Investigation of Sn grain growth in solder joints by numerical simulations

The microstructure of the solder joint determines the basic quality and reliability parameters of the solder joints, like the electrical and thermal conductivity, the mechanical parameters, the thermal stability, the corrosion resistance, etc. So, investigating the solder joints' microstructure is an important aspect of the soldering technology. The basic method of microstructural investigations is the optical observation of 2D cross-sections of the solder joints, which can be misleading since we make conclusions from a 3D structure according to a 2D view. Therefore, our aim is to develop a 3D numerical simulation environment that can calculate the Sn grain formation during the solidification of the solder joint. Our method is based on the decentred octahedron growth algorithm, which is a type of cellular automaton model, used to predict microstructure during solidification. The dendritic network in each cell is covered by a polyhedron envelope, while the growing envelopes during cooling capture neighbouring cells, resulting in grain growth.