关键词: 回流焊, 翘曲, 应力, 有限元仿真, IGBT功率模块

Abstract: Insulated-gate bipolar transistor (IGBT) power modules serve as the core components for energy conversion in new energy vehicles. However, due to the asymmetric internal structure of the modules and the significant mismatch in the coefficients of thermal expansion (CTE) among different materials, IGBT power modules are prone to warpage and stress concentration after the reflow soldering process, leading to severe degradation of their performance and service life. To investigate the factors affecting the warpage and stress of IGBT power modules, a finite element model of the IGBT power module is established based on Ansys Workbench. By integrating the "element birth and death" modeling technique and the Anand viscoplastic constitutive model for solder, a comparative analysis is conducted on the warpage and stress of the modules under different conditions, including baseplate thickness, the thicknesses of the ceramic layer and copper layers of the direct-bonded copper (DBC) substrate, and the spacing between adjacent DBC substrates. The results show that the maximum warpage of IGBT power modules decreases with increasing baseplate thickness, DBC copper layer thickness and DBC substrate spacing. The maximum warpage of the baseplate decreases with increasing baseplate thickness and DBC ceramic layer thickness. The baseplate thickness, DBC ceramic layer thickness, copper layer thickness and DBC substrate spacing have no significant effect on the maximum stress of the solder layer. Increasing the baseplate thickness can significantly inhibit the warpage of the IGBT power module, and the thickness of the DBC ceramic layer is the most critical factor affecting the warpage of the modules. The research results provide a reference for reducing the production cost and improving the product yield of IGBT power modules.

Key words: reflow soldering, warpage, stress, finite element simulation, IGBT power module