This paper reports the test results of vapor chambers using copper post heaters and silicon die heaters. Experiments were conducted to understand the effects of nonuniform heating conditions (hot spots) on the evaporative thermal performance of vapor chambers. In contrast to the copper post heater, which provides ideal heating, a silicon chip package was developed to replicate more realistic heat source boundary conditions of microprocessors. The vapor chambers were tested for hot spot heat fluxes as high as 746W/cm2. The experimental results show that evaporator thermal resistance is not sensitive to nonuniform heat conditions, i.e., it is the same as in the uniform heating case. In addition, a model was developed to predict the effective thickness of a sintered-wick layer saturated with water at the evaporator. The model assumes that the pore sizes in the sintered particle wick layer are distributed nonuniformly. With an increase of heat flux, liquid in the larger size pores are dried out first, followed by drying of smaller size pores. Statistical analysis of the pore size distribution is used to calculate the fraction of the pores that remain saturated with liquid at a given heat flux condition. The model successfully predicts the experimental results of evaporative thermal resistance of vapor chambers for both uniform and nonuniform heat fluxes.

1.
Mahajan
,
R.
,
Chiu
,
C.-P.
, and
Chrysler
,
G.
, 2006, “
Cooling a Microprocessor Chip
,”
Proc. IEEE
0018-9219,
94
(
8
), pp.
1476
1486
.
2.
Watwe
,
A.
, and
Viswanath
,
R.
, 2003, “
Thermal Implications of Non-Uniform Die Power and CPU Performance
,”
Proceedings of the InterPack ‘03 Conference
, Maui, HI, July 6–11, Paper No. IPACK 2003-35044.
3.
Dunn
,
P. D.
, and
Reay
,
D. A.
, 1994,
Heat Pipes
,
4th ed.
,
Pergamon
,
New York
/
Elsevier Science
,
New York
.
4.
Faghri
,
A.
, 1995,
Heat Pipe Science and Technology
,
Taylor & Francis
,
Washington, DC
.
5.
Peterson
,
G. P.
, 1994,
An Introduction to Heat Pipe
,
Wiley
,
New York
.
6.
Wang
,
Y.
, and
Peterson
,
G. P.
, 2005, “
Investigation of a Novel Flat Heat Pipe
,”
ASME J. Heat Transfer
0022-1481,
127
, pp.
165
170
.
7.
Vadakkan
,
U.
,
Garimella
,
S. V.
, and
Murthy
,
J. Y.
, 2004, “
Transport in Flat Heat Pipes at High Heat Fluxes From Multiple Discrete Sources
,”
ASME J. Heat Transfer
0022-1481,
126
, pp.
347
354
.
8.
DiStefano
,
E.
,
Pokharna
,
H.
, and
Machiroutu
,
S. V.
, 2004, “
Raising the Bar for Heat Pipes in Notebook Cooling
,”
Proceedings of the 13th International Heat Pipe Conference
, Shanghai, China, Sept. 21–25.
9.
Prasher
,
R. S.
, 2003, “
A Simplified Conduction Based Modeling Scheme for Design Sensitivity Study of Thermal Solution Utilizing Heat Pipe and Vapor Chamber Technology
,”
ASME J. Electron. Packag.
1043-7398,
125
(
3
), pp.
378
385
.
10.
Prasher
,
R. S.
,
Dirner
,
J.
,
Chang
,
J.-Y.
,
Myers
,
A.
,
Chau
,
D.
,
He
,
D.
, and
Prstic
,
S.
, 2007, “
Nusselt Number and Friction Factor of Staggered Arrays of Low Aspect Ratio Micro Pin Fins Under Cross Flow for Water as Fluid
,”
ASME J. Heat Transfer
0022-1481,
129
(
2
), pp.
141
153
.
11.
Avenas
,
Y.
,
Gillot
,
C.
,
Bricard
,
A.
, and
Schaeffer
,
C.
, 2002, “
On the Use of Flat Heat Pipes as Thermal Spreaders in Power Electronics Cooling
,”
Proceedings of the IEEE 33rd Annual Power Electronics Specialists Conference
, Vol.
2
, Cairns, Australia, June, pp.
753
757
.
12.
Kline
,
S. J.
, and
McClintock
,
F. A.
, 1953, “
Describing Uncertainties in Single-Sample Experiments
,”
Mech. Eng. (Am. Soc. Mech. Eng.)
,
75
, pp.
3
8
. 0025-6501
13.
Cheng
,
P.
, and
Ma
,
H. B.
, 2007, “
A Mathematical Model Predicting the Minimum Meniscus Radius Occurring in Mix Particles
,”
ASME J. Heat Transfer
0022-1481,
129
(
3
), pp.
391
394
.
14.
Ferrell
,
J. K.
, and
Alleavitch
,
J.
, 1970, “
Vaporization Heat Transfer in Capillary Wick Structures
,”
Chem. Eng. Prog., Symp. Ser.
0069-2948,
66
(
102
), pp.
82
91
.
You do not currently have access to this content.