Influence of Ni, Bi, and Sb additives on the microstructure and the corrosion behavior of Sn-Ag-Cu solder alloys

摘要

Sn-Ag-Cu solder alloys were usually modified using trace elements to achieve various properties. This paper investigated the effect of additives of Ni, Bi, and Sb on the microstructure and corrosion behavior of SAC alloys under application condition. Investigation was carried out using both solder alloy ingots and reflow-soldered surface insulation resistance interdigitated patterns by electrochemical methods under humid and corrosive conditions. Microstructure analysis was performed using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy etc. Volta potential distribution in the bulk of the alloy was analyzed by Scanning Kelvin Probe Force Microscopy. Results show the passivation domain of five tested solder alloys did not influence the susceptibility of electrochemical migration under 5 V DC bias loading. Ni and Bi additives resulted in lower susceptibility of electrochemical migration due to homogeneity of the IMCs distribution in the bulk alloys. Bi precipitates in InnoLot alloy participated micro-galvanic corrosion as cathode rather than Ag containing phase as known before.