Rubber-assisted micro forming of polymer thin films

Polymer thin films patterned with microstructures at a characteristic size greater than the film thickness are difficult to fabricate using the standard hot embossing technology. This study investigated a rubber-assisted embossing process for structuring polymer thin films. The main advantages of a rubber support, instead of a hard counter-tool, include simplification of the embossing tool, protection of the embossing master, buildup of uniform embossing pressure, and ease of demolding. The testing pattern for rubber-assisted embossing was a microgroove pattern with a characteristic size of 100 μm on a 25-μm thick polystyrene film. Results showed that the uniformity and replicability of the embossed pattern were significantly affected by the embossing temperature, the rubber hardness, and the embossing pressure. With an embossing temperature about 20°C above the glass transition temperature and appropriate rubber hardness and embossing force, uniform microgroove patterns were successfully replicated.