Title: Liquid crystal polymer for RF MEMS packaging

Authors: Faheem F. Faheem, Y.C. Lee

Addresses: Material Technology Group, Foster Miller, Inc., 350 2nd Avenue, Waltham, MA 02451, USA. ' Department of Mechanical Engineering, University of Colorado, Campus Box 427, Boulder, CO 80309, USA

Abstract: We have developed a Liquid Crystal Polymer (LCP) encapsulation technology for RF MEMS. The RF MEMS devices are flip-chip interconnected on 50 ohm microstrip transmission line on an alumina substrate. After flip-chip device transfer, LCP is used to encapsulate the device on the substrate. This approach is similar to glob-top encapsulation used for low-cost microelectronic packaging. The effectiveness of LCP (Vectra A950) sealing has been demonstrated by monitoring the moisture level inside the package under a 100% RH environment. In addition, the LCP|s permeabilities to helium and nitrogen were measured through a standard membrane characterisation setup. These permeabilities were proven to be in the same level as those of borosilicate glasses used for hermetic sealing at room temperature. LCP is an excellent encapsulation material for hermetic or near-hermetic packaging of RF MEMS.

Keywords: RF MEMS packaging; microelectromechanical systems; radio frequency MEMS; encapsulation; LCP; liquid crystal polymers; hermetic sealing; flip chip interconnections; hermetic packaging.

DOI: 10.1504/IJMPT.2009.022404

International Journal of Materials and Product Technology, 2009 Vol.34 No.1/2, pp.66 - 76

Published online: 04 Jan 2009 *

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