JPH05166974A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To enable epoxy resin composition to be enhanced in soldering heat resistance at soldering without deteriorating it in moldability and reliability by a method wherein specific epoxy resin, specific phenolic resin hardening agent, inorganic filler, and hardening accelerator are made to serve as essential ingredients of epoxy resin composition. CONSTITUTION:Epoxy resin which contains 30-100% copolycondensation novolac epoxy resin composed of O-cresol represented by a formula I and beta-naphthol by weight out of total epoxy resin is made to serve as a first component. Hardening agent which contains 30-100% phenolic resin hardening agent represented by a formula II by weight out of total hardening agent is made to serve as a second component. In the formulas I and II, a letter n denotes 1-6. In the formula II, R1 and R2 denote the same or a different atom or a group selected from hydrogen, halogen, a low class alkyl Furthermore, inorganic filler and hardening group. as essential ingredients. By this setup, a resin composition excellent in heat resistance and flexibility and low in water absorption properties can be obtained.

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.

[0002]

2. Description of the Related Art Most highly integrated IC devices are encapsulated by a resin encapsulation method using an epoxy resin encapsulating material which is excellent in reliability, cost and mass productivity. As the epoxy resin encapsulating material, a resin composition composed of an orthocresol novolac epoxy resin and a novolac type phenol resin, which are excellent in heat resistance, moisture resistance and moldability, is used. However, with the recent high integration and multi-functionalization,
Highly integrated IC packages have a strong tendency to be smaller and thinner due to the larger size of devices and the rationalization of mounting. Compared to the conventional DIP type, small and thin SOJs, SOPs, and QFs are used.
P and TSOP type surface mount packages are rapidly shifting.

This means that, unlike the conventional DIP type, the package itself is exposed to a high temperature of 215 to 260 ° C. at the time of soldering, and the surface mount type package in which a large chip is enclosed in a small and thin package exerts a large stress. This causes cracking of the package resin and peeling of the chip interface, which is a fatal problem in the reliability of the IC package. A highly reliable encapsulating resin composition suitable for encapsulating these surface mount packages is desired.

In order to alleviate the thermal shock during soldering in order to solve these problems, addition of a thermoplastic oligomer (JP-A-62-115849) and addition of various silicone compounds (JP-A-62-158). No. 115850, 62
-116654, 62-128162),
Furthermore, methods such as silicone modification (Japanese Patent Laid-Open No. 62-136860) are used, but in all cases cracks occur in the package during soldering, and a highly reliable epoxy resin composition for semiconductor encapsulation is obtained. It didn't reach.

On the other hand, in order to obtain a semiconductor encapsulating epoxy resin composition having excellent heat stress resistance during soldering, that is, solder stress resistance, use of a biphenyl type epoxy resin as a resin system (Japanese Patent Laid-Open No. 64-65116). Gazette) has been studied, but the use of a biphenyl type epoxy resin improves the adhesion to the lead frame and the low water absorption, improves the solder stress resistance, and particularly reduces the occurrence of cracks.
Since the heat resistance is poor, the solder stress resistance is insufficient especially at a high temperature of 250 ° C. or higher.

[0006]

SUMMARY OF THE INVENTION The present invention provides an epoxy resin composition for semiconductor encapsulation which is excellent in solder heat resistance during soldering without deteriorating moldability and reliability.

[0007]

The present invention comprises (A) a co-condensed novolak epoxy resin of orthocresol and β-naphthol represented by the following formula (1) in a total epoxy resin amount of 3: 1.
Epoxy resin containing 0 to 100% by weight,

[0008]

[Chemical 3] (N = 1 to 6)

(B) A curing agent containing a phenol resin curing agent represented by the following formula (2) in an amount of 30 to 100% by weight based on the total amount of the curing agent,

[0010]

[Chemical 4]

(Wherein R ₁ and R ₂ are the same or different atoms or groups selected from hydrogen, halogen and lower alkyl groups, n = 1 to 6) (C) inorganic filler and (D) curing An epoxy resin composition for semiconductor encapsulation containing an accelerator as an essential component,
It has extremely excellent solder heat resistance as compared with conventional epoxy resin compositions.

The co-condensed novolak epoxy resin of orthocresol and β-naphthol used in the present invention is an epoxidized novolak resin obtained by co-condensing orthocresol and β-naphthol from formaldehyde, and β-naphthol at the time of the co-condensation thereof. The amount is preferably 50% by weight or more, and the compound mainly has the structure of formula (1). Further, n is 1 to 6, and if it exceeds 6, the fluidity at the time of molding is poor. Formula (1) has the characteristics of excellent low water absorption, a small linear expansion coefficient of the resin, and excellent releasability at the time of molding, and shows good results for solder heat resistance during soldering. By adjusting the amounts of the orthocresol and β-naphthol co-condensed novolac epoxy resin to be used, solder heat resistance can be maximized.

In order to obtain the effect of solder heat resistance, orthocresol and β-naphthol co-condensed novolac epoxy resin are contained in an amount of 30% by weight or more, preferably 60% by weight or more of the total amount of epoxy resin.
It is desirable to use more than weight%. 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. When orthocresol and an epoxy resin other than the β-naphthol co-condensed novolac epoxy resin are used in combination, the epoxy resin to be used refers to all polymers having an epoxy group. For example, bisphenol type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, phenol novolac type epoxy resin and triphenol methane type epoxy resin, alkyl modified triphenol methane type epoxy resin, etc.
Functional epoxy resin, triazine nucleus-containing epoxy resin and the like.

