Investigation of Active Power Cycling Combined With Passive Thermal Cycles on Discrete Power Electronic Devices

Active power cycling (APC) is a standardized and well-established method for reliability assessment and product qualification in power electronics (PEs) technologies. Repetitive pulses of load current are applied to cause cyclic thermal swings in the p–n junction and in the whole semiconductor device. They induce thermo-mechanical stresses, which ultimately leads to the typical interconnect failure in the “devices under test.” However, these tests are insensitive with respect to new automotive system architectures, in which PEs devices are exposed to additional loads besides the intrinsic thermal swings. The trends in PEs toward miniaturization, higher power density, heterogeneous system integration, and the deployment of PEs in harsher environments combined with longer lifetime and higher uptime requirements strongly increase the reliability demands in general and the need for more improved reliability assessment methodologies in particular. The new testing methods shall be more comprehensive and more efficient, i.e., they shall simultaneously cover the real service conditions better and reduce testing time. One promising approach is the combination of loading factors—such as the superposition of active power cycling by passive thermal cycles (TC). Both loading factors are well known to cause most relevant failure mechanisms in PEs. In reality, the PE devices are exposed to both factors simultaneously. Hence, this load case should also be replicated in the test. The paper will report a systematic investigation of such superimposed test schemes, which cover the case of self-heating and passive heating (from neighboring elements) of the PEs devices under real service conditions. Typical discrete PEs components in TO-200 packages are selected as test vehicles as they are likewise relevant for the domains of consumer or automotive electronics. The paper details the test concept and discusses the quantitative and qualitative test results.