Investigation of a copper etching technique to fabricate metallic gas diffusion media

A new fabrication technique based on etching is employed to convert a copper foil into a porous structure with an array of micron size pores. The motivation stems from the need to develop a more efficient and controllable gas diffusion medium for fuel cell applications. The influence of mask shape, mask width and etching time was investigated experimentally. A correlation to predict trench width with etching time was derived; normalizing by mask width allows one to collapse the data. The etching rates to obtain micro-scale features, which are of the order of 1–2 μm min–1, are mainly dominated by the mask width due to mass-transport resistance. It is possible to control the pore dimensions, porosity and pore size distributions with this technique. (Some figures in this article are in colour only in the electronic version)