JPS61101524A - Sealing resin composition - Google Patents

Abstract

PURPOSE:To improve the thermal conductivity, moisture resistance, etc., by adding magnesium oxide powder at a specified weight ratio to an electronic part-sealing resin composition based on an epoxy resin and a novolak phenolic resin as a curing agent. CONSTITUTION:The purpose sealing resin composition is obtained by mixing an epoxy resin (A) with a novolak phenolic resin (B) and 25-90wt% small- diameter magnesium oxide powder (C) of an average particle diameter >=60 mesh at a molar ratio of epoxy groups in component A to phenolic hydroxyl groups in component B of 0.1-10. If desired, a mold release, a flame retardant, a colorant, a cure accelerator, etc., may be added to the composition. Because of its large thermal conductivity, the obtained sealing resin composition shows excellent heat radiation and particularly effective when used in devices such as power semiconductors of a large power consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a resin composition for sealing that has a high thermal conductivity, excellent moldability and mold abrasion resistance, and has well-balanced properties.

[Technical Background of the Invention and Problems Thereof 1 Conventionally, a method has been used in which electronic components such as diodes, transistors, and integrated circuits are sealed with a thermosetting resin. This resin sealing 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 1
For 1 fat, curing agents such as acid anhydrides, aromatic amines, novolac type phenolic resins, etc. are used. Among these, epoxy resins using novolac type phenolic resin as a curing agent have better moldability and better moldability than those using other curing agents.
It is widely used as a semiconductor encapsulation resin because it has excellent moisture resistance, is nontoxic, and is inexpensive. Further, as a filler, fused silica powder or activated silica powder is most commonly used together with the above-mentioned curing agent. BACKGROUND ART In recent years, with the increase in the density and power consumption of semiconductor components, there has been a demand for semiconductor encapsulation resins with better heat dissipation properties.

However, a resin composition consisting of an epoxy resin using a novolac-type phenolic resin as a curing agent and fused silica powder has a small coefficient of thermal expansion, good moisture resistance, and no open bonding wires or resin cracks in the Lagoon cycle test. Although it has the characteristic of being excellent in preventing pellet cracks, etc., it has a drawback that it has poor heat dissipation due to its low thermal conductivity, and cannot perform its function in power semiconductors with large power consumption. 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 disadvantage of poor reliability in moisture resistance. Furthermore, molded articles obtained from this resin composition tend to have poor mechanical properties and moldability, and also have the disadvantage that mold wear becomes slow and large. Therefore, there is a natural limit to the ability to increase the thermal conductivity of a sealing resin composition using silica powder.

[Object of the Invention] The present invention has been made in order to eliminate the above-mentioned drawbacks, and its purpose is to provide a material with high thermal conductivity, good heat dissipation, excellent moldability and mold abrasion resistance, The present invention also aims to provide a sealing resin composition that is highly reliable in terms of moisture resistance and has well-balanced properties.

[Summary of the Invention] As a result of intensive research to achieve the above object, the present inventors found that by blending magnesium oxide powder, the heat transfer rate is high, the moldability and the durability of the mold are improved. The present invention was achieved by discovering that a resin composition with excellent abrasion properties can be used for IJ.

That is, the present invention has (A) an epoxy resin, (B) a novolak type phenol resin, and (C) a magnesium oxide powder as essential components, and the above-mentioned (Called magnesium powder) in an amount of 25 to 90% by weight based on the resin composition. This is a sealing resin composition characterized by containing:

The (A) epoxy resin 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 <8 in its molecule, and includes a wide range of commonly used resins. can do. 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. (In the formula, R1 represents a hydrogen atom, a halogen atom, or an alkyl group, R2 represents a hydrogen atom or an alkyl group, and n represents an integer of 1 or more.) use

The (B) novolak type phenolic resin used in the present invention includes novolak type phenol resins obtained by reacting phenols such as phenol and alkylphenols with formaldehyde or paraformaldehyde, and modified resins thereof, such as epoxidized or butylated novolak types. Examples include phenol resins, and these may be used alone or in combination of two or more. The blending ratio of the novolac type phenolic resin is such that the molar ratio (a/b) of the epoxy W (a) of the (A>epoxy resin) and the phenolic hydroxy acid 1 (b) of the novolac type phenol resin (B) is 0.
It needs to be in the range of 1 to 10. molar ratio is 0
．． If it is less than 1 or more than 10, the moisture resistance, molding workability, and electrical properties of the cured product will deteriorate, which is not preferable.

The (C) magnesium oxide powder used in the present invention is as follows:
There are no particular restrictions and any material may be used, such as calcined magnesium oxide (#5000 manufactured by Asahi Glass Co., Ltd.)! Examples include fused magnesia (FMF-'E' manufactured by Ako Kasei Co., Ltd.), which may be used alone or in combination. The blending ratio of magnesium oxide powder needs to be 25 to 90% by weight based on the resin composition. If the amount is less than 25% by weight, the coefficient of thermal expansion will be large and the thermal conductivity will be low, which is not preferable. Moreover, if it exceeds 90% by weight, bulk will be large and moldability will be poor, making it unsuitable for practical use.

