A comparison of the corrosion resistance of Cu-Ni-stainless steel multilayers used for EMI shielding

Metallic coatings used for electromagnetic interference (EMI) shielding must have a low electrical resistance, in order for them to provide effective electromagnetic wave shielding, as well as good corrosion resistance and adhesion, in order to guarantee the reliability of the electronic devices. The ordinary metallic coatings used for EMI shielding consist of a conductive layer, a corrosion resistant layer and a buffer layer. When metallic coatings are used for this purpose, the malfunctioning of the EMI shielding can easily occur because of the delamination of the coating layer induced by corrosion. Therefore, in this paper, the effects of multilayer stacking on the corrosion resistance were investigated. Several metals were deposited onto polycarbonate by RIF magnetron sputtering. The structural characteristics of the resulting film were investigated by means of X-ray diffiractometry (XRD) and scanning electron microscopy (SEM). The protection of the copper film. by the multilayer was examined by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution. The results obtained from the potentiodynamic polarization and EIS measurements showed that the outer layer of duplex stainless steel afforded better protective efficiency than the other layers. (c) 2006 Elsevier B.V. All rights reserved.