The fabrication process begins with the deposition of a blanket Cu film on a Ti-coated Si wafer (Steps 1 and 2, Figure ). The Cu-coated substrate is then placed in a custom-built electrochemical 3D printer, where desired interconnect patterns are printed through the CED process (Step 3). At this stage, a pattern of Ni film is printed on the substrate . CED operates on the principle of localized electrochemical deposition. The process employs an aqueous electrolyte-filled nozzle to deposit thin films of metal or alloy on a conductive substrate, all controlled by a 3D positioning system. In this method, an electrolyte-filled nozzle, typically equipped with a metal electrode, is moved along predetermined paths above a substrate. An electric potential is applied between the nozzle electrode and the substrate, promoting the reduction of metal cations in the electrolyte to their metallic state. This results in the localized deposition of metal directly underneath the nozzle. Following the printing of the interconnect pattern, the blanket film is removed by wet etching (Step 4). This printed pattern serves as a seed layer for the subsequent electroless deposition process (Step 5). We utilized commercial Cu electroless plating solutions. In electroless plating, metal ions in a chemical solution are reduced onto the surface of the material, forming a metal coating. Unlike electroplating, which requires electrical input, electroless plating is solely reliant on a chemical reaction to induce metal deposition . In our process, the printed Cu confines Cu plating to the Ni traces printed on the substrate.