Synthesis of Sn-3.5Ag nanoparticles of tiny sizes

Sn-3.5Ag nanosolder in tiny sizes can provide a practical way to solve the high soldering temperature problem of lead-free solder alloy in fine pitch interconnectivity owing to the unique nanosize effect and meantime stand a higher working temperature just as the bulk material after welding. In this paper, a simple approach to synthesis Sn-3.5Ag nanoparticles by chemical reduction at room temperature is reported and sorts of influencing factors in both size and quality aspects, such as injection rate of the precursor solution/reduction solution, drying temperature, types and volume of solvent, are discussed. To prevent the formation of tin oxide, a reliably capping agent, polyvinylpyrrolidone (PVP), was added into liquid reaction mixture under vigorous stirring instead of blowing any protecting gas. The sizes of as-prepared Sn-3.5Ag can achieve several nanometers without oxidized.