JPH05206329A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain a semiconductor sealing material having excellent solder stress resistance for semiconductor package during substrate mounting by using a particular epoxy resin and a hardening agent, inorganic filler and a hardening accelerator as essential components. CONSTITUTION:As a resin component for semiconductor sealing material, a biphenyl type epoxy resin indicated by Equation I is used by 50 to 100wt.% of the total epoxy resin. R1 to R8 in Equation I are selected out of hydrogen, halogen and alkyl group. Also as a hardener, 2 multifunctional phenol melted and mixed is used by 15 to 100 weight pt. compared with 100 weight pt. of multifunctional phenol resin indicated by Equation II. n=1 to 6 in equation II. Also, an inorganic filling material and hardening accelerator are essential 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. Especially in integrated circuits, orthocresol novolac epoxy resin, which is excellent in heat resistance and moisture resistance, is a novolac type. Epoxy resin compositions that are cured with phenolic resins have been used.
However, in recent years, as the integration of integrated circuits has increased, the size of chips has gradually increased, and the package is a small and thin flat package that is surface-mounted from the conventional DIP type.
It has changed to SOP, SOJ, PLCC.

That is, a large chip is to be enclosed in a small and thin package, and cracks are generated due to stress, and moisture resistance due to these cracks is becoming a serious problem. Particularly, in the soldering process, there is a problem that moisture resistance is deteriorated due to cracking of the package and peeling of the chip from the resin when exposed to a high temperature of 200 ° C or more. Development of a highly reliable encapsulating resin composition suitable for encapsulating these large chips has been desired.

In order to solve these problems, use of an epoxy resin represented by the following formula (1) as an epoxy resin (Japanese Patent Laid-Open No. 64-65116) has been proposed.

[0005]

[Chemical 3]

(Wherein R _{1 to} R ₈ are hydrogen, halogen,
Same or different atoms or groups selected from among alkyl groups) have been investigated. By using the epoxy resin represented by the formula (1), it is possible to reduce the viscosity of the resin system. Therefore, by adding a larger amount of fused silica powder, the composition can have low thermal expansion and low water absorption after molding, and thus can be solder resistant. The stress property was improved. However, increasing the elastic modulus by blending a large amount of fused silica powder is also one of the harmful effects,
Further improvement of solder stress resistance is required.

[0007]

The present invention uses the epoxy resin represented by the formula (1) as an epoxy resin to solve the above problems and reduces the elastic modulus, water absorption amount, and thermal expansion coefficient of a molded product. In addition, a polyfunctional phenol resin represented by the formula (2) and a curing agent composed of a molten mixture of bifunctional phenols are used together to significantly improve the solder stress resistance of the semiconductor package when mounting on a semiconductor. An epoxy resin composition for use is provided.

[0008]

Means for Solving the Problems That is, the present invention provides (A)
An epoxy resin containing the epoxy resin represented by the following formula (1) in an amount of 50 to 100% by weight based on the total amount of the epoxy resin.

[0009]

[Chemical 4]

(Wherein R _{1 to} R ₈ are the same or different atoms or groups selected from hydrogen, halogen and alkyl groups), (B) 100 parts by weight of a polyfunctional phenol resin represented by the following formula (2) 1 part bifunctional phenols
5 to 100 parts by weight of a melt-mixed curing agent,

[0011]

[Chemical 5]

(N = 1 to 6) An epoxy resin composition for semiconductor encapsulation containing (C) an inorganic filler and (D) a curing accelerator as essential components, which is superior to conventional epoxy resin compositions. It has resistance to soldering stress.

The biphenyl type epoxy resin represented by the structure of the formula (1) is a bifunctional epoxy resin having two epoxy groups in one molecule and has a lower melt viscosity than the conventional polyfunctional epoxy resin and is transfer molded. Excellent fluidity over time. Therefore, a large amount of fused silica powder of the composition can be blended, low thermal expansion and low water absorption can be achieved, and an epoxy resin composition having excellent solder stress resistance can be obtained.

