JPH04283220A - Sealing resin composition and semiconductor device sealed therewith - Google Patents

Abstract

PURPOSE:To obtain the title composition improved in thermal properties, humidity resistance and moldability by mixing an epoxy resin with a novolac phenolic resin, a methyl methacrylate/butadiene/styrene compolymer resin and a specified Si3N4 powder. CONSTITUTION:A resin composition comprising an epoxy resin (A), a novolac phenolic resin (B) in an amount to give a molar ratio of the epoxy groups of component A to the phenolic hydroxyl groups of component B of 0.1-10, and 0.1-10wt.% methyl methacrylate/butadiene/styrene copolymer resin is mixed with 20-90wt.% Si3N4 powder hydrolyzed to a surface oxygen concentration of 0.5-14wt.%, freed from coarse particles retained on a 150-mesh screen and having a mean particle size of 10-50mum.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention has a small coefficient of thermal expansion,
The present invention relates to a sealing resin composition that has high thermal conductivity, excellent moisture resistance, moldability, and mold wear resistance, and has a good balance of these properties, and a semiconductor sealing device sealed with the same.

0002

2. Description of the Related Art Conventionally, electronic components such as diodes, transistors, and integrated circuits have been sealed using thermosetting resins. This sealing resin is economically advantageous compared to hermetic sealing methods using glass, metal, or ceramic, and is therefore widely put into practical use. Among thermosetting resins, epoxy resin is most commonly used as the sealing resin in terms of reliability and cost. Epoxy resins use curing agents such as acid anhydrides, aromatic amines, and novolac-type phenolic resins, but among these, epoxy resins that use novolac-type phenolic resins as curing agents are epoxy resins that use other curing agents. It is widely used as a resin for semiconductor encapsulation because it has excellent moldability and moisture resistance, is non-toxic, and is inexpensive. Further, as a filler, fused silica powder and crystalline silica powder are most commonly used together with the above-mentioned curing agent. In recent years, with the increasing density and power consumption of semiconductor components, there has been a demand for low-stress semiconductor encapsulation resins with good heat dissipation properties.

0003

[Problems to be Solved by the Invention] However, epoxy resins using novolac type phenolic resin as a curing agent,
Resin compositions made of fused silica powder have a small coefficient of thermal expansion, good moisture resistance, and are excellent in preventing bonding wire opens, resin cracks, pellet cracks, etc. in hot and cold cycle tests, but they have poor thermal conductivity. Power semiconductors with low heat dissipation and high power consumption have the disadvantage that they cannot perform their functions. On the other hand, in a resin composition consisting of an epoxy resin using a novolak type phenol resin as a curing agent and crystalline silica powder, increasing the blending ratio of crystalline silica powder increases the thermal conductivity and improves heat dissipation. However, it has the drawbacks of a large coefficient of thermal expansion and poor reliability in moisture resistance. Furthermore, the sealed products obtained from this resin composition have poor mechanical properties and moldability, and also have the drawbacks of large mold wear during molding. Therefore, there is a natural limit to the ability to increase the thermal conductivity of a sealing resin composition using silica powder.

The object of the present invention was to solve the above-mentioned drawbacks, and it has excellent moisture resistance, moldability, especially filling properties of thin-walled parts, and mold abrasion resistance, has a small coefficient of thermal expansion, and has high thermal conductivity. The object of the present invention is to provide a highly reliable sealing resin composition and a semiconductor sealing device that have good heat dissipation properties and well-balanced characteristics.

[0005]

[Means for Solving the Problems] As a result of intensive research to achieve the above object, the present inventors discovered that the above object could be achieved by blending a specific silicon nitride powder, and the present inventors have made the present invention. It is a completed invention.

That is, the present invention provides (A) an epoxy resin, (B) a novolac type phenol resin, (C) a methyl methacrylate/butadiene/styrene copolymer resin, and (D) a surface oxygen concentration of 0.5 to 15% by weight. %, and silicon nitride powder with an average particle size of 10 to 50 μm from which coarse particles on a 150 mesh sieve have been removed is an essential component, and the silicon nitride powder of (D) is This is a sealing resin composition characterized in that it contains 25 to 90% by weight. The present invention is also a semiconductor sealing device characterized in that a semiconductor chip is sealed with a cured product of this sealing resin composition.

The epoxy resin (A) used in the present invention is not particularly limited in molecular structure, molecular weight, etc., as long as it is a compound having at least two epoxy groups in its molecule, and commonly used epoxy resins can be used. can be included. Examples include aromatic resins such as bisphenol type, alicyclic resins such as cyclohexane derivatives, and epoxy resins such as epoxy novolak resins represented by the following general formula.

[0008]

[Chemical formula 1] (However, in the formula, R1 is a hydrogen atom, a halogen atom, or an alkyl group, R2 is a hydrogen atom or an alkyl group, and n is a hydrogen atom or an alkyl group.)
These epoxy resins (representing an integer of 1 or more) are used alone or in a mixture of two or more.

