Using the interactive software, this study was mainly focused on developing a 3-D joint shape after the as-reflowed soldering which is the one of chief factors affecting the reliability. From the results, the soldering process can be simulated and observed directly. By changing the various conditions and constraints, such as surface tension, wetting angle and specific gravity, it makes a comparison between the simulated result and the experimental one. The simulated parameters are based on those of the traditional eutectic Sn-Pb solder. After slicing and comparing the different profiles of the simulated shape, the 3-D simulated geometry fits well with the experimental one.