<p>This study investigates the thermal cycling and bonding performance of a Cu-Zn-Si (CZS) micro-alloyed Cu wire for power module applications. Compared with conventional pure Cu and Cu-P wires, the CZS wire demonstrated superior performance in electrical cycling, oxidation resistance, and mechanical durability. Microstructural analysis revealed that Zn remained in solid solution, contributing to solid solution strengthening, while Si migrated toward the surface during thermal and electrical cycling, forming antioxidative compounds that inhibited oxide delamination and reduced interface impedance. Thermal cycling also induced grain refinement through internal shear strain, increasing wire hardness via the Hall–Petch mechanism. Despite comparable fusing currents across all wire types, the CZS wire exhibited the highest electrical cycling lifetime. Wedge bonding tests confirmed stable interface behavior on both Cu and Ni pads. Notably, when bonded to Ni pads, the CZS wire effectively suppressed intermetallic compound (IMC) growth, particularly when the electron flow opposed the atomic diffusion direction. These results highlight the CZS micro-alloyed wire as a promising candidate for next-generation wire bonding in high-reliability IGBT modules, offering enhanced thermal stability, mechanical robustness, and interface integrity compared with existing bonding wire materials. Overall, the results suggest that Cu-Zn-Si micro-alloying represents a promising direction for improving the reliability of bonding wires in power electronics, while its industrial applicability awaits additional systematic verification.</p>