Exploration of Lead-Free Nanosolders for Nanowire Assembly

Solders (low-melting point metals or metal alloys) are widely used in electronics industries. Lead-free solders are being implemented due to the toxicity of lead, even though several challenging issues still exist. In this research, nanoscale lead-free solders are proposed to not only address/overcome the problems in the lead-free implementation process in electronics industries, but also meet the high demand for nanotechnology applications including nanoelectronics. Nanowires have been researched extensively as key elements in sensors, nano-optics, and nanoelectronics (such as resistors, diodes, field-effect transistors). We show in this presentation our initial study in using tin (Sn)-based nanosolders (Sn-Ag, Sn-Ag-Cu, etc) to assemble nanowires into ordered structures. Electrodeposition in nanoporous templates is utilized to synthesize lead-free solders directly onto nanowires. The structures of lead-free nanosolders are characterized, and thermal reflow properties are studied in the lab-scale ovens, following typical reflow profiles. Assembling techniques such as self-assembly, together with lead-free nanosolders, are used to efficiently integrate multisegmented nanowires into ordered arrays with low contact resistance.