Effect of indium on wettability of Sn–Ag–Cu solders. Experiment vs. modeling, Part I

The density and surface tension measurements of the Sn3.13Ag0.74Cu liquid alloys with 2, 3, 4, 15, 30, 50 and 75 at.% In additions were conducted in the temperature range from 431 K up to 1209 K by dilatometric technique and the maximum bubble pressure method, respectively. The results obtained in both techniques exhibited 2%–3% scattering of experimental errors, similarly to the previously investigated In–Sn and Sn–Ag–In systems. This was due to the very similar surface tension and density values of pure indium and tin. The experimental surface tensions were compared with calculated ones using data of the constituent systems, (a) by means of thermodynamic method of Butler, and (b) by the temperature and concentration relation of the surface tension. The improvement of wettability in liquid alloys containing different In additions was confirmed with a sessile drop method in the temperature interval 523 K–593 K up to 1800 s. The wetting angles decreased with temperature and increasing In concentrations in the solders from ∼37∘∼37∘ for the solder without In at 523 K down to ∼22∘∼22∘ for the solder with 75 at.% In at 593 K.In the following Part II, the structure investigations of the interface between relevant solder and Cu substrate of the same liquid solders after contact angle measurements will be carried out.