Effect of TiO2 Nanoparticles Addition on the Electrochemical Migration of Lead-Free Sn-Bi Alloys

This research aimed to investigate the susceptibility of Sn-58Bi alloys to Electrochemical Migration (ECM) when combined with TiO2 nanoparticles tested in various solutions, including deionized water (DI), 1 mM Na2SO4, 500 mM Na2SO4, 1 mM NaCl, and 500 mM NaCl, using water drop (WD) test. The results revealed a heightened ECM susceptibility in Sn-58Bi alloys with the addition of TiO2 nanoparticles, indicating an adverse impact of TiO2 nanoparticle incorporation. Furthermore, scanning electron microscopy and energy dispersive X-ray spectroscopy (SEMEDS) were utilized to analyze the surface morphology and elemental composition of dendrites formed after the WD tests. The outcomes showed the presence of dendrites and precipitates in both Sn-58Bi and Sn-58Bi-0.1% TiO2 cases. Sn was identified as the primary element in the dendrites, while Bi was not detected in the dendrites in any of the cases. Consequently, the reliability of electronics may be compromised when using Bi-Sn paste doped with TiO2 nanoparticles, particularly in terms of ECM. Nonetheless, these nanoparticles could enhance other properties associated with modified microstructure, such as mechanical or thermal properties, which warrant further investigation.