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Study on process of electroless palladium plating on copper

The process of electroless palladium plating on surface of copper was studied. The effects of plating temperature and time on bath's p H as well as deposition rate, porosity, and surface morphology of the deposit and its corrosion behavior in 3% Na Cl solution were studied by gravimetric method, ferroxyl method, scanning electron microscopy(SEM), and electrochemical polarization curve measurement, respectively. The composition and structure of the deposit were characterized by energydispersive spectroscopy(EDS) and X-ray diffraction(XRD). The suitable temperature and time for electroless palladium plating are 52 °C and 35 min, respectively. Under these conditions, the maximal deposition rate can be achieved as 1.16 mg/(cm2·h), and the deposit obtained is uniform and compact with a minimal corrosion current density, a maximal corrosion resistance, and a minimal corrosion rate. The palladium exists in a microcrystalline state in the deposit and it contains ca.5wt% phosphorus.