(575a) Shape-Controlled Tin Nanoparticle Synthesis and Its Application as Nanosoldering Materials

Shape-controlled synthesis of metal nanoparticles has opened many new possibilities to design ideal nano-building blocks for future nanofabrication and nanomanufacturing. These shaped controlled nanoparticles have been proposed for a wide variety of scientific, engineering, and technical applications. Surfactant-assisted synthesis and growth is one of the mostly used methods to obtain shape-controlled nanoparticles. Nanosolders, as a concept, have been proposed and many types of nanoparticles from silver, gold, copper, etc have been fabricated to prepare solder paste. However, the study on constructing ideal nanosolders from low melting-point soldering materials including tin (Sn), indium (In), and corresponding alloys is still limited. In the present study, we report a simple strategy to prepare tin nanostructures with various sizes and shapes by controlled growth in the presence of an anionic surfactant - sodium dodecyl sulfate (SDS). We demonstrate that by adjusting SDS concentration, stirring speed, and growth time, different shapes of tin nanoparticles can be obtained.

The tin nanoparticles are characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). Thermal reflow properties for the nanosolder particles were also studied. It was found that an inert environment of nitrogen (N2) was very important for the nanoparticle melting and reflow. Those tin nanoparticles show great promise as soldering material, which could enable the newly emerged nanodevice fabrication through forming robust interconnects by soldering. Constructing nanoink from these tin nanoparticles is currently underway in our laboratory.