Institute of Micro Production Technology, Leibniz University Hannover, Germany
Methods: a) Confocal Laser Scanning Microscopy b) Nanoindenter AFM Mode c) Stylus Profilometer d) White Light Interferometry e) Jupiter AFM, Oxford CLSM: A VK9700 from Keyence was used for the analysis. A 50x objective with a numerical aperture of 0.95 was used for the measurements. A z-step size of 0.01 µm was chosen. Two random locations were measured per sample. For the analysis, the analysis software of the company Keyence in version 3.1.1.1 was used. The surface roughness were calculated for an area of 200x200 µm and the cut-off filters λc and λs were selected based on the built-in filter function according to ISO 4288-1997. For the line roughness, lines were created with a single measurement distance of 0.25 mm and an average for 20 lines was calculated. The cut-off filters were selected and applied as before using the ISO. For both analytical methods, the mean value was calculated from the two recorded measuring points per sample. Nanoindenter AFM Mode: The measurements were carried out in the AFM mode of a Hysitron TI 900 triboindenter. A Northstar tip with a tip radius of 50 nm was used. AFM images with 0.08 Hz, 0.1 Hz and 0.2 Hz were acquired per sample with an area of 20 x 20 µm², a setpoint of 2 µN and a resolution of 256 x 256 px. Ra and Rq were determined, averaged from the recorded values and the standard deviation was calculated. For this purpose, a linear and a non-linear regression were carried out. Stylus Profilometer: A Dektak³ST Stylus Profilometer from Veecko was used for the analysis. A contact force of 9 mg and a measuring length of 2000 µm were selected. Three measuring points per sample were measured and averaged. Low mode was selected for the speed setting and High for the data resolution. The tip radius was 2.5 µm. White Light Interferometry The White Light Interferometer from the company Wyko was used for the analysis. Three measuring points were measured per sample and the roughness values were calculated at two points for each measuring point. This results in six measured values from which the mean value was calculated.