Effect of Ce on resistivity of Sn-3.8Ag-0.7Cu-xCe lead-free solders

The electrical resistivity of Sn-3.8Ag-0.7Cu-xCe (x takes 0, 0.2, 0.5 and 1.0 weight percent) alloy as a function of temperature was measured by DC four-probe technique. Abnormal changes occurred on the resistivity-temperature (-T) curves above the liquidus, which suggested that the temperature-induced liquid-liquid structure transition probably occurred in Sn-3.8Ag-0.7Cu-xCe melt, with some reversible characters. With the increasing of Ce, the melting range was expanded from 13.0 degrees C to 24.2 degrees C, and the resistivity increased sharply when the Ce composition increased to 0.2%, and then declined slightly. In addition, the temperature and behaviour of abnormal zone were affected by the different additions of Ce.