Electric Aging Mechanism of Polyimide Under High Pulse Voltage

The insulation lifetime,surface topography and thermally stimulated current(TSC) of polyimide were measured during electrical aging process under high pulse voltage. The trap property and variation of parameters were investigated through the TSC curve and surface topography. It is shown that two main well-resolved peaks,namely I and II,exist in the 20～200℃ range of TSC curve. The structure corresponding to II peak in polyimide is damaged more severely than the structure corresponding to I peak and its degradation is accelerated when frequency increases. Thus it could be deduced that the degradation of the structure corresponding to II peak is the main reason leading to breakdown of polyimide. The insulation lifetime of polyimide could be indicated by the activation energy and charge quantity of II peak.