Abstract: A plurality of through holes in a workpiece are filled with a solid conductive material. The workpiece is immersed in an electroplating solution, with the through holes covered at one end by a portion of a conductive plating base. The electroplating solution is permitted to fill the through holes in the workpiece and contact the portion of the conductive plating base. A voltage applied to the conductive plating base enables an electroplating operation that deposits the solid conductive material on the portion of the conductive plating base to thereby fill the through holes with the solid conductive material.