Improving the performance of lead-free solder reinforced with multi-walled carbon nanotubes

In this study, varying weight fractions of multi-walled carbon nanotubes were successfully incorporated into 95.8Sn-3.5Ag-0.7Cu solder, to synthesize novel lead-free composite solders. The composite solders were synthesized via the powder metallurgy route of: blending, compaction, sintering and extrusion. The extruded materials were then characterized for their physical, thermal and mechanical properties. With the addition of increasing weight percentage of carbon nanotubes, the composite solders experienced a corresponding decrease in density values and wetting property improved. The melting temperatures of the composite solders were found to be unchanged with the carbon nanotube additions. Thermomechanical analysis of the composites also showed that the presence of reinforcements decreased the average coefficient of thermal expansion of the solder matrix. An improvement in the mechanical properties was also recorded with the presence of increasing carbon nanotubes. An attempt was made, to correlate the increasing presence of reinforcements with the physical, thermal and mechanical properties obtained.