Mitigating thermal cycling-induced failures in SiC-based hybrid IGBT modules: optimization of solder and reliability enhancements

Abstract

The thermal–mechanical reliability of SiC-based hybrid IGBT modules is crucial for ensuring the long-term stability of high-power electronic systems, particularly under cyclic thermal stress. While prior research has extensively investigated traditional solder materials and individual reliability factors, these studies often lack comprehensive optimization strategies. To address this gap, the present study systematically enhances module reliability by combining finite element analysis (FEA) with the Taguchi optimization method. The focus is on enhancing the durability of solder interconnects under severe thermal cycling conditions, ranging from −40 °C to 125 °C. This work is novel in integrating nano-silver solder evaluation and optimization of Direct Bonded Copper (DBC) liner materials within a structured optimization framework, which significantly differentiates from previous studies. The results indicate that von Mises stresses are concentrated at the chip solder edges, reaching up to 157 MPa, which exceeds the yield strength and accelerates fatigue. The fatigue life predictions based on Engelmaier’s modified Coffin-Manson model show that nano-silver solder extends the module’s lifespan by approximately 90 % compared to conventional SAC305 solder. Additionally, the optimization results suggest that Si₃N₄ liners effectively reduce peak stress. These insights provide guidelines for designing highly durable SiC-based IGBT modules applicable to electric vehicles, renewable energy systems, and high-power converters.