The phenol resin curing agent represented by the formula (2) is a modification of para-xylene in the skeleton. In the formula, n is 1 to 6, and R ₁ and R ₂ are the same or different atoms or groups selected from hydrogen, halogen and lower alkyl groups. Among these, when n exceeds 6, the fluidity during molding is poor. The lower alkyl group has 1 to 4 carbon atoms, and when it exceeds 4, the fluidity at the time of molding becomes poor. Each of R ₁ and R ₂ is preferably a hydrogen atom. It features low elastic modulus above glass transition temperature and low internal stress during soldering.
Further, since it has characteristics such as excellent adhesion to the chip and the lead frame and low water absorption, it shows good results in resistance to solder stress. The amount of the phenol resin curing agent used is preferably 30% by weight or more, more preferably 60% by weight or more, based on the total amount of the curing agent.
If it is less than 30% by weight, the adhesion to the lead frame and the low water absorption will not be improved, and the solder stress resistance will be insufficient.

When another phenol resin curing agent is used in combination with the phenol resin curing agent represented by the formula (2), the phenol resin curing agent used means all polymers having a phenolic hydroxyl group. For example, generally, phenol novolac resin, cresol novolac resin, dicyclopentadiene modified phenol resin, co-condensation product of dicyclopentadiene modified phenol resin and phenol novolac or cresol novolac resin, paraxylene modified phenol resin and 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 crushing porous silica powder, alumina, etc., and particularly fused silica. Powders, spherical silica powders and mixtures of fused silica powders and spherical silica powders are preferred. In addition, as the compounding amount of the inorganic filler,
From the standpoint of 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 as long as it accelerates the reaction between the epoxy group and the hydroxyl group, and those generally used for the sealing material can be widely used. For example, organic phosphine compounds such as triphenylphosphine (TPP), tributylphosphine, tri (4-methylphenyl) phosphine, tributylamine,
Third such as triethylamine, benzyldimethylamine, trisdimethylaminomethylphenol, 1,8-diazabicyclo [5,4,0] -7-undecene (DBU)
Examples thereof include imidazole compounds such as secondary amine, 2-methylimidazole, 2-phenylimidazole and 2-ethyl-4-methylimidazole. These may be used alone or in combination of two or more.

In addition to the above, the composition of the present invention may optionally contain a coloring agent such as carbon black, a release agent such as carnauba wax and synthetic wax, a flame retardant such as brominated epoxy and antimony trioxide, and γ-. A coupling agent such as glycidoxypropyltrimethoxysilane and a rubber component such as silicone rubber and polybutadiene can be added.

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 and uniformly mixed with a mixer or the like, and then melt-kneaded with a hot roll, a kneader, or the like, cooled, and then pulverized to obtain a molding material. These molding materials can be applied to sealing, coating, insulating, etc. of electronic parts or electric parts.

[0020]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 The following composition Co-condensed novolak epoxy resin of orthocresol and β-naphthol (n is a mixture of 70% by weight of n = 3 and 30% by weight of n = 4, epoxy equivalent 225, softening point 84 ° C.) ) 13.5 parts by weight Phenolic resin curing agent represented by the following formula (3) (n is a mixture in which n = 2 is 30% by weight and n = 3 is 70% by weight, hydroxyl equivalent 175, softening point 75 ° C.) 10. 5 parts by weight

[0022]

[Chemical 5]

75 parts by weight of fused silica powder 0.2 parts by weight of triphenylphosphine 0.3 parts by weight of carbon black 0.5 parts by weight of carnauba wax are mixed in a mixer at room temperature and kneaded by a twin-screw roll at 70 to 100 ° C. The obtained molding material was made into a molding material that was crushed after cooling, and the obtained molding material was tabletized and a 6 × 6 mm chip was put in a 52p package for solder crack testing under the conditions of 175 ° C., 70 kg / cm ² and 120 seconds on a low-pressure transfer molding machine. And a 3 × 6 mm chip for a solder moisture resistance test in a 16 pSOP package. The sealed test element was subjected to the following solder crack test and solder moisture resistance test.

Solder crack test: The sealed test element was subjected to an environment of 85 ° C. and 85% RH for 48 hours and 72 hours.
After processing, 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
After 72 Hr treatment in an environment of% RH and then dipping in a solder bath at 260 ° C for 10 seconds, a pressure cooker test (12
The circuit was opened at 5 ° C. and 100% RH, and the open circuit failure was measured. The test results are shown in Table 1.

Examples 2 to 5 Compounding was performed 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 a test element was sealed with this molding material was obtained, and a solder crack test and a solder moisture resistance test were conducted using this molded product in the same manner as in Example 1. The test results are shown in Table 1.

Comparative Examples 1 to 5 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. 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 conducted using this molded product in the same manner as in Example 1. The test results are shown in Table 1.

[0027]

[Table 1]

[0028]

EFFECT OF THE INVENTION A resin composition having excellent heat resistance, low water absorption and flexibility can be obtained. As a sealing material for highly integrated IC packages to be surface-mounted on a printed circuit board, it has excellent solder heat resistance during soldering.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location C08L 63/00 MJS 8830-4J

Claims (1)

[Claims] 1. An epoxy resin containing (A) an orthocresol and β-naphthol co-condensed novolac epoxy resin represented by the following formula (1) in an amount of 30 to 100% by weight of the total epoxy resin: (N = 1 to 6) (B) A curing agent containing a phenol resin curing agent represented by the following formula (2) in an amount of 30 to 100% by weight based on the total amount of the curing agent: (Wherein R ₁ and R ₂ are the same or different atoms or groups selected from hydrogen, halogen and lower alkyl groups,
n = 1 to 6) An epoxy resin composition for semiconductor encapsulation, which comprises (C) an inorganic filler and (D) a curing accelerator as essential components.