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Temperature Measurement As an Airflow Measurement Tool

IP.com Disclosure Number: IPCOM000043214D
Original Publication Date: 1984-Jul-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Baker, DL: AUTHOR [+2]

Abstract

Accurate measurement of airflow in a system card-on-board (COB) assembly is extremely difficult because of turbulence, frame and cable interferences, blower directionality, etc. Since conventional airflow measurement probes are reasonably large when compared to the space in most COB packages, there is a strong possibility of measurement errors. A calibrated card can be used to measure the effective airflow, i.e., the airflow that is actually cooling the modules. This would verify the airflow assumptions usually made earlier in the machine design process. Thermal chips are integrated circuits (ICs) that are a combination of resistors and diodes that can be calibrated such that any change in temperature produces a corresponding change in output.

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Temperature Measurement As an Airflow Measurement Tool

Accurate measurement of airflow in a system card-on-board (COB) assembly is extremely difficult because of turbulence, frame and cable interferences, blower directionality, etc. Since conventional airflow measurement probes are reasonably large when compared to the space in most COB packages, there is a strong possibility of measurement errors. A calibrated card can be used to measure the effective airflow, i.e., the airflow that is actually cooling the modules. This would verify the airflow assumptions usually made earlier in the machine design process. Thermal chips are integrated circuits (ICs) that are a combination of resistors and diodes that can be calibrated such that any change in temperature produces a corresponding change in output. Modules with thermal chips of known power dissipations are placed on cards (such as Early Large-Scale Integration (ELSI)). Modules may be placed on any area of the card to achieve the proper physical layout. The card can then be calibrated in a controlled airflow chamber. The cards fit into the system boards and may have their own (non-system) power source for the thermal modules. Additional devices, i.e., thermocouples, may be placed on the module cans and in the inlet air stream to the board for complete thermal analysis. The external thermal resistance for a specific location in the system environment can then be determined by combining the thermal chip output and th...