Low cycle fatigue properties of Ni added low silver content Sn-Ag-Cu flip chip interconnects

Abstract

The straddle fatigue test has been performed to study the fatigue properties of Sn-1.2 mass%Ag-0.5 mass%Cu-0.05 mass%Ni for flip chip interconnections. The low cycle fatigue resistance of the alloy is equivalent to that of Sn-3mass%Ag-0.5mass%Cu alloy, even though the fatigue endurance of Sn-1 mass%Ag-0.5 mass%Cu alloy was poorer than that of the 3 mass%Ag alloy. The alloy has fine microstructure and Ag3Sn intermetallic compound makes a network structure together with fine (Cu.Ni)6Sn5 compound. The microstructure resulted in high cyclic strain hardening exponents, which leaded to good low cycle fatigue endurance of the alloy.