JPH068338B2 - Method for producing encapsulating resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method for producing a resin composition for encapsulating an electronic or electrical component, which has low stress and excellent moisture resistance.

(Prior Art) Conventionally, a method of sealing an electronic component such as a diode, a transistor, or an integrated circuit with a thermosetting resin has been performed. This resin encapsulation has been widely put into practical use because it is economically advantageous as compared with the hermetic sealing method using glass, metal, or ceramic. Among thermosetting resin compositions used for resin encapsulation, epoxy resin compositions are most commonly used. Curing agents such as acid anhydrides, aromatic amines and novolac type phenolic resins are used in the epoxy resin composition, but the epoxy resin composition using the novolac type phenolic resin as a curing agent may be replaced with other curing agents. It is widely used as a semiconductor encapsulating material because it is superior in moldability and moisture resistance, has no toxicity, and is cheaper than those used.

However, an epoxy resin composition using a novolac type phenol resin as a curing agent has a drawback that it shrinks during molding and curing and stress is applied to a semiconductor element, which deteriorates reliability of the element. When a cold cycle test of a molded product using such a resin composition is performed, opening of a bonding wire, resin crack, pellet crack, etc. occur,
There was a problem that the function as an electronic component could not be fulfilled. Further, there is a method of adding a third component in order to reduce the stress of the resin composition, but the third component forms a secondary aggregate and cannot be uniformly dispersed in the resin composition, which results in a low stress. There is a drawback that the characteristics vary.

(Problems to be Solved by the Invention) The present invention has been made in order to solve the above-mentioned drawbacks, has no variations in low stress characteristics, is excellent in moisture resistance, and has characteristics of conventional epoxy resin compositions. The present invention intends to provide a method for producing a highly reliable resin composition for encapsulation which holds the above.

[Structure of the Invention] (Means for Solving Problems) As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that a methylmethacrylate / butadiene / styrene copolymer resin is uniformly dispersed in an epoxy resin. The inventors have found that the dispersion of low stress characteristics can be eliminated by using a resin that is dispersed and mixed in, and the present invention has been completed. That is, according to the present invention, (A) an epoxy resin is melted, (B) a methyl methacrylate / butadiene / styrene copolymer resin is added thereto, and the resin [(A) + (B)] is uniformly dispersed and mixed. , (C) a novolac type phenolic resin, and then (D) an inorganic filler and optionally other components are added and mixed, further kneaded by heating, and then cooled, solidified and pulverized. It is a method of manufacturing a product.

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

(However, 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.) These epoxy resins are one kind or two or more kinds. Use by mixing.

Examples of the novolak type phenolic resin (C) used in the present invention include novolak type phenolic resins obtained by reacting phenols such as phenol and alkylphenol with formaldehyde or paraformaldehyde, and modified resins thereof, for example, epoxidized or butylated novolaks. Type phenolic resin. The mixing ratio of the novolac type phenol resin is the molar ratio [(a) / (b)] of the epoxy group (a) of the epoxy resin and the phenolic hydroxyl group (b) of the novolac type phenol resin.
Is preferably in the range of 0.1 to 10. If this molar ratio is less than 0.1 or exceeds 10, the moisture resistance, the molding workability, and the electrical properties of the cured product deteriorate, which is not preferable in any case.

Therefore, it is preferable to limit it to the above range.

The (B) methylmethacrylate / butadiene / styrene copolymer resin used in the present invention has a butadiene composition ratio of 70% by weight or less and a methylmethacrylate composition ratio of 70% by weight or less.
The content is preferably 15% by weight or more, and if the composition ratio is outside this range, the appearance of the molded product is impaired, which is not preferable. The mixing ratio of the methyl methacrylate / butadiene / styrene copolymer resin is 0.1 to 60% by weight with respect to the resin [(A) + (B)] in which the methyl methacrylate / butadiene / styrene copolymer resin is uniformly dispersed and mixed. It is desirable to contain it in a ratio. If the proportion is less than 0.1% by weight,
It has no effect of withstanding low stress and hot and cold cycles, and if it exceeds 60% by weight, it cannot be uniformly dispersed and mixed in the epoxy resin. The methylmethacrylate / butadiene / styrene copolymer resin is melt-mixed by heating in an epoxy resin and uniformly dispersed and mixed. The method of uniform dispersion in the epoxy resin is to put the epoxy resin in a device (container) that can heat it to a temperature above the melting point of the epoxy resin, heat it above the melting point to form a completely molten liquid, and then add methyl methacrylate. Add butadiene-styrene copolymer resin, preferably 15
Stir for 20 minutes or more at 0 ° C. or more to uniformly disperse and mix. Resin in which methylmethacrylate / butadiene / styrene copolymer resin is dispersed and mixed in epoxy resin [(A)
+ (B)] is 1 to 50% by weight based on the entire resin composition.
It is desirable to contain it in a ratio of. If the blending ratio is less than 1% by weight, there is no effect on the low stress, and if it exceeds 50% by weight, the dispersion of the methylmethacrylate / butadiene / styrene copolymer resin becomes non-uniform and the viscosity increases, which is not preferable.

