The Electronic industry is at the crossroad of moving forwards lead-free solders. Tin and tin alloys have been considered as alternatives for component finishes. Among a few remaining issues regarding plating processes, the whisker growth phenomenon has not been understood satisfactorily. Though many factors are identified as important in affecting whisker growth, there exists many inconsistent, often contradicting observations due to a lack of quantitative approach in whisker study and a lack of understanding of whisker growth mechanism. As a continuation of our understanding of whisker growth phenomenon, we report here our quantitative investigation of the whisker growth rates. In this work, we report the werk on whisker index that is obtained based on quantitative data collection and analysis. We intent to use whisker index as a quantitative measure for whisker propensity. In addition, by obtaining whisker index as a function of time, we are able to obtain whisker growth rate and to delineate in a clear-cut fashion the effect of external stress on whisker formation. This work provides the foundation for our mechanistic understanding of the whisker growth phenomenon, and adds to the whisker database that is essential for making sound assumptions for theoretical modeling.
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