Micro-electroforming high aspect ratio microstructures under magnetic field

High-aspect-ratio (HAR) micro-electroforming is a significantly challengeable implementation to manufacture metallic microstructures and microparts mainly due to mass transportation limitation effect. In this paper, flow pattern and flow rate change characteristics within HAR micro-cavity during electroforming under magnetic field are investigated, and evaluations of the electroformed micro-sized HAR nickel features under the improved magnetohydrodynamic (MHD)-governed condition are carried out. It was found that, five electrolyte flow-pattern zones can be formed within the horizontally placed micro-cavity under the MHD condition and favorable mass transfer effects can be created when the current field applied is perpendicular to the gravity field; HAR (≥ 7) nickel microstructure with good surface quality and few plating defects can be produced at a relatively high current density (up to 11 A/dm 2 ) under the combined actions of MHD-driven convection and external forced-convection; MHD-assisted nickel micro-electroforms have a higher microhardness, better surface morphologies and fewer defects than the ones obtained without the superimposition of the magnetic field. MHD-driven convection benefits the desirable implementation of HAR micro-electroforming processes.