High-speed roll-to-roll hot embossing of micrometer and sub micrometer structures using seamless direct laser interference patterning treated sleeves

In this study, we present a seamless high-speed roll-to-roll hot embossing process using a direct laser interference patterned nickel sleeve as a mold. Line-like patterns with spatial periods of 5.0, 3.9, and 1.5mm and structure heights of 572, 325, and 141nm, respectively are used for imprinting PET-foils. The influence of the web speed on the cavity filling and consequently on the structure height and homogeneity of the fabricated patterns is studied. The web speed is varied between 2 and 50mmin-1. For the 5.0 and 3.9mm periods, a decrease in structure height with the web speed occurs, while for the 1.5mm period the structure height remains constant in the tested interval. Also a decrease in homogeneity is observed with increasing web speed. Finally, an analytical model, based on the Navier-Stokes equation and Hertzian contact pressure, is used to explain the experimental results. The experimental data are in good agreement with the calculated theoretical values.