Friction measurements on LIGA-processed microstructures

Abstract

A cantilever microactuator made of a ceramic fibre was used to load LIGA processed microstructures by pushing them over different substrates. Static and kinetic friction coefficients in air were determined for the interfaces between the LIGA-processed microstructures and the different substrates. Microrotors disassembled from electrostatic micromotors made of Cu and Ni have been used for the experiments. The substrate materials were amorphous Al₂O₃ and sputtered Ag on Cr. The experiments were carried out in a clean environment under class 100 conditions. Different cleaning methods and surface treatments have been applied and the influence on the coefficient of friction studied. It was found that the cleanliness of the surface and adsorbed gas layers have a substantial effect on the static friction results. This dependence was higher for Cu than for Ni. The kinetic and static friction appeared to be lowest for sliding on the Ag substrate and sliding of Ni on sputtered Ag exhibited the lowest coefficients of friction.