JP2744499B2 - Epoxy resin composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an epoxy resin composition for semiconductor encapsulation having excellent heat stress resistance to a package during soldering in surface mounting.

[Conventional technology]

Conventionally, electronic components such as diodes, transistors, and integrated circuits are sealed with a thermosetting resin. Especially for integrated circuits, O-cresol novolak epoxy resin, which has excellent heat resistance and moisture resistance, is cured with a novolak type phenol resin. Epoxy resin is used.

However, in recent years, chips have become larger and larger as integrated circuits have become more highly integrated.
It is changing to SOP, SOJ, PLCC.

That is, a large chip is sealed 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 is a problem that the package is cracked due to sudden exposure to a high temperature of 200 ° C. or more in the soldering process, and the moisture resistance is deteriorated due to the separation of the resin and the chip.

Development of a highly reliable sealing resin composition suitable for sealing these large chips has been desired.

In order to solve these problems, thermoplastic oligomers were added to alleviate the thermal shock during soldering (Japanese Patent Laid-Open No.
No. 1-115849), addition of various silicone compounds (Japanese Patent Application Laid-Open Nos. 62-11585, 62-116654 and 62-128162), and silicone modification (Japanese Patent Application Laid-Open No. 62-136860). In all cases, cracks occurred in the package during soldering, and it was not possible to obtain a highly reliable epoxy resin composition for semiconductor encapsulation.

On the other hand, in order to obtain a heat-resistant epoxy resin composition having excellent solder stress resistance, use of a polyfunctional epoxy resin as a resin system (Japanese Patent Laid-Open No. 61-168620) has been studied. The use of an epoxy resin increases the crosslink density and improves heat resistance, but when exposed to a high temperature such as 200 ° C. to 300 ° C., the solder stress resistance was insufficient.

[Problems to be solved by the invention]

The present invention solves such a problem by using a tetrafunctional epoxy resin having an ether bond in a skeleton of a molecular structure as an epoxy resin, thereby providing an epoxy resin for semiconductor encapsulation having extremely excellent heat stress resistance during soldering. It is an object to provide a composition.

[Means for solving the problem]

The epoxy resin composition of the present invention is a tetrafunctional epoxy resin having a structure represented by the following formula (I) as an epoxy resin. (Wherein R ₁ and R ₂ are the same or different atoms or groups selected from hydrogen and an alkyl group, and R _{3 to} R ₁₄ are the same or different atoms selected from hydrogen, halogen and an alkyl group, or Resin, a phenolic resin curing agent, an inorganic filler and a curing accelerator, which is 40 to 100% by weight based on the total amount of the epoxy resin, and is extremely superior to the conventional epoxy resin composition. It has heat stress resistance during soldering, that is, solder stress resistance.

(Operation)

Since the tetrafunctional epoxy resin having the structure represented by the formula (I) has an ether bond in the skeleton, the cured product is excellent in low elasticity, that is, low stress. In addition, since it is polyfunctional, the crosslink density can be improved and the heat resistance is excellent. Therefore, an epoxy resin composition for semiconductor encapsulation using a tetrafunctional epoxy resin having a structure represented by the formula (I) can be said to be an epoxy resin composition having excellent soldering stress resistance against recent surface mounting of IC packages.

By adjusting the amount of the tetrafunctional epoxy having the structure represented by the formula (I), the solder stress resistance can be maximized. In order to exhibit the effect of resistance to soldering stress, it is desirable to use the tetrafunctional epoxy resin represented by the formula (I) in an amount of 40% by weight or more, preferably 60% by weight or more of the total epoxy resin amount. If it is less than 40% by weight, heat resistance and low stress properties are not increased, and solder stress resistance is insufficient. R ₁ and
R ₂ is preferably a methyl group, and R ₃ to R ₁₄ are preferably hydrogen atoms.

The epoxy resin used in combination with the tetrafunctional epoxy resin represented by the formula (I) generally means an epoxy resin having an epoxy group. For example, it refers to a bisphenol-type epoxy resin, a novolak-type epoxy resin, a biphenyl-type epoxy resin, a trifunctional-type epoxy resin, a triazine nucleus-containing epoxy resin, and the like.

The phenolic resin curing agent used in the present invention generally includes those having a phenolic hydroxyl group, such as phenol novolak resin, cresol novolak resin, trifunctional phenol resin, tetrafunctional phenol resin, dicyclopentadiene-modified phenol resin, It refers to a copolymer of cyclopentadiene-modified phenol resin with phenol novolak and cresol novolak resins, para-xylene-modified phenol resin, and the like.

