Plasma etching of polycarbonate surfaces for improved adhesion of Cr coatings

Polymers are widely used across multiple industries due to their distinct properties such as low density, tunable flexibility, ease of manufacture, and cost-effectiveness. The metallization of polymers by chromium (Cr) coatings allows such parts to replace decorative metal parts in the automotive industry. Good quality metallized polymer surfaces, however, are challenging to obtain. Several properties of the metal layers must be guaranteed, such as good adhesion, low pinhole and crack defect densities, high brightness, and intrinsic silver color. To overcome these challenges, different plasma etching treatments have been performed on polycarbonate (PC) substrates before the magnetron sputtering deposition of Cr coatings. Parameters such as bias voltage, pressure, and etching time were varied. The best plasma etching treatments in Ar atmosphere significantly improved the Cr coating quality.