An innovative shielding concept for EMI reduction

The design and realization of lightweight shields to reduce radiated emissions and electromagnetic interference (EMI) with sensitive electronic apparatus and systems is a challenge for electromagnetic compatibility (EMC) engineers. Techniques that are currently used to improve the shielding performances of light materials such as plastics and composites are: the insertion of conducting meshes in the substrate [1, 2], the use of conducting additives and fillers prior to injection molding [3, 4] and the use of conducting coatings [5-8]. Among these techniques the use of conducting coatings allows the realization of lightweight shields. The purpose of this paper is to demonstrate that thin coatings of conducting material, having thickness of a few micrometers, can provide good shielding performances in the radio-frequency range, up to a few gigahertz. The deposition of such coatings on polycarbonate foils leads to a new concept of lightweight thermoformable shield, which can be used to reduce EMI from and against printed circuit boards (PCBs) in electronic devices. Applications of the innovative shielding concept are in different fields, when the requirement of light weight is a stringent constraint in the design of the shields. Examples are: portable electronic devices (PEDs) such as cellular phones, walk-talkies, portable radios and CDs, equipment to be used or installed onboard aircraft, on satellites, etc..