Numerical investigation of diffusion induced coarsening processes in binary alloys

Microscopic small solder joints are part of most microelectronic packages. They show a variety of micro-morphological changes such as decomposition into phases and phase coarsening. In order to analyze the evolution of the alloy by means of a diffusion theory of heterogeneous solid mixtures we apply an extended Cahn-Hilliard phase-field model. The Cahn-Hilliard equation involves a bipotential operator and, accordingly, fourth-order spatial derivatives. In our contribution we discretize the diffusion equation spatially by means of rational B-spline finite element basis functions. To illustrate the versatility of this approach numerical simulations of phase decomposition and coarsening controlled by diffusion and by mechanical loading are discussed and compared with experimental results.