U.S. patent application number 09/741772 was filed with the patent office on 2002-06-20 for electronic device using evaporative micro-cooling and associated methods.
This patent application is currently assigned to Harris Corporation. Invention is credited to Gassman, Richard A., Newton, Charles M., Pike, Randy T..
Application Number | 20020075651 09/741772 |
Document ID | / |
Family ID | 24982125 |
Filed Date | 2002-06-20 |
United States Patent
Application |
20020075651 |
Kind Code |
A1 |
Newton, Charles M. ; et
al. |
June 20, 2002 |
Electronic device using evaporative micro-cooling and associated
methods
Abstract
An electronic device includes a package surrounding at least one
integrated circuit, a micro-fluidic cooler in the package, and a
controller for controlling the micro-fluidic cooler so that the
cooling fluid provides evaporative cooling, such as droplet
impingement cooling. The electronic device may comprise a power
consumption sensor connected to the at least one integrated
circuit, and the controller may control the micro-fluidic cooler
responsive to the power consumption sensor. A temperature sensor
may be connected to the at least one integrated circuit, and the
controller may control the micro-fluidic cooler responsive to the
sensed temperature. The micro-fluidic cooler may comprise at least
one droplet generator for generating and impinging droplets of
cooling fluid onto the integrated circuit. The at least one droplet
generator may comprise at least one micro-electromechanical (MEMs)
pump. The electronic device may also include at least one heat
exchanger carried by the package and connected in fluid
communication with the micro-fluidic cooler. The package may have a
parallelepiped shape with a first pair of opposing major surfaces,
a second pair of opposing side surfaces and a third pair of
opposing end surfaces. In these embodiments, the at least one heat
exchanger may preferably comprise a pair of heat exchangers coupled
to the second pair of opposing side surfaces.
Inventors: |
Newton, Charles M.; (South
East Palm Bay, FL) ; Pike, Randy T.; (Indian Harbour
Beach, FL) ; Gassman, Richard A.; (Palm Bay,
FL) |
Correspondence
Address: |
CHRISTOPHER F. REGAN
Allen, Dyer, Doppelt, Milbrath & Gilchrist, P.A.
P.O. Box 3791
Orlando
FL
32802-3791
US
|
Assignee: |
Harris Corporation
1025 West NASA Blvd.
Melbourne
FL
32919
|
Family ID: |
24982125 |
Appl. No.: |
09/741772 |
Filed: |
December 19, 2000 |
Current U.S.
Class: |
361/700 ;
165/80.4; 257/E23.08; 257/E23.1; 62/259.2 |
Current CPC
Class: |
H01L 2924/0002 20130101;
H01L 23/4735 20130101; H01L 2924/09701 20130101; H01L 23/34
20130101; H01L 2924/0002 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
361/700 ;
62/259.2; 165/80.4 |
International
Class: |
H05K 007/20 |
Claims
That which is claimed is:
1. An electronic device comprising: at least one integrated
circuit; a package surrounding said at least one integrated
circuit; a micro-fluidic cooler in said package and thermally
coupled to said at least one integrated circuit to remove heat
therefrom, said micro-fluidic cooler comprising a cooling fluid;
and a controller for controlling said micro-fluidic cooler so that
the cooling fluid provides evaporative cooling.
2. An electronic device according to claim 1 wherein said
controller is contained within said package.
3. An electronic device according to claim 1 further comprising a
power consumption sensor connected to said at least one integrated
circuit; and wherein said controller controls said micro-fluidic
cooler responsive to said power consumption sensor.
4. An electronic device according to claim 1 further comprising a
temperature sensor connected to said at least one integrated
circuit; and wherein said controller controls said micro-fluidic
cooler responsive to said temperature sensor.
5. An electronic device according to claim 1 wherein said
micro-fluidic cooler comprises at least one droplet generator for
generating and impinging droplets of cooling fluid onto said
integrated circuit.
6. An electronic device according to claim 4 wherein said at least
one droplet generator comprises at least one
micro-electromechanical (MEMs) pump.
7. An electronic device according to claim 1 further comprising at
least one heat exchanger carried by said package and connected in
fluid communication with said micro-fluidic cooler.
