CUED Publications database

On the percussion drilling of SI using a 20W MOPA based YB fiber laser

Li, K and O'Neill, W and Gabzdyl, J (2010) On the percussion drilling of SI using a 20W MOPA based YB fiber laser. 29th International Congress on Applications of Lasers and Electro-Optics, ICALEO 2010 - Congress Proceedings, 103. pp. 1055-1063.

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Abstract

A study on the nanosecond fiber laser interaction with silicon was performed experimentally for the generation of percussion drilled holes. Single pulse ablation experiments were carried out on mono crystalline 650μm thick Si wafers. Changes of the mass removal mechanism were investigated by varying laser fluence up to 68 J/cm2 and pulse duration from 50 ns to 200 ns. Hole width and depth were measured and surface morphology were studied using scanning electron microscopy (SEM) and optical interferometric profilometry (Veeco NT3300). High speed photography was also used to examine laser generated plasma expansion rates. The material removal rate was found to be influenced by the pulse energy, full pulse duration and pulse peak power. Single pulse ablation depth of 4.42 μm was achieved using a 200 ns pulse of 13.3 J/cm 2, giving a maximum machining efficiency of 31.86 μm per mJ. Holes drilled with an increased fluence but fixed pulse length were deeper, exhibited low recast, but were less efficient than those produced at a lower fluence. The increased peak power in this case led to high levels of plasma and vapour production. The expansion of which, results in a strong driving recoil force, an increase in the rate and volume of melt ejection, and cleaner hole formation. The experimental findings show that for efficient drilling at a given energy, a longer, lower peak power pulse is more desirable than a high peak power short pulse.

Item Type: Article
Uncontrolled Keywords: Drilling Fiber laser Pulse profile Silicon
Subjects: UNSPECIFIED
Divisions: Div E > Production Processes
Div B > Photonics
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 12:11
Last Modified: 08 Dec 2014 02:39
DOI: