (The value of n is a mixture showing a value of 0 to 3, and the weight ratio is 1 for n = 0, 0.67 for n = 1, 0.31 for n = 2, and 0.12 for n = 3. Is.)

Phenol / formaldehyde resin (softening point 75 ° C., hydroxyl equivalent 106 g / eq) 2.81 parts by weight Fused silica powder (average particle size 10 μm, specific surface area 2.0 m ² / g) 35.00 parts by weight Fused spherical Silica powder (average particle size 30 μm, specific surface area 2.5 m ² / g) 50.00 parts by weight 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) 0.20 parts by weight bromination Phenol novolak type epoxy resin (epoxy equivalent: 275 g / eq) 0.80 parts by weight Carbon black 0.50 parts by weight Carnauba wax 0.50 parts by weight is mixed at room temperature with a mixer, and the mixture is mixed at 70 to 100 ° C. using a biaxial roll. It was kneaded, cooled and pulverized to obtain a resin composition. The bending strength, solder stress resistance, and solder moisture resistance of the obtained resin composition were evaluated by the following methods. Table 1 shows the results
Shown in

Evaluation method Bending strength test: 240 ° C. according to JIS K 6911
Was measured for bending strength. Solder stress resistance test: 80 pQFP (thickness 2 mm, chip size 7.5 mm × 7.5 mm) at mold temperature 17
Molding was performed at 5 ° C., a pressure of 70 kg / cm ² , and a molding time of 120 seconds. Post-curing was performed at 175 ° C. for 8 hours.
8 packages in an environment of 85 ° C and 85% relative humidity.
After a treatment for 2 hours, an IR reflow treatment (240 ° C.) was performed. After the treatment, the presence or absence of internal peeling or cracking was observed with an ultrasonic flaw detector, and the number of defective packages was counted. Solder moisture resistance test: 16pSOP (chip size 3mm ×
6 mm) at a mold temperature of 175 ° C. and a pressure of 70 kg / c.
Molding was performed with m ² and a molding time of 120 seconds. Post-curing was performed at 175 ° C. for 8 hours. This was treated for 24 hours in an environment of 85 ° C. and 85% relative humidity, and then subjected to IR reflow treatment (240 ° C.). Further, a pressure cooker test (125 ° C., pressure 2.4 kg / cm ² ) was performed.
The open failure of the circuit was measured.

Examples 2 to 8 Compounded according to the formulation shown in Table 1, a resin composition was obtained in the same manner as in Example 1, and evaluated in the same manner as in Example 1. Table 1 shows the results. The epoxy compounds of Examples 5 and 6 have the formula (6)
(Melting point: 96 ° C., epoxy equivalent: 197 g / eq).

Embedded image

The dihydroxybenzene-alkyl aldehyde resins of Examples 6, 7, and 8 have the formula (7) (softening point of 95 ° C.,
It is shown by a hydroxyl equivalent of 77 g / eq).

Embedded image (The value of n and k is a mixture showing 0 to 4. The weight ratio is 1 for n + k = 1, 0.74 for n + k = 2,
n + k = 3 is 0.45 and n + k = 4 is 0.18. )

Comparative Examples 1 to 4 Compounded according to the formulation shown in Table 2, a molding material was obtained in the same manner as in Example 1, and evaluated in the same manner as in Example 1. Table 2 shows the results
Shown in

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

According to the present invention, the solder stress resistance when the semiconductor package is mounted on the substrate is improved, and the solder moisture resistance is also improved.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // C08G 8/04

Claims (2)

[Claims] 1. A resin composition comprising: (A) a crystalline epoxy compound having a melting point of 50 to 150 ° C .; and (B) a dihydroxybenzene / alkyl aldehyde resin curing agent represented by the following formula (1): % Of resin curing agent, (C)
An epoxy resin composition for semiconductor encapsulation containing an inorganic filler and (D) a curing accelerator as essential components. Embedded image (However, m = 2 to 7, n = 0 to 10, X is hydrogen or a hydroxyl group, and may be the same or different,
At least one of them is a hydroxyl group. ) 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the crystalline epoxy compound (A) is represented by the formula (2), (3) or (4). Embedded image (R ₁ in the formula is an atom or a group selected from hydrogen, an alkyl group, and a halogen, and they may be the same or different from each other.) (R ₂ in the formula is an atom or a group selected from hydrogen, an alkyl group, and a halogen, and they may be the same or different from each other.) (R ₃ in the formula is an atom or a group selected from hydrogen, an alkyl group, and a halogen, and they may be the same or different.)