The novolak type phenol resin (B) used in the present invention includes a novolak type phenol resin obtained by reacting phenols such as phenol and alkylphenol with formaldehyde or paraformaldehyde, and modified resins of these, such as epoxidized or Examples include butylated novolac type phenolic resins, which may be used alone or in combination of two or more. The blending ratio of the novolak type phenolic resin is determined by the molar ratio of the epoxy group (a) of the epoxy resin (A) to the phenolic hydroxyl group (b) of the novolak type phenol resin (B) [(
a)/(b)] is preferably within the range of 0.1 to 10. If the molar ratio is less than 0.1 or more than 10, the moisture resistance, molding workability, and electrical properties of the cured product will deteriorate, and either case is unfavorable.

The methyl methacrylate/butadiene/styrene copolymer resin (C) used in the present invention may be a copolymer of methyl methacrylate, butadiene, and styrene, and is not limited to the composition ratio of each monomer. . The blending ratio of methyl methacrylate/butadiene/styrene copolymer resin is 0.1 to the resin composition.
-10% by weight, more preferably 1.0-5.
It is desirable that the content be in the range of 0% by weight. If the proportion is less than 0.1% by weight, there is no effect of lowering the elasticity;
If it exceeds 0% by weight, moldability is poor and undesirable. Also,
It is preferable that the methyl methacrylate/butadiene/styrene copolymer resin is uniformly dispersed in the novolac type phenol resin.

The silicon nitride powder (D) used in the present invention is:
The coarse particles on the 150 mesh sieve are removed, and the average particle size is 10 to 50 μm. Average particle size is 1
If it is less than 0 μm or more than 50 μm, problems may occur in fluidity and workability, which is not preferable. In particular, if the particle size is as coarse as a 150 mesh sieve, it is not preferable because it may cause wire gate clogging, wire flow, mold wear, etc. during molding. On the other hand, if the diameter is too small, the specific surface area will increase and filling properties will deteriorate, which is not preferable. In addition, a SiO2 layer is formed on the surface of silicon nitride by hydrolysis, and the SiO2
It is desirable that the oxygen concentration at the surface of the layer is in the range of 0.5 to 15%. If the oxygen concentration is less than 0.5%, it has no effect on mold wear resistance and moisture resistance deteriorates. Moreover, if it exceeds 15%, the thermal conductivity and heat dissipation properties decrease, which is not preferable. Silicon nitride that undergoes hydrolysis is trigonal (α-Si3
N4) or hexagonal system (β-Si3N4), and these can be used alone or in a mixture of two or more types. The blending ratio of silicon nitride powder is 25 to 90% by weight based on the resin composition. If the proportion is less than 25% by weight, the coefficient of thermal expansion will increase and the thermal conductivity will decrease, which is not preferable. Also 9
If it exceeds 0% by weight, the bulk will increase and the moldability will be poor, making it unsuitable for practical use.

The sealing resin composition of the present invention contains an epoxy resin, a novolac type phenol resin, a methyl methacrylate/butadiene/styrene copolymer resin, and a specific silicon nitride powder as essential components, but this does not contradict the purpose of the present invention. Within limits and if necessary, for example natural waxes, synthetic waxes, metal salts of straight chain fatty acids, acid amides,
Mold release agents such as esters and paraffins, flame retardants such as chlorinated paraffin, bromotoluene, hexabromobenzene, and antimony trioxide, colorants such as carbon black and red iron oxide, and various hardening agents are added and blended as appropriate. be able to.

[0013] A general method for preparing the sealing resin composition of the present invention as a molding material includes epoxy resin, novolac type phenol resin, methyl methacrylate/butadiene/styrene copolymer resin, and specific silicon nitride powder. , and others in a predetermined composition ratio are sufficiently uniformly mixed using a mixer, etc., and then melted and mixed using heated rolls or mixed using a kneader, etc., and then cooled and solidified to an appropriate size. It can be crushed into a molding material. The molding material thus obtained can provide excellent properties and reliability when applied to sealing, covering, insulating, etc. electronic or electrical components such as semiconductor devices.

The semiconductor encapsulation device of the present invention can be easily manufactured by encapsulating a semiconductor chip using the above-mentioned encapsulation resin composition. The semiconductor chip to be sealed may be, for example, an integrated circuit, a large-scale integrated circuit, a transistor, a thyristor, a diode, etc., but is not particularly limited. The most common method for sealing is low-pressure transfer molding, but sealing by injection molding, compression molding, casting, etc. is also possible. The sealing resin composition is heated and cured during sealing, and a semiconductor sealing device sealed with a cured product of this composition is finally obtained. For curing by heating, it is desirable to heat the material to 150° C. or higher.

