JP3004463B2 - Epoxy resin composition - Google Patents

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 soldering stress resistance in surface mounting of a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, electronic components such as diodes, transistors, and integrated circuits are sealed with a thermosetting resin. In particular, in an integrated circuit, ortho-cresol novolak epoxy resin having excellent heat resistance and moisture resistance is made of a novolak type. An epoxy resin composition cured with a phenol resin is used.
However, in recent years, chips have become larger and larger as integrated circuits have become more highly integrated, and packages have become smaller and thinner flat packages that are surface-mounted from conventional DIP types.
It is changing to SOP, SOJ, PLCC.

That is, a large chip is enclosed in a small and thin package, and cracks are generated due to stress, and problems such as a decrease in moisture resistance due to the cracks have been greatly highlighted. In particular, there has been a problem in that abrupt exposure to a high temperature of 200 ° C. or more in a soldering process causes a crack in a package and a peeling of a resin and a chip to deteriorate moisture resistance. Development of a highly reliable sealing resin composition suitable for sealing these large chips has been desired.

[0004] In order to solve these problems, addition of thermoplastic oligomers (Japanese Patent Application Laid-Open No. 62-15849) and addition of various silicone compounds (Japanese Patent Application Laid-Open No. JP-115850,
62-116654 and 62-128162) and further modified with silicone (Japanese Patent Application Laid-Open No. 62-13686).
No. 0), however, cracks occurred in the package during soldering, and none of these methods resulted in obtaining a highly reliable sealing epoxy resin composition.

On the other hand, in order to obtain an epoxy resin composition for semiconductor encapsulation having excellent heat stress resistance during soldering, that is, excellent solder stress resistance, a biphenyl type epoxy resin is used as a resin system (Japanese Patent Application Laid-Open No. 64-65116). Although the use of a biphenyl-type epoxy resin improves the adhesion to the lead frame and low water absorption, the solder stress resistance is improved, and crack generation is particularly reduced. At a high temperature of at least ℃, the solder stress resistance is still insufficient.

[0006]

The present invention solves such a problem by using an epoxy resin represented by the formula (1) as an epoxy resin and curing the molded product in order to lower the water absorption and the coefficient of thermal expansion of the molded product. Epoxy resin for semiconductor encapsulation that has significantly improved the soldering stress resistance of a semiconductor package when mounted on a substrate by using a co-condensed novolak-type phenolic resin curing agent of α-naphthol and paracresol represented by the formula (2) as an agent It is an object to provide a composition.

[0007]

That is, the present invention provides (A) an epoxy resin represented by the following formula (1):

[0008]

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An epoxy resin containing (n = 1 to 6) in an amount of 30 to 100% by weight based on the total amount of the epoxy resin; (B) a phenol resin curing agent represented by the following formula (2):

[0010]

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(N = 1 to 6) is calculated as 30 to the total amount of the curing agent.
An epoxy resin composition for encapsulating a semiconductor comprising, as essential components, a curing agent containing (C) an inorganic filler and (D) a curing accelerator.
It has excellent solder stress resistance as compared with a conventional epoxy resin composition.

The epoxy resin represented by the formula (1) is a co-condensed novolak epoxy resin of paracresol and α-naphthol, and is characterized by low water absorption and a small coefficient of linear expansion. It shows good results in solder heat resistance. By adjusting the amount of the co-condensed novolak epoxy resin of paracresol and α-naphthol, the solder heat resistance can be maximized by adjusting the amount.
In order to achieve solder heat resistance, paracresol and α
It is desirable to use 30% by weight or more, preferably 60% by weight or more of the copolycondensed novolak epoxy resin of naphthol based on the total amount of the epoxy resin. If it is less than 30% by weight, low water absorption and low linear expansion coefficient cannot be sufficiently obtained, and solder heat resistance is insufficient. The value of n is from 1 to 6, and when it exceeds 6, the fluidity is reduced and the moldability is deteriorated. When an epoxy resin other than the para-cresol and α-naphthol co-condensed novolak epoxy resin is used in combination, the epoxy resin used generally refers to any polymer having an epoxy group. For example, bisphenol type epoxy resin, cresol novolak type epoxy resin,
It refers to a trifunctional epoxy resin such as a biphenyl epoxy resin, a phenol novolak epoxy resin, a triphenolmethane epoxy resin, an alkyl-modified triphenolmethane epoxy resin, and a triazine ring-containing epoxy resin.

The curing agent represented by the formula (2) is a co-condensed novolak phenol resin of α-naphthol with paracresol, has a characteristic of low water absorption and a small linear expansion coefficient, and has a solder heat resistance at the time of soldering. Shows good results. In order to obtain the effect of solder heat resistance, the phenolic resin represented by the formula (2) should be used in an amount of 30% by weight or more based on the total amount of the phenolic resin.
Preferably, 60% by weight or more is used. If the amount is less than 30% by weight, the flexibility becomes insufficient and the soldering heat resistance at the time of soldering cannot be sufficiently obtained. The value of n is from 1 to 6, and when it exceeds 6, the fluidity is reduced and the moldability is deteriorated. Equation (2)
The other curing agents to be used in combination other than the phenolic resin curing agent represented by the general formula (1) generally refer to all polymers having a phenolic hydroxyl group. For example, a phenol novolak resin, a cresol novolak resin, a dicyclopentadiene-modified phenol resin, or the like can be used.

