Analysis of Crack Failure in SMD Package Caused by Thermal Stress

Abstract

The surface mount device (SMD) packaging is becoming one of the most widely used high-power semiconductor device packaging forms because of its small size and low thermal resistance. However, the SMD package will suffer greater thermal stress when mounted on the PCB, because it has no lead-out terminals and is soldered to the PCB directly. This paper introduces a failure analysis case of a SMD-0.5 packaged device with stress fracture in the ceramic of package. Through analysis, it is found that package cracks occurred during the temperature cycling of the circuit board assembly. Based on the analysis of ceramic characteristics, the cause of the failure is the thermal mismatch between ceramic and PCB. In addition, the paper analyzes the influence of the PCB’s thermal expansion coefficient and solder joint morphology on the cracks of the package ceramic through simulation and experiments. Finally, the paper gives application suggestions for SMD packaged devices.