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Closed fence heatsink grounding for electromagnetic compatibility (EMC)

IP.com Disclosure Number: IPCOM000019826D
Original Publication Date: 2003-Sep-30
Included in the Prior Art Database: 2003-Sep-30
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Abstract

A "picture frame" element of a heatsink, electromagnetic compatibility (EMC) fence, module enclosure is discussed that describes a method of attaching a low cost shielding fence for the module while allowing a top cover and thermal heat sink to contact the module.

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At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 68% of the total text.

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Closed fence heatsink grounding for electromagnetic compatibility (EMC)

  The i dea is to provide low inductance heat sink grounding in a manner to provide additional shielding for module electromagnetic emissions.

    The invention is simply a process for attaching a picture frame structure to the heatsink , then to the staggered fence that is mounted on the printed circuit board (PCB). The open top of the picture frame allows thermal conduction to take place directly from the module to the heatsink without an additional thermal junction to cross. The picture frame can slide down onto the fence and seat at any position that allows thermal contact with the module. There is no pressure to lift the heatsink off the module or board. The picture frame provides a full enclosed shield of the module.

     The figure shows a an exploded assembly of a circuit board (green) with a module/chip (violet) mounted on the board followed by the alternating edge fence base (light grey) for board mounting. The solid fence (light grey) that slides into the base alternating fence completes the electromagnetic compatibility (EMC) enclosure. Upon assembly, the heat sink on top is in contact with the module either directly or through thermal pads. The alternating bottom fence portion already exists in the marketplace but the attachment to the alternating base fence through a "knife edge" to ground a heatsink does not and is the basis for the invention. The figure also shows an example of an option...