Strengthening Mechanisms of Sintered Ag Films with CuO Nanoparticles Using in-Situ SEM Tensile Loading System

The strengthening mechanisms of sintered silver (s-Ag) films, including copper oxide (CuO) nanoparticles (NPs), were investigated to enhance their mechanical and thermal reliability for power semiconductor device packaging applications. CuO NPs, synthesized via a chemical washing method, were incorporated into the s-Ag matrix at a 0.5 wt% ratio. In-situ SEM tensile testing at room temperature (RT) and 300°C revealed significant improvements in the mechanical performance of the CuO included s-Ag films. Although CuO inclusion had little effect on strength and fracture mechanisms at RT, it significantly enhanced mechanical performance at 300°C compared to pure s-Ag films. The reduction of oxygen content in CuO NPs during sintering, as analyzed by energy-dispersive X-ray spectroscopy (EDX), facilitated stronger interatomic bonding between CuO and Ag particles. Furthermore, the reduced CuO NPs acted as barriers to grain boundary degradation, reducing void growth and maintaining microstructural stability under elevated temperatures. The findings obtained in this study demonstrate the potential of CuO inclusion to improve the reliability of s-Ag films in power semiconductor die-attach applications.