Expediting Transient Thermal Frequency Response Characterization and Sensitivity Analysis

This paper develops a technique, requiring no dedicated temperature sensing calibration step, to rapidly characterize transient heat transfer in packaged, power semiconductor components. It is presented as an alternative to traditional step response characterization methods by exploiting the phase delay metric native to frequency response function (FRF) analysis in the field of system identification. The paper introduces electrothermal engineering steps needed to design the measurement system. It presents aspects of power device physics and dynamic analysis to identify design space in which FRF data extracted from experiments are insensitive to potential unknowns. Power electronic circuitry, providing the needed, periodic heat actuation, and probing, allowing for simple reconstruction of transient temperature data in post-processing, are introduced. The developed method is leveraged in-lab to make a key measurement confirming high-frequency-only thermal FRF sensitivity to component die-attach, highlighting the opportunity to achieve localized, power electronic converter degradation sensing in situ.