A Laser-Assisted Bonding Method Using a Liquid Crystal Polymer Film for MEMS and Sensor Packaging

Abstract

In this paper, we present the development of a laser-based bonding method using a liquid crystal polymer (LCP) film for cavity-based packaging of sensors and Microelectromechanical systems (MEMS) devices. LCP films possess the best properties among polymeric materials in terms of moisture resistance and temperature stability. We show that high-quality bonding of silicon and glass substrates as well as encapsulation of molded LCP packages can be obtained using a laser-assisted bonding method. Shear and leak tests were carried out to demonstrate good quality of the laser-bonded microcavities and packages. In situ temperature monitoring was obtained by embedding a small temperature sensor just below the bonding interface of an LCP package. The average shear strength ranges from 20.8 to 26.1 MPa depending on the design configurations and bonding conditions. The results of the color liquid-based, and gross and fine leak-based tests show pin-hole-free bonding and good hermeticity. The results of the temperature monitoring work show the potential of the laserbased approach for low-cost packaging of temperature-sensitive devices in molded LCP packages. Index Terms-Laser joining, liquid crystal polymer (LCP) film, MEMS, packaging, sensors.2156-3950 © 2015 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission.Changhai Wang (M'12) received the B.Sc. degree in semiconductor physics and devices from Jilin University, Changchun, China, in 1985, and the M.Sc. degree in optoelectronic and laser devices and the Ph.D. degree in low-power all-optical switching devices from Heriot-Watt University, Edinburgh, U.K., in 1988 and 1991, respectively. He is currently a Lecturer in Electrical and Electronic Engineering with the School of Engineering and Physical Sciences, Heriot-Watt University. His current research interests include fabrication and assembly of microstructures, MEMS devices and sensors, MEMS and 3-D packaging, and laser-assisted methods for MEMS and electronics manufacturing.Wei Liu received the B.Sc., M.Sc., and Ph.D. degrees in materials science and engineering from the Harbin Institute

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