Electrical probing for dimensional micro metrology

Each dimensional measurement is based on probed points on the surface of the measured object. However, the well-established tactile and optical probing techniques face limitations when small and delicate objects with complex shape have to be measured. With tactile measurements there is always the danger of damaging the workpiece by the probing force and the measurable point rate is quite low. With optical probing there is a principal resolution limit and accessibility to complex surfaces is hindered by the limited acceptable surface slope. Also undercuts are not measurable. To overcome these limitations a probing system based on an electrical probing interaction with a direct current of a few nanoamperes has been developed, tested and compared with traditional technologies. With this probing system coordinate measurements of micro parts as well as nanometer resolved surface topography measurements are feasible. By applying a wide range of probes accessibility problems can be drastically reduced compared to tactile or optical micro probing systems. (C) 2008 CIRP.