Electroless copper plating on PC engineering plastic with a novel palladium-free surface activation process

This paper proposes a new available palladium-free surface activation process on polycarbonate (PC) engineering plastic before electroless plating. Surface morphologies of the original plastic, activated plastic, surface and cross-sections after electroless plating were analyzed by field emission scanning electron microscopy (FE-SEM), energy dispersion spectrometry (EDS) and X-ray diffraction (XRD). The growth mechanism of copper layers was discussed. Results show that numerous folds, uneven steps, and other defects appear on the microscopic surface of activated plastic. After direct electroless plating, the plating layer on the plastic surface exhibits a closely bound granular distribution. Compared with the conventional pretreatment process, the plating layer possesses a similar morphology. The growth mechanisms are analyzed as follows: the reactant (Cu2 +) in the electroless plating solution disperses and is adsorbed by the plastic surface in the process of Cu plating. The Cu particles that settled form the nucleus and grow. The growth process involves repeated gathering of nano-level Cu grains to form physically agglomerated Cu granules. The Cu grains finally merge to allow closely bound and evenly distributed copper plating.