JPH09143345A - Epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sealant which exhibits excellent resistances to soldering heat and moisture in the surface mounting of a semiconductor device by compounding an arom. polyepoxy compd., a specific phenol resin curative, an inorg. filler, and a cure accelerator. SOLUTION: This epoxy resin compsn. for semiconductor sealing is prepd. by compounding an arom. polyepoxy compd., a phenol resin curative contg. 30-100wt.% curative represented by the formula (wherein R is H, an alkyl, or halogen; and (n) is 0-10), an inorg, filler, and a cure accelerator. Pref. the epoxy compd. is of a phenol novolak type, a cresol-novolak type, or a bisphenol type, and when the compsn. contains the filler in an amt. of 80-90wt.%, the compd. is pref. a crystalline one, such as of a biphenyl type or a bisphenol type. The compsn. is used for sealing a thin package of a large-size semiconductor integrated circuit, exhibiting a high reliability of resistances to cracks and moisture at the soldering step.

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 and moisture 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, as the integration of integrated circuits has increased, the size of the chips has gradually increased, and the packages used in conventional DI
Small and thin QFP, S surface mounted from P type
OP, SOJ, TSOP, TQFP, PLCC have been changed. That is, a large chip is enclosed in a small and thin package, and thermal stress causes cracking, and problems such as deterioration of moisture resistance due to these cracks are greatly highlighted. Especially in the soldering process, when exposed to a high temperature of 200 ° C or more,
There is a problem that moisture resistance is deteriorated due to cracking of the package and peeling of the resin and the chip. Therefore, development of a highly reliable resin composition for semiconductor encapsulation suitable for encapsulating these large chips is desired.

[0003]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of providing an epoxy resin composition for semiconductor encapsulation, in which the solder stress resistance and moisture resistance of the semiconductor package during substrate mounting are remarkably improved. Is.

[0004]

The present invention provides (1) (A)
An aromatic compound having two or more epoxy groups, (B) a resin curing agent containing 30 to 100 parts by weight of the phenol resin curing agent represented by the formula (1) with respect to the total amount of the resin curing agent, (C).
An epoxy resin composition for semiconductor encapsulation, which comprises an inorganic filler and (D) a curing accelerator as essential components.

[0005]

[Chemical 6] (In the formula, R ₁ is the same or different atom or group selected from hydrogen, alkyl group and halogens, n = 0 to 0
10)

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the aromatic compound having two or more epoxy groups used in the present invention include phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenol methane type epoxy compound,
Alkyl-modified triphenol methane type epoxy compound,
Biphenyl type epoxy compounds, bisphenol type epoxy compounds, stilbene type epoxy compounds and the like,
These may be used alone or as a mixture. Further, among these, particularly when the amount of the inorganic filler as the epoxy resin composition is 80 to 90% by weight, the biphenyl type epoxy compound of the formula (2) and the bisphenol type of the formula (3) having a low viscosity when melted. Crystalline compounds such as epoxy compounds and stilbene type epoxy compounds of formula (4) are preferred. Among these, formula (2) is formula (7), formula (3) is formula (8),
Further, the formula (4) more preferably has the structure represented by the formula (5).

The phenol resin curing agent represented by the molecular structure of the formula (1) is a resin curing agent obtained by polymerizing phenol and bismethylene biphenol by Friedel-Crafts alkylation reaction, and is a conventional phenol novolac resin. In comparison with the above, since it has a biphenyl structure, the cured product of the resin composition using this exhibits high strength characteristics. It also has the characteristic of having a relatively small amount of moisture absorption. N in the formula (1) is 0
It is preferable that it is 10 to 10 and the weight ratio of n = 0 to 2 is 50% or more. When the weight ratio of n = 3 or more increases, the resin viscosity increases, and the fluidity decreases. By adjusting the amount of the phenol resin curing agent used, solder stress resistance can be maximized. In order to bring out the effect of resistance to solder stress, it is desirable to use the phenol resin curing agent 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 the resin curing agent. If it is less than 30% by weight, the intended solder stress resistance is insufficient.

When other resin curing agents are used in combination with the phenol resin curing agent represented by the formula (1), polymers having a hydroxyl group may be generally used. For example, phenol novolac resin, cresol novolac resin, dicyclopentadiene modified phenol resin, phenol aralkyl resin, terpene modified phenol resin, triphenol methane compound and the like, particularly phenol novolac resin, dicyclopentadiene modified phenol resin, phenol aralkyl resin , Terpene modified phenolic resins and mixtures thereof are preferred. The amount of these curing agents to be added is preferably such that the number of epoxy groups in the epoxy compound matches the number of hydroxyl groups in the curing agent.

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 blending amount of the inorganic filler is preferably 70 to 90% by weight with respect to 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 70% by weight, low thermal expansion and low water absorption cannot be obtained, and the solder stress resistance is insufficient. On the other hand, if the amount of the inorganic filler exceeds 90% by weight, problems such as die pad in the semiconductor package and displacement of the gold wire will occur 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 encapsulating 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 they may be used alone or in combination.

