Surface mounted EMC gaskets
Surface mounted gaskets such as electrically conductive elastomeric gaskets, knitted wire mesh conductive fabric over foam, beryllium copper finger strips etc, aim to compress the gasket between 10% and 50%, 10% being the minimum with a solid conductive elastomer style of gasket and up to 50% with a hollow tubular or cellular styles.
Some form of compression stop or limit is essential with surface mounted gaskets to eliminate the possibility of over compression. These compression stops can be built into many styles of gaskets or made as an integral part of the flange and their height should be equal to that of the maximum compressed height of the gasket.
Conductive fabric over foam and beryllium copper fingers can be compressed further than mesh and elastomeric gaskets but lack the benefits of environmental sealing.
Very small land widths can be gasketed with a “form in place” conductive elastomer bead deposited directly to the gasket surface. This technology is particularly suited to gasketing complex multi compartment labyrinth machined enclosures. Bead sizes can be from 0.5mm wide, electrically conductive and non-conductive beads are available or in tandem to give EMI and environmental sealing.