An investigation on surface tensions of Pb-free solder materials

ABSTRACT
Surface tensions of some Pb-free solder systems such as Ag–Bi–Sn
with cross-sections Ag/Bi = 1/1, Ag/Bi = 1/2, Ag/Bi = 2/1, In–Sn–Zn
with cross-sections Sn/In = 1/1, Sn/In = 1/3 and (Ag7Cu3)100−x Snx with
cross-section Ag/Cu = 7/3 are calculated from the sub-binary surface
tension data using the models, such as the Muggianu, Kohler, Toop
models, Butler’s equation and Chou’s General Solution Model (GSM)
at 873, 923 and 1073 K, respectively. The surface tension of In–Sn–Zn
increases wavily with increasing amount of Zn and it is found that the
best models are the GSM for both cross-sections in question while
GSM becomes the best model for (Ag7Cu3)100−x Snx alloy in the whole
experimental range. Moreover, the surface tension of (Ag7Cu3)100−x
Snx decreases slightly with increasing amount of Sn. The Muggianu,
Butler and Butler models are determined as the best models for the
cross-sections in the order given above for entire measurement range,
respectively, and the surface tension of Ag–Bi–Sn decreases slightly
with an increasing amount of Bi and Ag but increases with increasing
Sn in liquid alloys.