Properties of SnZn lead free solders bearing rare earth Y

Rare earth (RE) Y has been incorporated into eutectic SnZn solders to study the wettability, mechanical properties, oxidation resistance, microstructures and thermal fatigue behaviours. The results indicate that adding trace amount of RE Y can remarkably improve the wettability of SnZn solders. When the content of RE Y is 0·06 wt-%, the tensile and shear forces of SnZn-xY solder joints give 24·1% and 27·2% increase after soldering. In addition, it is found that SnZn0·06Y has better oxidation resistance than that of SnZn solder, and the microstructures of SnZn solders can be refined by the addition of RE Y; the size of Zn rich phase can be reduced obviously. Moreover, SnZn0·06Y shows superior thermal fatigue property over SnZn solders. It can be concluded that the optimum content of RE Y is 0·06 wt-% for SnZn solders.