Effect of TiO2 Nanoparticles Addition on the Electrochemical Migration of Low-Silver Lead-Free SAC Alloys

The effect of the doping of TiO2 nanoparticles on the electrochemical migration (ECM) characteristics of low-Ag lead-free SAC0807 solder alloy was examined by the means of water drop (WD) tests in 0.1 M NaCl solution at 10 VDC bias voltage. The statistical and reliability analysis of WD results revealed that for both alloys, the lifetime results follow a clearly defined log-normal distribution. SAC0807+0.1%TiO2 showed a higher median time to failure (T50) than SAC0807 suggesting an advantageous effect of incorporating TiO2 nanoparticles onto SAC0807 from the ECM point of view. However, based on statistical and reliability analysis of WD results, this advantageous effect is not enough to consider doping with TiO2 nanoparticles promising. Scanning electron microscopy (SEM) showed a change in the morphology of the dendrites between SAC0807 and SAC0807+0.1%TiO2 where the former showed straight and perpendicularly branched morphology while the latter showed a mixture of the trunk and lace-type morphology. Energy dispersive spectroscopy (EDS) confirmed that Sn was the principal detected element in the dendrites in both cases.