Nanoindentation study of plasticity length scale effects in LIGA Ni microelectromechanical systems structures

This paper presents the results of a nanoindentation study of the effects of strain gradient plasticity on the elastic–plastic deformation of lithographie, galvanoformung, abformung (LIGA) Ni microelectromechanical systems (MEMS) structures plated from sulfamate baths. Both Berkovich and North Star/cube corner indenter tips were used in the study to investigate possible effects of residual indentation depth on the hardness of LIGA Ni MEMS structures between the micro- and nanoscales. A microstructural length scale parameter, , was determined for LIGA nickel films. This is shown to be consistent with a stretch gradient length-scale parameter, l_s, of approximately 0.9 μm.