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Ablation debris control by means of closed thick film filtered water immersion

Dowding, Colin and Lawrence, Jonathan (2010) Ablation debris control by means of closed thick film filtered water immersion. Proceedings of the Institution of Mechanical Engineers Part B: Journal of Engineering Manufacture, 224 (5). pp. 753-768. ISSN 0954-4054

Full content URL: http://dx.doi.org/10.1243/09544054JEM1711

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Ablation debris control by means of closed thick film filtered water immersion.
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Abstract

The performance of laser ablation generated debris control by means of open immersion techniques have been shown to be limited by flow surface ripple effects on the beam and the action of ablation plume pressure loss by splashing of the immersion fluid. To eradicate these issues a closed technique has been developed which ensured a controlled geometry for both the optical interfaces of the flowing liquid film. This had the action of preventing splashing, ensuring repeatable machining conditions and allowed for control of liquid flow velocity. To investigate the performance benefits of this closed immersion technique bisphenol A polycarbonate samples have been machined using filtered water at a number of flow velocities. The results demonstrate the efficacy of the closed immersion technique: a 93% decrease in debris is produced when machining under closed filtered water immersion; the average debris particle size becomes larger, with an equal proportion of small and medium sized debris being produced when laser machining under closed flowing filtered water immersion; large debris is shown to be displaced further by a given flow velocity than smaller debris, showing that the action of flow turbulence in the duct has more impact on smaller debris. Low flow velocities were found to be less effective at controlling the positional trend of deposition of laser ablation generated debris than high flow velocities; but, use of excessive flow velocities resulted in turbulence motivated deposition. This work is of interest to the laser micromachining community and may aide in the manufacture of 2.5D laser etched patterns covering large area wafers and could be applied to a range of wavelengths and laser types.

Keywords:KrF excimer laser, Ablation, Liquid Immersion, Debris Control, Flow Velocity, Bisphenol A Polycarbonate
Subjects:H Engineering > H680 Optoelectronic Engineering
F Physical Sciences > F361 Laser Physics
H Engineering > H700 Production and Manufacturing Engineering
H Engineering > H300 Mechanical Engineering
Divisions:College of Science > School of Engineering
ID Code:4031
Deposited On:17 Feb 2011 20:37

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