Effect of pulsed voltage on electrochemical migration of tin in electronics

Abstract

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.

Electrochemical migration of Sn and Sn solder alloys: a review

“…48,51 Verdingovas et al 48 found that there was a suppression effect of decreasing duty cycle on dendrite formation of Sn as it reduced the rate of the dendrite formation. Zhong et al 51 reported that no dendrite growth of Sn could be seen when the duty cycle was equal to 0.1 at the periods from 10 ms to 1000 ms.…”

“…42,43,48,49,52,53 The evolution of oxygen by water dissociation could occur at the anode surface as described by reaction (8) if the bias voltage is high enough.…”

“…48 studied the ECM of Sn under pulsed voltage using water drop test. It was found that varying of pulse width at a xed duty cycle had a minor effect under investigated conditions, whereas increasing duty cycle signi-cantly reduces the time-to-failure due to the dendrite formation and increases the charge transferred between the electrodes over time.…”

Electrochemical migration of Cu and Sn in Na2SO4 environment

“…Electrochemical migration (ECM) is a kind of humidity induced failure, which can lead to high reliability risk from the operating electronics point of view [1]. According to the classical model of ECM, the failure mechanism starts on the anode with the dissolution of metals and forms metal ions.…”

In Situ Study of the Electrochemical Migration of Tin under Bipolar Square Wave Voltage

“…24-26 In general, most of these studies were carried out under steady state electric field where a DC bias voltage was used. Only two of them were conducted on unsteady state electric field, 25,26 although the unsteady electric field which is generated by pulsed voltage or AC voltage widely exists in the operating environment of electronics.In these two publications, Verdingovas et al 25 and Zhong et al 26 respectively investigated the ECM of tin under unipolar square wave voltage in which one time period (T) consists of an ON time (T ON ) and an OFF time (T OFF ). During the ON time, a voltage with fixed amplitude was applied across the two electrodes, while during the OFF time, 0 V of voltage between the two electrodes was maintained.…”