Reliability of Self-assembled Hydropobic Coatings: Chemical Resistance and Mechanical Durability

Keywords:
MEMS, hydrophobic, self-assembled, monolayers, stability, durability, resistance

Abstract:
We report on hydrophobic self-assembled monolayers (SAM) with an improved chemical and mechanical stability on both Al and Si substrates. These improvements are obtained using a relatively new molecular vapor deposition method - MVDTM, which integrates the vapor deposition process of self-assembled mono-layers with various surface preparation techniques and adhesion layers. The results of liquid immersion tests, performed with a standard set of chemicals used in biochemistry and mass spectroscopy, show excellent chemical stability. Mechanical durability is studied on FDTS (Perfluorodecyltrichlorosilane) films and compared to a perfluorinated-DLC layer deposited using conventional PECVD technology. A dry wipe test, performed on both films using an HP-990 Maintenance Blades tester, reveals improved long-term mechanical stability of the FDTS hydrophobic film under intense mechanical impact. Nano-indentation scratch tests were performed using brass and steel balls and compared with acoustic emission signal and coefficient of friction measurements to evaluate durability of the mono- and multi-layer films. We have confirmed that film durability is proportional to the number of layers in a stack.

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Nanotech 2006 Conference Program Abstract