A novel method of reducing melting temperatures in SnAg and SnCu solder alloys

With the increasing use of lead-free solder alloys in modern electronics, low melting materials are often required to protect the heat-sensitive parts during soldering operation. Alloy systems based on Sn/Cu/Ag offer more reliable solutions and address the current problems involved with soldering process. Nanoparticles melt relatively at low temperatures compared to their bulk counter parts and we introduce a robust method of synthesizing nanoscale solder pastes for wave soldering applications. Nanoparticles of Sn-3.5Ag and Sn-0.7Cu alloys were prepared with stir casting followed by mechanical attrition. The size dependent melting properties of the eutectic alloys were studied by differential scanning calorimetry technique and the results showed a reduction of 4.7 and 5.0 A degrees C melting temperatures in the alloys when reduced from bulk to 92 nm and 96 nm sizes respectively. The nanosize effects were also theoretically calculated and compared with experimental data.