EFFECTS OF CURRENT-DENSITY AND CHIP TEMPERATURE DISTRIBUTION ON LIFETIME OF HIGH-POWER IGBT MODULES IN TRACTION WORKING-CONDITIONS

This paper deals with ageing parameters of high power IGBT modules in traction applications. Using the results of a great number of power cy cling tests on 400A modules, it shows that, in addition to the junctio n temperature excursion, other parameters like the maximal chip temper ature and the current density are involved in thermal fatigue failures . Besides, contact temperature measurements achieved on IGBT chip surf ace in cycling conditions to localise the maximal thermomechanical str ess are presented and correlated with modules failure analysis. The ro le of the current density in the ageing process is finally shown by de termining its influence on the temperature gradient on chip surface. ( C) 1997 Elsevier Science Ltd.