Enclosure for electronic modules

• US 5,398,822 A
• Filed: 11/10/1993
• Issued: 03/21/1995
• Est. Priority Date: 06/04/1992
• Status: Expired due to Term

• Current Assignee: Enterasys Networks Incorporated (Extreme Networks, Inc.)
• Original Assignee: Digital Equipment Corporation (HP Inc.)
• Inventors: McCarthy, William F., Brench, Colin E., Snow, Daniel M.
• Primary Examiner(s): Chin-Shue, Alvin C.
• Assistant Examiner(s): Purol, Sarah L.
• Application Number:
  US08/150,608
• Time in Patent Office: 496 Days
• Field of Search: 211/41, 211/184, 361/809, 361/415
• US Class Current: 211/41.17
• CPC Class Codes: H05K 7/1414 with power interlock
• CPC Class Codes: H05K 7/1425 of standardised dimensions, e.g. 19"-subrack
• CPC Class Codes: H05K 9/0062 Structures of standardised dimensions, e.g. 19" rack, chassis for servers or telecommunications

Abstract

A Faraday shield minimizes the leakage of electromagnetic interference (EMI) and radio frequency interference (RFI) of a maximum frequency and corresponding wavelength that emanates from electronic components contained within the shield. The top and bottom each contain apertures that are dimensioned to effectively block the escape of EMI and RFI from the shield and to permit the flow of air to dissipate heat without generating acoustic noise. The thickness of the top of the shield is at least one half of the diagonal length across the largest of the apertures located in the top. The length of the longest aperture side is less than one fourth of the wavelength of the maximum frequency of EMI and RFI contained by the shield. Corresponding relationships exist between the apertures located in the shield bottom and its thickness.

Claims

1. A device for preventing damage to a card cage by a circuit board, said card cage having a top, a bottom, a first side, a second side, a back and a front, wherein said top contains a plurality of top channels and said bottom contains a plurality of bottom channels, each of said top and bottom channels having a right side wall, a left side wall and a bottom, said channel bottom being substantially perpendicular to said first side and said second side, said bottom of said bottom channels being plated with conductive material to form part of a Faraday shield for preventing EMI/RFI radiation leakage from said card cage, said channels being oriented so that each top channel corresponds with a bottom channel to form a plurality of opposing channel pairs, each of said opposing channel pairs adapted to receive said circuit board, said circuit board having opposing edges in slidable engagement with one of said opposing channel pairs, said device comprising:

a plurality of ribs plated with conductive material to form part of a Faraday shield for preventing EMI/RFI radiation leakage from said card cage and extending along said bottom of each said bottom channel of each of said opposing channel pairs between said right side wall to said left side wall to prevent said circuit board from contacting said channel bottom during said slidable engagement and wearing away said conductive material plated to said bottom of each said bottom channel, thereby preventing a breach in said Faraday shield sufficiently large to leak EMI/RFI radiation from said card cage.

2. The device of claim 1, wherein a plurality of said ribs are spaced along the length of said at least one channel of each of said opposing channel pairs.

3. The device of claim 1, wherein said right side wall and said left side wall of each of said bottom channels is plated with conductive material to form part of a Faraday shield for preventing EMI/RFI radiation from said card cage, further comprising a plurality of second ribs extending along either said platted right side wall or said platted left side wall to said channel bottom to inhibit said circuit board from contacting said side wall along which said second rib extends during said slidable engagement and wearing away said conductive material plated to said side wall, thereby preventing a breach in said Faraday shield sufficiently large to leak EMI/RFI radiation from said card cage.

4. The device of claim 3, wherein each of said at least one second rib is positioned adjacent to said at least one rib.

5. The device of claim 1, wherein said at least one channel of each of said opposing channel pairs is contained by said bottom of said card cage.