Comparisons of nano-additives influence on properties of the bi-modal solder pastes for special applications

The paper presented the results of investigation of two solder pastes SnBi and SAC with different nano-particles, which could be applied for special application. It was presented that materials and samples preparation for investigation. The results of SEM analyzer of solder joints executed using these pastes and their shear strength measurements enable to make the comparison of nano-additives influence on properties of the bi-modal solders pastes. It was observed that addition of nano-particles into both solder pastes changed the microstructure of solder joints, and formed a large number of nano-sized grains with uniform distribution. For the SAC solder joints with nano-Ag particles it was also observed that specific Ag3Sn crystallites. We supposed that the Ag3Sn crystals, which created "internal net" and nano-sized grains with uniform distribution must influence the mechanical properties of the solder joints. The results of shear strength measurements of solder joints confirmed the significantly higher shear strength of bimodal solder joints in comparison to reference solder joints without nano-additives.