JPH0220547A - Sealing resin composition - Google Patents

Abstract

PURPOSE:To obtain a sealing resin composition having a low coefficient of thermal expansion and a high thermal conductivity and excelling in moldability, humidity resistance, etc., by adding a specified Al2O3 powder to an epoxy resin containing a novolac phenol resin as a curing agent. CONSTITUTION:A sealing resin composition containing an epoxy resin (A), a novolac phenol resin (B) and Al2O3 power (C) as essential components is produced so that component (C) may be a fine spherical Al2O3 powder having a mean particle diameter <=250mum, an aspect ratio of 1.0-1.4 and the content of each of alkali metal ions and halide ions <=10ppm, extracted under conditions of 121 deg.C, 2atm and 100% RH and that the amount of this powder added may be 25-90wt.% based on the whole resin composition. The above sealing resin composition has a low coefficient of thermal expansion and a high thermal conductivity, excels in moldability and humidity resistance and has a good balance among various properties.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention provides a well-balanced seal with a low coefficient of thermal expansion, high thermal conductivity, and excellent moldability and moisture resistance. The present invention relates to a resin composition for use.

(Prior Art) Conventionally, methods have been used to resin-seal electronic components such as diodes, transistors, and integrated circuits using thermosetting resins. 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. For epoxy resins, curing agents such as acid anhydrides, aromatic amines, and novolac-type phenolic resins are used.

Among these, epoxy resins that use novolak type phenolic resin as a curing agent are preferred as resins for semiconductor encapsulation because they have superior moldability and moisture resistance, are nontoxic, and are inexpensive compared to those that use other curing agents. Widely used. As the 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 semiconductor encapsulation resins with good heat dissipation properties.

(Problem to be Solved by the Invention) However, a resin composition consisting of an epoxy resin using a novolak type phenol resin as a curing agent and fused silica powder has a small coefficient of thermal expansion and good moisture resistance, and therefore has a low coefficient of thermal expansion and good moisture resistance. Although it has the characteristics of being excellent in preventing bonding wire opens, resin cracks, bullet cracks, etc., it has low thermal conductivity and poor heat dissipation.
Power semiconductors with 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, molded articles obtained from this resin composition tend to have poor mechanical properties and moldability. Therefore, there is a natural limit to the ability to increase the thermal conductivity of a sealing resin composition using silica powder.

The present invention was made to eliminate the above-mentioned drawbacks, and has high thermal conductivity, low thermal expansion coefficient, heat dissipation,
The present invention aims to provide a sealing resin composition with excellent moldability, high reliability in moisture resistance, and well-balanced properties.

[Structure of the Invention] (Means for Solving the Problems) As a result of intensive research to achieve the above object, the inventors of the present invention have found that when a specific aluminum oxide powder is blended, the coefficient of thermal expansion is small, and the coefficient of thermal expansion is low. The present invention was completed based on the discovery that the above objects can be achieved by having high conductivity, excellent moisture resistance, and moldability.

That is, the present invention includes (A) an epoxy resin, (B) a novolak type phenol resin, and (C) an aluminum oxide powder as an essential component, and the (C) aluminum oxide powder has the following components:
A spherical body with an average particle size of 250 μl or less and a ratio of major to minor axis of 1.0 to 1.4, at 121°C.

The content of alkali metal ions and halogen ions extracted under 2 atmospheres and 100% RH is 10 ppm or less, and the blending amount is 25 ppm or less with respect to the entire resin composition.
This is a sealing resin composition characterized in that the proportion is 90% by weight.

As long as the epoxy resin (A) used in the present invention is a compound having at least two epoxy groups in its molecule,
There are no particular limitations on the molecular structure, molecular weight, etc., and a wide range of commonly used ones can be included. Examples include aromatic resins such as bisphenol, alicyclic resins such as cyclohexane derivatives, and epoxy resins such as epoxy novolac resins represented by the following general formula.

(However, 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 the number represents an integer of 1 or more.) These epoxy resins may be used alone or in a mixture of two or more. I can do it.

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, which 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)] between the epoxy group (a) of the epoxy resin described above and the phenolic hydroxyl group (b) of the novolac type phenol resin is 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, which is undesirable.

As the aluminum oxide powder (C) used in the present invention,
It can be widely used without any particular restrictions as long as it meets the following conditions. First, the average particle diameter of the aluminum oxide powder is 250 μm or less, and the length ratio is 1.0 to 1.
Preferably, it is a spherical body with an average particle diameter of 25.
If it exceeds 0 μl and is coarse, gate clogging or wire flow may occur during molding, which is undesirable. Also, the length/breadth axis ratio is 1.
If it exceeds 4, the flow characteristics will deteriorate and mold wear will occur, which is undesirable.Secondly, aluminum oxide powder is
It is preferable that the content of alkali metal ions and halogen ions extracted under 121° C., 2 atm, and 100% RH is 10 fil)TI or less based on the bone dry weight of the powder. Exceeding 10 ppn+ is undesirable because it reduces the reliability of semiconductor devices. Examples of such aluminum oxide powder include As-20, As-40 (manufactured by Showa Denko Co., Ltd.,
(trade name), etc., and these can be used alone or in combination of two or more kinds. The blending ratio of aluminum oxide powder is preferably 25 to 90% by weight based on the entire resin composition. Blending ratio is 25% by weight
If it is less than 90% by weight, the coefficient of thermal expansion will be large and the thermal conductivity will be low, which is undesirable. If it exceeds 90% by weight, it will be bulky and have poor moldability, making it unsuitable for practical use. Therefore, it is limited to this range.

