Measured mechanical properties of LIGA Ni structures

Room and elevated temperature tensile, creep and high-cycle fatigue properties of electrodeposited LIGA Ni microsamples have been measured and are being used to predict the reliability of LIGA Ni MEMS structures. Tensile specimens with dimensions of hundreds of microns have been LIGA fabricated and characterized in terms of their underlying microstructure, elevated temperature tensile and creep, strength and their high-cycle fatigue performance. The stiffness of these LIGA Ni structures was found to be reduced by the introduction of porosity during the plating process. The strength of these structures was observed to decrease dramatically at temperatures above 200 degreesC. At stresses significantly below the yield strength, substantial creep deformation was observed at moderately elevated temperatures. The fatigue life of the LIGA Ni microsamples increased with decreasing stress amplitude in a manner comparable to what has been reported for wrought Ni. An apparent fatigue limit was observed for the LIGA Ni microsamples, but the importance of underlying microstructure and component geometry on the fatigue life was also highlighted. (C) 2003 Elsevier Science B.V. All rights reserved.