Diffusion behavior and reliability of sintered copper on different metallized substrates

This study systematically investigates the interfacial diffusion behavior of sintered copper on various metallized substrates (bare Cu, Ni/Ag, and Ni/Au) and its influence on joint performance and reliability. Through microstructure characterization, interfacial diffusion analysis, and shear strength testing, we revealed evolution mechanisms at Cu-Cu, Cu-Ag, and Cu-Au interfaces during sintering and thermal aging. At the Cu-Ag interface, local interfacial strain was found to cause orientation changes and texture randomization within the Ag layer, while the Cu-Au interface exhibited uniform diffusion and the formation of ordered solid solution phases. Among all configurations, Cu-Cu joints achieved the highest strength of 93.3 MPa under optimized sintering conditions (300 °C, 5 MPa, 30 min). Both Cu–Ag and Cu–Au joints demonstrated further strength enhancement after high-temperature aging and maintained stable performance under thermal cycling, confirming the long-term reliability of the sintered copper bonds. These findings provide a scientific foundation for the interfacial design and reliability evaluation of copper-based interconnects in high-power electronic packaging.