JP2991850B2 - 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, the chip has been gradually increased in size with the increase in the degree of integration of integrated circuits, and the package has been changed from the conventional DIP type to a small and thin QFP, SOP, S
OJ and PLCC are changing.

In other words, a large chip is enclosed in a small and thin package, and cracks occur due to stress.
Problems such as a decrease in moisture resistance due to these cracks have been greatly highlighted. In particular, in the soldering process, the above problem has occurred due to rapid exposure to a high temperature of 200 ° C. or more, and a highly reliable sealing material suitable for sealing these large chips. Development of resin compositions has been desired. In order to solve these problems, a thermoplastic oligomer is added for the purpose of reducing thermal shock at the time of soldering (JP-A-62-115849).
And addition of various silicone compounds (Japanese Patent Laid-Open No. 62-1158)
No. 50, 62-116654, 62-128
No. 162), and further modified with silicone (Japanese Unexamined Patent Publication No. Sho 62).
However, in both cases, cracks occurred in the package during soldering, and it was not possible to obtain 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 has improved adhesion to a lead frame and low water absorption, solder resistance has been improved, and crack generation has been particularly reduced. At a high temperature of not less than ℃, the solder stress resistance is insufficient.

[0005]

SUMMARY OF THE INVENTION The present invention is directed to providing an epoxy resin composition for semiconductor encapsulation in which the solder stress resistance of a semiconductor package at the time of mounting on a substrate is remarkably improved. is there.

[0006]

The epoxy resin composition of the present invention comprises (A) an epoxy resin containing 30 to 100% by weight of an epoxy resin represented by the following formula (1) based on the total epoxy resin amount:

[0007]

Embedded image (N = 1-6)

(B) The phenolic resin curing agent represented by the following formula (2) is added in an amount of 30 to
A phenolic resin curing agent containing 100% by weight,

[0009]

Embedded image (N = 1-6)

An epoxy resin composition for semiconductor encapsulation comprising (C) an inorganic filler and (D) a curing accelerator as essential components,
It has much better solder heat resistance than the conventional epoxy resin composition.

The epoxy resin represented by the formula (1) is a co-condensed novolak epoxy resin of ortho-cresol and β-naphthol, has excellent low water absorption, and has a small linear expansion coefficient.
It has good characteristics in soldering heat resistance during soldering. The amount of the co-condensed novolak epoxy resin of orthocresol and β-naphthol can be adjusted to maximize the solder heat resistance. In order to achieve the effect of solder heat resistance, it is desirable to use the epoxy resin of the formula (1) in an amount of 30% by weight or more, preferably 60% by weight or more of the total epoxy resin amount. 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 ortho-cresol and β-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, a trifunctional epoxy resin such as a bisphenol epoxy resin, a cresol novolak epoxy resin, a biphenyl epoxy resin, a phenol novolak epoxy resin, a triphenolmethane epoxy resin, an alkyl-modified triphenolmethane epoxy resin, and a triazine ring-containing resin Refers to epoxy resin and the like.

The curing agent represented by the formula (2) is a co-condensed novolak phenol resin of paracresol and α-naphthol, and has characteristics of low water absorption and low coefficient of linear expansion. In order to achieve the effect of solder heat resistance, it is desirable to use a co-condensed phenol resin of paracresol and α-naphthol represented by the formula (2) in an amount of 30% by weight or more, preferably 60% by weight or more of the total phenolic resin amount. If it is less than 30% by weight, the low water absorption becomes insufficient, and the solder heat resistance during 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. When other curing agents other than the phenolic resin curing agent represented by the formula (2) are used in combination, those used generally refer to polymers generally having a phenolic hydroxyl group. For example, phenol novolak resins, cresol novolak resins, dicyclopentadiene-modified phenol resins, copolymers of dicyclopentadiene-modified phenol resins with phenol novolak and cresol novolak resins, para-xylene-modified phenol resins, and the like can be used. These may be used alone or in combination of two or more.

Examples of the inorganic filler used in the present invention include fused silica powder, spherical silica powder, crystalline silica powder, secondary aggregated 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, it is desirable that the total resin composition contains 70 to 90% by weight.

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, triphenylphosphine (T
PP), organic phosphine compounds such as tributylphosphine and tri (4-methylphenyl) phosphine, tributylamine, triethylamine, benzyldimethylamine, trisdimethylaminomethylphenol, 1,8-
Diazabicyclo [5,4,0] -7-undecene (DB
Tertiary amines such as U) 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 releasing 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. .

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

Example 1 14.8 parts by weight of an epoxy resin represented by the formula (1) (a mixture of n = 1 to 6, an epoxy equivalent of 228, and a softening point of 83 ° C.) a mixture of n = 1 to 6, hydroxyl equivalent 140, softening point 110 ° C.) 9.2 parts by weight fused silica powder 74.7 parts by weight triphenylphosphine 0.3 parts by weight carbon black 0.5 parts by weight carnauba wax 0.5 Parts by weight were 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 low pressure transfer molding machine is used to enclose a 6 × 6 mm chip in a 52p package for a solder crack test at 175 ° C., 70 kg / cm ² for 120 seconds, 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.

Solder crack test: A sealed test element was subjected to 48 hours and 72 hours in an environment of 85 ° C. and 85% RH.
After the treatment, it was immersed in a solder bath at 260 ° C. for 10 seconds, and external cracks were observed with a microscope. Solder moisture resistance test: Sealed test element at 85 ° C, 85
% RH environment, and then immersed in a solder bath at 260 ° C. for 10 seconds, and then subjected to a pressure cooker test (1
(25 ° C., 100% RH), and the open failure of the circuit was measured. Table 1 shows the test results.

Examples 2 to 5 Compounded according to the formulation shown in Table 1, a molding material was obtained in the same manner as in Example 1, and evaluated in the same manner. The test results are shown in Table 1. Biphenyl type epoxy: 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxybiphenylglycidyl ether (epoxy equivalent 190, softening point 104 ° C.) Phenol novolak resin curing agent ( Hydroxyl equivalent 105,
(Softening point: 90 ° C.) Comparative Examples 1 to 4 Compounded according to the formulation in Table 1, a molding material was obtained in the same manner as in Example 1, and evaluated similarly. The test results are shown in Table 1. Orthocresol novolak type epoxy resin (epoxy equivalent 210, softening point 65 ° C).

[0020]

[Table 1]

[0021]

According to the present invention, it is possible to obtain an epoxy resin composition having solder stress resistance, which cannot be obtained by the prior art. 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 containing an epoxy resin represented by the following formula (1) in an amount of 30 to 100% by weight based on the total amount of the epoxy resin: (N = 1 to 6) (B) 30 to 100% by weight of the phenol resin curing agent represented by the following formula (2) based on the total amount of the phenol resin curing agent
A phenolic resin curing agent, including (N = 1 to 6) An epoxy resin composition for semiconductor encapsulation comprising (C) an inorganic filler and (D) a curing accelerator as essential components.