By adjusting the amount of the biphenyl type epoxy resin used, the solder stress resistance can be maximized. In order to exert the effect of resistance to soldering stress, the biphenyl type epoxy resin represented by the formula (1) is used in an amount of 50% by weight or more, preferably 70% by weight or more of the total amount of epoxy resin.
It is desirable to use more than weight%. If it is less than 50% by weight, low thermal expansion and low water absorption cannot be obtained, and the solder stress resistance is insufficient. Further, in the formula, R _{1 to} R ₄ are methyl groups, R _{5 to} R
₈ is preferably a hydrogen atom.

When an epoxy resin other than the biphenyl type epoxy resin represented by the formula (1) is used in combination, the epoxy resin used means all polymers having an epoxy group. For example, bisphenol type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, triphenol methane type epoxy resin, trifunctional epoxy resin such as alkyl modified triphenol methane type epoxy resin, triazine nucleus-containing epoxy resin, etc. Say.

When a curing agent prepared by melt-mixing a polyfunctional phenol resin represented by the molecular structure of the formula (2) and a bifunctional phenol is used, the temperature around the soldering temperature is higher than that of the conventional phenol novolac resin curing agent. It is possible to obtain a high heat resistance because it lowers the elastic modulus and improves the adhesion between the lead frame and the semiconductor chip, and the trifunctional structure is introduced in the molecule. Therefore, it is effective in preventing the reduction of the generated stress against the thermal shock at the time of soldering and the defective peeling from the semiconductor chip or the like.

By adjusting the amount of such a resin curing agent used, solder stress resistance can be maximized. In order to bring out the effect of resistance to soldering stress, the melt mixing ratio of the polyfunctional phenol resin represented by the formula (2) and the bifunctional phenols is 15 to 100 parts by weight of the polyfunctional phenol resin. 10
It is 0 part by weight, preferably 25 to 70 parts by weight. If the mixing amount of the bifunctional phenols exceeds 100 parts by weight, the balance of high heat resistance and low elasticity and the adhesion to the lead frame and the semiconductor chip are insufficient, and the improvement of the solder stress resistance cannot be expected. If it is less than 10 parts by weight, the viscosity of the molten mixture becomes high, the dispersibility during kneading work using a mixer, a biaxial roll, etc. is insufficient, and the fluidity at the time of transfer molding of a composition using the curing agent decreases. Formability is reduced.

Further, the value of n in the formula (2) is preferably in the range of 1 to 6, and when the value of n exceeds 6, the fluidity at the time of transfer molding is lowered and the moldability tends to be lowered. .. The bifunctional phenols melt-mixed with the polyfunctional phenol resin curing agent represented by the formula (2) refer to all compounds having two phenolic hydroxyl groups. For example, bisphenol A, bisphenol F, bisphenol Z,
4,4'-dibiphenol, cyclohexylidene bisphenol A and the like can be mentioned. The conditions for melt-mixing the polyfunctional phenol resin of the formula (2) and the bifunctional phenols are not particularly limited as long as they are uniformly mixed and dispersed. Formula (2)
The molten mixture of the polyfunctional phenol resin and the bifunctional phenols may be used alone or in combination with another curing agent.
Polymers having a phenolic hydroxyl group can be used for the curing agent used in combination. For example, a phenol novolac resin, a cresol novolac resin, a dicyclopentadiene modified phenol resin, a copolymer of a dicyclopentadiene modified phenol resin and a phenol novolac or a cresol novolac resin, and a paraxylene modified phenol resin can be used. You may use these individually or in mixture of 2 or more types.

As the inorganic filler used in the present invention, fused silica powder, spherical silica powder, crystalline silica powder, secondary agglomerated silica powder, porous silica powder, secondary agglomerated silica powder or silica obtained by crushing porous silica powder is used. Examples thereof include powder and alumina, and fused silica powder, spherical silica powder, and a mixture of fused silica powder and spherical silica powder are particularly preferable. Further, the amount of the inorganic filler compounded is 70 to 9 relative to the total amount of the composition in view of the balance between solder stress resistance and moldability.
0% by weight is preferred.

