Effect of pulsed voltage on electrochemical migration of tin in electronics

The effect of pulsed voltage on electrochemical migration of tin was studied on size 0805 surface mount capacitors. The study was performed under water droplet condition using 0.0156 and 0.156 g L−1 concentrations of NaCl. The amplitude and the offset of rectangular shape pulse were fixed respectively at 10 and 5 V, while the duty cycle and the pulse width were varied in the range of ms. The results showed that varying of pulse width at fixed duty cycle has a minor effect under investigated conditions, whereas increasing duty cycle significantly reduces the time to short due to dendrite formation and increases the charge transferred between the electrodes over time. With increase of duty cycle, increases the anodic dissolution of tin, which was visualized using a tin ion indicator applied on the components prior to applying the voltage. The anodic dissolution of tin significantly influences the dendritic growth, although a tendency for more hydroxide precipitation was observed for lower duty cycles. The precipitation of tin hydroxides was identified as influencing factor for the reduction of charge transfer under pulsed voltage with low duty cycles, therefore resulting in the suppression of dendrite growth.