About cookies on this site Our websites require some cookies to function properly (required). In addition, other cookies may be used with your consent to analyze site usage, improve the user experience and for advertising. For more information, please review your options. By visiting our website, you agree to our processing of information as described in IBM’sprivacy statement. To provide a smooth navigation, your cookie preferences will be shared across the IBM web domains listed here.
Publication
JOM
Paper
Electromigration performance of Pb-free solder joints in terms of solder composition and joining path
Abstract
The electromigration (EM) performance of Pb-free solder joints is investigated in terms of solder composition (Sn-0.5 Cu vs. Sn-1.8Ag) and joining path to Cu vs. Ni(P) under bump metallization (UBM). In the double-sided joints of Ni(P)/solder/Cu, the microstructure of solder joints and the interfacial intermetallic compound (IMC) layers are significantly affected by solder composition and joining path. The as-reflowed microstructure of Sn-0.5 Cu joints consists of small columnar grains with thin IMC layers at both UBM interfaces, independent of the joining path, while Sn-1.8Ag joints have a few large grains of low-angle grain boundaries with thick IMC layers when joined first to Ni(P) UBM, but a few 60° twins with thin IMC layers when joined first to Cu UBM. The EM stressing under high current densities at I50°C reveals that Sn-1.8Ag joints have a superior lifetime compared to Sn-0.5 Cu joints. In addition, the EM lifetime of Sn-1.8 Ag joints reflowed first on Ni(P) UBM is the longest among four groups of the solder joints examined.