Power Semiconductor IGBT Packaging Technology and Reliability

Recently, IGBT has found an increasingly wide utilization, resulting in higher power density and thermal flux difficulty, which promotes the researches of new materials and structures to face up to the challenges of thermal reliability. As the crucial step in the packaging process, the reflow process is also an important part of the quality control, while typical IGBT module will result in large residual stress and warpage due to various temperature characteristics and the thermal mismatch of packaging materials. Existing researches mainly improve the quality of welding by changing the control mode, however, the cost is high and the manufacture is difficult. In this work, the thermal conduction of double-sided cooling IGBT modules in the reflow process and the reliability in the presence of voids were analyzed. Furthermore, transient temperature gradient was explored by a thermal simulation model, meanwhile, the reflow temperature curve of solder layer, the temperature gradient curve, and the influence of the void rate on the junction temperature of the chip was optimized and evaluated. The result indicates that the temperature gradient of the solder layer reduced by 50%, and the junction temperature of chip increased by approximately 3°C when the void rate changed from 0% to 3%.