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Laser Micro-machining Process-monitoring Technologies  

Sohn, Hyon-Kee (Korea Institute of Machinery & Materials)
Lee, Jae-Hoon (Korea Institute of Machinery & Materials)
Hahn, Jae-Won (School of Mechanical Engineering, Yonsei Univ.)
Kim, Ho-Sang (Institute for Advanced Engineering)
Publication Information
Journal of the Korean Society for Precision Engineering / v.27, no.2, 2010 , pp. 34-39 More about this Journal
Abstract
In order to achieve and maintain dimensional accuracy in laser micro-machining, dominant parameters such as laser power and laser focus position need to be monitored and controlled real time. Also, in order to selectively machine multi-layered materials, the material being presently machined need to be recognized. This paper presents an auto-focusing (AF) module to keep laser focus on a large-area surface; a real-time laser power stabilizing module based on optical attenuation; and a laser-induced breakdown spectroscopy (LIBS) module. With these monitoring modules, position error in laser focus on a 4" silicon wafer was kept below $4{\mu}m$, initially $51{\mu}m$, and laser power stability of a UV laser source was improved from 1.6% to 0.3%. Also, the material transition from polyimide to copper in machining of FCCL (flexible copper clad laminate) was successfully observed.
Keywords
Auto-focusing; Laser Power Stabilization; Laser Induced Breakdown Spectroscopy;
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