Therefore, it is limited to the above range. The average particle diameter of the magnesium oxide powder must be 60 mesh or more. If the particle size is less than 60 mesh, it is not preferable because wire gate clogging occurs during molding, wire flow, mold wear, etc.

The sealing resin composition of the present invention contains an epoxy resin, a novolac type phenol resin, and a magnesium oxide powder as essential components, but may optionally contain natural waxes, synthetic waxes, metal salts of straight chain fatty acids, etc. , release agents such as acid amides, esters, paraffins, chlorinated paraffins,
Flame retardants such as bromotoluene, hexabromobenzene, and antimony trioxide, colorants such as carbon black and red iron oxide, silane coupling agents, various curing accelerators, and the like may be appropriately added and blended.

A general method for preparing the sealing resin composition of the present invention as a molding material is to use a raw material composition in which epoxy resin, novolak type phenol resin, magnesium oxide powder, and others are selected in a predetermined composition ratio. After sufficiently uniformly mixing with a mixer or the like, the mixture can be further melt-mixed using hot rolls or mixed using a kneader, etc., then cooled and solidified, and pulverized to an appropriate size to form 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.

[Effects of the Invention] The sealing resin composition of the present invention has high thermal conductivity, good heat dissipation, excellent moldability and mold abrasion resistance, and has good moisture resistance and has passed greenhouse cycle tests. There are no open bonding wires, resin cracks, pellet cracks, etc., making it effective for use in devices such as power semiconductors that consume large amounts of power. The resin composition of the present invention has well-balanced properties and can provide excellent reliability when used for sealing electronic and electrical components.

[Examples of the Invention] The present invention will be specifically explained with reference to Examples, but the present invention is not limited to the following Examples.

In Examples and Comparative Examples, "1%" means "wt%"
” means.

Example 1 Cresol novolac epoxy resin (epoxy weight Q 2
15) 18%, novolak type phenolic resin (phenolized W 107) 9%, magnesium oxide)
70% powder (average particle size 15 μm), 3% mold release agent, etc. were mixed at room temperature, and further kneaded at 90 to 95° C. to produce a sealing resin composition. After cooling, this was crushed to obtain a molding material. The molding material was made into a tablet, and the molded product was injected into a mold that had been preheated and heated to 110° C. by transfer molding and hardened. The obtained molded product was tested for thermal conductivity, moldability, and other properties. The results are shown in Table 1.

Example 2 Everything was the same as Example 1 except that 30% of magnesium oxide powder (average particle size 15 μm) and 40% crystalline silica powder (average particle size 28 μm) were used instead of the magnesium oxide powder alone in Example 1. A resin composition, a molding material, and a molded article were obtained, and the properties of the molded article were tested. The results are shown in Table 1.

Comparative example 1 Talesol novolac epoxy resin (epoxy
215) 18%, novolak type phenolic resin (
Phenolized fi 107) 9%, fused silica powder 70%, mold release agent, etc. 3% were treated in the same manner as in Example 1 to obtain a resin composition, a molding material, and a molded article. The obtained molded product was tested for mechanical properties and the results are shown in Table 1.

Comparative Example 2 A resin composition, molding material, and molded article were obtained in the same manner as in Comparative Example 1 except that crystalline silica powder (average particle size 28 μm) was used instead of the fused silica powder in Comparative Example 1. . The molded product was tested for two properties, and the results are shown in Table 1.

Comparative Example 3 Cresol novolak epoxy resin (epoxy
2+5) 10%, novolak type phenolic resin (phenol 51107) 5%, crystalline silica powder (
A resin composition, a molding material, and a molded article were obtained in the same manner as in Comparative Example 1 except that 85% (average particle size: 28 μm) was used.

Since we tested two characteristics of the molded product, we will use the results in the first
Shown in the table.

Table 1 *1 The obtained molded product was measured using a rapid thermal conductivity meter (product name: QT~1-MD, manufactured by Showa Denko)! Measured under 1

Claims (1)

[Scope of Claims] 1 (A) an epoxy resin, (B) a novolak type phenol resin, and (C) a magnesium oxide powder are essential components, and the (C) magnesium oxide powder is contained in an amount of 25 to 90% by weight based on the resin composition. % of the sealing resin composition. 2 The molar ratio of the epoxy group (a) of the epoxy resin to the phenolic hydroxyl group (b) of the novolac type phenolic resin (
The sealing resin composition according to claim 1, wherein a/b) is in the range of 0.1 to 10. 3. The sealing resin composition according to claim 1 or 2, wherein the magnesium oxide powder has an average particle size of 60 mesh or more.