Dresden 2011 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 11: Liquid and Amorphous Metals III

MM 11.6: Vortrag

Montag, 14. März 2011, 17:00–17:15, IFW D

Surface Tension and Reactive Wetting in Solder Connections — •Andre Wedi and Guido Schmitz — Institut für Materialphysik, Westf. Wilhelms-Universität, Wilhelm-Klemm-Strasse 10, 48149 Münster, Germany

Wetting is an important pre-requisite of a reliable solder connection. However, it is only an indirect measure for the important specific energy of the reactive interface between solder and base metallization. In order to quantify this energy, we measured wetting angles of solder drops as well as surface tension of SnPb solders under systematic variation of composition and gaseous flux at different reflow temperatures. For the latter, we used the sessile drop method placing a solder drop on a glas substrate. From the two independent data sets, the important energy of the reactive interface is evaluated based on Young`s equation. Remarkably, although both, the tension between the solder and flux and the wetting angle, reveal significant dependence on solder composition. So the adhesion energy reveals distinguished plateaus which are related to different reaction products in contact to the solder. TEM analysis and calculations of phase stabilities show that there is no Cu6Sn5 for high lead concentrations. The experiments confirm a model of reactive wetting by Eustathopoulos[1].

[1]N. Eustathopoulos; Current Opinion in Solid State and Materials Science, 9 (2005) 152-160.