Effects of process parameters in synthesizing Sn nanoparticles via chemical reduction

In order to prepare solder particles for fine pitch interconnections, Sn nanoparticles were synthesized via chemical reduction methods. A number of the process parameters, i.e., injection rate of a precursor solution, application of sonication, reaction temperature, types of reaction medium and capping agent, and drying temperature, are varied in order to study their effect on this process. Using a methanol solution containing 1,10-phenathroline monohydrate, the size of Sn nanoparticles collected after the synthesis decreases as the injection rate increases. An increase in the drying temperature strengthens the degree of agglomeration between Sn nanoparticles, and, in addition, the application of sonication accelerates the process of agglomeration and aggregation between nanoparticles during synthesis. Much smaller Sn nanoparticles are synthesized in diethylene-glycol solutions containing PVP, compared to the methanol solutions with 1,10-phenathroline monohydrate. In the synthesis using diethylene-glycol solutions, the Sn nanoparticle size increases quickly with the reaction temperature.