Thermal Degradation of Power Modules

Abstract

One of the main problems in power devices is the increase of the junction temperature due to internal heat dissipation. Different packaging technologies have different thermal management. This management changes during the life time of the device due to thermal mechanical stresses. The degradation of the thermal resistance is one of the main limitations in life time of power devices. In this study different substrate technologies have been compared on their degradation during reliability testing. Thermal shock (liq. to liq.), thermal cycling (air to air) and power cycling test were applied. For power cycling test, the degradation of the devices is measured as a change in thermal resistance (Rth). For the DCB substrate technology, this change is measured at different power dissipation levels to study the influence of temperature difference between junction and case on the degradation behaviour.