JPS63230725A - Epoxy resin composition for semiconductor encapsulation - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin composition for semiconductor sealing, which can be decreased in stress without detriment to moisture resistance, by adding an inorganic filler to a novolac epoxy resin as a base resin and adding a specified plurality of substances to it. CONSTITUTION:An epoxy resin composition for semiconductor sealing, containing a novolac epoxy resin as a base resin, 50-85wt.%, based on the total composition, inorganic filler and containing 25-75pts.wt. copolymer (A) of bisphenol A or bisphenol F-derived epoxy resin with butadiene rubber, 1-50pts.wt. carboxyl-terminated butadiene/acrylonitrile copolymer (B) of the formula [wherein x, y and z are positive integers, 1<=x/y<=20, 5<=z<=20, 1,800<=Mn<=7,000 (wherein Mn is the number-average molecular weight)], 25-75 pts.wt. phenolic curing agent, 0.5-5pts.wt. phosphine curing agent (D), and 0.1-15pts.wt. coupling agent (E) per 50pts.wt. base resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention provides an epoxy resin composition for semiconductor encapsulation that can suppress stress that may cause defects in resin-encapsulated semiconductor devices.

[Industrial application field]

The present invention relates to an epoxy resin composition for semiconductor encapsulation, and more particularly to an epoxy resin composition for semiconductor encapsulation that suppresses stress that causes aluminum wiring deformation, puff sealant cracks, package cracks, and the like.

[Conventional technology]

The mainstream method for sealing electronic components such as ICs and LSIs is to use a thermosetting resin.

This is because the sealing method using resin is cheaper and superior in mass production than the hermetic sealing method using glass, metal, or ceramics.

The base resin of the resin composition for semiconductor encapsulation has moldability,
Epoxy resin is most commonly used because it has excellent moisture resistance and electrical properties, and is inexpensive.

However, as chips become larger and patterns become finer due to increased integration of LSIs, and puff cages become smaller due to high-density packaging, problems have arisen that cannot be addressed by conventional epoxy resin compositions for semiconductor encapsulation. In other words, since a resin-sealed LSI is made of resin and a Si chip, which are materials with different thermal expansion coefficients, stress acts between these materials, causing the LSI to
The problem is that I is damaged. This stress increases as the chip becomes larger, and as the pattern becomes finer, it becomes more susceptible to damage. Damage modes of resin-sealed LS■ due to stress include deformation and disconnection of aluminum wiring, passivation cracks, and package cracks.

For this reason, it has become necessary to develop a resin for semiconductor encapsulation that can suppress the stress applied to the chip.

[Problem that the invention seeks to solve]

The following method can be considered as a method for reducing the stress of semiconductor sealing resin.

(a) Lower the coefficient of thermal expansion.

(b) Decrease the elastic modulus.

(C) Lowering the glass transition temperature.

Of these, lowering the glass transition temperature of the sealing resin reduces stress, but it also causes deterioration of moisture resistance, heat resistance, mechanical properties, etc., so essentially as a means of reducing stress,
(a) and (b) are possible.

Adding a large amount of inorganic filler can be considered as an effective means of lowering the coefficient of thermal expansion of the cured resin. However, when a large amount of inorganic filler is added, although the coefficient of thermal expansion decreases, the modulus of elasticity also increases, so there is almost no change in stress after all. In addition, if the amount added is too large, the melt viscosity of the resin will increase, resulting in deformation or breakage of the bonding wire, and unfilled areas where the resin does not reach every corner of the mold, resulting in a significant deterioration in workability during molding. do.

Furthermore, as a means for reducing the elastic modulus of the sealing resin, a method of adding a flexibility imparting agent has been proposed. but,
This method has the drawback that the glass transition temperature of the cured resin decreases, and the moisture resistance, heat resistance, mechanical properties, and high temperature electrical properties deteriorate. Further, as a method of reducing the elastic modulus without lowering the glass transition temperature, silicone is added, but this causes defects such as repelling printing ink.

That is, in the prior art, when trying to reduce stress, it is extremely difficult to reduce stress without deteriorating other properties such as deterioration of moisture resistance.

Therefore, the present invention solves the problems of the prior art, and
The present invention aims to provide a resin composition for semiconductor encapsulation that can reduce stress without deteriorating moisture resistance or other properties.

[Means for solving problems]

The present invention uses a novolac type epoxy resin as a base resin,
Provided is an epoxy resin composition for semiconductor encapsulation containing an inorganic filler in an amount of 50 to 85 wt% based on the total composition, and this composition contains an inorganic filler containing 50 parts by weight of a base resin.
By weight: (1) Copolymer of bisphenol A or bisphenol F type epoxy resin and butadiene rubber 25 to 75
(2) 1 to 30 parts of a butadiene-acrylonitrile copolymer with a carboxyl group at the terminal represented by the following formula (a), (3) 25 to 75 parts of a phenolic curing agent, (4) a phosphine curing accelerator and (5) 0.1 to 15 parts of a coupling agent.

