The Influence And Failure Mechanism Analysis Of The Load Current On The IGBT Lifetime

IGBT as a composite fully controlled voltage driven power semiconductor device,can realize the conversion flexibly,control and transmission of electric energy in the power system.It is an indispensable core component of converter valve and DC circuit breaker in the flexible DC transmission system.Improving the reliability of the device is the future development trend.The life model can be established through the power cycle test of the device,which can be used to predict the life under the actual working conditions.It is a very important reliability evaluation method.Through the power cycle experiment of the device,a life model can be established.For example,the most commonly used CIPS08,which is used to predict the life condition under actual working conditions.In known studies,the maximum junction temperature and junction temperature fluctuations have the greatest impact on life.But in the power cycling test,different combinations of load current and load pulse duration can achieve the same maximum junction temperature and junction temperature fluctuations.It reflects the strong coupling relationship of those parameters.In order to further evaluate the contribution of load current and load pulse duration to the lifetime of bonding wire,in this paper,650V/20A IGBT devices are tested under the same maximum junction temperature and junction temperature fluctuation but in different load current and load pulse duration.Meanwhile,the junction temperature,on-state voltage drop in each cycle are monitored in real time during the test.The results show that the load current has a significant effect on the lifetime of the IGBT device.Higher current will significantly reduce the life of IGBT devices.Furthermore,an electric-mechanical-thermal multi-physics finite element model of the TO package IGBT device is established.At the same time,the elastic-plastic characteristics of the aluminum bonding wire and the surface metal layer is considered,the mechanism of the current effect on the stress of the bonding wire is analyzed.At the same time,the crack propagation model is introduced to analyze the life of the bond line qualitatively.The metal fatigue life model was used for quantitative analysis,which are consistent with the test results.This paper can provide guidance for accurate model building-up and lifetime prediction of bonding wire in IGBT device.