Plastic package is currently the most popularly used process for encapsulating semiconductor packages. At present, transfer molding is the leading method in the world. New packages such as TSOP, TQFP and BGA require new technology because of their difficulty as compared to older package such as DIP and SOP. Some packages show various molding problems such as wire sway, voids, etc. In order to reduce such defects, adjustments in molding parameters as well as adjustments in the property of molding compound, on the basis of trial-and-error prevail. Normally, parameters such as spiral flow, gel time and flow-tester viscosity are used to explain such phenomenon. These trial-and-error adjustments lead to delays in correcting problem. Using our background experience we devised a mold support system in order to fully understand the relationship between the molding phenomenon, molding parameters, properties of molding compound and its formulation. In this study, we applied C-SET that is the simulating software of the flow mechanism with thermosetting provided by AC Technology. Initially we prepare several molding compounds each having its own fluidity property formulation for this study. >