JPS61101523A - Sealing resin composition - Google Patents

Abstract

PURPOSE:An electronic part-sealing resin composition having large thermal conductivity and excellent moldability, moisture resistance, etc., obtained by mixing an epoxy resin with a novolak phenolic resin and boron nitride powder at a specified weight ratio. CONSTITUTION:The purpose sealing resin composition is obtained by mixing an epoxy resin (A) with a novolak phenolic resin (B) and 25-90wt%, based on the resin composition, small diameter boron nitride (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 sealing resin composition that has high thermal conductivity, excellent moldability and moisture resistance, and has well-balanced properties.

[Technical background of the invention and its problems] Hitherto, 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. As the sealing resin, epoxy resin is most commonly used among thermosetting resins due to its reliability, quality, and price.

For epoxy resins, curing agents such as acid anhydrides, aromatic amines, and novolac-type phenolic resins are used.
Among these, epoxy resins using novolac-type phenolic resin as a curing agent have better moldability and moisture resistance than those using other curing agents, have no iη properties, and are inexpensive, so they are suitable for semiconductors. It is widely used as a resin for Further, as a filler, fused silica powder or crystalline silica powder is most commonly used together with the above-mentioned curing agent. In recent years, as the density of semiconductor components has increased and power consumption has increased, there has been a demand for semiconductor encapsulation resins with better heat dissipation properties.

However, a resin composition consisting of an epoxy resin and fused silica powder using a novolac-type phenol resin as a curing agent has a small coefficient of thermal expansion, good moisture resistance, and a bonding wire oven, resin cracks, and cracks in the hot and cold t-Nikle test. Although it has the characteristic of being excellent in preventing bullet cracks, etc., it has a drawback that its heat dissipation is poor due to its low heat transfer rate, and its performance cannot be improved 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. Therefore, J3 naturally had a limit in increasing 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 having high thermal conductivity, excellent heat dissipation properties, excellent moldability, and high reliability in moisture resistance. The present invention aims to provide a resin composition for IJ stopping with well-balanced properties.

[Summary of the Invention] As a result of intensive research to achieve the above objects, the present inventors have found that by blending boron nitride powder, the above objects can be achieved, such as having high thermal conductivity and excellent moldability. I have found that it can be fulfilled.

That is, the present invention includes (Δ) an epoxy resin, (B) a novolak type phenol resin, and (C) a boron nitride powder as essential components, and the (C) boron nitride powder is added to the resin composition in a ratio of 25 to 25%. This is a sealing resin composition characterized by containing 90% by weight.

The epoxy resin (A) used in the present invention is not particularly limited in molecular structure, molecule m, etc., as long as it is a compound having at least two epoxy groups <a) in its 9 molecules, and commonly used epoxy resins can be used. Can be broadly encompassed. 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). These epoxy resins may be used alone or in combination of two or more.

The novolac type phenolic resin (B) used in the present invention includes phenol, such as phenol and alkylphenol;
Novolak type phenol resins obtained by reacting formaldehyde or paraformaldehyde with formaldehyde or paraformaldehyde, and modified resins thereof such as epoxidized or butylated novolak type phenol resins are mentioned, and these can be used alone or in combination of two or more types. The blending ratio of the novolac type phenolic resin is such that the molar ratio of the epoxy group (a) of the epoxy resin (A) to the phenolic hydroxyl group (b) of the novolac type phenol resin (B) < a/b ) is 0.1 to It needs to be in the range of 10. If the molar ratio is less than 0.1 or more than 10, the moisture resistance, molding workability J'3, and electrical properties of the cured product will deteriorate, which is undesirable.

The <C) boron nitride powder used in the present invention is not particularly limited and may be of any type, but examples include Denka Boron Nitride GP manufactured by Denki Kagaku Kogyo Co., Ltd., which may be used alone or in combination. be done. The blending ratio of boron nitride powder is 2% to the resin composition.
It is necessary that it is 5 to 901%. Mixture m is 2
If it is less than 5 times, the coefficient of thermal expansion is large and the thermal conductivity is low, which is not preferable. Moreover, if it exceeds 90% by weight, the bulk will be large and the moldability will be poor, making it unsuitable for practical use.

Therefore, it is limited to the above range. The average particle size of the boron nitride powder needs to be as small as 60 mesh. If the particle diameter is less than 60 Mepsch, 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 novolak type phenol resin, and a boron nitride powder as essential components, but may optionally contain natural waxes, synthetic waxes, metal salts of straight chain fatty acids, etc. Mold release agents such as acid amides, esters, paraffins, chlorinated paraffin, plastic
Flame retardants such as mutluene, hexabromobenzene and antimony trioxide, colorants such as carbon black and red iron,
A silane coupling agent, various curing accelerators, etc. may be added and blended as appropriate.

A general method for preparing the sealing resin composition of the present invention as a molding material is to use raw material compositions of epoxy resin, novolac type phenol resin, boron nitride powder, and others selected in a predetermined composition ratio. After sufficiently uniformly mixing using a mixer, etc., it can be further melted and mixed using hot rolls, or mixed using a kneader, etc., then cooled and solidified, and pulverized to an appropriate size to be used as 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, excellent heat dissipation properties, and moldability, and also has good moisture resistance, and has excellent resistance to open bonding wires and resin in hot and cold cycle tests. There are no cracks, pellet cracks, etc., and it is effective when used in power-consumption devices such as power half-body bodies. The resin composition of the present invention has well-balanced properties and can provide excellent reliability when used for sealing electronic and electrical components.

[Example 1 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, "%" means 11%.
means.

Example 1 Talesol novolak epoxy resin (epoxy 121
5) Mix 18% with 9% novolac type phenol resin (phenol equivalent al 107), 70% boron nitride powder (average particle size 5 μ-), 3% release agent etc. at room temperature, and further heat to 90-95°C. A sealing resin composition was produced by kneading the mixture. 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 various properties such as thermal conductivity and moldability. The results are shown in Table 1.

Example 2 Instead of the single boron nitride powder in Example 1, 30 boron nitride powders (average particle size 5μ1) were used.
% and crystalline silica powder (average particle size 28μ) except that 40% was used (all procedures were carried out in the same manner as in lill) to obtain a resin composition, molding material, and molded article, and test various properties of the molded article. The results are shown in Table 1.

Comparative Example 1 Cresol novolac epoxy resin (121% per epoxy
5) 18%, 9% novolac type phenol resin (phenol 5 suspension 107), 70% fused silica powder, 3% mold release agent, etc. were added in the same manner as in Example 1 to obtain a resin composition, molding material, and molding. I got the item. The obtained molded product was tested for various 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 products were tested for various properties and the results are shown in Table 1.

1 Comparative Example 3 Cresol novolak epoxy resin (φ2 per epoxy
15> The resin composition and molding material were all the same as in Comparative Example 1 except that 5% of novolak type phenol resin (phenol 71107) and 85% of crystalline silica powder (average grain (¥28 μm) were used for 10%). , a molded article was obtained.

We tested the quality of the molded product, and the results are shown in the first section.
Shown in the table.

Table 1 *2: Using a 120-cavity, 16-bin DIP mold, transfer molding was performed at 170°C for 3 minutes to test filling properties.

Claims (1)

[Scope of Claims] 1 (A) an epoxy resin, (B) a novolac type phenol resin, and (C) boron nitride powder are essential components, and the (C) boron nitride powder is added to the resin composition in an amount of 25%. A sealing resin composition characterized by containing up to 90% by weight. 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 boron nitride powder has an average particle size of 60 mesh or more.