Spreading and Solidification of Liquid Metal Droplets on a Substrate: Experiment, Analytical Model and Numerical Simulation

摘要

The comprehensive investigation that includes the experimental study, analytical modeling and numerical simulations of the fluid dynamics and heat transfer phenomena during the impingement of a liquid solder droplet upon a substrate was presented. The main motivation for this work was in the connection with the novel micromanufactacturing process called solder-drop-printing technology. It was shown that the features of the shape of solidified droplets deposited at conditions corresponding to the moderate Weber numbers is determined by the ratio of the time of droplet's solidification and period of oscillations for a liquid part of droplet. The analytical model of liquid metal droplet's solidification was developed. The formulas for estimation of the characteristic time of droplet solidification and base geometrical parameters characterizing the shape of solidified droplets was offered. The theoretical study was based on the numerical solution of the Navier-Stokes equations describing the liquid droplet deformation process together with the relevant energy conservation equations that determine the heat transfer process and the moving of the solidification front. The numerical simulation data agreed well with the experimental results at all stages of the droplet spreading and solidification processes.