Failure Analysis And Condition Monitoring Of Bonding Wire For IGBT Power Modules

The implementation of the national energy strategy has promoted the development of a variety of new-energy technologies vigorously, such as electric vehicles, train traction, aviation power supply, solar power, etc,among which the core technology is energy conversion. Thus as the carrier of these new technologies, the reliability of the power electronic devices is of crucial importance. Once the system goes wrong, it may cause great losses if people fail to monitor the faults and take measures quickly and efficiently. Related statistic studies have found that one of the main components affecting the reliability of power electronic system is power device, so the research of reliability of the related power device has become the emphases and hotspots. At present, the majority of people at home and abroad focus on failure analysis and condition monitoring with simulation method which based on model. This topic takes the typical IGBT power module as the research object, carrying on research in terms of structure, temperature, external characteristics of the device ends and condition monitoring of bonding wire by experiments. The concrete contents are as follows:ccording to the typical IGBT power module, the research starts with the mechanical structure and physical structure. The analysis on the failure of IGBT power module primarily based upon the thermal damage theory and it mainly includes: the failure mechanism of solder layer damage and the failure mechanism of bonding wire fault. Based on the analysis of the failure mechanism, the bonding wire fault of IGBT power module can be further explored including cause, characteristic, impact and condition monitoring of bonding wire.s the main reason for the failure of bonding wire lifting off, temperature is also the most obvious fault feature after bonding wire lifting off. Therefore, this study make a comprehensive research on the relationship among temperature,the thermal resistance at steady state and the number of bonding wire lift off through contrast experiments.t proves that the reliability of the system can be effectively improved by monitoring the condition of bonding wire for IGBT power module. So this research concentrates first on the impact of bonding wire’s fault on internal parasitic capacitance Cge and Cgc,then studies on the relationship between Vge(the external characteristics of the device ends) and the state of the bonding wire. And finally, it puts foward a scheme of monitoring the condition of bonding wire based on the temperature and the Vge.Research shows that These is a linear relationship between the temperature of chip surface, the temperature of the bottom plate at chip center corresponding to and the number of bonding wire lift off; Bonding wire’s fault will not give rise to the module layer structure damage or increase the thermal impedance at steady state from the chip to the bottom. Althrough the scheme for monitoring the condition of bonding wire still need to be improved in precision, it has higher engineering applicability including advantages as: scheme without opening the module, simple circuit structure, high safety and low cost.This paper made a in-depth study both in theoretical analysis and experimental study. Especially the fault characteristics after bonding wire lift off which acquired through a large number of contrast experiments have important reference value for system’s fault diagnosis and condition monitoring in the future. Besides, the experimental principle and the research method used in this research have the same function of reference for further research of reliability of other power devices.