HOOC-((CH2-CH=CH-C)lz)X-(
CHz-CHCN)y )-COOH(a) However, x
, y, z are positive integers, 1≦x/y≦20, 5≦2≦2
0, and the number average molecular tMn of this compound is 18
It is assumed that 00≦Mn≦7000.

[For production]

In the present invention, it is essential to add a copolymer of bisphenol A type or bisphenol F type epoxy resin and butadiene rubber and a butadiene-acrylonitrile copolymer represented by (a). The butadiene-acrylonitrile copolymer has a high flexibility imparting ability, and the terminal carboxyl group easily reacts with the novolac type epoxy resin of the base material, so it is possible to lower the elastic modulus of the sealing material without lowering the glass transition temperature. Can be done. However, if a large amount of butadiene-acrylonitrile copolymer is added to reduce stress (more than 30 parts by weight per 100 parts by weight of epoxy resin), the butadiene-acrylonitrile copolymer may bleed out or cause mold stains to become significant. . Furthermore, since the butadiene-acrylonitrile copolymer is no longer uniformly dispersed in the resin, stress is not reduced as much.

As a result of extensive research by the present inventors in order to solve this problem, by using a copolymer of butadiene-acrylonitrile copolymer, bisphenol A type or bisphenol F type epoxy resin, and butadiene rubber together, The inventors have discovered that the above problems can be solved, and have completed the present invention.

That is, the compatibility between the base epoxy resin and the butadiene-acrylonitrile copolymer is improved by adding a copolymer of bisphenol A type or bisphenol F type epoxy resin and butadiene rubber.
The most significant feature of the present invention is that a large amount of acrylonitrile copolymer can be added. Moreover, since the copolymer of bisphenol A type or bisphenol F type epoxy resin and butadiene rubber itself has flexibility, the stress is even greater than when butadiene-acrylonitrile copolymer is added alone. It has the characteristic of reducing Further, unlike silicone, even if a copolymer of bisphenol A type or bisphenol F type epoxy resin and butadiene rubber and a butadiene-acrylonitrile copolymer are added at the same time, the printing ink will not be repelled.

The amount of the copolymer of bisphenol A type or bisphenol F type epoxy resin and butadiene rubber added is 25 to 7 parts per 50 parts (parts by weight, same hereinafter) of the epoxy resin.
The amount of the butadiene-acrylonitrile copolymer added is 1 to 50 parts based on 50 parts of the epoxy resin.

The type of copolymer of bisphenol A type or bisphenol F type epoxy resin and butadiene rubber in the present invention is not particularly limited, but one containing less ionic impurities is preferred. Moreover, the properties of these copolymers may be either liquid or solid.

The epoxy resin used in the present invention is not particularly limited as long as it is a novolac type epoxy resin, but Talesol novolac type is preferred from the viewpoint of moisture resistance, heat resistance, and mechanical strength.

A phenolic resin is used as the hardening agent. Examples of the phenolic curing agent include novolac type phenolic resins such as phenol novolak, cresol novolac, and nonylphenol novolak, bisphenol A, and the like, and among these, novolac type phenol resins are preferred from the viewpoint of moisture resistance. The amount of the curing agent added is preferably 25 to 75 parts per 50 parts of the epoxy resin from the viewpoint of moisture resistance, mechanical properties, heat resistance, etc.

Further, in order to promote the reaction between the epoxy resin and the curing agent, it is essential to use a phosphine-based curing accelerator. The phosphine curing accelerator used in the present invention includes triphenylphosphine, methyldiphenylphosphine, tributylphosphine, phenylphosphine, triphenylphosphine tetraphenylborate, etc., but triphenylphosphine is preferred from the viewpoint of moisture resistance and workability. preferable. However, in the present invention, the material is not particularly limited as long as it is a phosphine and has the effect of promoting the reaction between the epoxy resin and the curing agent.

The amount of the phosphine curing accelerator used in the present invention is 0.5 to 5 parts. The reason for this is that if the amount is less than 0.5 part, the effect of accelerating curing is weak and the curing time becomes longer. Further, if the amount is 5 parts or more, the curing time of the sealing resin becomes too short. That is, if the amount of the phosphine curing accelerator added is outside the above range, workability may deteriorate.

In the present invention, the use of an inorganic filler is essential. Silica, alumina, calcium carbonate, etc. are used as the inorganic filler, but silica powder is preferable in order to reduce the coefficient of thermal expansion, and the amount of the inorganic filler added is 50 to 85 wt% of the entire composition. It is preferably within the range. The reason for this is that the amount of inorganic filler added is 50wt.
If it is less than 85wt%, not only will the thermal conductivity and mechanical properties deteriorate, but the workability will also be significantly lowered, such as Paris flowing out.If it is added more than 85wt%, the flowability will decrease, which may cause deformation or breakage of the bonding wire. It is from.