8. An electronic device according to claim 7 wherein said package
has a parallelepiped shape with a first pair of opposing major
surfaces, a second pair of opposing side surfaces and a third pair
of opposing end surfaces; and wherein said at least one heat
exchanger comprises a pair of heat exchangers coupled to said
second pair of opposing side surfaces.
9. An electronic device according to claim 7 further comprising
electrical connectors carried by at least one of said first pair of
opposing major surfaces and said third pair of opposing end
surfaces.
10. An electronic device according to claim 1 wherein said package
comprises a base and a lid connected thereto defining a cavity
receiving said at least one integrated circuit.
11. An electronic device according to claim 10 wherein said
micro-fluidic cooler comprises at least one micro-fluidic
passageway extending through said base and directed toward said at
least one integrated circuit.
12. An electronic device according to claim 10 wherein said at
least one integrated circuit comprises an active surface comprising
active devices therein; and wherein at least one integrated circuit
is positioned so that the active surface is adjacent said at least
one micro-fluidic passageway.
13. An electronic device according to claim 10 further comprising a
plurality of bodies connecting said at least one integrated circuit
to said base in spaced apart relation therefrom so that cooling
fluid flows adjacent said bodies and into the cavity.
14. An electronic device according to claim 1 wherein said package
comprises low temperature co-fired ceramic (LTCC) material.
15. An electronic device comprising: at least one integrated
circuit; a package surrounding said at least one integrated
circuit; a micro-fluidic cooler in said package and thermally
coupled to said at least one integrated circuit to remove heat
therefrom, said micro-fluidic cooler comprising a cooling fluid and
at least one micro-electromechanical (MEMs) pump for generating
cooling fluid droplets; a sensor for sensing a condition of said at
least one integrated circuit; and a controller carried by said
package for controlling said at least one MEMs pump based upon said
sensor so that the cooling fluid provides droplet impingement
evaporative cooling.
16. An electronic device according to claim 15 wherein said sensor
comprises a power consumption sensor connected to said at least one
integrated circuit.
17. An electronic device according to claim 15 wherein said sensor
comprises a temperature sensor connected to said at least one
integrated circuit.
18. An electronic device according to claim 15 further comprising
at least one heat exchanger carried by said package and connected
in fluid communication with said micro-fluidic cooler.
19. An electronic device according to claim 18 wherein said package
has a parallelepiped shape with a first pair of opposing major
surfaces, a second pair of opposing side surfaces and a third pair
of opposing end surfaces; and wherein said at least one heat
exchanger comprises a pair of heat exchangers coupled to said
second pair of opposing side surfaces.
20. An electronic device according to claim 18 further comprising
electrical connectors carried by at least one of said first pair of
opposing major surfaces and said third pair of opposing end
surfaces.
21. An electronic device according to claim 15 wherein said package
comprises a base and a lid connected thereto defining a cavity
receiving said at least one integrated circuit.
22. An electronic device according to claim 15 wherein said package
comprises low temperature co-fired ceramic (LTCC) material.
23. An electronic device comprising: at least one integrated
circuit; a package surrounding said at least one integrated
circuit, said package having a parallelepiped shape with a first
pair of opposing major surfaces, a second pair of opposing side
surfaces and a third pair of opposing end surfaces; a micro-fluidic
cooler in said package and thermally coupled to said at least one
integrated circuit to remove heat therefrom, said micro-fluidic
cooler comprising a cooling fluid; and a pair of heat exchangers
connected to said second pair of opposing side surfaces and
connected in fluid communication with said micro-fluidic
cooler.
24. An electronic device according to claim 23 further comprising
electrical connectors carried by at least one of said first pair of
opposing major surfaces and said third pair of opposing end
surfaces.
25. An electronic device according to claim 23 wherein said
micro-fluidic cooler comprises at least one droplet generator for
generating and impinging droplets of cooling fluid onto said
integrated circuit.
26. An electronic device according to claim 23 wherein said at
least one droplet generator comprises at least one
micro-electromechanical (MEMs) pump.
