from the conferences organized by TANGER Ltd.
In the present work the corrosion resistance of candidate lead-free solder alloys in simulated seawater conditions was investigated. Four different alloys were studied: Sn-0.7Cu, Sn-3.5Ag, Sn-0.3Ag-0.7Cu and Sn-3.5Ag-0.7Cu (composition in wt.%). The alloys were prepared by induction melting from high purity Sn, Ag and Cu lumps. Each alloy was heterogeneous as it was found to consist of β-Sn and different binary intermetallic compounds. The alloys were corrosion-monitored in 3.5 wt.% NaCl aqueous solution at 21 °C. The electrochemical polarization was conducted in a standard 3–electrode cell provided by Sensortechnik Meinsberg Ltd. The potential–current density curves were measured by using a PGU 10V–1A–IMP–S potentiostat/galvanostat (Jaissle Electronic Ltd., Germany). The corresponding corrosion potentials and corrosion rates were determined by Tafel extrapolation of the experimental polarization curves. The effects of chemical composition and sample microstructure have been evaluated. Conclusions for the solder alloy corrosion resistance in humid environments are provided. The local nobility of individual IMCs is discussed. The results can be used as a guideline for selecting the proper lead-free solder composition for microelectronic applications.
Keywords: solder, corrosion, intermetallic compound.© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.