Furthermore, as the inorganic filler used in the present invention, one with a particle size of 1 μm or less accounts for 1 to 30 w of the total filler.
It is preferably within the range of t%.

This is because if the particle size is 1 μm or less and the content is 1 wt % or less, flakes are likely to occur, and if the content is 30 wt % or more, the fluidity of the composition when melted is likely to deteriorate.

In addition, in order to improve the moisture resistance of the resin, a silane coupling agent such as 3-glycidoxyprobyltrimethoxysilane or a titanium coupling agent such as tetraoctyl bis(phosphite) titanate is used as a coupling agent. It is essential to add it. The amount of the coupling agent added depends on the amount and specific surface area of the inorganic filler used and the minimum area covered by the coupling agent, but in the present invention it is preferably 0.1 to 15 parts.

Furthermore, carnauba wax, stearic acid and its metal salts, montan wax, etc. may be added as a mold release agent, a brominated epoxy resin, antimony dioxide, etc. may be added as a flame release agent, and carbon black or the like may be added as a pigment.

The epoxy resin composition for semiconductor encapsulation of the present invention can be prepared by mixing the above-mentioned components using a conventional means such as a roll, a niegu, or an extruder.

〔Example〕

The details of the implementation are described below. The raw materials used are as follows: - Epoxy resin: Cresol novolac type epoxy resin, epoxy equivalent: 200, softening point: 72°C Nippon Kayaku ■ EQCN-1025 - Curing agent: Phenol novolac, hydroxyl equivalent: 103, softening point: 93°C - Hardening accelerator: Nitri Phenylphosphine Kei Kasei-PP-360 ・Filler Nijirika Tatsumori @ VL-002 (particle size 1μm or less 10wt%) ・Coupling agent: 3-glycidoxyprobyltrimethoxysilantho ■S-510 ・Release Molding agent: Ester wax Hoechst Javan ■Hoechst Wax E・Flame retardant: Brominated epoxy resin・Flame retardant aid: Antimony trioxide・Pigment dicarbon black・Additive A: Copolymer of bisphenol A type epoxy resin and butadiene rubber Combined Dainippon Ink & Chemicals ■TSR-960/Additive B: Butadiene-acrylonitrile copolymer Molecular weight Mn = 3500 Ube Industries In Hycar CTBN-10081J
SP/Additive C: Silicone Toray Silicone ■SH6018.

The compositions shown in Examples and Comparative Examples were all prepared by kneading with a pressurized double-arm kneader. Moreover, the preparation of the test piece was performed as follows.

First, the composition obtained by kneading was made into powder of 8 mesh passes, and then made into φ35 dragon tablets at 2 tons/cd. Transfer mold this tablet (1
75°C, 60kg/c+J, 2.5win) The dried material was after-cured at 175°C for 8 hours.

Characteristics of the composition thus obtained were evaluated as follows.

- Flexural modulus: Compliant with JIS K 6911.

- Thermal expansion coefficient Measured by TMA (thermo mechanical testing machine) method.

-Glass transition temperature Measured by TMA (Thermomechanical Testing Machine) method.

・Water absorption rate Based on the weight increase of the test piece by PCT (Pressure Kutsuker test: 121°C, 2at..., 100%RH, 168h).

- Pipe stress The stress measurement method for semiconductor sealing resin disclosed in Japanese Patent Application No. 60-250258 was followed.

Table 1 shows the results of Examples and Comparative Examples of the present invention.

According to Table 1, it can be seen that all of the examples satisfy both lower stress and lower moisture absorption than the comparative example.

Table 1 Note: All numerical units other than fillers are parts by weight.

〔Effect of the invention〕

According to the present invention, by adding several substances such as a copolymer of bisphenol A or bisphenol F type epoxy resin and butadiene rubber, and a butadiene-acrylonitrile copolymer, stress can be reduced without deteriorating moisture resistance. can be reduced.

Claims (1)

[Scope of Claims] 1. In an epoxy resin composition for semiconductor encapsulation, which uses a novolac type epoxy resin as a base resin and contains an inorganic filler in an amount of 50 to 85 wt% of the entire composition, the base resin 5
(1) Copolymer of bisphenol A or bisphenol F type epoxy resin and butadiene rubber 25 to 75 parts by weight
(2) 1 to 50 parts of a carboxyl-terminated butadiene-acrylonitrile copolymer represented by (a) below, (3) 25 to 75 parts of a phenolic curing agent, (4) 0.5 parts of a phosphine curing accelerator. 5 parts, and (5) 0.1 to 15 parts of a coupling agent. HOOC-[(CH_2-CH=CH-CH_2)_x
-(CH_2-CHCN)_y〕_z-COOH(a)
However, x, y, z are positive integers, 1≦x/y≦20,
5≦z≦20, and the number average molecular weight Mn of this compound is 1800≦Mn≦7000.