Examples of the inorganic filler (D) used in the present invention include silica powder, alumina, antimony trioxide, talc, calcium carbonate, titanium white, clay, asbestos, mica,
Red iron oxide, glass fiber, carbon fiber and the like are mentioned, and these are used alone or in combination of two or more. Among these, silica powder and alumina are particularly preferable. The blending ratio of the inorganic filler is preferably 25 to 90% by weight based on the total composition. If the blending ratio is less than 25% by weight, the moisture resistance, heat resistance, mechanical properties and moldability are not effective, and if it exceeds 90% by weight, the bulkiness becomes large and the moldability is poor, which is not suitable for practical use.

The encapsulating resin composition in the present invention contains an epoxy resin, a methyl methacrylate / butadiene / styrene copolymer resin, a novolac type phenolic resin, and an inorganic filler as essential components, but if necessary, for example, natural waxes or synthetic waxes. , Metal salts of straight chain fatty acids, acid amides,
Releasing agents such as esters and paraffins, flame retardants such as chlorinated paraffin, bromtoluene, hexabromobenzene, antimony trioxide, silane coupling agents, various curing accelerators, and the like can be appropriately added and blended.

The method for producing the encapsulating resin composition of the present invention may be a resin in which a methylmethacrylate / butadiene / styrene copolymer resin is heated and mixed in an epoxy resin and uniformly dispersed and mixed, and particularly a method for producing the same. It is not limited to. However, it is usually manufactured as follows. Use a device (container) that can heat to a temperature above the melting point of the epoxy resin, such as a universal mixer, strong kneader, heating reaction kettle, etc., charge the epoxy resin into this, and heat it above the melting point to completely melt After that, 0.1 to 60 relative to the epoxy resin
Add methylmethacrylate / butadiene / styrene copolymer resin in an amount of wt%, preferably 20
Stir for at least one minute to uniformly disperse and mix. Epoxy resin in which methyl methacrylate / butadiene / styrene copolymer resin is uniformly dispersed and mixed, and novolac type phenol resin are crushed, and then a raw material composition in which an inorganic filler and other components are selected in a predetermined composition ratio is blended. Etc., after sufficiently uniform mixing, the mixture is further heated and kneaded by a hot roll, an extruder, a kneader or the like, cooled and solidified, and then crushed to an appropriate size to produce a sealing resin composition. As described above, the manufacturing method in which the methyl methacrylate / butadiene / styrene copolymer resin is dispersed and mixed in the epoxy resin and then the other components are compounded has been described.
In the process of producing an epoxy resin, a resin in which a methylmethacrylate / butadiene / styrene copolymer resin is uniformly dispersed and mixed may be prepared and kneaded and kneaded with a necessary amount of other components as necessary.

(Function) By uniformly dispersing and mixing the methyl methacrylate / butadiene / styrene copolymer resin in the epoxy resin, it is possible to reduce the production of secondary aggregates and eliminate the variation in low stress characteristics. The particle size of methylmethacrylate / butadiene / styrene copolymer resin is originally several μm or less, but when mixed and kneaded with other components, the particles of methylmethacrylate / butadiene / styrene copolymer resin aggregate to form particles. Secondary agglomerates having a diameter of several hundreds of μm are generated, the low stress characteristics are deteriorated, and the low stress characteristics vary, resulting in deterioration of reliability.

Therefore, instead of simply mixing and kneading the methyl methacrylate / butadiene / styrene copolymer resin, epoxy resin, novolac type phenol resin, and inorganic filler, the methyl methacrylate / butadiene / styrene copolymer resin is sufficiently dispersed in the epoxy resin in advance. If mixed,
It was confirmed that the secondary agglomerates were small, the amount of the secondary agglomerates was small, the low stress characteristics were excellent, and the variations were eliminated. The particle size of the methylmethacrylate / butadiene / styrene copolymer resin can be adjusted arbitrarily depending on the mixing conditions (temperature, time, etc.).
It is preferably within the range of 50 μm.

