Synergistic Optimization of IGBT Modules Based on Thermal-Bottleneck Mitigation and Thermal-Shortcut Enhancement

To address the thermal bottlenecks in high-power-density liquid-cooled IGBT modules, a synergistic optimization method integrating thermal-bottleneck mitigation and thermal-shortcut enhancement is proposed. The thermal conductivity and thickness of the DBC ceramic layer, solder-layer thickness, pin-fin configuration, and coolant flow rate are selected as design variables, and eight staged optimization cases are constructed. The thermal performance of the IGBT module is evaluated using the maximum junction temperature, total equivalent thermal resistance, thermal bottleneck index, thermal shortcut index, and pressure drop. A BP neural-network surrogate model is further developed for rapid prediction and screening of candidate parameter combinations. The results show that the DBC ceramic layer is the dominant internal thermal bottleneck and that its optimization provides the largest contribution to junction-temperature reduction. Enhancement of the external pin-fin structure and coolant flow rate strengthens the thermal shortcut, although a clear diminishing marginal effect is observed. CFD verification demonstrates that, compared with the baseline design O0, the engineering trade-off design O9 reduces the maximum junction temperature by 28.26 K and the total equivalent thermal resistance by 37.6%. Moreover, the junction-temperature swing of the target chip is reduced by 23.85%, and the predicted lifetime of the IGBT chip is approximately 2.83 times that of the baseline design. These results demonstrate that the synergistic integration of internal thermal-bottleneck mitigation, external thermal-shortcut enhancement, and single-objective screening can effectively improve both the thermal performance and reliability of liquid-cooled IGBT modules.