Analysis of insulation failure modes in high power IGBT modules

Abstract

Increasing operating voltages of Insulated Gate Bipolar Transistor (IGBT) modules results in higher demands on electrical insulation capabilities as well as partial discharge resistance. This paper discusses the insulation failure modes observed in high voltage power modules; most critical are water trees, Partial Discharge (PD) and electrical trees. Besides the review of insulation failure mechanisms, an experimental analysis method is discussed in order to identify possible failure source. Presented is a PD setup that includes a light sensitive CCD camera for optical inspection. Within the optical measurements, electroluminescence maps are also recorded in order to identify critical regions of high electrical fields. This method permits an analysis even before PD or electrical treeing begins. Optical PD inspections allow identifying PD failure root causes like protrusions or irregular edge shapes. In addition, investigations of PD failures on the ceramic substrate level have been performed and the distribution of inception voltages for one substrate type analyzed.

Review of active thermal and lifetime control techniques for power electronic modules

“…For protection against corrosion and environmental influences, a gel filling immerses the module to guarantee dielectric strength [14]. The main aging processes of this silicone gel are water trees, partial discharge and electrical trees, which are degrading effects causing aging but not the destruction [15]. Module manufacturers provide estimations for the lifetime of their devices in dependence of the number of thermal cycles the modules have to undergo during their lifetime.…”

Dielectric strength and thermal performance of PCB-embedded power electronics

“…Initially, the thermal performance in these samples was simulated. Temperature dependent partial discharge tests have been measured to evaluate the dielectric strength of the PCB material [6][7][8].…”

Computational light junction temperature estimator for active thermal control

“…For protection against corrosion and environmental influences, a gel filling immerses the module to guarantee dielectric strength. The main aging processes of the silicone gel are water trees, partial discharge and electrical trees, which are degrading effects causing aging but not the immediate destruction [12].…”