Thermal Degradation of Electroplated Nickel Thermal Microactuators

Luo, J. K., Fu, Yong Qing, Williams, John A. and Milne, William (2009) Thermal Degradation of Electroplated Nickel Thermal Microactuators. Journal of Microelectromechanical Systems, 18 (6). pp. 1279-1287. ISSN 1057-7157

Full text not available from this repository. (Request a copy)

Abstract

In this paper, the thermal degradation of laterally operating thermal actuators made from electroplated nickel has been studied. The actuators investigated delivered a maximum displacement of ca. 20 mum at an average temperature of ~ 450degC , which is much lower than that of typical silicon-based microactuators. However, the magnitude of the displacement strongly depended on the frequency and voltage amplitude of the pulse signal applied. Back bending was observed at maximum temperatures as low as 240degC. Both forward and backward displacements increase as the applied power was increased up to a value of 60 mW; further increases led to reductions in the magnitudes of both displacements. Scanning electron microscopy clearly showed that the nickel beams began to deform and change their shape at this critical power level. Compressive stress is responsible for nickel pileup, while tensile stresses, generated upon removing the current, are responsible for necking at the hottest section of the hot arm of the device. Energy dispersive X-ray diffraction analysis also revealed the severe oxidation of Ni structure induced by Joule heating. The combination of plastic deformation and oxidation was responsible for the observed thermal degradation. Results indicate that nickel thermal microactuators should be operated below 200degC to avoid thermal degradation.

Item Type:	Article
Uncontrolled Keywords:	Back bending, electroplating, oxidation, plastic deformation, thermal actuator, thermal degradation
Subjects:	F200 Materials Science
Department:	Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User:	Becky Skoyles
Date Deposited:	23 Mar 2015 10:16
Last Modified:	12 Oct 2019 19:06
URI:	http://nrl.northumbria.ac.uk/id/eprint/21669

Downloads