Surface structuring of metals and non-metals for printing tools and embossing dies with an ultrafast ps-laser machining system

摘要

With roll-to-roll processes, millions of reproductions (e.g. RFID-antennas or Fresnel-lenses) can be produced in a fast and economical way. The processing of replica tools for such printing and embossing applications requires in many cases sub-μm and μm-structures. Ultra-short pulse lasers with ps- and fs-pulse durations and in single pulse or burst mode operation are appropriate tools to generate this micro- or nanostructures. In recent years the ongoing development of this laser sources and of fast beam delivery optics allows higher ablation rates combined with a superior quality for several materials like copper and brass as well as glass and dielectrics. Different ps-laser systems at 10 ps with up to 80 W at 1064 nm with a pulse repetition rate up to 8 MHz and energies up to 50 μJ (at lower repetition rate) have been used in a micro-engraving system for large cylindrical workpieces. This setup allows the micro structuring of cylinder surfaces as well as the processing of thin film substrate sheets up to a thickness of approximately 300 μm. Dimensions up to 7 m face length and circumferences up to 1,3 m can be processed with an accuracy of about 1 μm. A variety of metals have been investigated by structuring 2D and 3D elements. The process is nearly melt-free, but the resulting surface structure of the ablated zone depends on the sort of metal. The high fluencies also enable the engraving of transparent materials which allow a much faster micro processing speed compared to metals. This work shows examples of micro-structuring melamine-resin coated cylinder surfaces and hybrid materials.