EMI SHIELDING: WHAT YOU NEED TO KNOW - AND WHY.

Contributions to ″electromagnetic pollution″ make computing devices a source of public annoyance as they persistently distort television reception and create bothersome static on the radio. Such devices (including various types of computers, electronic games, electronic watches and calculators) emit electromagnetic radiation; and, when not controlled, this radiation energy interferes with the electrical fields of radio communications sytems and also with other electronic devices. Plastic materials do not naturally conduct electricity and are therefore ″transparent″ to electromagnetic radiation. Thus, a plastic electronic enclosure must incorporate a conductive additive or a conductive surface coating in order to provide an effective barrier to electromagnetic interference, or EMI. This paper reviews techniques used for making plastics parts, that are used in electronic equipment as casing, conductive to electricity. Metallization is a common technique employed for EMI, shielding of plastics parts. Details on various metallurgy techniques are given.