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

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 laser-based approach for low-cost packaging of temperature-sensitive devices in molded LCP packages.