Anisotropic wetting of copper alloys induced by one-step laser micro-patterning

• Published in: Applied surface science Vol. 263; pp. 416 - 422
• Main Authors: Hans, M., Müller, F., Grandthyll, S., Hüfner, S., Mücklich, F.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-12-2012; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Contact angle; Copper; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Laser Interference Metallurgy; Physics; Surface functionalization; Wetting; PSD; Surface functionalization; Wetting; WLI; Laser Interference Metallurgy; Contact angle; Copper; LIMET; LISS; CA; Patterning; Copper alloys; Transition elements; Step; Metallurgy
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2012.09.071

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► One-step, contactless micro-patterning of copper alloys has been achieved. ► Anisotropic wetting properties are tailored by line-like structures. ► Both topographical and chemical patterns contribute to the phenomenon. ► The topographic shape and homogeneity are found to be governing factors.
Copper alloys (CuSn8, CuZn23Al3Co) have been micro-patterned with line-like geometries by Laser Interference Surface Structuring (LISS). In the presented study two high power pulsed laser beams are recombined to create unique, line-like intensity distributions with a chosen, constant periodicity of 10μm at varying laser fluencies. Anisotropic wetting properties on these surfaces have been confirmed by drop shape analysis and static contact angle measurements, which were conducted parallel and perpendicular to the structures revealing up to 25% difference in contact angle. The topography and chemistry of the tailored line structures have been characterized and analyzed by white light interferometry, spatial frequency distribution, AFM and X-ray photoelectron spectroscopy. The topographic shape and homogeneity are considered as key parameters for anisotropic wetting design, although it is concluded that both, the geometry as well as the locally varying chemical composition of the surface structures contribute to the phenomenon. Parallel capillarity effects and perpendicular contact line pinning are found to be the governing mechanisms.