Diffusivities And Atomic Mobilities Of An Sn-Ag-Bi-Cu-Pb Melt

The recently developed Arrhenius formula of a modified Sutherland equation was employed to calculate the self- and impurity diffusivities in liquid Sn, Ag, Bi, Cu and Pb. The reliability of the calculated self-and impurity diffusivities was validated by comparing the calculated diffusivities with the critically reviewed literature data. Based on the reliable tracer, intrinsic and chemical diffusivities available in the literature, the atomic mobility parameters in an Sn Ag Bi Cu Pb melt were then evaluated by the DICTRA (DIffusion-Controlled TRAnsformations) software package with the aid of the available thermodynamic description for the liquid phase. Comprehensive comparisons show that most of the measured and theoretical diffusivities in Sn Ag Bi Cu Pb melts can be reasonably reproduced by the currently obtained atomic mobilities. The atomic mobilities were further verified by comparing the model-predicted concentration profiles with the measured ones in various liquid Ag Pb, Bi Pb and Sn Bi Pb diffusion couples. Finally, the simulation of dissolution of Ag and Cu substrates into liquid solder alloys during the reflow process was performed by using the presently obtained atomic mobilities in the Sn Ag Bi Cu Pb melts.