Abstract
A quantitative dynamic solder wettability measurement was utilized to evaluate the effects of reflow processing on the wettability parameters associated with the lead-free solders 96.5Sn-3.5Ag and 58Bi-42Sn. Solder wettability was determined with respect to the final degree of spread and the extent of solder wetting onto the terminal areas of surface-mount components. The solder alloy composition of 96.5Sn-3.5Ag exhibited better wetting characteristics than the 58Bi-42Sn alloy. This wetting behavior was enhanced under the reflow conditions of a nitrogen atmosphere and the use of a gold metallization. The wetting of the conventional 63Sn-37Pb solder alloy was improved over the comparatively processed 58Bi-42Sn alloy. However, the 63Sn-37Pb solder alloy displayed a greater sensitivity to reflow atmosphere than the 96.5Sn-3.5Ag alloy, which generally exhibited better wetting characteristics than the Sn-Pb alloy.
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References
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Melton, C. The effect of reflow process variables on the wettability of lead-free solders. JOM 45, 33–35 (1993). https://doi.org/10.1007/BF03222378
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DOI: https://doi.org/10.1007/BF03222378