Performances of 1200 V punch-through and nonpunch-through IGBTs under unclamped inductive switching

In this paper, we investigate the behavior of 1200 V punch-through (PT) and nonpunch-through (NPT) IGBTs under unclamped inductive switching (UIS) stress at various temperature and peak collector current values. UIS conditions, occurring when the freewheeling diode in parallel to the load has failed, submit the device to high voltage and high current simultaneously. The results show that 1200 V NPT-IGBTs, which did not fail in these experiments, present a higher ruggedness than 1200 V PT-IGBTs. Generally, NPT-IGBTs are more sensitive to the peak collector current variation than to the temperature. Furthermore, the dynamic breakdown voltage value is equal to the static breakdown voltage during the avalanche mode. As for the PT-IGBTs, their behaviour depends strongly on the temperature and also on the peak collector current values. More precisely, the dynamic breakdown voltage value is reduced and is considerable depending on the test conditions. This reduction is due to an excess of positive charges in the drift region which does not allow the expansion of the electric field. This phenomenon is emphasized when the temperature rises.