JPH0160163B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an epoxy resin composition for semiconductor encapsulation, and more specifically, a novolak type epoxy resin is used as the epoxy resin, a phenol novolak resin is used as a hardening agent, and a filler is used in the composition.
An epoxy resin composition for semiconductor encapsulation made by mixing an epoxy resin composition containing 50 to 90% by weight of silica powder as an essential component, 0.1 to 10% by weight of a bisphenol type epoxy resin, and 0.05 to 10% by weight of a polyester elastomer. It has heat resistance, water resistance, and excellent crack resistance. Epoxy resin compositions for semiconductor encapsulation contain a polyfunctional epoxy compound, phenols as a curing agent, silica powder as a filler, and a curing catalyst as essential components in terms of electrical properties, heat resistance, water resistance, etc. This is widely known. In recent years, semiconductor devices have become larger and more highly integrated, and when semiconductor devices are encapsulated with conventional epoxy resin compositions, cracks may occur in the encapsulation resin or chips when heat cycle tests are performed. A problem has arisen in which the reliability of semiconductor components is lowered, such as by the occurrence of. This is due to the fact that the cured products of epoxy resin compositions for semiconductor encapsulation, which have been developed from the viewpoint of heat resistance and water resistance, such as polyfunctional epoxy resins, phenols, and silica, are extremely hard and lack flexibility. It is something to do. The present inventors conducted research on these problems and completed the patent application No. 57-66035 entitled "Epoxy resin composition for semiconductor encapsulation."However, as a result of further research, the composition of the earlier application was completed. When a bisphenol type epoxy resin is added as another component,
The present invention was completed by discovering that a composition can be obtained which has even higher crack resistance while maintaining heat resistance. The configuration of the present invention will be explained below. The novolak type epoxy resin used in the present invention is commonly known, and examples include phenol novolak type epoxy resin and cresol novolak type epoxy resin, but semiconductor encapsulation resins that require high reliability are used. Particularly preferred are cresol novolak type epoxy resins which have excellent water resistance and have an epoxy equivalent of 180 to 250. The phenol novolak resin used in the present invention is known as a curing agent for epoxy resins, but from the viewpoint of flow characteristics and heat resistance, the molecular weight
400 to 2000 is preferred, and the free phenol content is preferably 3% or less. In the present invention, the blending ratio of the novolac type epoxy resin and the phenol novolac resin is preferably 0.5 to 1.5 in terms of the ratio of hydroxyl groups to epoxy groups. The silica powder used in the present invention is fused silica,
Natural crystalline silica is mentioned, and its content in the composition is 50 to 90% by weight, preferably 65 to 80% by weight. The maximum particle size of the silica powder is 200μ or less, preferably 150μ or less, for ease of molding. In addition, the average particle size is 1 to 50 μm from the viewpoint of moldability.
In particular, 5 to 25μ is preferable. Further, depending on the purpose, other fillers such as carbon fiber, glass fiber, boron nitride, alumina powder, magnesia powder, etc. may be used in combination to the extent that the reliability of the sealing material is not impaired. The bisphenol-type epoxy resin used in the present invention is known from many documents (e.g., "Epoxy Resin", Nikkan Kogyo Shimbun, 1978), and is obtained by a dehydrochlorination reaction between bisphenol and epichlorohydrin. It is something. The average molecular weight is 300 for semiconductor encapsulation resin that requires high reliability.
-4000, preferably 350-3000. Further, the content in the composition is 0.1 to 10% by weight, preferably 0.2 to 5% by weight. If the amount of bisphenol type epoxy resin in the composition is less than 0.1%, crack resistance as a semiconductor encapsulating material will not be improved sufficiently, and if it is more than 10%, heat resistance will decrease, which is not preferable. The polyester elastomer used in the present invention is Plastics Vol. 30 (3) P11-19, P33-41.
