Alternative technology for fabrication of nano- or microstructured mould inserts used for optical components

Abstract

For mass production of multiscale-optical components, micro- and nanostructured moulding tools are needed. Metal tools are used for hot embossing or injection moulding of microcomponents in plastics. Tools are typically produced by classical forming processes such as mechanical manufacturing e.g. turning or milling, laser manufacturing or electrical discharge machining (EDM). Microstructures with extremely tight specifications, e.g. low side wall roughness and high aspect ratios are generally made by lithographic procedures such as LIGA or DPW technology. However, these processes are unsuitable for low-cost mass production. They are limited by the exposure area and structure design. In cooperation with international partners alternative manufacturing methods of moulding tools have been developed at the Institute of Microstructure Technology (IMT). In a new replication procedure, mould inserts are fabricated using micro- and nanoscale optics. The multiscale structured prototypes, either in plastics, glass, metal or material combinations are used as sacrificial parts. Using joining technology, electroforming and EDM technology, a negative copy of a prototype is transferred into metal to be used as a moulding tool. The benefits of this replication technique are rapid and economical production of moulding tools with extremely precise micro- and nanostructures, large structured area and long tool life. Low-cost mass replication is possible with these moulding tools. In this paper, an established manufacturing chain will be presented. Multiscale and multimaterial optical prototypes e.g. out-of-plane coupler or microinterferometer were made by DPW or laser technology. The mould insert fabrication of each individual manufacturing step will be shown. The process reliability and suitability for mass production was tested by hot embossing.