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Thin Heat Pipe for Cooling Components on Printed Circuit Boards

IP.com Disclosure Number: IPCOM000122647D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 98K

Publishing Venue

IBM

Related People

Bellar, RJ: AUTHOR [+3]

Abstract

Advances in electronic packaging density and higher chip power output require more efficient management of the thermal aspects of board and component design. While the practical limits of forced air cooling are generally known and many methods have been developed to surmount these limitations (1,2) recent developments in heat pipe technology make it possible to use this method to cool extremely dense high-power printed circuit boards.

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Thin Heat Pipe for Cooling Components on Printed Circuit Boards

      Advances in electronic packaging density and higher chip
power output require more efficient management of the thermal aspects
of board and component design.  While the practical limits of forced
air cooling are generally known and many methods have been developed
to surmount these limitations (1,2) recent developments in heat pipe
technology make it possible to use this method to cool extremely
dense high-power printed circuit boards.

      By using a heat pipe that is an integral part of the printed
circuit board and providing a thermally conductive path from
power-dissipating components to this heat pipe, greatly increased
thermal efficiency can be realized over conduction and/or forced
convection methods.

      The heat dissipated by the modules is transferred to the
evaporator side of the heat pipe by conduction.  It may be desirable
to attach the module substrate directly to the heat pipe evaporator
in order to reduce the thermal resistance.  This can be accomplished
by routing holes through the adjacent board planes and exposing the
evaporator plane for subsequent module attachment.  A silver epoxy or
other thermally conductive adhesive, or, in case mechanical
attachment is prescribed, a thermal oil or grease can be used as an
interface for this attachment.

      By using the heat pipe as one of the "planes" of the printed
circuit board, a 70:1 improvement in heat dissipation can be gained
over conventional solid copper planes presently used.  An additional
advantage of this concept is that heat can be removed from a critical
area such as an equipment enclosure or a computer room to less
critical areas like roof tops or to external chilling systems.

      The thermally conductive heat pipe housing can be fabricated
from copper or aluminum plates attached in a manner to provide an
internal chamber for the working fluid. The module or chip contact
area can be an embossed area extending through the adjacent planes of
the printed circuit or added pi...