27. An electronic device according to claim 23 wherein said package
comprises a base and a lid connected thereto defining a cavity
receiving said at least one integrated circuit.
28. An electronic device according to claim 23 wherein said package
comprises low temperature co-fired ceramic (LTCC) material.
29. An electronic device comprising: a plurality of electronic
modules arranged in stacked relation, each electronic module
comprising: at least one integrated circuit, a package surrounding
said at least one integrated circuit, said package having a
parallelepiped shape with a first pair of opposing major surfaces,
a second pair of opposing side surfaces and a third pair of
opposing end surfaces, a micro-fluidic cooler in said package and
thermally coupled to said at least one integrated circuit to remove
heat therefrom, said micro-fluidic cooler comprising a cooling
fluid, and a pair of heat exchangers connected to said second pair
of opposing side surfaces and connected in fluid communication with
said micro-fluidic cooler.
30. An electronic device according to claim 29 further comprising
electrical connectors carried by at least one of said first pair of
opposing major surfaces and said third pair of opposing end
surfaces.
31. An electronic device according to claim 29 wherein said
micro-fluidic cooler comprises at least one droplet generator for
generating and impinging droplets of cooling fluid onto said
integrated circuit.
32. An electronic device according to claim 29 wherein said at
least one droplet generator comprises at least one
micro-electromechanical (MEMs) pump.
33. An electronic device according to claim 29 wherein said package
comprises a base and a lid connected thereto defining a cavity
receiving said at least one integrated circuit.
34. An electronic device according to claim 29 wherein said package
comprises low temperature co-fired ceramic (LTCC) material.
35. An electronic device comprising: at least one integrated
circuit; a package comprising a base and a lid connected thereto
defining a cavity receiving said at least one integrated circuit; a
micro-fluidic cooler in said package comprising a cooling fluid and
at least one micro-fluidic passageway extending through said base
and directed toward said at least one integrated circuit; and a
plurality of bodies connecting said at least one integrated circuit
to said base in spaced apart relation therefrom so that cooling
fluid flows adjacent said bodies and into the cavity.
36. An electronic device according to claim 35 wherein said at
least one integrated circuit comprises an active surface comprising
active devices therein; and wherein at least one integrated circuit
is positioned so that the active surface is adjacent said at least
one micro-fluidic passageway.
37. An electronic device according to claim 35 further comprising
at least one heat exchanger carried by said package and connected
in fluid communication with said micro-fluidic cooler.
38. An electronic device according to claim 37 wherein said package
has a parallelepiped shape with a first pair of opposing major
surfaces, a second pair of opposing side surfaces and a third pair
of opposing end surfaces; and wherein said at least one heat
exchanger comprises a pair of heat exchangers coupled to said
second pair of opposing side surfaces.
39. An electronic device according to claim 38 further comprising
electrical connectors carried by at least one of said first pair of
opposing major surfaces and said third pair of opposing end
surfaces.
40. An electronic device according to claim 35 wherein said package
comprises low temperature co-fired ceramic (LTCC) material.
41. A method for cooling at least one integrated circuit in a
package also including a micro-fluidic cooler therein, the
micro-fluidic cooler comprising a cooling fluid, the method
comprising: controlling the micro-fluidic cooler so that the
cooling fluid provides evaporative cooling.
42. A method according to claim 41 wherein controlling further
comprises sensing power consumption of the at least one integrated
circuit and controlling the micro-fluidic cooler responsive
thereto.
43. A method according to claim 41 wherein controlling further
comprises sensing a temperature of the at least one integrated
circuit and controlling the micro-fluidic cooler responsive
thereto.
44. A method according to claim 41 wherein the micro-fluidic cooler
comprises at least one micro-electromechanical (MEMs) pump; and
wherein controlling the micro-fluidic cooler comprises controlling
the at least one MEMs pump.
45. A method according to claim 41 further comprising connecting at
least one heat exchanger carried to the package and connected in
fluid communication with the micro-fluidic cooler.
