Contact surface resistivity: its effect on shielding effectiveness

In order to reduce potential EMI leakage from seams of enclosures, gasketing is usually added to the seams in an attempt to seal them up. Conductive areas must be available for these gaskets to function properly. However, the problem is that normally exposed metal is not desirable due to problems with oxidation and/or corrosion and sometimes physical appearance. Therefore, many times a layer of conductive plating that covers the bare metal is added. It is the effect of this added plating finish that can and does impact the shielding effectiveness of the enclosure especially as operating frequencies continue to go higher.