Failure Analysis Of IGBT Based On Physics Of Failure And Study On Accelerated Life Models Of Electronic Devices

IGBT,as the most popular power electronics devices,are active in various military aircraft and civilian electronic devices for their excellent performance and high reliability.However,many high-precision products in China can't be produced currently because of limited production capacity,so we have to import industrial products from abroad.How to ensure the effectiveness of such products and improve the reliability of Chinese IGBT products is urgently needed to be studied.So far,the research on IGBT in our country is still not deep enough,how to find its failure location and failure mode accurately and efficiently,how to establish an accurate physical model of failure,how to design the accelerated life test of electronic products and establish an accelerated life model under multiple stresses.The lack of these researches has made our country stagnate the development of high quality IGBT.Therefore,it is necessary to carry out the above research on IGBT.This paper takes aerospace power electronic device IGBT as the research object,make the study of its failure mechanism and key failure parts,establishes its probabilistic failure physical model,and studies the acceleration life model under the multi-stress.The main research content is as follows:(1)Describe the detail of the electrical structure and mechanical structure of the IGBT,and comb the working principle of the IGBT.First,through literature research,it is found that temperature is the main cause of device failure,and then combined with IGBT dynamic electrical model and mechanical packaging structure electro-thermal-force coupling simulation to confirm the key failure location of IGBT.(2)In addition to the external working environment,various internal and external factors of the device have an impact on the fatigue life of the device,such as the geometry of the solder joint at the device,the fatigue properties of the material,and the profile of the thermal cycle load.By incorporating these factors into the IGBT fatigue life model,a more accurate fatigue life model can be established.Based on this,this paper updates the prior distribution information based on Bayesian update theory and proposes a more posteriori life distribution which fits the actual situation.Improve the accuracy of fatigue life prediction.(3)Electronic devices are often stored,so it is necessary to evaluate them for accelerated life.This article describes the current process of establishing an accelerated life model for a single factor in electronic devices.However,due to the complexity of electronic device operating environments,many factors need to be considered.Therefore,a wet-heat accelerated life model for electronic devices is proposed.The maximum likelihood estimation method is used to obtain the three parameters of the acceleration model.The resulting life prediction is more suitable for the real situation.