The feasibility of ultrasonic bonding for hermetic microelectromechanical systems (MEMS) packaging has been demonstrated utilizing the solid phase vibration and welding process to bond two elements rapidly at low temperature. Two different approaches have been developed including lateral and vertical ultrasonic bonding setups with three sets of material bonding systems: In-to-Au, Al-to-Al, and plastics-to-plastics. The process utilizes purely mechanical vibration energy to enable low temperature bonding between similar or dissimilar materials without precleaning of the bonding surfaces. In these prototype demonstrations, the typical bonding process used tens of Watts at room temperature environment and the bonds were accomplished within seconds for bonding cavities with areas of a few mm2. Preliminary tests show that packaged MEMS cavities can survive gross leakage tests by immersing the bonded chip into liquids. As such, ultrasonic bonding could potentially be broadly applied for hermetic MEMS sealing and packaging especially where temperature limitation is a critical issue. Ultrasonic polymeric bonding could be applied for capping polymer-based microfluidic chips. This paper describes the ultrasonic bonding and hermetic sealing processes as well as the characterizations of bonding tools and equipment setups.
Bibliographical noteFunding Information:
Manuscript received November 30, 2007; revised October 07, 2008. First published March 16, 2009; current version published May 28, 2009. This work was supported by Seoul R&BD Program under Grant GR070039 and Grant 11032. This work was recommended for publication by Associate Editor A. Chiou upon evaluation of the reviewers comments. J. Kim and B. Jeong are with the School of Mechanical Engineering, Yonsei University, Seoul 120-749, Korea (e-mail: firstname.lastname@example.org). M. Chiao is with the Department of Mechanical Engineering, University of British Columbia, Vancouver, BC, V6T 1Z4 Canada. L. Lin is with the Berkeley Sensor and Actuator Center, University of California, Berkeley, CA 94720 USA. Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TADVP.2008.2009927
All Science Journal Classification (ASJC) codes
- Electrical and Electronic Engineering