Examples of the inorganic filler used in the present invention include fused silica powder, spherical silica powder, crystalline silica powder, secondary agglomerated silica powder, silica powder obtained by pulverizing porous silica powder, and alumina. Powders, spherical silica powders and mixtures of fused silica powder and spherical silica powder are preferred. In addition, as the compounding amount of the inorganic filler,
From the balance between solder stress resistance and moldability, 70 to 90% by weight based on the total resin composition is desirable.

Further, the curing accelerator used in the present invention may be any one which promotes the reaction between an epoxy group and a phenolic hydroxyl group, and those generally used for a sealing material can be widely used. For example, organic phosphine compounds such as triphenylphosphine, tributylphosphine and tri (4-methylphenyl) phosphine, tributylaluminum, triethylamine, benzyldimethylamine, trisdimethylaminomethylphenol, 1,8-diazabicyclo [5,4,0]- Examples include tertiary amines such as 7-undecene, and imidazole compounds such as 2-methylimidazole, 2-phenylimidazole and 2-ethyl-4-methylimidazole. These can be used alone or in combination of two or more.

The composition of the present invention may further comprise a coloring agent such as carbon black, a release agent such as carnauba wax or synthetic wax, a brominated epoxy resin, etc., if necessary.
Flame retardants such as antimony trioxide, coupling agents such as γ-glycidoxypropyltrimethoxysilane, and low-stress components such as silicone oil and rubber can be added.
The epoxy resin composition of the present invention is an epoxy resin, a curing agent,
After uniformly mixing the inorganic filler, the curing accelerator, and other additives with a mixer or the like, the mixture is hot-melt-kneaded with a general kneading device such as a roll or an extruder, and then cooled and pulverized to form a molding material. .

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. Example 1 Epoxy resin represented by the formula (1) (a mixture in which n = 1 is 40% by weight and n = 2 is 60% by weight, epoxy equivalent 230, softening point 65 ° C.) 4.5 parts by weight ortho-cresol novolak epoxy resin (Epoxy equivalent: 200, softening point: 62 ° C.) 10.5 parts by weight A phenolic resin curing agent represented by the formula (2) (a mixture of 70% by weight for n = 3 and 30% by weight for n = 4, OH equivalent of 140, softening) 2.5 parts by weight Phenol novolak resin (OH equivalent 105, softening point 90 ° C.) 5.8 parts by weight Fused silica powder 75 parts by weight Triphenylphosphine 0.2 parts by weight Carbon black 0.3 parts by weight Carnauba wax 0.5 part by weight was mixed at room temperature with a mixer, kneaded at 70 to 100 ° C. with a biaxial roll, cooled and pulverized to obtain a molding material. The obtained molding material is tableted, and a 6 × 6 mm chip is sealed in a 52p package for a solder crack test at 175 ° C., 70 kg / cm ² for 120 seconds using a low pressure transfer molding machine, and for a solder moisture resistance test. A 3 × 6 mm chip was sealed in a 16pSOP package. The sealed test element was subjected to the following solder crack test and solder moisture resistance test. Table 1 shows the test results.

Solder crack test: The sealed test element was heated at 85 ° C. for 8
48 hours and 72 hours of treatment were performed in an environment of 5% RH, and then immersed in a solder bath at 260 ° C. for 10 seconds, and external cracks were observed with a microscope. Solder moisture resistance test: 85 ° C, 8
After treating for 72 hours in an environment of 5% RH, and then immersing in a solder bath at 260 ° C. for 10 seconds, a pressure cooker test (1
(25 ° C., 100% RH), and the open failure of the circuit was measured.

Examples 2 to 5 Compounded according to the formulation shown in Table 1, and a molding material was obtained in the same manner as in Example 1. A molded product in which a test element was sealed with this molding material was obtained, and a solder crack test and a solder moisture resistance test were performed using this molded product in the same manner as in Example 1. Table 1 shows the test results.

Comparative Examples 1-2 Compounds were prepared according to the formulation shown in Table 1 and molding materials were obtained in the same manner as in Example 1. A molded product in which the element for TETOS was sealed with this molding material was obtained, and a solder crack test and a solder moisture resistance test were performed using this molded product in the same manner as in Example 1. Table 1 shows the test results.

[0021]

[Table 1]

[0022]

According to the present invention, an epoxy resin composition having solder stress resistance, which cannot be obtained by the prior art, can be obtained. It is suitable for a highly integrated large chip IC mounted on a surface mount package because of its good performance.

Claims (1)

(57) [Claims] (A) an epoxy resin represented by the following formula (1): (N = 1 to 6) is 30 to 10 with respect to the total epoxy resin amount.
An epoxy resin containing 0% by weight; (B) a phenolic resin curing agent represented by the following formula (2): An epoxy resin composition for semiconductor encapsulation comprising, as essential components, a curing agent containing 30 to 100% by weight of (n = 1 to 6) based on the total amount of the curing agent, (C) an inorganic filler and (D) a curing accelerator. .