Partial Discharge Failure Analysis of AIN Substrates for IGBT Modules.

Increasing operating voltages of Insulated Gate Bipolar Transistor (IGBT) modules results in higher demands on the electrical insulation as well as partial discharge resistance. The most critical component is the ceramic substrate, which electrically insulates the high voltage side with the IGBT chip from the ground potential of the heat sink. Investigations on the Partial Discharge (PD) failures on the ceramic level as well as Phase Resolved Partial Discharge (PRPD) measurements have been performed and the distribution of the inception voltages for one substrate type analyzed. Electrical field simulations and optical discharge visualization are used for partial discharges localization. The edges of the copper metallization as well as voids at the ceramic-copper interface are identified as major PD sources.