VTI Vacuum Technologies recently partnered with William D. Kimmel, PE (principal in the engineering consulting firm of Kimmel Gerke Associates) on a white paper that was written to educate people in related industries who aren’t familiar with how shielding works. The technical paper, EMC Shielding Simplified, explains the fundamentals of the EMC shielding process. The whitepaper discusses basic physics and concepts to ensure shielding effectiveness, as well as the shielding materials used. In addition, the artile details how to make shielding work properly, some typical shielding failures and how to solve those failures.
EMC Shielding Simplified White Paper Intro
EMI shielding effectiveness analysis can take up whole books, but the basics can be covered easily, providing the reader with enough information to show where shields fail to perform as intended. As will be discussed, almost any reasonable conductor will provide adequate shielding effectiveness for the overwhelming majority of shielding needs. The key issue is the openings in the shield and the wires piercing the shield. This paper will start with a few concepts, using rules of thumb, to serve as the basis for the key issues in shielding effectiveness. This will be followed by a discussion of the shielding effectiveness of the material and the shielding failures and how to solve them.
EMC Shielding Simplified Technical Paper Summary
Effective shielding requires the openings be minimized, and the wire penetrations be blocked. The openings can be minimized by providing for positive conductive contact along the entire path, perhaps with the aid of EMI gasketing. The penetrations can be blocked using cable shields or filters placed immediately at the penetration point. Conductivity of shielding materials is almost never a pacing factor – you need to do a very good job on closing the openings and blocking the wire penetrations before the shielding material even enters into the equation. But make no mistake – if you don’t control the openings and penetrations, your shield won’t work.
More information: EMC Shielding Simplified Whitepaper