(1979) and Japan Rubber Association Journal Vol51(10) P779-796
(1978), heterogeneous blocks of a hard segment with a certain length (hard segment) and a soft segment with a certain length (soft segment) are repeatedly connected in two dimensions within a molecular chain. It is a type of thermoplastic elastomer that exhibits elastic properties like vulcanized rubber at room temperature, and is a polymeric material that can be plasticized and molded at high temperatures.It is generally a polymeric material that is made of diols, aromatic dicarboxylic acids, and polyalkylene ethers. It is made by polycondensation reaction of glycol and has a hard segment of polyester part and a soft segment of polyether part in its molecular structure. One example of the polyester elastomer used in the present invention is as shown in the following formula (1),
In this example, the hard segment of the polyester part is (molecular weight approx. 220×n) and the soft segment of the polyether part (l is 14 on average; molecular weight approx. 1156×
m). The molecular weight of the polyester elastomer in the present invention is 5,000 to 50,000, preferably 10,000 to 40,000, and it is preferable that the amount of soft segments in the molecule is greater than the amount of hard segments. The content of polyester elastomer in the composition is 0.05 to 10% by weight, particularly preferably 0.1 to 5.0%.
Weight%. If the amount of polyester elastomer in the composition is less than 0.05%, crack resistance as a semiconductor encapsulating material will not be sufficiently improved, and if it is more than 10%, water resistance will decrease, which is not preferable. It is also possible to add a silane coupling agent, a mold release agent, and a pigment flame retardant to the epoxy resin composition for semiconductor encapsulation of the present invention as described above, if necessary. This will be specifically explained below using Examples and Comparative Examples. In Examples and Comparative Examples, parts and % refer to parts by weight and % by weight. Examples 1 to 5 Cresol novolac type epoxy resin (trade name: ESCN220L, manufactured by Sumitomo Chemical Co., Ltd.), phenol novolac resin, bisphenol type epoxy resin (trade name: Epicote 1004, Yuka Ciel Epoxy Co., Ltd.) ), polyester elastomer (product name;
Puruprene P-40H (manufactured by Toyobo Co., Ltd.), fused silica powder, and other raw materials were mixed in the composition ratios shown in Table 1, then heated, kneaded, and cooled to prepare a sealing material. Using these sealing materials, test pieces were molded and post-cured at 175°C for 5 hours, and the glass transition temperature was measured.
A treatment (referred to as PCT treatment) was performed for 100 hours in a steam pressure cooker at 121° C. and 2 atm, and the volume resistivity was measured. In addition, after molding and post-curing a 40Pin IC, we conducted a heat cycle test (crack resistance) by repeatedly dipping it in silicone oil at 150°C for 60 seconds and in liquid nitrogen for 60 seconds, and found that there were no cracks on the surface of the IC's sealing resin. The number of cycles until this occurred was measured. These results are shown in Table 1. From the above results and a comparison with the comparative examples shown in Table 1, the semiconductor encapsulation material of the present invention has superior crack resistance (number of heat cycles) to both bisphenol-type epoxy resin and polyester elastomer. It was found to be extremely superior to those without it (Comparative Example 1) or with only one of them (Comparative Examples 2, 3, 4), and the glass transition temperature, volume resistivity, heat resistance, water resistance, etc. It can be seen that there is no deterioration. Comparative Examples 1 to 5 In the Examples, there are cases in which both bisphenol-type epoxy resin and polyester elastomer are not used (Comparative Example 1), cases in which only one is used (Comparative Examples 2, 3, and 4), and cases in which bisphenol-type epoxy resin is used. In the case of using a large amount (Comparative Example 5), the same procedure as in the example was carried out except that the composition ratios shown in Table 1 were mixed. The results are shown in Table 1.

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Claims (1)

[Claims] 1 Add 0.1% of bisphenol type epoxy resin to an epoxy resin composition consisting of a novolac type epoxy resin as an epoxy resin, a phenol novolac resin as a curing agent, and 50 to 90% by weight of silica powder as a filler in the composition. ~10% by weight of an epoxy resin composition for semiconductor encapsulation, mixed with 0.05~10% by weight of a polyester elastomer.