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Mechanical Characterizations of Laser Microwelds for MEMS Packaging

Published online by Cambridge University Press:  01 February 2011

Wei Han  and
Ryszard J. Pryputniewicz
Wei Han
Affiliation:
NEST – NanoEngineering, Science and Technology CHSLT – Center for Holographic Studies and Laser micro-mechaTronics Mechanical Engineering Department Worcester Polytechnic Institute Worcester, MA 01609
Ryszard J. Pryputniewicz
Affiliation:
NEST – NanoEngineering, Science and Technology CHSLT – Center for Holographic Studies and Laser micro-mechaTronics Mechanical Engineering Department Worcester Polytechnic Institute Worcester, MA 01609
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Abstract

Laser micromachining has proven to be a very powerful and successful tool for precision machining and microfabrication with applications in electronics, MEMS, medical, and biomedical fields. For MEMS fabrication and packaging, several approaches based on localized heating and bonding have been proposed such as localized eutectic bonding, fusion bonding, solder bonding, and chemical vapor deposition (CVD) bonding. However, these approaches are based on resistive heating which requires intimate contact at the electrodes, and this is not preferred for MEMS packaging applications. As a good alternative, laser microwelding has advantages of non contact, low heat distortion, high speed, high precision, and consistent weld integrity. Therefore, it is finding increasing use in MEMS fabrication and packaging applications. In laser microwelding, the material in the HAZ of the workpiece experiences heating, melting, and re-solidifying stages, and the final characterizations of the laser microwelds can be influenced by various factors such as the laser beam properties, the system cooling condition, and the surface roughness/reflectivity of the component. This paper presents characterization of laser microwelds, with emphasis on study of deformation and strength of the microwelds made by a Nd:YAG pulsed laser. Optical interferometry is used to nondestructively record fringe patterns of the shape and deformation of the laser microwelded workpiece before, during, and after the microwelding process, and tensile tests are performed to study strength of the laser microwelds as a function of different welding parameters. Results indicate that quality of the laser microwelds depends on selection of an appropriate set of parameters controlling the microwelding process.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 782: Symposium A – Micro- and Nanosystems , 2003 , A5.82
Copyright
Copyright © Materials Research Society 2004

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References

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