Hot embossing of transparent high aspect ratio micro parts

Abstract

Accurate replications of complex, high aspect ratio nano and micro structured parts are still challenging due to the comparatively high surface-volume ratio. The critical process step of automated, undistorted demoulding in high precision replication techniques like hot embossing or thermal nano imprint require good process control at elevated temperatures just below the solidification of the thermoplastic material and higher adhesive forces of the polymer part to the substrate plate than to the structured tool insert. The required increase in interfacial surface to the substrate plate is typically done by a rough substrate plate which results in milky, in-transparent residual layer. We demonstrate a process modification which keeps the advantage of precise automated demoulding and allows for replication of micro structured parts with optically transparent residual layer even for high aspect ratio structures resulting in high demoulding forces.