Measurement techniques for the thermal characterization of power modules

The thermal properties of power semiconductor devices are in general characterized by their thermal impedance which is derived from single-pulse measurements applying measurement techniques as IR-thermography or indirect electrical methods. These measurement techniques are compared and evaluated concerning their feasibility to determine chip temperatures in power modules under continuous converter operation. Specifically, the trade off between time and spatial resolution using IR thermography is discussed. A sampling method is presented which is based an the consecutive sampling of periodic actions. The application of this method yields a high time resolution without restrictions in spatial resolution.