Effects of Zinc Oxide Nanoparticles on Properties of SAC0307 Lead-Free Solder Paste

This research investigates the effects of zinc oxide (ZnO) nanoparticles of varying concentrations 0.0, 0.25, 0.50, 0.75, and 1.0 wt.% on the melting temperatures, wettability, printability, slwnp, and interfacial microstructure of the ZnO-doped Sn-0.3Ag-0.7Cu lead-free solder pastes on the copper substrate. The results revealed that the introduction of the ZnO particles had no effect on the solidus and liquidus temperatures of the solders. The maximum wettability was achieved with 0.25 wt.% ZnO nanoparticles, while the printability was inversely correlated with the nano-ZnO concentrations. The findings also indicated that, at room temperature, the slumping and the nano-ZnO concentrations were positively correlated and that, under the 150 degrees C thermal condition, the maximum slumping was achieved with 0.25 wt.% ZnO. The slumping mechanism of the SAC0307-xZnO solder pastes is also provided herein. Moreover, the experiments showed that Cu6Sn5 was the single intermetallic compound present in the interfacial layer between the solders and the copper substrate, with the maximum intermetallic layer thickness realized at the 0.25 wt.% ZnO concentration.