Modeling the atomic transport kinetics in high-lead solders

The atomic mobilities of Au, In, Pb, and Sn in face-centered cubic Pb-Sn an d Pb-In alloys are modeled using the available literature data. A set of pa rameters describing the composition and temperature dependence of diffusion al mobility are provided. The calculated tracer diffusivities of Pb in tern ary Pb-Sn-In and Pb-Sn-Au alloys are in very good agreement with the experi mental data. Using the model parameters, both tracer and chemical diffusivi ties can be calculated in the composition and temperature ranges where expe rimental data is not available. On the assumption of local equilibrium, the simulation of dissolution kinetics of Pd in liquid Pb is demonstrated. The major source of discrepancy between the calculated and experimental diffus ion profiles is the uncertainty of the atomic transport kinetics data in th e liquid phase. The implications of current kinetic modeling are discussed briefly.