Temperature monitoring inside IGBT modules at forward bias from the cross section and its finite element analysis

Temperature distribution inside IGBT modules is considered as the key factor for their reliability and applications. In the present work, the IGBT module with cross section was prepared by metallographic technologies. Microstructure of the IGBT module was characterized from the cross section by scanning electron microscope (SEM). Electrical characteristics of the IGBT modules after cross section operation were tested at conduction and switching status. It indicates that the IGBTs remained well electrical functions. Temperature distribution inside the IGBT was measured by high resolution IR camera from the cross section at forward biased status, based on which the transient and steady thermal impedance were calculated. Finally, a 2D finite element model concerning on the heat conduction process inside IGBT was realized, which exhibited that the simulated results were quite consistent with the experiment. Although the mechanical cross-section method is impossible to employ in practical applications of IGBT, this work may provide a new insight on the study of the package fatigue and thermal behavior inside IGBTs at forward bias.