Numerical simulation of solder spreading and solidification during solder jet bumping process

A VOF model is developed to simulate the solder spreading and solidification during solder jet bumping process. This model is based on fixed mesh method, and accounts for the surface tension, wetting effects, and heat transfer with solidification. The visualizations of the transient impact processes are employed in order to compare and validate the numerical model presented. Results show the spreading and recoiling process coupled with the solidification leads to a final cone-shaped solder bump. The variation of gravitational potential energy in the impingement is too small to be neglected. The simulated results are in excellent agreement with the photographic images.