Development of a Gasbag-Roller-Assisted UV Imprinting Process and Its Application

This study devoted to developing gasbag-roller-assisted UV imprinting technique and its application. The technique combines UV-based imprinting technique, gasbag-roller press and a belt-type flexible mold, to replicate patterns on the polymer substrate. Polydimethylsiloxane (PDMS) is employed as the material for the belt-type mold. A gasbag-roller is manufactured by wrapping and sealing a silicon tube around an aluminum dumbbell-shaped roller. The gasbag-roller is employed to increase the contact area and to ensure the conformity of contact between the mold and the substrate. The uniform pressure distribution on the substrate has been proven using pressure sensitive films. ANSYS software is also used to simulate the effects of inner gas pressure and pressure applied on the shaft of the gasbag roller. The result proves that contact area is increased and pressure distribution is uniform with aid of gasbag-roller, even when the substrate is non-uniform.
In this study, a gasbag-roller-assisted UV imprinting facility is designed and implemented. Microlens array has been successfully fabricated on the 2 mm-thick PMMA substrate. It proves that gasbag-roller-assisted UV imprinting process is feasible for microstructures replication. Compared with the system with rigid roller press, gasbag-roller can increase the contact area and ensure the conformity of contact between the mold and the substrate. The exposure time can also be prolonged to ensure the complete curing of patterns before detaching from the mold. The gasbag-roller-assisted UV-based imprinting process can increase the rolling speed and the productivity.
The gasbag-roller-assisted UV imprinting system is further employed to replicate nanostructures on the non-planar substrate. Anodic aluminum oxide (AAO) template is embossed on the PC film. PDMS mold with nanostructures is then cast from the AAO template and used as the mold. The results show that AAO nanostructures can be successfully fabricated on the curved surface. The anti-reflection characteristic of nanostructures on the curved surface is measured. The reflectivity of AAO nanostructures on the PMMA curved surface is reduced to below 2 % at wavelength of 300 nm – 800 nm.