Extrusion Roller Imprinting with a Variotherm Belt Mold

Raymond Frenkel,Byung Kim,Donggang Yao

doi:10.3390/machines2040299

Raymond Frenkel, Byung Kim + Show 1 more

Open Access

https://doi.org/10.3390/machines2040299

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Abstract

Although many precision fabrication techniques have demonstrated the ability to produce microstructures and micro-devices with sub 100 nm accuracy, we are yet to see a scalable manufacturing process for large-area production. One promising solution to scalable micro- and nanofabrication is thermal roller imprinting. However, existing investigations on thermal roller imprinting revealed poor pattern transfer fidelity, especially for high aspect ratio features. The standard roller imprinting process suffers from the lack of an effective holding and cooling stage so that the adverse effects from the viscoelastic nature of polymers are not managed. To rectify this problem and further improve the production rate, a new extrusion roller imprinting process with a variotherm belt mold is designed, and its prototype was established at a laboratory scale. The process testing results demonstrate that a 30 μm sawtooth pattern can be faithfully transferred to extruded polyethylene film at take-up speeds higher than 10 m/min. The results are promising in that microfeatures or even nanofeatures may be successfully replicated by a robust and scalable industrial process suitable for large-area, continuous production.

Highlights

Roll-to-roll imprinting, or roller imprinting, represents a category of micro-replication processes where roll-to-roll engagements are utilized for continuous replication of micro- and nanostructures onto polymer substrates
The extruded polymer film is imprinted between the belt mold and the pressure roller
A variotherm extrusion roller imprinting system that is specially designed for continuous production of large-area micro- and nanostructures on polymer substrates is described

Summary

Introduction

Roll-to-roll imprinting, or roller imprinting, represents a category of micro-replication processes where roll-to-roll engagements are utilized for continuous replication of micro- and nanostructures onto polymer substrates. Fagan et al [10] demonstrated that a belt mold can be rapidly heated by induction heating, and a temperature difference of more than 200 °C can be achieved in continuous roller imprinting. With this imprinting system, they were able to replicate both micrometer and sub-micrometer patterns at a film feed speed exceeding 1.5 m/min. The extrusion speed and the roller speed can be independently controlled yet synchronized so as to impart a suitable tension and microstructural development on the film Due to these similarities, the broad knowledge base developed in conventional polymer processing may be adapted to the new micro- and nanofabrication process. The feasibility of the overall manufacturing system was tested, and continuous production of microstructured polyethylene film was established

Design of Variotherm Extrusion Roller Imprinting Process

Rapid Thermal Cycling of Belt Mold

Experimental Investigation

Conclusions