Polymer Jet Printing of SU-8 Micro-Dot Patterns on Si Surface: Optimization of Tribological Properties

Tribological properties of optimized SU-8 patterns (micro-dots with varying pitch) on Si (silicon) were evaluated using a ball-on-disk tribometer. Sliding tests on the patterns were conducted against a 2-mm diameter Si₃N₄ ball at varying normal loads and sliding velocities. It was observed that the pitch of the SU-8 pattern on Si substrate had a significant effect on the initial coefficient of friction and wear durability. Initial coefficient of friction studies have concluded that the SU-8 polymeric micro-dots improved the tribological properties by sharing the normal force and reducing the contact area. For the wear durability test, ultra-thin layer of perfluoropolyether was over-coated onto SU-8 micro-dot specimens, and the optimized pitch specimens have shown wear durability of more than 100,000 cycles at a normal load of 350 mN.