Failure Analysis Of Power Device IGBT Under High Temperature Vibration Condition

During daily use and transportation,the power device IGBT module is often subjected to thermal and random vibration loads at the same time,causing high-cycle fatigue failure of the weld layer.Therefore,this paper focuses on the reliability of the IGBT welding layer of power devices,comparative study of the failure modes and fatigue life calculation methods of IGBT under three loads of thermal cycle,random vibration and thermal vibration coupling.The main work of this article is now introduced as follows:(1)Based on the modal analysis method,the dynamic characteristics of the IGBT module are studied.Use the modal analysis module in ANSYS to calculate the natural frequency of the IGBT module under different constraint conditions.By comparing with the experimental modal analysis results,the first six natural frequencies of the module and the modal shapes at the corresponding frequencies are obtained,which verifies the feasibility of the finite element method and lays the foundation for subsequent work.(2)Comparison of thermal cycling,vibration,and the random failure mode thermally coupled vibration load in IGBT module.When studying the response characteristics of the module under thermal cycling conditions,a model of the IGBT module is constructed.The temperature cycle is applied to the model to obtain the stress and strain distribution of the solder layer for analysis.When studying the response characteristics of the module under random vibration,the module is subjected to modal analysis,and then random vibration load is applied to extract the PSD response curve of the dangerous position of the welding layer to obtain the resonance point of the module.Different from random vibration analysis,thermal vibration coupled load considers the random vibration of the module under three different environments.(3)Calculate the fatigue life of the module under thermal cycling conditions,random vibration conditions and thermal vibration coupling conditions.Use the Coffin-Manson equation to calculate the life under thermal cycling conditions.The Manson-Coffin equation is used to calculate the fatigue life of the module under random vibration conditions,and the damage value is obtained according to the Miner linear fatigue cumulative damage theory.Calculate the damage value of the module under three different environments,adopt the incremental damage calculation method to obtain the fatigue life under the thermal vibration coupled load condition,and analyze the results.(4)Optimize and analyze the module.Study the influence of the distribution and size of the solder layer voids on the performance of the device.Analyze the influence of the material and thickness of the solder layer on the thermal performance of the device.Chang the material of the substrate and the thickness of the substrate,the material of the ceramic substrate.Analyze the temperature distribution of the IGBT module,optimize the heat transfer performance of the module,and determine the optimal solution.The research results of this paper provide a certain reference for the theoretical study of structural fatigue life under thermal-vibration coupling.