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Abstract:

This paper describes the fabrication and experimental characterization of bent-beam (V-shaped) electrothermal actuators for use in microelectromechanical systems (MEMS). The actuators are of the polymer SU-8, a negative photoresist notable for its suitably large coefficient of thermal expansion, and are fabricated on FR-4 substrate, a typical printed circuit board material that is better matched to expanding SU-8 than the more commonly used silicon substrates. The fabrication technology used is ultraviolet lithography and electroplating, known by its German acronym UV LIG (Lithographie, Galvanoformung). These actuators have beams 6 to 10 mm across with widths of 200 to 400 µm and heights of roughly 800 µm for the structural SU-8 and 7 µm for the metal heating structures.

The focus of this work is on the effects of placing a nickel heating structure on the underside of the SU-8 beam as well as the fabrication challenges. This placement allows for electrical contacts to lie on the substrate and removes the difficulty of wire bonding. The resistance of this heating structure is measured with respect to geometry and the results suggest that surface roughness in the Ni due to the use of FR-4 substrate measurably affects the electrical resistance at film thicknesses less than 7 µm. Typical resistances of the nickel heating structures were measured to be roughly 3 - 5 Ohm for one geometry used and 0.4 - 0.8 Ohm for the other. Displacements of over 100 µm are achieved by the actuators at a power of 400 to 500 mW. The performance of this configuration is compared to the typical thin film on top heating method and shows that it is less energy efficient due to increased heat loss, creating a trade-off of simpler electrical connections but higher power consumption.

EMK-spezifische Daten:

Lagerort Dokument: Archiv EMK, Kontakt über Sekretariate,

Bibliotheks-Sigel: 17/24 EMKS 1733

Art der Arbeit: Studienarbeit

Beginn Datum: 05-10-2009

Ende Datum: 14-12-2009

Querverweis: keiner

Studiengang: Maschinenbau (Masch)

Vertiefungsrichtung: Studienrichtung unbekannt

Abschluss: Bachelor of science (BSc)