抄録
Residual voids in degassing process of encapsulation gel for a power device limit the lifetime and the performance of the device itself because of the partial discharges occurrence in it. In this paper the limit of the degassing capability is evaluated based on the equation of equilibrium. It turns out that the gas in defects such as holes and cracks at the rim of the chip-mounted electrode on ceramic substrates cannot be completely removed by vacuum degassing. Then the size of voids that are likely to form in defects is also calculated with a simple model. This analysis is also experimentally checked with a pierced PMMA plate. The measured results can be explained well by the above mentioned model.
