JPH07173255A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin composition excellent in soldering crack resistance and humidity resistance after soldering by mixing a specified epoxy resin with a specified curing agent, an inorganic filler and a cure accelerator. CONSTITUTION:This resin composition is used for semiconductor sealing and essentially consists of an epoxy resin (A) containing 30-100wt.%, based on the total weight of the epoxy resin, epoxy resin represented by formula I (wherein R is H, halogen or alkyl; and n is 0-20), a phenolic resin curing agent (B) containing 30-100wt.%, based on the total weight of the phenolic resin curing agent, phenolic resin curing agent of formula II (wherein R and n are each as defined above), an inorganic filler (C), and a cure accelerator (D). By using a combination of resin A with curing agent B, this composition can give a cured product markedly excellent in cracking resistance under thermal stress resulting from a rapid temperature change in the soldering step and having good humidity resistance, and therefore being desirable for sealing, coating insulation or the like of electronic or electrical 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 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, 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. Therefore, development of a highly reliable resin composition for semiconductor encapsulation suitable for encapsulating these large chips is desired.

[0003]

The present invention addresses the above problems by using an epoxy resin 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 30 to 100% by weight of an epoxy resin represented by the following formula (1) with respect to the total amount of epoxy resin:

[0005]

[Chemical 3] (R in the formula is the same or different atom or group selected from hydrogen, halogens and alkyl groups, n = 0 to 2
0)

(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, n = 0 to 2
0)

An epoxy resin composition for semiconductor encapsulation containing (C) an inorganic filler and (D) a curing accelerator as essential components, and solder crack resistance and solder treatment which are superior in reliability as compared with conventional epoxy resin compositions. The latter has moisture resistance.

The epoxy resin represented by the molecular structure of the formula (1) is obtained by polymerizing paraxylene and phenol by Friedel-Crafts-alkyl reaction and glycidyl etherification with epichlorohydrin. Compared with the conventional cresol novolac epoxy resin, the elastic modulus of the cured product in the rubber region is low, the moisture absorption is low, and the adhesiveness to metals such as lead frame (42 alloy, copper alloy) is excellent. By adjusting the amount of the epoxy resin 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 resin 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 in the formula is preferably a hydrogen atom. In the formula, n is 0 to 20, but if it exceeds 20, fluidity deteriorates. 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 phenol by Friedel, crafts and alkylation reaction in the same manner as the epoxy resin. Compared with the conventional phenol novolac resin, the elastic modulus of the cured product in the rubber region is low, the moisture absorption is low, and the adhesion to metals such as lead frame (42 alloy, copper alloy) is excellent. 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. If it is less than 30% by weight, the target solder crack resistance is insufficient. Further, R in the formula is preferably a hydrogen atom. In the formula, n is 0 to 20, but if it exceeds 20, fluidity deteriorates. 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 can be mentioned, in particular phenol novolac resin, dicyclopentadiene modified phenol resin, terpene modified phenol resin and mixtures thereof. Is 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.

As described above, conventionally, the resin having the paraxylylene structure represented by the formula (2) has been used only as a curing agent for a phenol resin, but it has been converted into a glycidyl ether to obtain an epoxy resin. By using the paraxylylene structure not only in the phenol resin curing agent but also in the epoxy resin, the paraxylylene structure is introduced into all the resins. 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 and spherical silica are used. Mixtures with powders are preferred. The amount of the inorganic filler compounded is preferably 80 to 90% by weight based on the total amount of the epoxy resin composition in view of resistance to solder cracking. The amount of inorganic filler is 80
If it is less than wt%, low thermal expansion and low water absorption cannot be obtained and solder crack resistance is insufficient. In addition, the amount of inorganic filler is 90
If it exceeds 5% by weight, problems such as displacement of the die pad and the gold wire in the semiconductor package due to high viscosity may occur.

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.
What is generally used as a sealing material can be widely used. For example, there are 1,8-diazabicycloundecene, triphenylphosphine, benzyldimethylamine, 2-methylimidazole and the like, which may be used alone or in combination. The epoxy resin composition of the present invention contains an epoxy resin, a 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, antimony trioxide, hexa Flame retardants such as brombenzene, colorants 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 may be appropriately blended. There is no. Also,
In order to produce the encapsulating epoxy resin composition of the present invention as a molding material, an epoxy resin, a curing agent, a curing accelerator, a filler, and other additives are sufficiently uniformly mixed with a mixer or the like, and then further heated. A sealing material can be obtained by melt-kneading with a roll or a kneader, cooling and pulverizing. 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 Epoxy resin represented by the formula (3) (softening point 50 ° C., epoxy equivalent 250 g / eq) 6.76 parts by weight

[0014]

[Chemical 5] (The value of n is a mixture showing 0 to 3, and the polymerization ratio of n = 0 is 1, n = 1 is 0.70, and n = 2 is 0.
45 and n = 3 is 0.30. )

Orthocresol novolac epoxy resin (softening point 58 ° C., epoxy equivalent 200 g / eq) 1.69 parts by weight Phenolic resin curing agent represented by the formula (4) (softening point 63 ° C., hydroxyl equivalent 170 g / eq) 4.28 parts by weight

[0016]

[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. )

Phenolic novolac resin curing agent (softening point 65 ° C., hydroxyl equivalent 105 g / eq) 1.07 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 pulverization was measured for spiral flow according to EMMI-I-66 under the conditions of 175 ° C., 70 kg / cm ² , and 120 seconds. Further, the obtained molding material is tabletized and is treated with a low-pressure transfer molding machine at 175 ° C.
A 6 x 6 mm chip is sealed in 52p QFP for a solder crack test under the conditions of 0 kg / cm ² and 120 seconds, and a 3 x 6 mm chip is 16p for a solder moisture resistance test.
Sealed to SOP. 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 placed in 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 carried out 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 performed according to the formulation shown in Table 2, and a molding material was 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.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

According to the present invention, it is possible to obtain excellent crack resistance when subjected to thermal stress due to a rapid temperature change in the soldering process, which cannot be obtained by the prior art, and further excellent moisture resistance. Therefore, when it is used for encapsulation, coating, insulation, etc. of electronic and electrical parts, it is suitable for products that require extremely high reliability, especially in highly integrated large-sized chips mounted in surface mount packages. is there.

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Claims (1)

[Claims] 1. An epoxy resin containing (A) an epoxy resin represented by the following formula (1) in an amount of 30 to 100% by weight based on the total amount of epoxy resin: (R in the formula is the same or different atom or group selected from hydrogen, halogens and alkyl groups, n = 0 to 2
0) (B) The phenol resin curing agent represented by the following formula (2) is contained in an amount of 30 to 100% by weight based on the total amount of the phenol 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, n = 0 to 2
0) An epoxy resin composition for semiconductor encapsulation, which comprises (C) an inorganic filler and (D) a curing accelerator as essential components.