Micromachining of carbon materials and Laser Micropatterning of metal films used as masks for reactive ion etching

Abstract

Microstructured carbon materials are interesting for electrochemical systems such as micro fuel cell electrodes and flow fields. Glassy carbon (Sigradur G) can be microstructured by various methods such as sawing, laser machining, and reactive ion etching (RIE). An alternative for fuel cell applications is Sigracet, a graphite in a polymer matrix. Various laser wavelengths ranging from 308 to 1064 nm can be used for the micromachining of channels in both materials, but the use of UV wavelength results in channel structures with higher aspect ratios and less debris. Compared to glassy carbon, the ablation characteristic of Sigracet is much more inhomogenous, caused by the very different properties of the two components of this material. The lack of mechanical stability limits the line density for channels in Sigracet. Reactive ion etching in oxygen plasma is not a suitable method for structuring Sigracet, as the PVDF component inhibits the etching of the carbon.