Fabrication of Metallic Microstructures via Electrolyte-Confined Jet Electrochemical Deposition with Micro-Scale Ceramic Nozzle

Abstract Jet-electrochemical deposition (Jet-ECD) offers a unique advantage over thermal-driven additive manufacturing techniques for fabricating metallic microstructures in an athermal manner. However, traditional Jet-ECD always suffers from stray deposition, which limits its application in microelectromechanical systems, microelectronics, and biomedical sectors, where precise metallic microstructures are required. We present a novel method of electrolyte-confined Jet-ECD to enhance microstructure quality. A micro-ceramic nozzle was used to supply electrolyte to the workpiece surface and a high-density electrically insulating fluid (perfluorotripropylamine) was used to confine flowing electrolyte within the processing area to improve deposition localization. Simulations and experiments demonstrated that the radial flow distance of electrolyte reduced with increasing inter-electrode gap, improving deposition localization. Additionally, the current density distribution shifted from Gaussian to flat-top, enhancing the shape accuracy. Furthermore, the workpiece was chemically treated with a hydrophobic layer to reduce electrolyte-workpiece adhesion to stabilize the electrolyte confinement effect during nozzle reciprocating motion. This treatment facilitated deposition of microstructures with high surface quality (surface roughness down to 0.018 μm). Finally, microstructures with high localization and shape accuracy were deposited, including micro-cylinder with diameter of 165 μm and aspect ratio of 5.5, thin-wall with width of 69 μm and aspect ratio of 1.9, and a micro-square pattern.