Backlight device fabricated by roll-to-roll nanoimprinting

In the high volume manufacturing long term stability of process the parameters is essential. In this work we demonstrate the fabrication of backlight device on 50 mm wide and 95 micron thick cellulose acetate (CA) web (from Clarifoil). Optical binary grating design and Ni-mold were produced by Modines Ltd. The fabrication process for flexible Ni-master is shown e.g. in ref. The size of backlight structure is 30 mm x 60 mm consisting a blocks of 5 micron wide cavities as shown in Fig. 1. More than 500 devices was printed on CA-film in continuous roll-to-roll process. Printing speed was varied from 0.1 to 1.0 m/min when temperature was maximized at 118 oC, which is close to the glass transition temperature (125 oC) of CA film. Pressure of ca. 20 MPa was applied in the process. These parameters were optimized for continuous printing process. Higher temperatures or pressures can lead to a break of the web, which prevents continuous processing. In this process we have used a custom made nanoimprinter device.