The Use of Insoluble Anodes in Acid Copper Plating

ABSTRACT Electrolytic acid copper is the process that builds the traces that carry the current throughout the PWB. How to optimize your electrolytic acid copper plating for today’s designs. ( aspect ratios > 20:1 for thru hole and >1:1 aspect ratios for blind via fill) is the challenge. The use of insoluble (MMO coated titanium mesh) produces a consistent and reproducible plated product, it is environmentally friendly (eliminates waste) and eliminates anode maintenance thus increasing the productivity of the plating line. Vertical acid copper plating remains a very common way for plating wiring boards. For best results the equipment should be optimized with proper rectification and connectivity. The electrolyte and the additives used, current density of plating, all play a role in the copper thickness distribution on the plated panel. The anodes have a direct impact on copper thickness distribution. The anode shape, size and location play a critical role in the thickness distribution of the plated copper in vertical plating of panels in a tank. The vertical plating tank is challenging in its own way, unlike horizontal conveyorized plating where all the panels are exposed to the identical set of anodes as the part is conveyed thru the plating module. In horizontal plating if the anode setup is not optimum, the thickness distribution within the panel may vary, however the variation from panel to panel is eliminated.