Continuous roll-to-flat thermal imprinting process for large-area micro-pattern replication on polymer substrate

Conventional imprinting process in flat-pressing mode meets with the problem of limited efficiency as a discontinuous batch-wise process in many new applications that demand micro-/nano pattern replication over large area with low cost and high throughout in mass production manufacturing. To overcome such problem, alternative imprinting process in a continuous roller-pressing mode has been gaining more attention since it has many advantages. However, few studies have been reported on the investigation of filling mechanism in roller-pressing type imprinting process. In order to have a better understanding of polymer flow behavior in roller-pressing type imprinting process, it is necessary to establish a criterion of evaluation for roller-pressing type imprinting process. In this paper, an analytical model for the cavity-filling of polymer flow in roll-to-flat (R2F) imprinting process is derived based on Hertz contact pressure distribution and Navier–Stokes equation. The feasibility of the model is evaluated using a lab-scaled prototype of a R2F micro thermal imprint system for micro-pattern replication over large area on polymer substrate. Series of tests are conducted to investigate the effects of process control parameters on the replication ratio. In results, there is good agreement between the model prediction and experiments when pattern replication is examined according to the change of control parameters such as rolling speed and loading pressure.