Examples of the inorganic filler used in the present invention include fused silica powder, spherical silica powder, crystalline silica powder, secondary aggregated silica powder, porous silica powder, silica powder obtained by pulverizing secondary aggregated silica powder or porous silica powder, alumina And the like, and a fused silica powder is particularly preferred.

The curing accelerator used in the present invention may be any one that promotes the reaction between the epoxy group and the phenolic hydroxyl group,
Generally used materials for sealing can be widely used, for example, diazabicycloundecene (DB
U), triphenylphosphine (TPP), dimethylbenzylamine (BDMA), 2-methylimidazole (2MZ) and the like are used alone or in combination of two or more.

The epoxy resin composition for sealing of the present invention is an epoxy resin,
A curing agent, an inorganic filler and a curing accelerator are essential components, but if necessary, a silane coupling agent, a brominated epoxy resin, a flame retardant such as antimony trioxide, hexabromobenzene, carbon black, red iron oxide, etc. And various additives such as a release agent such as natural wax and synthetic wax, and a low stress additive such as silicone oil and rubber.

Further, in order to produce the epoxy resin composition for sealing of the present invention as a molding material, epoxy resin, a curing agent, a curing accelerator, a filler, and other additives are sufficiently uniformly mixed by a mixer or the like, Furthermore, it can be melt-kneaded with a hot roll or a kneader, cooled, and pulverized to obtain a molding material. These molding materials can be applied to sealing, coating, insulating and the like of electronic parts or electric parts.

Example 1 The following composition: 16 parts by weight of a tetrafunctional epoxy resin represented by the formula (II) Orthocresol novolak epoxy resin 4 parts by weight Phenol novolak 10 parts by weight Fused silica powder 68.8 parts by weight Triphenylphosphine 0.2 parts by weight Carbon black 0.5 parts by weight Carnauba wax 0.5 parts by weight is mixed at room temperature with a mixer and mixed at 70-100 ° C. The molding material was kneaded by a shaft roll, cooled, and ground.

The obtained molding material is tableted, and a 6 × 6 mm chip is sealed in a 52 package for solder crack test at 175 ° C., 70 kg / cm ² , 120 seconds using a low pressure transformer molding machine. 3 x 6mm chip for performance test
Sealed in a 6pSOP package.

The sealed test element was subjected to the following solder crack test and solder moisture resistance test.

Solder crack test: Sealed test element at 85 ° C, 85%
After 48 hours and 72 hours treatment in an RH environment, and then immersed in a 250 ° C. solder bath for 10 seconds, external cracks were observed with a microscope.

Solder moisture resistance test: 85% of the sealed test element at 85 ° C
Treated in a RH environment for 72 hours, then immersed in a 250 ° C solder bath for 10 seconds, and then subjected to a pressure cooker test (125 ° C, 100% R
H) was performed and the oven failure of the circuit was measured.

 The test results are shown in Table 1.

Examples 2 to 4 Compounded according to the prescription shown in Table 1, and a molding material was obtained in the same manner as in Example 1. A sealed molded product for a test was obtained from this molding material, 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. The test results are shown in Table 1.

Comparative Examples 1 to 3 Compounded according to the formulation shown in Table 1 and obtained in the same manner as in Example 1. A sealed molded product for a test was obtained from this molding material, 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. Test results first
It is shown in the table.

[Effect of the Invention] According to the present invention, it is possible to obtain an epoxy resin composition having heat resistance and impact resistance that could not be obtained by the prior art, so that thermal stress due to a rapid temperature change due to a soldering process is reduced. Very good crack resistance when receiving, and also good moisture resistance, so when used for sealing, coating, insulating, etc. of electronic and electrical parts, especially high integration mounted on surface mount package It is suitable for products that require very high reliability in large chip ICs.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 23/31

Claims (1)

(57) [Claims] 1. A tetrafunctional epoxy resin having a structure represented by the following formula (I): (Wherein R ₁ and R ₂ are hydrogen, the same or different atoms or groups selected from alkyl groups, and R _{3 to} R ₁₄ are the same or different atoms or hydrogen or halogen atoms selected from alkyl groups or Resin containing 40 to 100% by weight based on the total amount of epoxy resin. (B) Phenolic resin curing agent. An epoxy resin composition for semiconductor encapsulation comprising (C) an inorganic filler and (D) a curing accelerator as essential components.