Surface conditioning of ABS for metallization without the use of chromium baths

Surface conditioning (also referred to as etching) of plastics prior to metallization is generally conducted with sulfuric/chromic acid solutions. Although these baths perform well technically, the presence of Cr(VI) imposes serious operating problems of an environmental nature. The present work reports the results of a study of surface conditioning of acrylonitrile-butadiene-styrene (ABS) using solutions based on sulfuric acid, with hydrogen peroxide and/or nitric acid, replacing chromic acid, as oxidants. Process performance was evaluated by SEM and by the uniformity and adherence of electroless nickel coatings applied on selected conditioned samples. The results showed that the types of solutions evaluated could be optimized to perform as well as the chromic-based baths, however, providing a process which is far more environmentally friendly.