Fabrication of periodic surface micropatterns on polymers using nickel stamps processed with direct laser interference patterning

In this study, we present a simple single-step approach for fabricating micrometer structures on metallic hot embossing molds using direct laser interference patterning. Line-like patterns with spatial periods of 1.8 mm and 2.5 mm were structured on a nickel-mold and used for embossing a PET-foil. The influence of the laser parameters used on the structure height of the produced patterns on the metallic substrate as function of the spatial period was investigated. A rapid increase in structure height was observed to a specific laser fluence level from which it stays constant for both periods. Thermal simulations by finite element method were realized permitting to find a linear correlation between the measured structure heights and the simulated amount of molten material at the maxima positions of the interference pattern. Hot embossing of PET foils using the produced mold, considering the imprint time and temperature, were successfully performed. The results show that both the imprint temperature and time do not have any significant influence on the structure height of the imprints.