Screening Technology For Aerospace Critical Power Electronic Devices IGBT

Insulated gate bipolar transistor(IGBT)is the key of power electronic devices used in space launch vehicle in our country for their good performance,high input impedance and low turn-on voltage drop.The reliability of IGBT determines whether the launch vehicle can successfully complete the space mission.At present,IGBT has not yet made breakthroughs in localization for the limitations in domestic production and research technology.Our country mainly relies on importing foreign industrial-grade products to meet the needs of space missions.The design,manufacture,and screening of industrial-grade products have not been carried out in accordance with the requirements for aerospace-grade devices.When these industrial-grade finished products are used in aerospace missions,the environmental conditions and task loads experienced are often more complex and harsh than the original industrial-grade design standards.It is difficult for ESS to effectively screen out the defects caused by the the design and manufacturing process,resulting in poor reliability of the device and affecting the smooth development of space missions.Therefore,in order to improve the reliability of IGBT and promot the smooth development of the aerospace industry,it is necessary to study more efficient screening technology,screening out as many of its early defects as possible.This article takes the IGBT as the research object and studies its screening technology.The main research contents are as follows:(1)Aiming at the numerous failure modes of IGBT and the complex failure mechanism,combined with its structural and functional characteristics,the FMECA analysis is used to sort out the IGBT failure modes.According to the degree of risk obtained,the comprehensive impact index of the failure modes of IGBT is ranked accordingly,and the weakness and the main failure modes of IGBT are preliminarily determined.Based on the physical characteristics of IGBT,finite element analysis software is used to simulate the actual IGBT operating conditions,and this paper performed electro-thermal-force multiphysics coupling analysis of IGBT.Based on the analysis of the temperature and stress distribution cloud diagrams,the FMECA analysis results is further verified.(2)In view of the problem that routine screening techniques are no longer applicable under aerospace missions,the method of Highly Accelerated Stress Screening(HASS)is used to screen IGBT.On the basis of the preliminary failure analysis,the three aspects of screening scheme design,screening profile establishment and screening profile verification are respectively taken into account to illustrate the HASS technology.In the establishment of the screening profile,the aerospace operating environment,IGBT failure analysis and screening efficiency are taken into account.Subsequently,based on the screening degree model and finite element simulation,the validation of IGBT screening profile is studied.(3)The research of IGBT screening technology is to improve their reliability.According to the characteristics of the long-life use of IGBT,the reliability of the IGBT is analyzed from the perspective of accelerated life testing.The design of accelerated life testing for IGBT is briefly described.Combining with the experimental data,the lifetime distribution and life model of IGBT are determined by statistical analysis and significance test.Finally,this paper extrapolates the lifetime of the IGBT device under normal conditions to complete its reliability analysis.