Analysis And Application Based On Thermal Deformation For Cracked Bonding Wire Of IGBT Module

Insulated Gate Bipolar Transistor(IGBT)is the key semiconductor power device in the field of power electronics with the advantages of large capacity,fast switching speed,easy driving,low on-voltage and high input impedance.IGBT modules are subjected to long-term power cycling during operation.Due to temperature changes and mismatches in the thermal expansion coefficients of internal materials,thermal stress is generated between the bonding wires and the silicon chip,resulting in thermal deformation.This thermal deformation is one of the key factors causing IGBT bonding wire faults.Therefore,it is of great significance to study the thermal deformation field characteristics and application of IGBT module bonding wire faults.At present,the research on the thermal-mechanical characteristics of IGBT modules still focuses on exploring the temperature and stress distribution characteristics of the module by means of simulation,and few comprehensive and in-depth research has been carried out on the thermal deformation field characteristics of IGBT modules under bond wire faults.Therefore,the thesis intends to conduct a comprehensive analysis of the thermal deformation field characteristics of IGBT module bonding wire faults from two aspects of finite element simulation and experimental testing.And using the obtained thermal deformation field distribution law,the application of bonding wire fault diagnosis based on thermal deformation field signals is carried out.The main research contents are as follows:1.Through the theoretical analysis of thermal deformation of the IGBT module,the finite element simulation model is established,and the fluctuation characteristics of thermal deformation signal and the distribution law of thermal deformation are summarized.In addition,the thermal deformation field distribution characteristics of the intact and faulty bonding wires were compared,and the results shows that the thermal deformation fluctuation amplitude of the broken bonding wire decreased by 82%,while the thermal deformation amplitude of the unbroken wire increased by 35% on average.2.The thermal deformation characteristics of IGBT bonding wire faults are explored experimentally.The IGBT thermal deformation test platform is set up to measure the thermal deformation signal.A visual reconstruction method is designed to reconstruct the thermal deformation field cloud map based on the spatial position of the IGBT chip.And the thermal deformation field characteristics in the case of IGBT bonding wire crack are analyzed.The experimental results are in good agreement with the simulation conclusions.3.Based on the thermal deformation field distribution,a fault diagnosis method for IGBT bonding wires is proposed.Different thermal deformation sample data sets are constructed,and the results of three data classification algorithms of support vector machine,recurrent neural network and convolutional neural network are compared.The results show that the average accuracy of the method based on convolutional neural network reaches 98.8% for the thermal deformation field binary classification problem of intact and cracked bonding wires.The thermal deformation field characteristics of IGBT modules are explored by means of finite element simulation and experiment in the thesis,and the data classification algorithm is used to the bonding wire fault diagnosis,which provides the performance test of the IGBT module before leaving the factory and contributes to the research of IGBT module thermal-mechanical reliability and lays a foundation for the realization of high-efficiency and high-accuracy bond wire fault diagnosis methods.