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MM: Fachverband Metall- und Materialphysik

MM 61: Liquid & Amorphous Metals I

MM 61.5: Vortrag

Donnerstag, 14. März 2013, 16:45–17:00, H26

Reactive wetting and solder spreading — •André 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 of Cu and Ni. In order to quantify this energy, we measured wetting angles of solder drops as well as surface tension of SnPb and SnBi solders under systematic variation of composition and gaseous flux at different reflow temperatures by the sessile drop method. Remarkably, the tension between solder and flux and the wetting angle reveal characteristic dependence on solder composition. From the two independent data sets, the specific energy of the reactive interface, the adhesion tension, is evaluated. In detail, the adhesion energy reveals distinguished plateaus which are related to different reaction products in contact to the solder. Using a dedicated geometry [1], which enables investigation of the wetting kinetics, spreading speed and maximum spreading distance are measured. We demonstrate correlations between the latter kinetic parameters and the phase structure in the reaction zone.

[1] F.M. Hosking et al, Journal of Electronic Materials, Vol. 25, No. 7, 1996.