Modified imprinting process using hollow microneedle array for forming through holes in polymers

This paper presented a novel thermal imprinting technique for forming through holes in polymers with high quality and extremely high throughput. By using an array of out-of-plane, hollow silicon dioxide (SiO"2) microneedles, we successfully fabricated through holes with a diameter of approximately [email protected] in polypropylene films (thickness: [email protected]) and polyimide films (thickness: [email protected]). No burr was observed on the entrance and exit of the through holes, and the inner surface of these holes was very smooth. Moreover, the entrance and exit diameters were almost the same, indicating that the through holes had an almost perfectly vertical sidewall. The results indicate that our proposed technique has the potential of enabling high-throughput and low-cost fabrication of through holes with a minimum feature of a few tens of micrometers in a wide variety of polymers.