1. Micro-etching
The micro-etching process removes excess carbon from the copper surface and corrodes the copper surface by penetrating the carbon coating. This enhances the micro-rough surface provided by the carbon coating on the copper surface, increasing the bond with electroplated copper. Microetching fluids contain oxidizing agents such as persulfates or peroxides, acids and other additives. Etch rates vary with oxidant concentration and operating temperature or concentration of other ions and additives.
The micro-etch system minimizes the loss of clean copper surfaces. Especially applying high technology in the cleaning process of small holes or micro-blind vias on the inner layer copper, it is very important to improve the micro-etching performance through chemical changes and good adjustment. New additive achieves effective low etch rates of 10-20 microinches per minute on clean copper surfaces.
Another important carbon removal process should be micro-etching after a short water wash. Since long-term water washing or a little pickling will loosen the dried carbon particles, the cleaning process should be accelerated after micro-etching, and the best cleaning process conditions should be selected to prevent the reduction of the conductive layer on the surface of the medium.