Effect of Flow Field Changes on Copper Deposition Layer during Jet Electrodeposition

In jet electrodeposition technology, the flow field is coupled with the electric field, and the flow field state and parameters are closely related to the quality of the deposition layer. The flow field state directly affects the mass transfer process of ions, further affecting the scale accuracy and micro morphology of the deposition layer. Previous research has mostly focused on the analysis of the performance and structure of electric fields and deposited materials, with limited analysis of the flow field state. The parameters that affect the flow field include flow velocity, jet height, nozzle, etc. The nozzle state can strongly reshape the flow field, directly affecting the mass and velocity fields of the flow field, and is particularly important. At present, further research is needed on the impact of changes in flow field parameters caused by nozzle shape changes on the apparent quality and microstructure of the deposition layer. The work aims to mainly explore the effect of flow field parameters of electroplating solution on the microstructure, roughness, localization, and deposition rate of copper deposition layer during jet electrodeposition process. The platinum wire was used as the anode and the nickel plate was adopted as the cathode. The electroplating solution flew out from the nozzle with the built-in anode platinum wire, contacting the nickel plate cathode. Under the action of an external electric field, copper ions were reduced to form a copper deposition layer. The jet state and flow field parameters were changed by controlling the nozzle shape, length width ratio (1∶1, 2∶1, 4∶1 and 6∶1), etc. The effect of changes in flow field parameters on the roughness, localization, and defects of copper deposition layers was analyzed by laser three-dimensional topography, scanning electron microscopy, COMSOL simulation, and other methods. When the nozzle area was fixed, the change of the aspect ratio of the rectangular nozzle significantly affected the roughness, nodular deposits, localization and internal defects of the copper deposition layer. When the aspect ratio was 1∶1, the roughness of the sedimentary layer was Sa=5.40 μm, the localization was poor, the deposition range was 192% of the nozzle width, and there were many nodular deposits. With the decrease of the aspect ratio, the surface roughness gradually decreased, the structure tended to be uniform, the nodule sediment also decreased, and the localization accuracy increased. When the aspect ratio was 6∶1, the roughness of the copper deposition layer was Sa=2.76 μm, the localization error was −1%, and the nodule deposits were significantly reduced. Scanning electron microscope (SEM) observation showed that when the aspect ratio was 6∶1, the microcracks and pores in the deposit layer were the least. COMSOL flow field was used to simulate the velocity distribution of the flow field under different aspect ratios, and the results were consistent with the experiment. The uniformity of velocity distribution in the flow field significantly affects the surface quality and internal structure of copper deposits. If the uniformity of flow velocity distribution in the flow field increases, the surface roughness of the sedimentary layer decreases, with bubbles, nodules, etc. decreasing, and the internal density increases. Sedimentary defects such as microcracks and micropores are significantly reduced. © 2024 Chongqing Wujiu Periodicals Press. All rights reserved.