Study of solder based self assembled 3D micro scale structures via surface evolver

Surface-Evolver is an interactive program used to study surface profiles that are influenced by surface tension. The tool is an open source software, developed by Professor Kenneth Brakke in Susquehanna University, USA. Solder based self assembled (SBSA) 3D structure was studied previously via experiments using lithography, deposition, wet etching, and dip soldering methods. SBSA 3D structure has wide applications which includes 3D packaging, 3D antenna design and other emerging areas. To completely study SBSA technology via experiments that are infrastructure dependent is not feasible, hence simulation study via Surface-Evolver is discussed in this paper. Simulation studies to understand the variations in forming 3D structures via Surface-Evolver is discussed. The SBSA 3D structure is represented by labeling vertices, edges, faces and volume in the simulation tool. The energy applied to the body defined, includes surface tension, and gravity. The minimization is completed by evolving the surface by energy gradient method. In this paper, the effect of design parameters such as gap size between metal patterns, and solder thickness on the formation of SBSA 3D structures are studied. The design parameters are analyzed for truncated square pyramid (TSP) and open cube (OC) 3D structures using Surface-Evolver tool.