Microstructure and mechanical properties of Sn-Bi solder joints reinforced with Zn@Sn core-shell particles

We proposed Zn@Sn particles to improve the mechanical properties of the Sn-58 wt% Bi (Sn58Bi) solder. The effects of 3, 6, and 9 wt% Zn@Sn particles on the microstructure and mechanical properties of Sn58Bi were investigated. The addition of Zn@Sn to Sn58Bi solder inhibited microstructural coarsening, which mitigated the brittleness of Sn58Bi solder joints during aging. The zinc-rich phases dispersively distributed in the solder joints effectively inhibited the coarsening of the Bi-riched phase. At the same time, Cu5Zn8 instead of Cu6Sn5 formed at the composite solder/Cu interface. After 21 days of aging, the shear strengths of solder joints doped with 6 wt% Zn@Sn decreased from 54.06 to 36.41 MPa. Compared with the undoped solder joints before and after aging, the shear strengths increased by 34% and 173.1%, respectively. Thus, the composite solder paste has great potential to be used as a low-temperature lead-free solder in the electronic packaging industry.

Automated summary

The effects of Zn@Sn particles on the microstructure and mechanical properties of Sn58Bi solder were studied. The addition of Zn@Sn inhibited microstructural coarsening and improved the mechanical properties of the solder. The composite solder paste has great potential to be used in the electronic packaging industry.