Electronic Package Characterisation Using Thermal Structure Functions

This paper presents an overview of advanced thermal analysis methods. The measured 4 Triple-well heating or cooling curves allow the derivation of time constant spectra, structure functions and complex thermal impedances. These characteristics contain a lot of information on the device, and can be used to investigate the internal structure of the electronic package. The entire methodology is illustrated based on the example of two silicon carbide power diodes. These diodes provided by different manufacturers have the same ratings and package type but one of the diodes exhibits oscillatory behaviour when used in a power converter. The presented results of thermal tests and analyses confirmed that there exist between the two devices important differences in their internal structures, possibly indicating the presence of some imperfections in the die attach or the wire bonds.