In recent years, due to the high density of the power semiconductor devices, heat dissipation and high heat resistance properties are required for the sealing epoxy resin. In this paper, we have developed with the aim of both high glass transition temperature and high thermal conductivity of the sealing epoxy resin. It was possible that a glass transition temperature of the epoxy resin (DGEBA) cured with cyanate (BADCY) had over than 200℃ by considering the ratio of the DGEBA/BADCY. Moreover, it was possible to improve 7W/(m・K) or more the thermal conductivity by filling Al₂O₃ and BN filler.

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Recently, as the calorific value of the electronic equipment increases, the development of the thermal interface material is strongly demanded. For improving the thermal conductivity of composite material which is used as thermal interface material, we focused graphite which has high thermal conductivity. And we examined which characteristics of the filler affected thermal conductivity of composite material. Therefore, we developed the production technology of the ramentum-shaped graphite powder and the mixing technology of the powder. The sheet shows high thermal conductivity in comparison with other materials.

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The improvement in the thermal conductivity of the matrix resin is effective to improve the thermal conductivity of the composite. The developed mesogenic epoxy resin forms self-arranged domain when cured, which contributes to the high thermal conductivity. But, the higher order structure in the mesogen-containing epoxy composite has not been confirmed. So, we observed the structure directly using X-ray diffraction, and clarified the relationship between higher order structure and thermal conductivity of the mesogen-containing epoxy composite. We also confirmed diffraction peak of the smectic structure of resin by X-ray diffraction. Thus, the higher order structure formed in the filler-rich composite of mesogenic epoxy resin was clarified to contribute to the high thermal conductivity of the composite. In addition, it was clarified that the liquid crystalline ordering of the mesogenic epoxy resin was further enhanced by fillers.

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In the power module products, insulated materials, such as the insulated sheet used for them, are asked for high heat dissipation along with achievement of downsizing and high efficiency of the electronic equipment. In this paper, the details of research about the high heat dissipation organic / inorganic composite material based on the thermosetting resin are introduced. In order to raise thermal conductivity to the thermosetting resin like the epoxy resin, composite with high heat conduction ceramic, such as boron nitride (BN), is investigated. However, even if highly filled up with flake-like BN particles, the great improvement in the thermal conductivity of the thickness direction of the insulating sheet is not obtained because BN particles orient in the direction of a field. On the other hand, if orientation of BN particles is controlled by blending the aggregated BN filler, the thermal conductivity of the thickness direction can be greatly improved with lower filler content. The value of thermal conductivity is 18W/(m・K), and attained the thermal conductivity of the ceramic material level. The technology for improving the thermal conductivity of the epoxy resin also progresses, and development of the organic / inorganic composite material which has a higher thermal conductivity is expected in future.

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To maintain the temperature of heated or cooled air inside a room, one needs to put thermal insulation on the transparent glass windows where heat most frequently comes and goes. Fibrous materials and gas-foamed plastics provide some insulation due to the low thermal conductivity of air but are not transparent. Here we show that a nano-spaced polymer film consisting of hollow silica nanoparticles dispersed in a polyurethane matrix provides good thermal insulation and is transparent. One advantage of using hollow particles is that a quasi-vacuum state in the nano-space is formed when the size of the space is close to the length of the mean free path of the air molecules in the space. Heat tends to be transferred along the silica shells of hollow particles instead of through other materials in the film. To depress flocculation of the hollow particle in the film is the key to both transparency and good thermal insulation.

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