Electrochemical and Mechanical Behavior of Sn-Zn-x Lead Free Solders

The electrochemical, mechanical, structural and thermal behavior of lead-free SnZn9, SnZn9Bi2, SnZn9Bi2Cu2, SnZn9Bi2Ag2 solder alloys were investigated by different methods and compared with conventional eutectic tin-lead solder. Results of differential scanning calorimeter (DSC) analysis showed that alloying of Bi to SnZn9 decreases the melting temperature from 198 oC to 195.9 oC and also the alloying of Cu and Ag to SnZn9Bi2 resulted in reducing the melting temperature more to become 194.5 oC and 194 oC, respectively. The addition of different elements to SnZn9 alloy system such as Ag and Cu allows many complex intermetallic (IMC) phases to form as shown by XRD. The electrochemical behaviour of these alloys in 3.5% NaCl solution was studied using potentiodynamic polarization and electrochemical frequency modulation (EFM) techniques and the results obtained are in good agreement.