Breakthrough solutions in laser patterning of drum-moulds for large-area nano-imprinted polymer films

High throughput manufacturing requires continuous lithography processes capable of reproducing micro and/or nanoscale structures with high precision and without any discontinuities. Alternative lithography techniques tribute to the development of novel materials giving rise to added functionalities and properties. Despite the progress of manufacturing processes made, it still remains a bottleneck to realise large area flexible surfaces at low cost and without discontinuities. 

Within LADRUM project we have established the manufacturing chain to realise large area micro/nanopatterned films with tailored surface properties. In particular, hierarchical features have been realised by ultrashort pulse laser sources with high power in combination with fast scanning technologies. Direct engraving of tailored threedimensional features into a nickel cylindrical drum/mould have been exploited and transferred in a continuous mode into a commercial UV curable resist material. The Nickel drum mould was in the form of a sleeve (no-discontinuities) and has been treated and engraved with high precision within a machining tool capable of processing multiple laser machining wavelength while state of the art beam splitting and accurate scanning tools were used to avoid discontinuous boundary issues and low thermal impact. With the aim to obtain super-hydrophobic surfaces, particular designs and structures ranging from sub-1 μm up to 100 μm were examined. Partner Nanotypos performed a roll-to-roll ultraviolet light assisted nanoimprint lithography (R2R UV-NIL) to replicate at the high rate our textured nickel surfaces produced at IOM.

Throughout our experiments, the emphasis was given to generate 3D topographies which tend to have the best performance according to our theoretical calculations. All processing parameters were optimised to have a robust replication technology starting from the laser processing values up to the final R2R embossing step. Based on our experiments, hierarchical topographies which combine two level features, resulted in having the best water repelling values hence water contact angle values of 158 deg.