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 sealing materials can be widely used. Zabicyclo undecene (DBU),
Triphenylphosphine (TPP), dimethylbenzylamine (BDMA) and 2-methylimidazole (2MZ)
Etc. are used alone or in combination of two or more. The encapsulating 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 other than this, a silane coupling agent, a brominated epoxy resin, and trioxide may be added if necessary. Flame retardants such as antimony and hexabromobenzene, colorants such as carbon black and red iron oxide, release agents such as natural wax and synthetic wax, and various additives such as low-stress additives such as silicone oil and rubber are appropriately mixed. But there is no problem.

In order to produce the encapsulating epoxy resin composition of the present invention as a molding material, an epoxy resin, a curing agent,
After the filler, the curing accelerator, and other additives are sufficiently and uniformly mixed by a mixer or the like, the mixture can be melt-kneaded with a hot roll or a kneader, 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.

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

Example 1 13 parts by weight of an epoxy resin represented by the following composition (3)

[0023]

[Chemical 6]

A polyfunctional phenol resin curing agent (a) represented by the formula (4) (n is a mixture of 1 to 6, hydroxyl group equivalent 106, softening point 145 ° C.) and bisphenol A (b) in weight ratio (a) / (B) 7/1 by weight of the melt mixture of 4/1

[0025]

[Chemical 7]

Fused silica 78.8 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, and the mixture is mixed with a biaxial roll at 70 to 100 ° C. A molding material was obtained by kneading, cooling and pulverizing. The obtained molding material is made into a tablet, and a 6 × 6 mm chip for solder crack test is put on a low pressure transfer molding machine under conditions of 175 ° C., 70 kg / cm ² and 120 seconds for 52 p.
3 × 6 for sealing in package and for solder moisture resistance test
The mm chip was encapsulated in a 16p SOP 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 for 8
After 72 Hr treatment in an environment of 5% RH, and after dipping in a solder bath at 260 ° C. for 10 seconds, a pressure cooker test (125 ° C., 100% RH) was performed to measure open circuit failure. The test results are shown in Table 1.

Examples 2 to 5 Compounding was performed according to the formulation shown in Table 1, molding materials were obtained in the same manner as in Example 1, and evaluated in the same manner. The test results are shown in Table 1.

Comparative Examples 1 to 5 Compounding was carried out in accordance with the formulation shown in Table 1, and molding materials were obtained in the same manner as in Example 1. Bisphenol A in Comparative Examples 1 and 3
Since the resin is not used, the resin melting step is not applied. Evaluation was performed in the same manner as in Example 1. The test results are shown in Table 1.

[0030]

[Table 1]

[0031]

According to the present invention, it is possible to easily uniformly disperse a resin which cannot be applied because it is difficult to uniformly disperse by the conventional method, and it is possible to obtain a soldering resistance which cannot be obtained by the conventional technique. Since it is possible to obtain an epoxy resin composition having a stress property, it is very excellent in crack resistance when it is subjected to thermal stress due to a rapid temperature change in the soldering process, and since it has good humidity resistance When it is used for sealing, covering, insulating, etc. of parts, it is suitable for a product particularly requiring high reliability in a highly integrated large chip IC mounted in a surface mount package.

[Procedure amendment]

[Submission date] February 4, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0024

[Correction method] Change

[Correction content]

A polyfunctional phenol resin curing agent (a) represented by the formula (4) (n is a mixture of 1 to 6, hydroxyl group equivalent 106, softening point 145 ° C.) and bisphenol A (b) in weight ratio (a) / (B) 2/1 melted mixture 7 parts by weight

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

Claims (1)

[Claims] 1. (A) An epoxy resin represented by the following formula (1) is contained in an amount of 50 to 100% by weight based on the total amount of epoxy resin.
Epoxy resin containing (Wherein R _{1 to} R ₈ are the same or different atoms or groups selected from hydrogen, halogen and alkyl groups), (B) a polyfunctional phenol resin 1 represented by the following formula (2)
15 to 10 parts of bifunctional phenol with respect to 00 parts by weight
0 parts by weight of a melt-mixed curing agent, (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.