Browse Prior Art Database

COOLING METHOD FOR ADJACENT CIRCUIT CARDS

IP.com Disclosure Number: IPCOM000009539D
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Aug-30
Document File: 2 page(s) / 99K

Publishing Venue

Motorola

Related People

Mark Summers: AUTHOR

Abstract

Fans have long been used to cool electronic components in enclosures. Unfortunately as minia- turization of electronic systems, such as computers and communication equipment, continues the ther- mal problem of getting the heat out of tightly spaced circuit cards. This paper discusses a novel approach to removing heat from adjacent circuit cards when no other means of spot cooling is avail- able and rewiring the cabinet to add more cabinet flushing fans is deemed non-cost effective.

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Technical MOIWROLA @ Developments

COOLING METHOD FOR ADJACENT CIRCUIT CARDS

by Mark Summers

  2. The plug-in fan-card can be placed between hot neighboring cards that need to be cooled in the simple retro-fit manner of just plugging in the fan- card.

  3. The fan-card utilizes the principle of forced impingement convection cooling which is superior to standard convection cooling because impinge- ment cooling blows away the thermal layer on the hot components.

Examples of coefficients of convection

h=lx free convection

h=7x standard forced convection

h=25x forced impingement

  Impingement cooling is superior to standard forced convection cooling because it blows the insu- lating 'thermal layer' off the surface. The 'thermal layer' acts like a blanket of dead air that is right on the surface of the circuit card. Removing this 'ther- mal layer' allows for improved cooling of the elec- tronics

  This concept makes use of impingement cooling for the adjacent cards but would still require an overall cabinet cooling approach to flush the heated air out of the systems cabinet.

IN SUMMARY

  The concept described in this paper and illustrat- ed in Figure 1 solves the problems of cooling hot spots on tightly stacked circuit cards with plug-in impingement fan-cards. The novelty is not only the approach to cooling, but the retrofit capability which does not require rewiring a system enclosures.

B Mommla. Inc. ,999 222 September 1999

ABSTRACT

  Fans have long been used to cool electronic components in enclosures. Unfortunately as minia- turization of electronic systems, such as computers and communication equipm...