An investigation on the sources of shielding degradation for gaskets with zinc coated steel enclosures

With the increase in CPU speeds, the performance of high speed boards are becoming more vulnerable to invasive EMI suppression techniques like filters and common mode chokes. Better enclosure design and effective electromagnetic sealing, using gaskets, have become one of the most important methods of EMI containment. This paper studies the shielding effectiveness of gaskets in zinc coated steel enclosures. The study looks into the chemical effects of corrosion around the gaskets and how it reflects on the gasket impedance over the frequency spectrum. In order to model the high frequency behavior, the skin effect loss is also taken into account.