A thermodynamics model for solder profile evolution

A thermodynamics model for describing the solder profile evolution and the triple point line motion driven by surface tensions and gravity field is proposed. Attention is focused on the kinetic process as the solder profile evolves toward its equilibrium shape in its molten state. Based upon non-equilibrium thermodynamics, a theoretical model is proposed by introducing the kinetic laws that characterize the motions of the solder surface and the triple point line. The presented model leads to a nonlinear dynamic system, which describes the entire time-dependent process of the solder wetting. It can be applied not only to predict the equilibrium shape of the solder, but also the shape at any time during the spreading process. A computer numerical simulation and examples for the solution of the dynamic system are described.