Fabrication of High-speed Signal Transmission Rigid Substrate by Silver-seed Copper Plating Technique

Cu signal transmission line with a flat and smooth substrate/copper interface and high adhesion strength was fabricated on a low-loss type rigid substrate by using newly developed silver-seed plating technique. The microstrip lines by silver-seed method showed better transmission characteristics than that fabricated with commercial CCL of same PPE type substrate. The importance of the surface morphology of conductor line for low signal transmission loss is experimentally confirmed. Silver-seed plating technique, which enables the formation of flat and smooth electric conductors, is expected to be useful for the formation of high-speed transmission wiring on a rigid substrate.