Influence of Gravitational Orientation on the Formation of Electrodeposited Copper Wicks

Porous wicks ensure capillary liquid transport in heat pipes and vapour chambers. Manufacturing them through electrochemical deposition is a promising method that yields competitive results. The gravitational orientation during electrochemical deposition, however, has rarely been taken into consideration. In this study, the effect of deposition orientation relative to gravity on the capillary performance of electrodeposited copper wicks was investigated. In total, 24 samples were prepared in three configurations defined by the angle between the cathode surface normal and gravitational acceleration: Top (22.8°, downward-facing), Vertical (90°, sideways-facing), and Bottom (157.2°, upward-facing). All other electrodeposition conditions were kept identical. Capillary performance was evaluated for 5 samples per configuration using a capillary lift rate test. The Top configuration achieved up to 44.8% greater mean capillary lift height than the Bottom configuration after 5 s. The Bottom and Vertical configurations exhibited similar capillary rise behaviour, whereas Top samples reached 15 mm in 19.4 s, compared with 42.9 s and 41.4 s for the Bottom and Vertical configurations, respectively. These results suggest that gravitational orientation affects the capillary performance of electrodeposited copper wicks and should be considered during their fabrication.