Facile Preparation of sintered Cu-Ag bimetallic nanoparticle Paste with low porosity

Cu-Ag bimetallic nanoparticles (NPs) with tiny sized Ag NPs completely covering the surfaces of Cu NPs were successfully prepared by a mild two-step method. High resolution transmission electron microscope (HRTEM) results indicated that as-prepared Ag NPs were directly grown on the surfaces of Cu NPs through an in situ substitutional reaction with Cu-Ag metallic bonds forming at the interface between them. Growth evolution results showed that Ag NPs on the surfaces of Cu NPs could continue growing into Ag nanorods when the reaction time increased. Furthermore, NPs paste consisting of the Cu-Ag bimetallic NPs showed much high density and low porosity, which would increase mechanical strength and enhance thermal conductivity as well as electrical conductivity of joints.