Frequency Dependent Dielectric Breakdown of Thin Polyimide Films Prepared by Vapor Deposition Polymerization

Abstract

Dielectric breakdown of thin polyimide films prepared by vapor deposition polymerization has been investigated for various ac voltages. Real time measurements were made automatically with a system composed of a digital oscilloscope, controllable signal generator and microcomputer. The self-healing breakdown takes place at the peak of the applied voltage. The ac electric strength decreases with temperature, and it increases with frequency in the range of 10 Hz–3 kHz. The frequency dependent breakdown has been explained tentatively in terms of the establishment of a conductive path leading to the breakdown.