Study of Insulating Properties for HV Power Modules

Abstract:
Partial discharge is one of key challenges on high voltage IGBT module packaging design. Electrical field intensity during the operation of the IGBT module is the most important factor affecting its dielectric properties. The finite element method is used to analyze the electrical field intensity distribution and investigate the effect of insulating substrate stacking and geometrical variations on partial discharge for high voltage power modules. Results demonstrate that maximum electrical field intensity occurs at edge of interface between ceramic layer and the upper copper layer of the substrate. Substrates stacking and the increasing distance of the upper copper edge to ceramic edge both could decrease the maximum electrical field intensity and improve module isolating properties. Furthermore, the geometry at edge of substrate upper copper layer has a significant effect on the electrical field intensity distribution. If the geometry changes from right angle to sidestep shape, the electrical field intensity tends to decrease.