Space charge distribution of polyimide films in high temperature region

Abstract

We have been studying the breakdown characteristics of polyimide (PI) films. The purpose of this study is to clarify the effect of space charge on breakdown mechanism of PI films in the high temperature region. The electric strength (Fb) decreased with temperature and the DC conduction current (I) increased with temperature. Between room temperature and 100/spl deg/C, there is no space charge detected in PI films. In the high temperature region, hetero space charge tends to be formed near the anode under the high electric field approaching to the breakdown field, but it decreases just before breakdown. These results show a thermal breakdown process based on the space charge modified conduction current is considered as a possible breakdown mechanism of PI films in the high temperature region.