The encapsulating resin composition obtained by the production method of the present invention can be applied to encapsulation, coating, insulation and the like of electronic or electric parts.

(Examples) The present invention will be specifically described by way of examples, but the present invention is not limited to the following examples. In the following Examples and Comparative Examples, "%" means "% by weight".

Cresol novolac epoxy resin (epoxy equivalent 21
5) Put 85% into universal mixer and heat to 150 ℃. After cresol novolac epoxy resin is completely melted, methylmethacrylate / butadiene / styrene copolymer resin 15
%, And the mixture was heated and stirred for 1 hour to prepare a resin (hereinafter referred to as E-MBS resin) in which the methylmethacrylate / butadiene / styrene copolymer resin was uniformly dispersed and mixed.

Example 1 20% of E-MBS resin and 10% of novolac type phenolic resin (phenol equivalent 107) were crushed with a screen 2 mm of a yaiya crusher, and fused silica powder 65% and other components 5
% At room temperature, further kneaded and cooled at 90 to 100 ° C., and then pulverized to produce a sealing resin composition. The obtained composition was transfer-injected into a mold heated to 175 ° C. and cured to obtain a molded product (sealed product). The molded product was tested for moisture resistance, strain, particle size of MBS resin, and other tests, and the results are shown in Table 1. The MBS resin was well dispersed in the encapsulating resin composition of the present invention, and the encapsulating resin composition was excellent in hot and cold cycles, moisture resistance, and low stress characteristics, and the remarkable effects of the present invention were recognized.

Example 2 18% of E-MBS resin and 12% of novolac type phenol resin (phenol equivalent 107) were screened to 2 m of the screen of a yaiya grinder.
Pulverized at m, and mixed with 65% of fused silica powder and 5% of other components, a sealing resin composition and a molded product were prepared in the same manner as in Example 1. Further, various properties were similarly tested, and the results are shown in Table 1. Similar to Example 1, the remarkable effect of the present invention was confirmed.

Comparative Example 1 Cresol novolac epoxy resin (epoxy equivalent 21
5) 18% of novolac type phenolic resin (phenol equivalent 107) 9%, MBS resin 3%, fused silica powder 65% and other components 5% are mixed at room temperature, further kneaded and cooled at 90 to 100 ° C, and then pulverized. Then, a resin composition for sealing was manufactured. Then, a molded product was obtained using this composition, and various properties were tested in the same manner as in Examples. The results are shown in Table 1.

Comparative Example 2 Cresol novolac epoxy resin (epoxy equivalent 21
5) 20% to 10% novolac type phenolic resin (phenol equivalent 107), fused silica powder 65% and other components 5%
Was obtained in the same manner as in Comparative Example 1, and various properties were tested in the same manner as in Comparative Example 1, and the results are shown in Table 1.

[Effects of the Invention] As is clear from the above description and Table 1, according to the method for producing a resin composition for sealing of the present invention, a methylmethacrylate / butadiene / styrene copolymer resin is heated and mixed in an epoxy resin. By homogeneously dispersing and mixing, secondary aggregates were small, excellent low stress characteristics, no variation, excellent moisture resistance, and characteristics equivalent to those of conventional epoxy resin compositions were obtained. . Excellent reliability can be imparted to an electronic part or an electric part using this composition.

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI Technical indication location H01L 23/31 (72) Inventor Masayuki Kawauchiyama 5-14-25 Ryoke, Kawaguchi City, Saitama Toshiba Chemical Corporation Kawaguchi In the factory (72) Inventor Akira Zensaku 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Inside Toshiba Research Institute (56) Reference JP-A-55-125166 (JP, A) JP-B 47-45193 JP, B1)

Claims (1)

[Claims] 1. A resin [(A) +, in which (A) an epoxy resin is melted and (B) a methyl methacrylate / butadiene / styrene copolymer resin is added thereto and uniformly dispersed and mixed.
(B)] and (C) novolac type phenolic resin are pulverized, then (D) an inorganic filler and optionally other components are added and mixed, and the mixture is further heated and kneaded, and then cooled, solidified and pulverized. A method for producing a sealing resin composition.