Wettability enhancement by rough surfaces generated by thin film technology

Wettability is a very important property of surfaces, especially in microsystem applications. It can be manipulated directly by surface properties-especially by the roughness of the surface. The wettability of smooth hydrophilic surfaces is improved by L roughening them. The contrary effect is observed with smooth hydrophobic surfaces-by roughening, the contact angle will increase. In this article, a thin film process with excellent edge coverage is demonstrated. A sputtered tin (Sri) layer forms a reproducible. well-defined rough surface with an average roughness of approximately 188 nm. Wettability can be manipulated in a wide range with a Wenzel-relation of approximately r = 2.6. (C) 2003 Elsevier Science B.V. All rights reserved.