Created: 5/21/95 Updated: 8/18/98

Flow-through Cooling of SEM-E Modules

Project Number : C93-11

Point of Contact:
Dr. Michael Osterman
CALCE EPRC
email: osterman@calce.umd.edu
Phone: (301) 405-8023
Fax: (301) 314-9269
Objectives Background Work Accomplised

Objectives

To implement design correlations to predict the heat transfer and pressure drop performance of liquid flow-through SEM-E modules. To validate the CALCE model against experimental data for the full range of SEM-E design parameters.

 

Background

Air-cooled cold plates using offset strip-fin structures are routinely used as heat sinks for electronics. Due to the high thermal resistance between junction and coolant, such heat sinks can accommodate only low board power levels. Flow-through liquid cooling is an attractive alternative for higher power densities. Power levels of 160 to 200 watts appear possible for a SEM-E module, while still maintaining junction temperatures below 85oC. Although offset fin heat exchangers have been widely used in industrial applications, very little work has been reported using liquids.

In order to accommodate the higher heat fluxes associated with high-density/high- speed multi- chip packages and wafer-scale integration, a liquid flow-through SEM-E module was developed and tested under the Wright Laboratory Advanced Aircraft Avionics Packaging Technology Program.

 

Work Accomplished

An experimental facility was designed to test the thermal characteristics of SEM-E modules using liquids as coolant. The modules were heated from both sides by patch heaters. The surface temperature distribution as well as the fluid temperature were measured by thermocouples and the coolant flow rate by a turbine flow meter. In addition to the temperature distribution, pressure drop across the module was also measured as a function of flow rate.

Tests were conducted on 11 modules, including the 3-pass SEM-E module obtained from WPAFB and the GE module with a serpentine flow path. Tests were conducted with both PAO and water as coolants. The new capability of modelling a 3-pass SEM-E was added to the CALCE software. The 3-pass SEM-E was simulated using the software, and compared well with the test data.

 The TI ALADDIN SEM-E module was modeled using the CALCE software. The module was simulated in both a two-pass and a four-pass configuration, using PAO as coolant over a range of flow rates. A large number of assumptions as required, due to a lack of detailed data on the module. The results of the simulations show reasonable agreement with TI data.

 The thermal analysis software was also modified to accommodate the perpendicular offset fin configuration. Based on experimental results, the heat transfer coefficient was modified to accurately predict the enhanced heat transfer performance obtained with this flow configuration. Tests were also conducted with water as coolant to gauge the effect of coolant types on heat transfer performance.