Failure Analysis And Research Of Bond Wire In IGBT Power Module

In recent years,With the wide application of power converter in new energy power generation,electric vehicles,rail transit,aerospace and other fields.The core role of power converter in various systems is also highlighted.Power devices are the most vulnerable part of the system in power conversion devices.Thus,more and more attention has been paid to the reliability of power devices.Insulated gate bipolar transistor?IGBT?are the most widely used power devices because of their advantages of fast switching speed,low loss,low driving current and simple control circuit.Studying the aging and failure process of IGBT module,mastering the changes of internal parasitic parameters after module failure and the changing rules of external characteristic signals are very important for module failure monitoring,reliability improvement and safe operation of the whole device.Bonding wire is the most fault-prone part of IGBT module,this paper carries out a series of theoretical,simulation and experimental analysis,aiming at the reliability of bonding wire in IGBT module.The main research contents and innovations are as follows:Firstly,taking SKM75GB12T4IGBT module as the research object,the 3D model of SKM75GB12T4IGBT module is established.The electric-thermal field and thermal-stress field are comprehensively analyzed in ANSYS,and the heat and stress of bonding wire are mastered in the work of IGBT module.Through sub-model analysis,we can understand the relationship between the falling area of bonding wire and device temperature,and grasp the influence of thermal characteristics of bonding wire on module reliability.Secondly,the influence of bond wire shedding on parasitic parameters of the module is explored.The parasitic parameters of the module are measured and extracted by the precise impedance analyzer and Ansoft Q3D Extractor software,and compared with each other to verify the change of the parasitic parameters of the module after bond wire shedding to different degrees.The simulation circuit model is built in saber software,and the influence of parasitic parameters on switching waveform is analyzed.The parasitic parameters will directly lead to the change of external measurable electrical signals.The experimental circuit is built to get the influence of bond wire shedding on external electrical signals,and make a regular analysis,which provides a theoretical basis for the follow-up study.Thirdly,a method to estimate junction temperature accurately considering the effect of equivalent resistance on the interconnect material in IGBT module is proposed.Based on the indirect influence of bond wire shedding on external measurable electrical signals,the on-state voltage drop V_ceone_on is selected as the parameter to monitor the bond wire failure of IGBT module.Because V_ceone_on is affected by junction temperature T _j and collector current I _c at the same time,the lookup table of bonding wire failure monitoring is established by using these three parameters,which makes the bonding wire failure monitoring more accurate.Finally,the full text is summarized and then the future research and development of IGBT module bonding wire reliability are prospected.