Failure investigation of packaged SiC-diodes after thermal storage in extreme operating condition

Ageing tests through thermal storage at high temperature (240 degrees C) are carried out on commercial Schottky diodes in TO220 package, in "derating mode" operational conditions. The analysis revealed a failure mechanism, resulting into vaporization of the moisture present in significant quantity in the resin/sole interface. As a consequence, a degradation of the resin, freeing up space, caused the solder to spread under the chip. The X-ray analyses, acoustic microscopy SAM, optical and electron microscopy are used to describe the failure mechanism. We note that the resin package has undergone a strong degradation. Investigations show that this phenomenon is fully responsible for the degradation process taking place in derating mode use. Most components behave similarly with respect to the ageing; however, an atypical and unusual result is revealed for one component after the ageing process. Thus, the specific case is presented as a potentially decisive case for the validation of a failure analysis, so that technical solution can be formed.