Localized electrodeposition micro additive manufacturing of pure copper microstructures

Abstract The fabrication of pure copper microstructures with submicron resolution has found a host of applications, such as 5G communications and highly sensitive detection. The tiny and complex features of these structures can enhance device performance during high-frequency operation. However, manufacturing pure copper microstructures remain challenging. In this paper, we present localized electrochemical deposition micro additive manufacturing (LECD-μAM). This method combines localized electrochemical deposition (LECD) and closed-loop control of atomic force servo technology, which can effectively print helical springs and hollow tubes. We further demonstrate an overall model based on pulsed microfluidics from a hollow cantilever LECD process and closed-loop control of an atomic force servo. The printing state of the micro-helical springs can be assessed by simultaneously detecting the Z-axis displacement and the deflection of the atomic force probe cantilever. The results showed that it took 361 s to print a helical spring with a wire length of 320.11 μm at a deposition rate of 0.887 μm s^-1, which can be changed on the fly by simply tuning the extrusion pressure and the applied voltage. Moreover, the in situ nanoindenter was used to measure the compressive mechanical properties of the helical spring. The shear modulus of the helical spring material was about 60.8 GPa, much higher than that of bulk copper (∼44.2 GPa). Additionally, the microscopic morphology and chemical composition of the spring were characterized. These results delineate a new way of fabricating terahertz transmitter components and micro-helical antennas with LECD-μAM technology.