Method of operating an electroplating cell with hydrodynamics facilitating more uniform deposition on a workpiece with through holes

A method for electrodepositing a metal on a workpiece, the workpiece serving as a cathode, the workpiece having at least one through hole extending from a first major surface of the workpiece to a second major surface of the workpiece comprising:

• providing a plating cell comprising:
• an electrolyte solution containing metal ions,
• a workpiece holder, the workpiece holder defining a plane,
• on each side of the plane defined by the workpiece holder an anode that is housed in an anode chamber of a size greater than the workpiece,
• on each side of the plane defined by the workpiece holder a solution flow dampening member coextensive with the anode chamber on the same side of the plane, each solution flow dampening member including a flow-directing surface longer than the workpiece,
• on each side of the plane defined by the workpiece holder at least one eductor adapted to eject electrolyte solution toward the flow-dampening surface of the flow dampening member on the same side of the plane, and
• valves for modulating the flow of the electrolyte solution to the eductors;
• mounting the workpiece on the workpiece holder;
• passing the electrolyte solution from the eductors over the flow-directing surfaces of the solution flow dampening members to produce a solution flow that is uniform and parallel to both the first and the second major surfaces of the workpiece;
• adjusting the valves such that the flow velocity of the electrolyte solution that passes over the first major surface of the workpiece is greater than or less than the flow velocity of the solution that passes over the second major surface of the workpiece so as to induce electrolyte solution to flow through the at least one through hole;
• and
• passing an electric current between the anode and the cathode whereby the metal ions in the electrolyte solution are deposited on the workpiece and the through hole.