Selecting metal alloy electric contact materials for MEMS switches

• Published in: Journal of micromechanics and microengineering Vol. 14; no. 8; pp. 1157 - 1164
• Main Authors: Jr, Ronald A Coutu, Kladitis, Paul E, Leedy, Kevin D, Crane, Robert L
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.08.2004; Institute of Physics
• Subjects: Applied sciences; Electronics; Exact sciences and technology; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mechanical engineering. Machine design; Mechanical instruments, equipment and techniques; Microelectronic fabrication (materials and surfaces technology); Micromechanical devices and systems; Physics; Precision engineering, watch making; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Gold; Platinum; Wear; Properties of materials; Contact resistance; Electric contact; Selector switch; Experimental study; Modeling; Microelectromechanical device; Binary alloy; Thin film
• ISSN: 0960-1317; 1361-6439
• DOI: 10.1088/0960-1317/14/8/006

This paper presents a method for selecting metal alloys as the electric contact materials for microelectromechanical systems (MEMS) metal contact switches. This procedure consists of reviewing macro-switch lessons learned, utilizing equilibrium binary alloy phase diagrams, obtaining thin film material properties and, based on a suitable model, predicting contact resistance performance. After determining a candidate alloy material, MEMS switches were designed, fabricated and tested to validate the alloy selection methodology. Minimum average contact resistance values of 1.17 and 1.87 Omega were measured for micro-switches with gold (Au) and gold-platinum (Au-(6.3%)Pt) alloy electric contacts, respectively. In addition, 'hot-switched' life cycle test results of 1.02 X 108 and 2.70 X 108 cycles were collected for micro-switches with Au and Au-(6.3%)Pt contacts, respectively. These results indicate increased wear with a small increase in contact resistance for MEMS switches with metal alloy electric contacts.