A green approach of synthesizing of Cu-Ag core-shell nanoparticles and their sintering behavior for printed electronics

In this article, uniform and anti-oxidative Cu-Ag core-shell nanoparticles with average particle diameter of 50 nm and Ag/Cu atomic ratio of 1/10 were synthesized by an environmental-friendly method. The morphology and core-shell structure of the obtained nanoparticles were observed through scanning electron microscope, transmission electron microscopy , energy-dispersive spectroscopy, and x-ray diffraction. Conductive inks were prepared by mixing the synthesized nanoparticles with the mixture of ethylene glycol and ethanol. The structure evolution and electrical resistivity of the Cu-Ag core-shell nanoparticle deposits were investigated upon heating up to 350 °C in comparison with pure Cu nanoparticles with similar sizes. A sintering mechanism was proposed to understand the sintering behavior of the Cu-Ag core-shell nanoparticles. It showed that dewetting of Ag shell through surface diffusion could effectively improve sintering performance at lower temperature besides its protection of Cu core from oxidation up to 156.3 °C.