Research On Design Of Multi-stress Accelerated Testing And Degradation Modeling Of Power MOSFET

Power MOSFET,which is widely used as switch and driver,is one of the most important electronic device of switching power supply.Because power MOSFET often works in the switching state,its electrical stress switches between high voltage and high current at high frequency,which leads to its high failure rate.In addition,the complex and changeable environmental stress will further promote the occurrence of various failures of power MOSFET,making it one of the short boards restricting the reliability of switch power supply.Therefore,the research on multi stress accelerated test and degradation modeling of power MOSFET can lay a foundation for its reliability evaluation and life quantitative evaluation under complex environmental stress,which is of great significance and application value.In this paper,the failure mechanism analysis and degradation sensitive parameter selection of power MOSFET,multi stress accelerated degradation test and parameter test system design,multi stress accelerated degradation modeling and reliability evaluation related research work are mainly carried out,trying to build a complete and accurate quantitative life evaluation method of power MOSFET under multi stress.Firstly,the failure mode,mechanism and failure characterization parameters of power MOSFET under multi stress are analyzed.Because of its complex failure mechanism and numerous characterization parameters,based on the method of electro thermal coupling simulation and multi parameter sensitivity analysis,this paper selects the on resistance and threshold voltage which have the greatest impact on the output of the superior power supply as the degradation sensitive parameters,and continuously tests them in the subsequent multi stress accelerated degradation test.Then,by analyzing the mission profile of power MOSFET in a single power supply and the influence of various environmental stresses,the types of acceleration stress and the stress range are determined.On this basis,based on the orthogonal uniform experimental design,the multi stress accelerated degradation test scheme of power MOSFET is given,and the test circuit design,test system and test system construction are completed,which can realize the synchronous test of batch devices,automatic parameter test and data management.Finally,according to the characteristics of the degradation trajectory of power MOSFET performance parameters under multi stress coupling,a Wiener process model considering the nonlinearity of degradation process,individual differences of samples and measurement error is constructed.At the same time,taking the generalized log linear model as the multi stress acceleration model,the functional relationship between drift coefficient and temperature stress,electrical stress and vibration stress in the degradation model is described,and the extrapolation of model parameters and reliability index under different stress combinations is realized,and then the reliability evaluation and life quantitative evaluation of power MOSFET under multi stress conditions are completed.