Aging tendencies of power MOSFETs — A reliability testing method combined with thermal performance monitoring

Die attach degradation in power electronic devices is a common failure mode besides bond wire damage. This paper describes the chip and packaging level effects of high cycle count power cycling on novel mid-power automotive MOSFETs. The related investigation is carried out in controlled ambient conditions. The thermal transient measurements during the active temperature cycling reliability test were evaluated along with K-factor calibration to identify different failure modes. The described measurement method gives the opportunity to distinguish between electrical and thermal related structural error modes. The newly developed thermal interface used in the DUTs was found to withstand the 150 °C thermal amplitude well beyond 100,000 cycles without fatal failures. The thermal performance degradation was less than 28.5% after 70,000 cycles for the complete assembly.