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Proceedings Paper

Scaling ablation rates for picosecond lasers using burst micromachining
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Paper Abstract

High-precision micromachining with picosecond lasers became an established process. Power scaling led to industrial lasers, generating average power levels well above 50 W for applications like structuring turbine blades, micro moulds, and solar cells. In this paper we report, how a smart distribution of energy into groups of pulses can significantly improve ablation rates for some materials, also providing a better surface quality. Machining micro moulds in stainless steel, a net ablation rate of ~1 mm3/min is routinely achieved, e.g. using pulse energy of 200 μJ at a repetition rate of 200 kHz. This is industrial standard, and demonstrates an improvement by two orders of magnitude over the recent years. When the energy was distributed to a burst of 10 pulses (25 μJ), repeated with 200 kHz, the ablation rate of stainless steel was 5 times higher with the same 50 W average power. Bursts of 10 pulses repeated with 1 MHz (5 μJ) even resulted in an ablation rate as high as 12 mm3/min. In addition, optimized pulse delays achieved a reduction of the surface roughness by one order of magnitude, providing Ra values as low as 200 nm. Similar results were performed machining silicon, scaling the ablation rate from 1.2 mm3/min (1 pulse, 250 μJ, 200 kHz) to 15 mm3/min (6 pulses, 8 μJ, 1 MHz). Burst machining of ceramics, copper and glass did not change ablation rates, only improved surface quality. For glass machining, we achieved record-high ablation rates of >50 mm3/min, using a new state-of-the-art laser which could generate >70 W of average power and repetition rates as high as 2 MHz.

Paper Details

Date Published: 23 February 2010
PDF: 6 pages
Proc. SPIE 7585, Laser-based Micro- and Nanopackaging and Assembly IV, 75850H (23 February 2010); doi: 10.1117/12.842318
Show Author Affiliations
Ralf Knappe, LUMERA LASER GmbH (Germany)
Hatim Haloui, LUMERA LASER GmbH (Germany)
Albert Seifert, LUMERA LASER GmbH (Germany)
Alexander Weis, LUMERA LASER GmbH (Germany)
Achim Nebel, LUMERA LASER GmbH (Germany)

Published in SPIE Proceedings Vol. 7585:
Laser-based Micro- and Nanopackaging and Assembly IV
Wilhelm Pfleging; Yongfeng Lu; Kunihiko Washio; Jun Amako; Willem Hoving, Editor(s)

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