Prediction of solder interconnects wetting and experimental evaluation

A new analysis methodology to predict solder interconnect wetting is developed to reveal the causes of poor wetting during flip chip assembly and to provide solutions. The analysis methodology characterizes solder wetting as two different processes: the wetting dynamics of the solder contact line and the generation of the minimum energy surface of the molten solder. Surface Evolver is implemented to generate the surface shape of solder during wetting. Since there are no quantified dynamics models for solder materials, a solder wetting dynamics model is developed based on former wetting models proposed for other materials. The contact angle relaxation of spreading over time is measured in specially designed experimental setup for model development. As a result of experiment and model evaluation, a best wetting dynamics model is developed and the development of analysis methodology is completed. The study of reflow process parameter effects is ongoing.