[0015]

[Examples] The present invention will be specifically explained by examples, but the present invention is not limited to the following examples. In Examples and Comparative Examples, "%" means "% by weight".

Example 1 Cresol novolac epoxy resin (epoxy equivalent weight 2
15) 16%, novolac type phenolic resin (phenol equivalent: 107) 8%, hexagonal silicon nitride powder (
Average particle size excluding the 150 mesh sieve: 17 μm, surface oxygen concentration: 71%, methyl methacrylate/butadiene/styrene copolymer resin: 2%, mold release agent, etc.
3.0% were mixed at room temperature, further kneaded at 90 to 95°C, cooled and ground to produce a molding material.

Example 2 In Example 1, instead of the hexagonal silicon nitride powder, 31% hexagonal silicon nitride powder (average particle size 17 μm excluding the surface on a 150 mesh sieve, surface oxygen concentration 7%) and crystals were used. A molding material was produced in the same manner as in Example 1 except that 40% mixed powder of silica powder (average particle size 38 μm) was used.

Comparative Example 1 Cresol novolak epoxy resin (epoxy equivalent: 2
15) 16%, novolak type phenol resin (phenol equivalent: 107) 8%, methyl methacrylate-butadiene-styrene copolymer resin 2.0%, fused silica powder (average particle size 35 μm) 71%, and mold release agent, etc. 3
．． A molding material was produced in the same manner as in Example 1 with the addition of 0%.

Comparative Example 2 A molding material was produced in the same manner as in Comparative Example 1 except that crystalline silica powder (average particle size 28 μm) was used instead of fused silica powder.

Comparative Example 3 Cresol novolac epoxy resin (epoxy equivalent: 2
15) 18%, novolac type phenolic resin (phenol equivalent: 107) 9%, hexagonal silicon nitride powder (
Average particle size (excluding those on a 150 mesh sieve: 17 μm) 70
A molding material was produced in the same manner as in Comparative Example 1, adding 3% of mold release agent and the like.

Comparative Example 4 Everything was the same as in Comparative Example 3 except that hexagonal silicon nitride powder (average particle size passing through 60 mesh 60 μm) was used instead of hexagonal silicon nitride powder. A molding material was produced.

[0022] Semiconductor chips were sealed using the molding materials produced in Examples 1 to 2 and Comparative Examples 1 to 4 and cured by heating at 170°C to produce semiconductor sealing devices. Various tests were conducted on the molding material and the semiconductor sealing device, and the results are shown in Table 1. The present invention has good thermal properties, moisture resistance, and moldability, and the effects of the present invention were confirmed.

[0023]

[Table 1] *1: Measured according to JIS-K-6911, *2
: The semiconductor encapsulation device was measured at room temperature using a rapid thermal conductivity meter (manufactured by Showa Denko, trade name QTM-MD). *3:
Using a 16-pin P mold with 120 cavities, the molding material was transfer-molded at 170°C for 3 minutes, and the filling properties were evaluated: ○...good, × mark...poor, *4
: Using the molding material, a semiconductor chip having two aluminum wirings was transfer molded at 170° C. for 3 minutes, and then aged for an additional 8 hours. 120℃ for 100 pieces of this semiconductor sealing equipment
A moisture resistance test was conducted in high-pressure steam to evaluate the time required for 50% wire breakage (defect occurrence) due to aluminum corrosion. Due to the mold, 17
Transfer molding is performed at 5°C. The evaluation was based on the number of shots when the hole diameter was worn down by 5%.

[0024]

Effects of the Invention As is clear from the above explanation and Table 1, the encapsulating resin composition and semiconductor encapsulating device of the present invention improve the thermal properties, moisture resistance, moldability, and In particular, it is possible to obtain a highly reliable semiconductor encapsulation device that has excellent filling properties in thin-walled portions and mold wear resistance, and has a low elastic modulus, and has a good balance between these properties.

Claims (2)

[Claims] Claim 1: (A) epoxy resin, (B) novolac type phenolic resin, (C) methyl methacrylate-butadiene-styrene copolymer resin, and (D) surface oxygen concentration of 0.5 to 15% by weight. An essential component is silicon nitride powder with an average particle size of 10 to 50 μm, which has been hydrolyzed and coarse particles on a 150 mesh sieve have been removed.
A sealing resin composition characterized by containing 90% by weight of the resin composition. 2. (A) epoxy resin, (B) novolac type phenol resin, (C) methyl methacrylate-butadiene-styrene copolymer resin, and (D) surface oxygen concentration of 0.5 to 15% by weight. An essential component is silicon nitride powder having an average particle size of 10 to 50 μm, which has been hydrolyzed and coarse particles on a 150 mesh sieve have been removed.
A semiconductor encapsulation device characterized in that a semiconductor chip is encapsulated with a cured product of a encapsulation resin composition containing 90% by weight.