Evidence of filamentary electrical conduction in polyimide films before breakdown using fast infrared thermography

This paper reports a visual experimental evidence of the detection of the filamentary electrical conduction process in a polyimide (PI) film at 300°C. This was obtained using fast infrared thermography technique coupled to current-voltage measurements in the last 100 ms before the dielectric breakdown. While the full-electrode conduction process leads to an increase in the PI absolute temperature of ~40°C, the filamentary conduction process gives rise to a larger increase (~100°C) in a short time bringing the PI sample to the dielectric breakdown. This work highlights clearly the thermal origin of the breakdown where such an increase in PI temperature is compatible with its thermal degradation.