Temperature distribution in multichip IGBT module and its impact on collector current sharing

Abstract

Multichip Insulated Gate Bipolar Transistor (IGBT) power modules are widely used in high power applications. However, the parallel connection of IGBT chips results in an inhomogeneous temperature/current distribution. In this paper, a thermographic camera is used to capture the temperature distribution of an opened Infineon IGBT module FF600R17ME4 where each IGBT switch has three IGBT chips. The influence of temperature distribution on collector current sharing is then examined in both healthy conditions and bond wire lift-off scenarios. In this research, the critical temperature distribution is demonstrated experimentally at both chip and switch levels. The experimental results reveal that there are, depending on the collector current, 8 °C to 60 °C temperature difference at the chip level and 2 °C to 10 °C maximum temperature variation at the switch level. The severe temperature distribution impacts the collector current sharing less than 1 % variation under healthy conditions and 0.507 % at IC = 240 A upon the first bond wire lift-off. Other findings are that during homogeneous temperature distribution current densities are nearly similar per chip and less dependent on chip temperatures. Findings of this research have the potential to influence multichip Insulated Gate Bipolar Transistor (mIGBT) layout design. For example, having investigated the current density distribution at different operating points, it is recommended to increase the number of bond wires by 11 % for the chip placed in the middle for this particular module in order to increase reliability. Potential future research areas have also been identified.