Thermal stress failure analysis of power diode SMBF package

With the development of power devices, the thermal reliability of power devices has become a research hot spot. The research object of this paper is the power diode of SMBF package. Through X-ray scanning and resin removal observation, it can be concluded that the excessive thermal stress of SMBF package may be the cause of its failure. Using ANSYS Workbench software simulation, the results show that the reduction of thermal expansion coefficient of resin can reduce the thermal stress. When the coefficient of thermal expansion is reduced from 11*10^-6C^-1 to 9*10^-6C^-1, the maximum shape variable of the device is reduced by 80.72%. When the thermal conductivity of the resin is reduced from 4.75W/(m*C) to 5.58W/(m*C), the junction temperature is reduced by 7.76%.

I. Introduction

With the increase of the packaging density of power semiconductor devices, higher requirements are put forward for the thermal reliability of devices. The mismatch of coefficient of thermal expansion between packaging materials will lead to excessive thermal stress of the device[1]. The thermal conductivity of the material is related to the chip's heat dissipation performance, which affects the thermal reliability of the device. Therefore, it is necessary to study the thermal reliability of power devices.