Electric field DC conductivity dependency of polyimide films

The isolation behaviour of polyimide thin films has been studied. Properties such as DC conductivity and the threshold electrical fields were obtained through a steady state current measurement under an applied voltage across a metal-insulator-metal capacitor. An inverse relationship has been found between the curing temperature and threshold electric field that would be applied to the structure. The results correlate with high voltage endurance life-time curves for digital isolators processed at different temperatures.