Abstract
The oxidation and drossing characteristics of agitated molten 60Sn-40Pb solder containing low levels of seven different individual impurities are reported. The experimental work was performed using a simple stirring technique, with the aim of simulating one form of agitation occurring in a mass soldering machine. Weight-gain measurements were made which showed the same stepped relationship between oxygen uptake and temperature as previously observed for the uncontaminated alloy. For those impurities studied extensively the same function appeared to govern the relationship between time and weight gain as was found for the pure alloy. Additions of 0·01 and 0·1%Al, 0·2 and 2·0%Sb, 0·01 and 0·1%Cd, 0·1 and 0·5%Cu, 0·01 and 0·001%P, 0·2 and 2·0%Ag, and 0·006 and 0·05%Zn were investigated. The effects of these impurities on oxidation over the temperature range 220° to about 320°C are discussed and compared with the uncontaminated alloy; only phosphorus was found to produce a reduction in oxidation over the whole temperature range. In order to attempt to correlate these results with drossing on a wave-soldering machine, some preliminary data on the effects of time, temperature, and ‘wave speed’ on the weight of dross produced are presented and compared with the results from the stirring experiments.
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