JPH0562612B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a resin composition for sealing electrical parts, etc., which has excellent moisture resistance, resistance to hot and cold cycles, and low stress. [Technical background of the invention and its problems] In recent years, methods have been used to seal electronic components such as diodes, transistors, and integrated circuits using thermosetting resins. This resin sealing method 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 composition, thermosetting resin compositions are used, and among them, epoxy resin compositions are most commonly used. By the way, acid anhydrides,
Aromatic amines, novolac type phenolic resins, etc. are used. Among these, epoxy resin compositions using novolac-type phenolic resin as a curing agent have excellent moldability and moisture resistance, are non-toxic, and are inexpensive, compared to those using other curing agents, so they are widely used in semiconductor encapsulation. Widely used as a stopper material. However, epoxy resin compositions using a novolak type phenolic resin as a curing agent have the disadvantage that they shrink during molding and curing, applying stress to semiconductor devices, resulting in poor reliability. In other words, when hot and cold cycle tests are performed on molded products using such resin compositions, bonding wire opens, resin cracks, bonding cracks,
There was a problem that pellet cracks were generated and the electronic component could no longer function as an electronic component. These problems have become even more serious as semiconductor devices have recently become more highly integrated and larger. For these reasons, it has been desired to develop a sealing resin composition that maintains the advantages of the conventional epoxy resin compositions and has low stress. [Object of the Invention] The object of the present invention was to solve the above-mentioned drawbacks and problems, and to provide a resin composition for sealing that has excellent moisture resistance, resistance to hot and cold cycles, low stress, and high reliability. This is what we are trying to provide. [Summary of the Invention] As a result of extensive research in order to achieve the above object, the present inventors have discovered that the conventional sealing resin can be improved by blending a polyvinyl butyral modified novolak type phenolic resin as described below. It has been found that a resin composition for sealing that exhibits excellent moisture resistance, thermal and cold cycling properties, and has low stress can be obtained compared to
This has led to the completion of the present invention. That is, the present invention provides (A) an epoxy resin, (B) a polyvinyl butyral-modified novolak type phenolic resin obtained by reacting polyvinyl butyral, phenols, and formaldehyde, or polyvinyl butyral, phenols, and paraformaldehyde, and (C) an inorganic material. A sealing resin composition containing a filler and containing the inorganic filler (C) in an amount of 25 to 90% by weight based on the resin composition. The polyvinyl butyral modification rate of the polyvinyl butyral modified novolak type phenolic resin is 10 to 50% by weight, and the equivalent weight of the epoxy group (a) of the epoxy resin and the phenolic hydroxyl group (b) of the polyvinyl butyral modified novolak type phenolic resin. A sealing resin composition having a ratio [(a)/(b)] of 0.1 to 10. 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 restrictions on its molecular structure or molecular weight, and the epoxy resin is one that is generally used for sealing materials. can include a wide range of Examples include aromatic resins such as bisphenol, alicyclic resins such as cyclohexane derivatives, and epoxy novolac resins represented by the following general formula. These epoxy resins may be used alone or in combination of two or more. (In the formula, R ¹ represents a hydrogen atom, a halogen atom, or an alkyl group, R ² represents a hydrogen atom or an alkyl group, and n represents an integer of 1 or more.) (B) Polyvinyl butyral modified novolak used in the present invention The type phenolic resin is a polyvinyl butyral modified novolak type phenolic resin obtained by reacting a polyvinyl butyral resin with a phenol and formaldehyde or paraformaldehyde. These may be used alone or in combination of two or more. The blending ratio of the polyvinyl butyral-modified novolak type phenolic resin is determined by the equivalent ratio of the epoxy groups (a) of the epoxy resin (A) and the phenolic hydroxyl groups (b) of the polyvinyl butyral-modified novolak type phenolic resin (B) [(a)/ (b)] is preferably within the range of 0.1 to 10. If the equivalence ratio exceeds 0.1 end or 10,
Moisture resistance, molding workability, and electrical properties of the cured product deteriorate, which is undesirable in all cases. Therefore,
Limited within the above range. Further, the modification rate of the polyvinyl butyral resin in the polyvinyl butyral modified novolak type phenolic resin is preferably 10 to 50% by weight. When the modification rate is less than 10% by weight,
It is not effective in withstanding low stress and hot/cold cycles, and if it exceeds 50% by weight, water absorption and moldability deteriorate, making it unsuitable for practical use. These polyvinyl butyral-modified novolac type phenolic resins are thought to impart flexibility to the sealing resin composition, relieve stress, and reduce stress. Inorganic fillers (C) used in the present invention include silica powder, alumina, antimony trioxide, talc,
