Roll-to-roll UV nanoimprinting using flexible polymer stamp

Alternatives for a method to produce organic electronics, optoelectronics and functional surfaces with low cost and high throughput have been recently developed actively. Imprinting of a large area requires relative high force and may also cause high adhesion force making the demolding difficult. Roll-to-roll UV imprinting represents an excellent alternative for a low pressure and adhesion force process. In this work we demonstrate the fabrication of roll-to-roll UV stamps and a process for continuous roll-to-roll UV nanoimprinting. We have used a custom made nanoimprinter device to demonstrate the stamp preparation and manufacturing of polymer structures. The flexible UV stamps were produced by roll-to-roll nanoimprinting on fluorinated mold material (F-template) on polycarbonate substrate from Asahi Glass, or on cellulose acetate film from Clarifoil. The mold material was patterned with conventional thermal roll-to-roll nanoimprinting process using a flexible Ni-master as a stamp. The approach allows us to prepare tens of UV molds for further processing. Patterned templates were cut off from the web and wrapped on the two printing rolls thereby making a “printing belt”. This belt works as a mold for roll-to-roll UV nanoimprinting. Patterned F-template is wrapped around two metallic cylinders and about 10 cm long contact area with the web can be achieved. Fluorinated phosensitive polymer NIF-A from Asahi Glass Co or Ormoclad from micro resist technology GmbH coated on the polymer web were used as UV resists. The web was coated with the resist using reverse gravure coating method. Resist was cured by a UV-exposure unit (EFOS Ultracure 100ss). Printing speed of 0.1 - 0.2 m/min (corresponding to 30 s curing time) and pressure less than 0.1 MPa were used in the process.