Interfacial reaction and shear strength of Pb-free SnAg2.5Cu0.86b0.5 and SnAg3.0Cu0.5Sb0.2 solder bumps on Au/Ni(P) metallization

Abstract

This study investigates the metallurgical reaction and shear strength of Pb-free SnAg2.5Cu0.8Sb0.5 and SnAg3.0Cu0.5Sb0.2 solder bumps on Au/Ni(P) metallization pads. It is found that (Cu,Ni)(6)Sn-5 intermetallic compound (IMC) formed at the interface between the Sn2.5Ag0.8Cu0.5Sb solder and the metallization pad; whereas (Cu,Ni)(6)Sn-5 and (Ni,Cu)(3)Sn-4 IMCs formed when the SnAg3.0Cu0.5Sb0.2 reacted with the Au/Ni(P) metallization pad. The difference in the Cu concentration in the two solders may be responsible for the different interfacial IMC formation. The shear strengths for the SnAg2.5Cu0.8Sb0.5, SnAg3.0Cu0.5Sb0.2, SnAg3.0Cu0.5, and SnAg4.0Cu0.5 solders were also measured. The shear strength test revealed that the SnAg2.5Cu0.8Sb0.5 solder has the highest shear strength, which may be due to the solid-solution strengthening of the Sb atoms. (c) 2005 Elsevier B.V. All rights reserved.