Abstract-The impact of chloride ion concentration on electrochemical migration (ECM) of tin and silver was studied by using an in-situ optical and electrical inspection system. It was found, that in both cases, dendrites grow not only in an electrolyte solution at low chloride concentration but also in an electrolyte at medium and high or even saturated chloride concentrations as well. According to the results, the migration susceptibility has decreased at low and medium concentration levels in both cases. However, the ECM susceptibility of Ag has increased, while the migration susceptibility of Sn was decreased at the saturated concentrations.

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Abstract:

The impact of chloride ion contamination on electrochemical migration (ECM) of SAC305 lead-free solder alloys, and galvanic tin surface finish was studied using water drop tests and by using an in-situ electrical and optical measuring set up as well. Tests were performed with the use of 3.5 wt% NaCl solution. The "A" type SAC305 alloy had a rosin&acid/flux paste ratio of 12.5 wt%, however by the "B" type SAC305 alloy it was only 9.3 wt%. According to the meantime to failure (MTTF) data it was shown that "A" and "B" type solder alloys have approximately the same ECM susceptibility, but in the case of tin surface finish failures happened typically after shorter period of time.

Abstract-The effect of sulphate ion concentration on electrochemical migration (ECM) of silver was investigated by applying an insitu optical and electrical inspection system. It was found that dendrites grow not only in an electrolyte solution with low sulphate ion concentration but also in electrolytes with medium and high or even saturated sulphate ion concentrations. According to the MeanTime-To-Failure (MTTF) values, the migration susceptibility was decreased with the increase of sulphate ion concentration in case of low and medium concentration levels. However, the ECM susceptibility was increased at saturated concentration level.