Study on Accelerated Deterioration and Early Failure Mechanism of Silicone Elastomers Under Nanosecond Pulsed Electric Field

The pulsed electric field caused by the operating conditions of high-voltage and high-power semiconductor devices will exacerbate the insulation deterioration of silicone elastomers for packaging.This paper will comprehensively study the degradation mechanisms of silicone elastomers under nanosecond pulse electric fields from both macroscopic and microscopic levels.Macroscopically, the study conducts research on bubble discharge under nanosecond pulse electric fields through Comsol simulation.Microscopically, on one hand, the paper investigates the behavior of charge-induced molecular vibrations under nanosecond pulse electric fields; on the other hand, it calculates the dynamic behavior of charges by constructing a molecular dynamics model.The research finds that, macroscopically, nanosecond pulse electric fields lead to charge separation which causes field distortion and triggers bubble discharge, and as the rate of change increases, the discharge current intensifies, the production of ozone increases, and the resultant damage to material insulation is more severe.Microscopically, on one hand, the study reveals that at the edges of nanosecond pulses, charges cannot respond to the rapidly changing electric fields, experiencing greater resultant forces that excite molecular vibrations, which intensify with the increase in the rate of change of the pulse electric field.On the other hand, it is found that the relaxation time of space charges exhibits an exponential increase with the depth of traps, and when the relaxation time matches the frequency of the pulse electric field, electrons enter into resonance, leading to an intensified detrapping.This research will provide a theoretical foundation for improving the insulation performance of encapsulating materials.