Study of electrochemical migration based transport kinetics of metal ions in for Sn-9Zn alloy

In microelectronic circuit exposed to humid environment, the growth phenomenon of dendritic deposits due to the electrochemical migration (ECM) of metallic ions, generates a serious reliability issue. ECM of Sn and Zn ions in deionized water with Sn-9Zn electrodes, has been in-situ studied at gap potentials of 3 and 5 V. At 3 V, tin ions (with 15.61 wt%) dominate the composition of metallic dendrites whereas Zn ions (with 20.99 wt%) show greater presence in the experiment with 5 V. The Nemst-Planck transport equation has been solved using finite element method in order to describe the kinetics of ECM of Sn2+ and Zn2+ ions. The composition of resultant dendrites is governed by the competition between advection rate, transport time scale and anodic surface concentration of metallic species.