High-field conductivity measurements and search for threshold in PET films

In the paper results of measurements of DC charging current performed at different values of electrical field and temperature on PET films are presented. The aim is to investigate the threshold of space charges trapping, detected on the basis of the appearance of a maximum in the charging current vs. time characteristics. The values of threshold (function of temperature) thus derived are compared with the results of accelerated life tests performed, under DC voltage and temperature, on the same films until the occurrence of electrical breakdown. It is shown that a relationship exists between the threshold of charge trapping, detected by charging current measurements, and that of electrical breakdown, deriving from multi-stress life tests.