The epoxy resin composition of the present invention contains an aromatic compound having two or more epoxy groups, a phenol resin curing agent, an inorganic filler and a curing accelerator as essential components. Coupling agents, brominated epoxy resins, flame retardants such as 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 addition of silicone oil and rubber. Various additives such as agents may be appropriately blended. Further, in order to produce the encapsulating epoxy resin composition of the present invention as a molding material, the epoxy resin, dihydroxybenzene resin curing agent, curing accelerator, inorganic filler, and other additives are sufficiently homogenized with a mixer or the like. After mixing, 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 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 below with reference to examples. Example 1 The following composition 7.75 parts by weight of an epoxy resin represented by the formula (5) (melting point 150 ° C., epoxy equivalent 162 g / eq).

[0012]

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2.12 parts by weight of a phenol resin curing agent represented by the formula (6) (softening point 80 ° C., hydroxyl group equivalent 198 g / eq)

[0014]

Embedded image (The value of n is a mixture showing 0 to 3. The weight ratio is 0.59 for n = 1, 0.35 for n = 2, and 0.16 for n = 3 with respect to 1 for n = 0. Is)

Phenol novolac resin curing agent (softening point 75 ° C., hydroxyl equivalent 106 g / eq) 3.93 parts by weight Fused silica powder (average particle size 10 μm, specific surface area 2.0 m ² / g) 35.0 parts by weight spherical silica Powder (average particle size 30 μm, specific surface area 2.5 m ² / g) 50.0 parts by weight 1,8-diazabicyclo (5,4,0) undecene-7 (DBU) 0.2 parts by weight carbon black 0.5 parts by weight 0.5 parts by weight of carnauba wax are mixed in a mixer at room temperature, and then mixed at 70 to 100 ° C. for 2 hours.
The mixture was kneaded by a shaft roll, cooled and pulverized to obtain a molding material. The obtained molding material is made into tablets, which are then subjected to a low pressure transfer molding machine at 175 ° C., 70 kg / cm ² , 120
Under the condition of seconds, a 6 × 6 mm chip was sealed in 52pQFP for a solder stress test, and a 3 × 6mm chip was sealed in 16pSOP for a solder moisture resistance test. The following solder stress test and solder moisture resistance test were performed on the sealed test element.

Evaluation method Solder stress test: The sealed test element was tested at 85 ° C.
Treated in an environment of 85% RH for 24 hours, 48 hours, 72 hours and 120 hours, and then immersed in a solder bath at 260 ° C for 10 seconds, and then observed external cracks with a microscope (number of cracks generated / total number). Expressed as Solder moisture resistance test: Sealed test element at 85 ° C, 8
After processing in an environment of 5% RH for 24 hours and then immersing it in a solder bath at 260 ° C. for 10 seconds, a pressure cooker test (125 ° C., 100% RH) was performed to measure the open circuit failure. Bending strength test: Measured at 240 ° C. according to JIS K6911. Table 1 shows the evaluation results.

Examples 2 to 6 Compounding was carried out according to the formulation shown in Table 1, and a molding material was obtained in the same manner as in Example 1. The epoxy resin represented by the formula (7) used in Example 5 had a melting point of 108 ° C. and an epoxy equivalent of 195.
It is g / eq. The epoxy resin represented by the formula (8) used in Example 6 had a melting point of 77 ° C. and an epoxy equivalent of 192.
It is g / eq.

[0018]

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[0019]

Embedded image

Sealed molded articles for testing were obtained from these molding materials, and the solder stress test and solder moisture resistance test were carried out in the same manner as in Example 1 using these molded articles. Table 1 shows the evaluation results. Comparative Examples 1 to 6 Compounding was carried out according to the prescription of Table 2, and a molding material was obtained in the same manner as in Example 1. The ortho-cresol novolac type epoxy resin used in Comparative Example 1 has a softening point of 58 ° C. and an epoxy equivalent of 200 g / eq. Sealed molded articles for testing were obtained from these molding materials, and solder stress test and solder moisture resistance test were conducted in the same manner as in Example 1 using these molded articles. Table 2 shows the evaluation results.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

The semiconductor package encapsulated with the resin composition of the present invention has significantly improved soldering stress resistance and moisture resistance when mounted on a substrate.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01L 23/31

Claims (4)

[Claims] 1. A phenolic resin containing (A) an aromatic compound having two or more epoxy groups and (B) a phenolic resin curing agent represented by the formula (1) in an amount of 30 to 100% by weight based on the total amount of the resin curing agent. Curing agent, (In the formula, R ₁ is the same or different atom or group selected from hydrogen, an alkyl group and a halogen group, and n = 0.
10) An epoxy resin composition for semiconductor encapsulation, which comprises (C) 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 aromatic compound having two or more epoxy groups is a crystalline epoxy resin having a melting point of 50 to 150 ° C. 3. The epoxy resin composition for semiconductor encapsulation according to claim 2, wherein the crystalline epoxy resin has the formula (2), the formula (3) or the formula (4). Embedded image (Wherein R ₂ is the same or different atom or group selected from hydrogen, alkyl group and halogen group) (In the formula, R ₃ is the same or different atom or group selected from hydrogen, an alkyl group and a halogen group.) (R ₄ in the formula is the same or different atom or group selected from hydrogen, alkyl group and halogen group) 4. The epoxy resin composition for semiconductor encapsulation according to claim 1, 2 or 3, wherein the phenol resin curing agent of formula (1) is of formula (6). Embedded image