Study on non-isothermal hot-embossing of polymer micro-prism array with efficiency and accuracy

Abstract

The isothermal hot-embossing leads to inefficiency because of heating and cooling whole polymer workpiece for precision micro-forming. Hence, a non-isothermal hot-embossing is proposed by compressing and melting a micron-scale surface layer into heated core microgrooves without changing the solid-state workpiece. The objective is to understand how the upper layer micro-prism array is formed on large-size polymer surface with regard to core microgroove parameters and hot-embossing variables. First, the micro-prism shape and sizes were in-process modeled through a hybrid of mechanical compression and hot-melt flowing inside core microgrooves; then the micro-grinding with the trued wheel micro-tip was employed to fabricate various microgrooves on macro-size die cores; finally, the micro-forming accuracy and efficiency were experimentally investigated in hot-embossing. It is shown that the integrated micro-prism array with nanometer-scale surface roughness is rapidly generated inside accurate and smooth core microgrooves with 1–3 seconds. The micro-forming accuracy is dominated by the hot-embossing variables under the limitations of core microgroove parameters. Moreover, the hot-embossed surface roughness reaches 10–30 nm through the hot-melt layer flowing even if the core surface roughness is larger. It is confirmed that the rapid micro-forming sizes and surface roughness may be predicted by the micro-nano core topographies and the hot-embossing variables.