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Proceedings Paper

New random trigger-feature for ultrashort-pulsed laser increases throughput, accuracy and quality in micromachining applications
Author(s): Andreas Oehler; Hubert Ammann; Marco Benetti; Dominique Wassermann; Beat Jaeggi; Stefan Remund; Beat Neuenschwander
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Paper Abstract

For most micromachining applications, the laser focus has to be moved across the workpiece, either by steering the beam or by moving the workpiece. To maximize throughput, this movement should be as fast as possible. However, the required positioning accuracy often limits the obtainable speed. Especially the machining of small and complex features with high precision is constrained by the motion-system’s maximum acceleration, limiting the obtainable moving spot velocity to very low values. In general, processing speed can vary widely within the same processing job. To obtain optimum quality at maximum throughput, ideally the pulse energy and the pulse-to-pulse pitch on the workpiece are kept constant. This is only possible if laser-pulses can be randomly triggered, synchronized to the current spot velocity. For ultrafast lasers this is not easily possible, as by design they are usually operated at a fixed pulse repetition rate. The pulse frequency can only be changed by dividing down with integer numbers which leads to a rather coarse frequency grid, especially when applied close to the maximum used operating frequency.

This work reports on a new technique allowing random triggering of an ultrafast laser. The resulting timing uncertainty is less than ±25ns, which is negligible for real-world applications, energy stability is <2% rms.

The technique allows using acceleration-ramps of the implemented motion system instead of applying additional override moves or skywriting techniques. This can reduce the processing time by up to 40%.

Results of applying this technique to different processing geometries and strategies will be presented.

Paper Details

Date Published: 20 February 2017
PDF: 9 pages
Proc. SPIE 10091, Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXII, 100910I (20 February 2017); doi: 10.1117/12.2252599
Show Author Affiliations
Andreas Oehler, Lumentum Switzerland AG (Switzerland)
Hubert Ammann, Lumentum Switzerland AG (Switzerland)
Marco Benetti, Lumentum Switzerland AG (Switzerland)
Dominique Wassermann, Lumentum Switzerland AG (Switzerland)
Beat Jaeggi, Bern Univ. of Applied Science (Switzerland)
Stefan Remund, Bern Univ. of Applied Science (Switzerland)
Beat Neuenschwander, Bern Univ. of Applied Science (Switzerland)

Published in SPIE Proceedings Vol. 10091:
Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXII
Beat Neuenschwander; Costas P. Grigoropoulos; Tetsuya Makimura; Gediminas Račiukaitis, Editor(s)

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