Laser-Based Micromachining Gets Practical
Micromachining with Nd:YAG and excimer lasers, with their short pulse duration and high peak power, have come of age in applications ranging from display technology to semiconductor manufacturing.
Paula M. Powell
According to professor Y. Lawrence Yao and colleagues at Columbia University in New York, laser-based micromachining has advantages in micron- and millimeter-scale processing of high-strength materials where mechanical methods are not strong enough and etching-based methods are too slow. Typical devices used in such applications are the Q-switched Nd-YAG laser with nanosecond pulse width — especially its third harmonic of 355 nm — and the excimer laser. Such tools offer short pulse duration and high peak power to limit heat-affected zones in the workpiece.
The following stories explore how micromachining with these two systems has come of age in applications ranging from display technology to semiconductor manufacturing. Specifically, this article will explore micromachining of glass for application in bar-code labeling, large-area micropatterning of polymers to facilitate light management in transflective displays and the trimming of embedded passives.
Large-area patterning of polymer LED displays. Courtesy of Exitech Inc.
Even as these techniques become cost-effective on a commercial scale, however, research continues into use of ultrashort-pulsed lasers in the pico- and femtosecond ranges. Scientists such as Yao also believe that more detailed modeling work is needed to predict optimal process conditions for micromachining of metals with pico- and femtosecond-pulse lasers.
One ongoing research project to take note of is Laser Forming of Complex Structures, which was partially funded late last year by the National Institute of Standards and Technologies (www.atp.nist.gov) in Gaithersburg, Md., through its Advanced Technology Program. Besides Columbia, the consortium involved in the project includes GE Global Research in Niskayuna, N.Y., Caterpillar Tech Center in Peoria, Ill., Native American Technologies in Golden, Colo., and A. Zahner Co. Inc. in Kansas City, Mo.
Scheduled for completion at the end of 2005, the $7 million project has the goal of “developing technologies for a controllable, repeatable laser forming process that can make and repair a wide range of complex sheet-metal, tubular and ductlike parts meeting specific requirements.” The impact of fine-tuning current micromachining technologies as well as new ones that are developed in the project could be significant.
According to the consortium researchers, “With time to market reduced by up to 50 percent and production costs of some parts reduced by up to 80 percent, US manufacturers in the metal-forming industry could save as much as $320 billion by 2010.
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