JPH0221419B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to an epoxy resin molding material, and particularly to an epoxy resin molding material that has excellent mold releasability and is resistant to mold staining. [Technical Background of the Invention] Conventionally, epoxy resin molding materials have poor fluidity and
It has excellent water resistance, dimensional stability, and electrical properties, and is widely used as a material for encapsulating semiconductors such as diodes, transistors, and ICs. Transfer molding is generally used as a resin sealing method, and during this molding, an internal mold release agent is added to the molding material in advance to make it easier to remove the molded product from the mold. . However, when conventional molding materials are continuously molded, this internal mold release agent not only bleeds onto the surface of the molded product, but also gradually adheres to the mold, causing poor appearance of the molded product and staining of the mold. [Problems with the Background Art] If a fatty acid such as stearic acid, zinc stearate, or metal soap is used as an internal mold release agent, mold staining will not be a problem, but workability will be impaired due to poor mold release properties. In addition, when conventional ester waxes with a large carbon number such as carnauba wax or montan acid wax are used, mold release properties are improved, but as mentioned above, they may bleed onto the surface of the molded product.
There was a problem that the mold became dirty and required cleaning, impairing workability. Furthermore, attempts have been made to solve these problems by blending fatty acids or metal soaps into conventional ester waxes, but the drawbacks of both have emerged and the problem has not been essentially solved. [Purpose of the Invention] The present inventors have conducted intensive research to address the above-mentioned points, and have aimed to provide an epoxy resin molding material that simultaneously improves mold releasability and mold staining, and is also significantly improved. It is said that [Summary of the Invention] The epoxy resin molding material of the present invention is characterized by containing an ester wax having 36 or more carbon atoms and an acid value of 40 or more as an internal mold release agent. The epoxy resin molding material used in the present invention contains an epoxy resin, a curing agent, and an internal mold release agent. The epoxy resin used in this molding material can be any compound having two or more epoxy groups in one molecule, such as bisphenol type epoxy resin, novolac type epoxy resin, alicyclic epoxy resin, glycidyl ester. There are mold epoxy resins, etc. The curing agent for the epoxy resin may be any of the commonly used amine, acid anhydride and phenol novolac curing agents. In the present invention, the ester wax, which is the most important component, is made by reacting a fatty acid with a fatty alcohol, and can be easily manufactured by considering the number of carbon atoms and reaction molar ratio of each fatty acid and fatty alcohol. Can be done. In addition to this, it can also be obtained using a transesterification reaction (acidolysis reaction) using a basic catalyst. The ester wax of the present invention must have a carbon number of 36 or more and an acid value of 40 or more. The number of carbons
Anything less than 36 has poor mold release properties regardless of the acid value.
In addition, those with an acid value of less than 40 and a carbon number of 36 or more tend to bleed onto the surface of the molded product, causing mold stains. Further, it is necessary that the molar ratio of fatty acid to fatty alcohol be 1 or more. molar ratio is 1
If it is less than that, the purpose of the present invention will not be fully achieved and the effect will not be achieved. Commercially available ester waxes of the present invention include "Ricaflow SS-50", "Ricaflow BB-62" [trade name of Shin Nippon Chemical Co., Ltd.], "Hoechst Wax KFO", "Hoechst Wax U ” [Hoechst Japan Co., Ltd. product name], “BASF Wax S”,
“BASF Wax L” [BASF Japan Co., Ltd. product name]
and so on. The blending ratio of the ester wax of the present invention is desirably 0.05 to 2.0% by weight, preferably 0.1 to 1.0% by weight, based on the total weight of the epoxy resin molding material. By blending in this way, mold releasability and mold staining can be improved at the same time. If necessary, the present ester wax may be used in combination with a known internal mold release agent such as a fatty acid, a metal soap, or a fatty acid amide. The epoxy resin molding material of the present invention contains an epoxy resin, a curing agent, and an internal mold release agent as described above, but it also contains commonly used curing accelerators such as imidazoles and tertiary amines, silica, and alumina. Of course, inorganic fillers such as talc, flame retardants such as antimony oxide, halides, and phosphorus compounds, other silane coupling agents, coloring agents, etc. may be added depending on the purpose. [Embodiments of the Invention] Examples of the present invention will be described below. Example 1 100 parts of cresol novolac type epoxy resin,
25 parts of tetrabromo bisphenol type A epoxy,
50 parts of phenol novolac, 400 parts of fused silica powder
1 part of 2-methylimidazole, 10 parts of antimony oxide, 2 parts of 3,4-epoxycyclohexylethyltrimethoxysilane, 2 parts of carbon black, and ``Ricaflow SS-50'' (stearic acid and stearyl alcohol) as an internal mold release agent. 3 parts of an ester wax (acid value 102, carbon number 36) was blended, kneaded with hot rolls and pulverized to obtain a molding material. Example 2 Instead of the internal mold release agent in Example 1, “Ricaflow” was used.
An epoxy molding material was obtained in the same manner by blending 3 parts of "BB-62" (ester wax of behenic acid and behenyl alcohol, acid value 56, carbon number 44). Example 3 Instead of the internal mold release agent of Example 1, 3 parts of "Hoechstwax KFO" (acid value 90, carbon number 65) was blended,
An epoxy molding material was obtained in the same manner. Example 4 100 parts of bisphenol A type epoxy resin, 20 parts of phenol novolac, 10 parts of diaminodiphenylmethane, 330 parts of crystalline silica powder, 2 parts of 3,4-epoxycyclohexylethyltrimethoxysilane
An epoxy resin molding material was obtained in the same manner as in Example 1 by adding 3 parts of Hoechstwax KFO as an internal mold release agent to 2 parts of carbon black. Comparative Example A A milky white ester wax was obtained by reacting lauric acid and stearyl alcohol at a molar ratio of 2:1 (acid value: 98, carbon number: 30). Three parts of this was added in place of the internal mold release agent in Example 1, and an epoxy resin molding material was obtained in the same manner as in Example 1. Comparative Examples B, C Instead of the internal mold release agent of Comparative Example A, 3 parts of stearyl stearate (acid value 30, carbon number 36) and 3 parts of montanic acid wax (acid value 15, carbon number 60-65) were used. A molding material was obtained in the same manner as in Comparative Example A. These were designated as Comparative Examples B and C. Using each of the molding materials of the above Examples and Comparative Examples, semiconductors were encapsulated with resin by transfer molding in a mold for 240 DO-15 type diodes at 180° C. for 2 minutes. When we investigated mold releasability and mold stains during these moldings, we found that
The results were as shown in Table 1. As can be seen from Table 1, the epoxy resin molding material of the present invention has excellent mold releasability and is resistant to mold staining, making it an excellent molding material.

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Claims (1)

[Claims] 1. As an internal mold release agent, the number of carbon atoms is 36 or more, and the acid value is 40.
An epoxy resin molding material characterized by containing the above ester wax. 2. The epoxy resin molding material according to claim 1, wherein the ester wax is a reaction product consisting of a fatty acid (a) and a fatty alcohol (b), and the molar ratio of (a)/(b) is 1 or more. . 3. The epoxy resin molding material according to claim 2, wherein the ester wax is 0.05 to 2.0% by weight based on the total weight of the epoxy resin molding material.