—-’
.
THERMAL PERFORMANCE MODELING AND MEASUREMENTS OF
LOCALIZED WATER COOLED COLD PLATE
Seaho Song, Kevin P. Moran, Donald P. Rearick
Enterprise Systems
IBM
Coq20ration
Poughkeepsie, NY
and
Seri Lee
Aavid Engineering, Inc.
Laconia,
NH
ABSTR4CT
Two different water-cooled cold plate designs to handle highly localized heat dissipations in
electronic packaging applications are introduced. One design employs drilled holes as the flow conduit,
and the other uses a specially formed copper tube. These designs offer high thermal performance at
low
water flow and pressure drop requirements.
Measurements and models for thermal and hydraulic
petiormance are presented. The model predictions and the measurements are in excellent agreement.
I. INTRODUCTION
As the electronics industry continues to face the increasing trend of heat dissipation in electronic
components, water cooling is fast becoming an attractive design option for high performance thermal
management. In designing a water-cooled cold plate the followings are some of the important design
parameters:
o
0
0
0
0
0
0
thermal pefiormance
water flow rate
pressure drop
mechanical strength
corrosion & fouling
manufacturability
cost
Water flow rate and pressure drop influence the size of pumping and plumbing requirements, and
ultimately the cost and the physical volume of coolant distribution system. Therefore in designing cold
plates, it is of great importance to minimize the water flow rates and the pressure drop, yet ensuring
sufficient thermal
pefionnance.
In dense electronic packaging applications, there may be a few high heatdissipating components
which require a cold plate with a
vexy
high level of cooling performance. Certain components with odd
physical shapes, such as transformers, may present the cold plate designer with the challenge of
providing water passages to restricted areas. Figure 1 shows the cooling requirements for a cold plate
69
r
used with a high-heat dissipating power
SUpp&.
Each of
the
six
shad~
~em
(shown
as four areas, A,
B, C & D) in the figure must COOI a heat dissipation rate of 5 to 15
Waw
per
~qum
centimeter.
Also
shown in the figure are areas (designated as ‘open area’) where water
passaEe
is not
allowed
due to other
packaging requirements. The combination of requirements for highly
localk~
pe~ommce
and restricted
flow passage adds additional challenge to the cold plate design for this
application.
r“”
A
/-��“
c
,
..—
-.
—
Figure 1: Typical Cooling Requirements
In this paper, two rather unique cold plate design concepts are presented to address the
requirements outlined in Figure 1. They are:
o drilled hole design
o press-fit tube design
The cross sections for the designs are shown in Figure
2. These two concepts are suitable to
accommodate requirements for localized high-cooling performance, and allow water passages to be laid
out around the geometric restrictions.
Developments of the cold plates using these concepts to meet the requirements shown in Figure
1 are presented in this paper. Prototype cold plates have been built, and measurements were made for
thermal
petiormance and pressure drop. Models were developed to predict the
t.h-l
ptiorrnance
and
the pressure drop. Comparisons between the predicted and the measured values over a range of water
flow rate are presented.
II. COLD PLATE DESIGN AND MANUFACTURABILITY
When using water
fol
in order to prevent corrosion
the cooling medium special care must be given t
O
the
selection
of materials
and the buildup of fouling deposits. Copper
WaS chosen as the material for
70