Effects of cerium on microstructure and properties of SnAgCu solders

Abstract

Effects of small amount of cerium on the wettability, mechanical properties, thermal fatigue performance and microstructure of SnAgCu solder were investigated by means of scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) systematically. The results indicated that adding a small amount of Ce could remarkably improve the wettability, mechanical strength and thermal fatigue life of SnAgCu soldered joints at room temperature. However, the addition of an excessive amount of Ce would deteriorate these properties of SnAgCu alloy. By analyzing microstructures of SnAgCu-XCe soldered joints, it was observed that a small amount of Ce in SnAgCu solder might refine the joint matrix microstructure and reduce the thickness of intermetallic compound (IMC) layer significantly because of the higher affinity of Ce to Sn in the alloy system.