Pre-breakdown currents in polyimide films

Abstract

The electrical breakdown processes in synthetic polymers have been actively investigated these decades. However, their details have not yet been fully understood. Recently, the authors have developped a system for measuring a pre-breakdown current and tried to clarify the mechanism of a breakdown from pre-breakdown currents in polymeric insulators [1-4]. In the previous paper [2], we found that a pre-breakdown current in polyimide (PI) started to increase rapidly around 10−3 s just before a breakdown at 90 C and explained it in terms of the thermal breakdown.