Effect of thermal aging on intermetallic compounds and properties of Sn-Cu-Ni-xPr/Cu soldered joints

Chip resistors were joined with Sn-0.7Cu-0.05Ni-xPr solder. To guarantee the reliability of the Sn-0.7Cu-0.05Ni-xPr/Cu joints in service requirement,the growth rate of intermetallic compounds of Cu side was evaluated and the effects of the intermetallic compound layer on the electrical and mechanical properties have been investigated under various aging time. The shear strength of Sn-0.7Cu-0.05Ni-xPr/Cu joint gradually decreased during thermal aging. Meanwhile,under the same condition, the Sn-0.7Cu-0.05Ni-xPr/Cu joint achieved good mechanical properties when the addition of Pr was about 0.05%.