The Limits to Hardening Electronic Boxes to IEMP Coupling

Experimental investigations of the IEMP coupling processes within electronics enclosures have determined that there are practical limits to the effectiveness of IEMP hardening approaches. The use of low-electron-emission coatings or potting compounds and ground planes reduces the IEMP coupling to those processes which occur within the circuit boards themselves. Depending on the thickness of the circuit board, the IEMP coupling may be dominated by the bulk photocurrents emitted within the dielectric or the dipole layer formed over the metallic conductors. Results of this study indicate that IEMP also has a low-impedance coupling mechanism governed by secondary electrons which may be collected by circuit potentials as low as +5 volts.