The sealing resin composition of the present invention contains an epoxy resin, a novolac type phenol resin, and an aluminum oxide powder as essential components, but may optionally contain natural waxes, for example, as long as it does not contradict the purpose of the present invention. Synthetic waxes, metal salts of straight chain fatty acids, acid amides, esters, mold release agents such as paraffins, chlorinated parahynes, bromotoluene,
Flame retardants such as hexabromobenzene and antimony trioxide,
Coloring agents such as carbon black and red iron oxide, coupling agents, various curing accelerators, and the like can be appropriately added and blended.

A general method for manufacturing the sealing resin composition of the present invention as a molding material is to mix raw materials selected at predetermined composition ratios, such as epoxy resin, novolac type phenolic resin, aluminum oxide powder, etc. After sufficiently uniformly mixing the mixture using a heating roller or the like, the mixture can be further melt-mixed using a hot roll or mixed using a kneader, etc., and then cooled to solidify and pulverized to an appropriate size to form a molding material. The molding material thus obtained can be used for sealing electronic or electrical parts, and can provide excellent properties and reliability when applied to coatings, insulation, etc.

(Examples) Next, the present invention will be specifically explained by examples, but the present invention is not limited by these examples. In the following Examples and Comparative Examples, "%" means "% by weight".

Example 1 Cresol novolak epoxy resin (epoxy J12
15) Mix 18% with 9% novolac type phenol resin (phenol equivalent: 104), 70% aluminum oxide with the properties shown in Table 1, and 3% mold release agent, etc. at room temperature, and then add 90%
The mixture was kneaded at ~95°C, cooled, and then pulverized to produce a molding material.

Example 2 Cresol novolac epoxy resin (epoxy equivalent weight 21
5) A molding material was produced in the same manner as in Example 1, adding 10%, 5% novolac type phenol resin (phenol equivalent: 104), 82% aluminum oxide powder having the characteristics shown in Table 1, and 3% mold release agent.

Comparative Example 1 A molding material was produced in the same manner as in Example 1 except that the aluminum oxide powder shown in Table 1 was used.

Comparative Example 2 A molding material was produced in the same manner as in Example 1 except that the aluminum oxide powder shown in Table 1 was used.

The molding materials produced in Examples 1 and 2 and Comparative Examples 1 and 2 were tabletted, preheated, and injected into a mold heated to 170°C by transfer molding and cured to obtain a sealed molded product. Ta. The obtained molded product was tested for thermal conductivity and moisture resistance, and the molding material was tested for moldability and mold wear.The results are shown in Table 1 and confirm the effectiveness of the present invention. It was done.

*1: The molded product was measured at room temperature using a rapid thermal conductivity meter (manufactured by Showa Denko, trade name QTM-MD).

Ne2: Transfer molding an electrical component with two aluminum wirings at 170°C for 3 minutes using the molding material,
Thereafter, it was post-cured at 180°C for 8 hours. 100 molded products (sealed products) obtained in this way were subjected to a moisture resistance test in high-pressure steam at 120°C.
The time required for wire breakage (occurrence of defects) in % number was evaluated.

*3: Using a mold in which the nest was replaced with an A1 nest 1
A after transfer molding at 70℃ and 100 shots
The amount of wear on the insert No. 1 was measured.

*4: 120-1 (transfer molding was performed at 170° C. for 3 minutes using a 16-pin DIP mold with a groove and the filling property was evaluated. O mark indicates good quality.

As is clear from the above explanation and Table 1, the sealing resin composition of the present invention has a high thermal conductivity, a low coefficient of thermal expansion, and a low heat dissipation property. Therefore, it is particularly effective when used in power semiconductor equipment that consumes a large amount of power. In addition, due to its excellent moisture resistance, there are no open bonding wires, resin cracks, pellet cracks, etc. in hot and cold cycle tests, and it has a good balance of properties such as excellent moldability, making it suitable for sealing electronic and electrical parts. If used, sufficient reliability can be imparted.

Claims (1)

[Scope of Claims] 1 (A) an epoxy resin, (B) a novolak type phenol resin, and (C) an aluminum oxide powder as essential components, the aluminum oxide powder (C) comprising:
It is a spherical body with an average particle size of 250 μm or less and a ratio of major to minor axis of 1.0 to 1.4.
The content of alkali metal ions and halogen ions extracted under 00% RH is 10 ppm or less, and the amount thereof is 25 to 90% by weight based on the entire resin composition. A sealing resin composition.