Q: How to implement shielding for EMI reduction in industrial enclosures?
Answer
EMI shielding implementation: (1) Conductive enclosure: aluminum die-cast or sheet aluminum (1.5-2 mm thick) provides >60 dB attenuation at 1 GHz. (2) RF gasket: compressible conductive gasket (fabric-over-foam or spring finger) around enclosure seams – compress 20-50% of free height. (3) PCB shielding: solder-down metal cans over noise sources (crystals switching regulators). (4) Ventilation: use honeycomb waveguide vents which act as waveguide below cutoff. (5) Cable shielding: braid coverage >85% for effective shielding. Bond shield to chassis with 360-degree circumferential connection (EMC cable gland or conductive gasket). (6) Apertures: maximum aperture dimension < lambda/20 at the highest frequency of concern (e.g. <1.5 mm at 10 GHz). Multiple small holes are better than one large slot. (7) Conductive coatings: copper/nickel spray for plastic enclosures.
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