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Back Side Cooling for Printed Circuit Board

IP.com Disclosure Number: IPCOM000038314D
Original Publication Date: 1989-Dec-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Keller, CJ: AUTHOR

Abstract

The thermal resistance between the back of a printed circuit board (PCB) and the main stream of the cooling air can be improved by providing a metal back cover that redirects the flow of cooling air while suppling physical protection and structural stiffening.

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Back Side Cooling for Printed Circuit Board

The thermal resistance between the back of a printed circuit board (PCB) and the main stream of the cooling air can be improved by providing a metal back cover that redirects the flow of cooling air while suppling physical protection and structural stiffening.

Currently, a gap is included between the PCB and the back cover. The PCB frame blocks most of the air flow into that gap, causing an effective loss of forced convection. The gap itself is usually narrow enough so that only laminar flow free convention operates in the gap. The length of the card in the direction of air flow further decreases the effectiveness of cooling by the air stream.

The thermal resistance can be improved by eliminating the gap completely as an air flow path and replacing it with a thermal conduction path to the metal back cover. The net effect is to decrease the resistance between the PCB and the air stream. Ideally, the gap can be reduced to the minimum space required for mechanical clearance. This permits a larger space for front side cooling. The metal back cover and the component side of the adjacent card then provide a cooling channel similar to the channel between the PCB back side and the front side. The cooling enhancement may be further improved by contouring the back cover to improve heat transfer by promoting turbulence.

The gap may be filled with a material with good adhesion to the PCB and the back cover. The material should be s...