Date of Award

12-9-2009

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Aeronautics and Astronautics

First Advisor

Shankar Mall, PhD

Abstract

This research examines the physical and electrical processes involved in lifecycle failure of Microelectromechanical (MEMS) Radio-Frequency (RF) cantilever beam ohmic contact switches. Failures of these switches generally occur at the contact, but complete details of performance of microcontacts are difficult to measure and have not been previously reported. This study investigated the mechanics of microcontact behavior by designing and constructing a novel experimental setup. Three representative contact materials of varying microstructure (Au, Au5%Ru, Au4%V2O5) were tested and parameters of contact during cycling were measured. The Au4%V2O5, a dispersion strengthened material developed at Lehigh University, showed the most promise of the materials tested with the longest-life contact lasting more than 15.5 x 106 cycles. Evidence of time-dependent deformation and contact heating during cycling was noted in all materials tested. Material hardness was not proportional to contact lifetime or adhesive forces measured during testing. Surfaces of post-cycling contact surfaces were evaluated and failures were categorized by ductile or brittle separation characteristics. Separation characteristics were correlated by contact lifetime.

AFIT Designator

AFIT-DS-ENY-09-J03

DTIC Accession Number

ADA511098

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