Experimental and numerical study of microchannel formation in rubber-assisted hot embossing with an open-channel mold

In comparison to conventional hot embossing with a precisely aligned pair of hard mold plates, the rubber-assisted hot embossing process with a modified embossing tool that employs only one hard mold plate containing through-thickness open microchannels was investigated both experimentally and numerically. The numerical process dynamics model was constructed using a hyperelastic constitutive model to describe the large deformation behavior of the embossing film at an embossing temperature near the glass transition temperature. Both experimental and numerical results showed that excellent replication of microchannel patterns can be achieved using the simplified tool setup and an embossing temperature slightly above Tg is suitable for achieving a uniform embossing thickness. Additional advantages from the use of open channels on the embossing mold include reduced diesel effect in the mold cavity and improved surface smoothness of the embossed film. The simulation results agreed very well with the experimental observations for the effects of the main process parameters on the replication quality, and this study demonstrated that the hyperelastic process model is capable of predicting the basic characteristics of the rubber-assisted embossing process with an open-channel embossing mold.