Measurement of Space Charge Distribution in Epoxy Resins Cured Using Novel Imide Type Hardeners at High Temperature under High DC Stress

Abstract

Recently, some next-generation semiconductors such as SiC, which can be operated at high temperature under high electric field, have been developed, and power devices using these semiconductors have been reduced in size with higher power output. However, while the semiconductors themselves are available at high temperature under high electric stress, there is no suitable material which shows a good performance as the insulating material under such a severe condition. Therefore, to realize the usage of the next-generation semiconductors with the inherent ability, it is required to develop the insulating material that shows an excellent characteristic even under such severe conditi ons. Generally, epoxy resin is used as such a molding insulation material, and this study also evaluated the insulating performance of the epoxy resin. For this purpose, several imide type hardeners for the epoxy resin were developed provide the characteristics of both high heat resistance and low dielectric properties. A feature of the imide type hardener is that an imide group is introduced into the hardener to maintain high heat resistance without lowering the crosslinking density. In this study, we estimated the insulating properties of those epoxy resins by observing space charge accumulation behaviors in them at high temperature under high electric field. From the measurement results, it is found that some of them shows a good performance as the insulating materials even under such severe conditions.