Examples include calcium carbonate, titanium white, clay, asbestos, mica, red iron oxide, glass fiber, and carbon fiber, with silica powder and alumina being particularly preferred. The blending ratio of the inorganic filler is preferably 25 to 90% by weight of the resin composition. If the amount is less than 25% by weight, it will have no effect on moisture resistance, heat resistance, mechanical properties, or moldability, and if it exceeds 90% by weight, it will be bulky and have poor moldability, making it unsuitable for practical use. The sealing resin composition of the present invention includes an epoxy resin,
The essential ingredients are a polyvinyl butyral modified novolak type phenolic resin and an inorganic filler, but if necessary, release materials such as natural waxes, synthetic waxes, metal salts of straight chain fatty acids, acid amides, esters, paraffins, etc. can be added. A flame retardant such as chlorinated paraffin, bromotoluene, hexabromobenzene, and antimony trioxide, a coloring agent such as carbon black and red iron oxide, a silane coupling agent, various curing accelerators, etc. may be appropriately added and blended. A general method for producing the encapsulating resin composition of the present invention as a molding material includes using epoxy resin, polyvinyl butyral modified novolak type phenolic resin, polyurethane-methyl methacrylate copolymer resin, inorganic filler, etc. After the raw material composition selected to have a predetermined composition ratio is mixed sufficiently uniformly using a mixer, etc., it is further melt-mixed using a heated roll or mixed using a kneader, etc., and then cooled and solidified to form an appropriate size. It can be crushed into a molding material. The molding material made of the encapsulating resin composition according to the present invention can be applied to encapsulating, covering, insulating, etc. electronic or electrical components. In addition, when the phenolic resin is modified with polyvinyl butyral in the reaction stage as in the present invention, the glass transition point of the sealing resin composition is lower than when the phenolic resin is blended with butyral resin in the molding material kneading stage. As a result, the strain test result of the sealing device shows that the stress strain is considerably small (see Japanese Patent Laid-Open No. 161423/1983). [Effects of the Invention] The encapsulating resin composition of the present invention is a composition that has excellent moisture resistance and thermal cycle resistance, has low stress, and has good molding workability, and is suitable for encapsulating and coating electronic and electrical components. When used for electrical purposes, insulation, etc., a sufficiently reliable product can be obtained. [Examples of the Invention] The present invention will be specifically explained by examples, but the present invention is not limited to the following examples. In the Examples and Comparative Examples below, "%" means "% by weight". Example 1 19% cresol novolak epoxy resin (epoxy equivalent: 215), 10% polyvinyl butyral, 11% modified novolak type phenolic resin, and 70% fused silica powder were mixed at room temperature, and the mixture was further kneaded at 90 to 95°C and cooled. Thereafter, it was crushed to obtain a molding material. The obtained molding material was transfer-injected into a mold heated to 170°C and cured to obtain a molded product. This molded article was tested for various properties such as moisture resistance and stress, and the results are shown in Table 1. Example 2 18% cresol novolac epoxy resin (epoxy equivalent 215), 30% polyvinyl butyral, 12% modified novolac type phenolic resin, and 70% fused silica powder were mixed, kneaded, and ground in the same manner as in Example 1 to obtain a molding material. Ta. Molded articles were then obtained in the same manner, and these molded articles were tested for various properties such as temperature resistance and stress in the same manner as in Example 1. The results are shown in Table 1. Comparative example: 20% cresol novolac epoxy resin (epoxy equivalent 215), 10% novolac type phenolic resin (phenol equivalent 107), and 70% silica powder.
A molding material was obtained from raw materials in the same manner as in the examples. This molding material was used to make a molded article, and the various properties of the molded article were tested in the same manner as in the Examples, and the results are shown in Table 1.

[Table] As is clear from Table 1, it was confirmed that the sealing resin composition of the present invention has excellent moisture resistance, excellent heat and cold cycle performance, and low stress.

Claims (1)

[Scope of Claims] 1 (A) an epoxy resin, (B) a polyvinyl butyral-modified novolak type phenolic resin obtained by reacting polyvinyl butyral, phenols, and formaldehyde, or polyvinyl butyral, phenols, and paraformaldehyde, and (C) A sealing resin composition containing an inorganic filler, characterized in that the inorganic filler (C) is contained in an amount of 25 to 90% by weight based on the resin composition. 2 The polyvinyl butyral modification rate of the polyvinyl butyral modified novolac type phenolic resin is 10~
50% by weight of the sealing resin composition according to claim 1. 3 The equivalent ratio [(a)/(b)] between the epoxy group (a) of the epoxy resin and the phenolic hydroxyl group (b) of the polyvinyl butyral modified novolac type phenolic resin is 0.1.
The sealing resin composition according to claim 1 or 2, which is within the range of 10 to 10.