Mold filling analysis of an alignment structure in micro hot embossing

Hot embossing is one of the most popular fabrication methods to replicate polymer microdevices in the field of micro-fluidics and micro-optics. Numerical models for hot embossing were constructed to analyze the advance of flow front of the molten polymer using commercial software, DEFORM-2D. A hemisphere tipped post, used as an alignment structure in the assembly of micro devices, was modeled to demonstrate the flow behavior of the molten polymer in mold filling. Hot embossing experiments were performed to validate the feasibility of the numerical models. Most of the simulations showed agreement with experiments. The mold filling was estimated with the heights of the embossed posts in the analysis. No significant mold filling with the molten polymer was observed below the glass transition temperature of 105 °C. The mold cavity was completely filled with the polymer at the molding temperature of 137.5 °C and 150 °C while the embossing forces were 300, 600, and 900 N.