Direct 3D microprinting of highly conductive gold structures via localized electrodeposition. (March 2023)

• Record Type: Journal Article
• Authors: Schürch, Patrik; Osenberg, David; Testa, Paolo; Bürki, Gerhard; Schwiedrzik, Jakob; Michler, Johann; Koelmans, Wabe W.
• Is Part Of: Materials & design. Volume 227(2023)
• Publication Date: 2023-03
• Subjects: 3D microprinting -- Additive micromanufacturing -- Electrodeposition -- Electrochemical 3D printing -- Conductivity -- FluidFM; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2023.111780
• Languages: English
• ISSNs: 0264-1275

Abstract

Graphical abstract: Highlights: A room-temperature, 3D microprinting process is introduced that produces void-free gold microstructures using localized electrodeposition and cyanide-free chemistry. The vertical printing rate of the gold is controlled using the electrodeposition potential and goes up to 1.2 µm s −1 . The printing throughput of the gold is controlled using air pressure and reaches up to 20 µm 3 s −1 . The as-deposited resistivity of the gold is 2.5 times higher than bulk and that of the copper only 10 % higher than bulk. Abstract: Directly 3D-printed metal microstructures could enable hybrid micromanufacturing, combining conventional micromanufacturing with additive micromanufacturing (µAM). The microstructure's material properties, including the electrical resistivity, are of decisive importance for a wide range of applications in microelectronics, high-frequency communication, and biomedical engineering. In this work, we present a room-temperature process for µAM of gold structures based on local electrodeposition. We demonstrate control of the electrodeposition process by regulating the precursor species supply rate through air pressure and by regulating the reaction rate through the electrodeposition potential. We 3D printed complex gold microscale structures and characterized the resistivity of the printed gold by developing hybrid devices with integrated four-point probe measurement capability. Additionally, we printed copper microwires, building on a previously shown copper µAM process, and characterized the copper resistivity. We demonstrate near-bulk resistivity values of 65 nΩ·m (about 2.5 times higher than bulk) and 19 nΩ·m (only 10% higher than bulk) for the gold and copper wires, respectively, without post-treatment. Microstructural analysis of the gold wires revealed a dense metal deposit free of voids. Finally, we printed gold structures on a pre-patterned substrate, paving the way to hybrid devices in which additive micromanufacturing is combined with existing micromanufacturing techniques.