Effects of Ce on spreadability of Sn-Cu-Ni lead-free solder and mechanical properties of soldered joints

Effects of rare earth Ce on spreadability of Sn-Cu-Ni solder on copper, mechanical properties of soldered joints and the microstructure of Sn-Cu-Ni-Ce solder were investigated respectively.The results indicate that with the increase of the content of Ce added to the Sn-Cu-Ni solder, the spreading area of Sn-Cu-Ni-Ce solder on copper was enlarged.When the content of Ce is about 0.05%, the spreading area is the largest and the microstructure of Sn-Cu-Ni solder is fine and uniform, and the mechanical properties of soldered joints are improved observably.Experimental results also show when the content of Ce is over 0.05%, the grains of the solder gradually become coarse, the spreadability of the solder descend, and the mechanical properties of soldered joints deteriorate as well.