COMPUTATIONAL MODELING OF POLYMER FLOW IN MICROCAVITIES THROUGH A MICROSCREEN

This paper investigates a new technique for rapid replication of electroforming micromolds with integral microscreens. The process is based on injection molding or hot embossing of plastic replicates with integral metallic screens onto a LIGA-fabricated master microtool, to produce sacrificial electroforming molds in which the metallic screen acts as the conducting base and the plastic features provide insulating sidewalls for electrodeposition of the desired metallic micropart. A computational model is developed for the polymer flow during the fabrication of electroforming micromolds incorporating the temperature dependent, non-Newtonian rheology of the polymer melts. The model is used to analyze the effects of the process parameters and micro-feature geometry on the polymer flow patterns.