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Method for decreasing electromagnetic leakage through enclosure seams

IP.com Disclosure Number: IPCOM000007553D
Publication Date: 2002-Apr-04
Document File: 3 page(s) / 36K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for decreasing electromagnetic leakage through enclosure seams. Benefits include improved design environment, improved productivity, and improved reliability.

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Method for decreasing electromagnetic leakage through enclosure seams

Disclosed is a method for decreasing electromagnetic leakage through enclosure seams. Benefits include improved design environment, improved productivity, and improved reliability.

Background

              Processor and chipset operating frequencies continue to increase. To cost-effectively meet the increasing electromagnetic interference (EMI) requirements, advances in EMI containment are required. Enclosure slots and apertures must decrease to keep pace with the smaller wavelengths (higher frequencies). For example, a slot that is 2 inches in length may attenuate frequencies at or below 100 MHz very effectively. However, for frequencies in the GHz range, this slot offers very little EMI attenuation, especially at its resonant frequency. In a shielded enclosure, the shielding effectiveness of the slot decreases as frequencies increase. These slots (seams) are common in enclosures in which metal panels connect. However, to provide good EMI containment for high frequencies, conductive gaskets are often used.  These gaskets work well, but are expensive, require extra assembly costs (more than $1 per foot), and can adversely affect product quality when misaligned or bent.

              A U-seam is a method of attaching two sheet metal edges together so that one edge bends tightly around the other (see Figure 1). This tight U-shaped bend traps EMI inside the enclosure. Its performance is governed by the geometry of the seam including the...