46. A method according to claim 45 wherein the package has a
parallelepiped shape with a first pair of opposing major surfaces,
a second pair of opposing side surfaces and a third pair of
opposing end surfaces; and wherein the at least one heat exchanger
comprises a pair of heat exchangers connected to the second pair of
opposing side surfaces.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of electronic
devices, and, more particularly, to electronic devices including
micro-fluidic cooling of one or more integrated circuits and
associated methods.
BACKGROUND OF THE INVENTION
[0002] Integrated circuits are widely used in many types of
electronic equipment. An integrated circuit may include a silicon
or gallium arsenide substrate including a number of active devices,
such as transistors, etc. formed in an upper surface of the
substrate. It is also typically required to support one or more
such integrated circuits in a package that provides protection and
permits external electrical connection.
[0003] As the density of active devices on typical integrated
circuits has increased, dissipation of the heat generated has
become increasingly more important. In particular, a relatively
large amount of heat may be generated in multi-chip modules (MCMs),
microwave transmitters, and photonic devices, for example. U.S.
Pat. No. 5,987,803 to Schulz-Harder et al. discloses a cooling
package, such as for a laser device, including channels through
which cooling water flows. Heat is removed using a series of
Peltier elements in the package.
[0004] Advances in micro-electromechanical (MEMs) technology have
allowed designers to develop further cooling techniques for
integrated circuits based on circulating dielectric cooling fluids
adjacent an integrated circuit to thereby remove waste heat. For
example, U.S. Pat. No. 5,876,187 to Afromowitz et al. discloses
micro-pumps with associated valves that may be used for a number of
applications, such as environmental, biomedical, medical,
biotechnical, printing, analytical instrumentation, and miniature
cooling applications.
[0005] Heat may be removed from an integrated circuit by free
convective cooling of gases or liquids. The liquids typically
remove more heat. Forced convective cooling may provide additional
efficiency as the gases or liquids are circulated in contact with
the device to be cooled. Cooling using boiling liquid provides yet
higher efficiency.
[0006] Unfortunately, an integrated circuit may operate at
different power levels and thereby generate different amounts of
waste heat. Accordingly, a typical MEMs micro-cooling system may
not operate efficiently over all of the possible operating ranges
of the integrated circuit.
SUMMARY OF THE INVENTION
[0007] In view of the foregoing background it is therefore an
object of the invention to provide an electronic device and
associated methods which provide highly efficient cooling for the
one or more integrated circuits in the overall package.
[0008] This and other objects, features and advantages in
accordance with one aspect of the present invention are provided by
an electronic device comprising a package surrounding at least one
integrated circuit, a micro-fluidic cooler in the package, and a
controller for controlling the micro-fluidic cooler so that the
cooling fluid provides evaporative cooling. The controller may also
be provided in the package. Evaporative cooling provides very
efficient cooling since it may be based upon droplet impingement
and boiling of the cooling fluid. Such evaporative micro-cooling is
considerably more efficient than free convective or forced
convective cooling. The electronic device may be relatively compact
and yet have a highly efficient cooling system for the removal of
waste heat from the at least one integrated circuit.
[0009] The electronic device may comprise a power consumption
sensor connected to the at least one integrated circuit, and the
controller may control the micro-fluidic cooler responsive to the
power consumption sensor. Alternately or additionally, a
temperature sensor may be connected to the at least one integrated
circuit, and the controller may control the micro-fluidic cooler
responsive to the sensed temperature.
[0010] The micro-fluidic cooler may comprise at least one droplet
generator for generating and impinging droplets of cooling fluid
onto the integrated circuit. More particularly, the at least one
droplet generator may comprise at least one micro-electromechanical
(MEMs) pump.
[0011] The electronic device may also include at least one heat
exchanger carried by the package and connected in fluid
communication with the micro-fluidic cooler. In one particularly
advantageous class of embodiments, the package may have a
parallelepiped shape with a first pair of opposing major surfaces,
a second pair of opposing side surfaces and a third pair of
opposing end surfaces. In these embodiments, the at least one heat
exchanger may preferably comprise a pair of heat exchangers, each
coupled to a respective one of the second pair of opposing side
surfaces. This configuration may facilitate stacking of a plurality
of such units or modules. Each module may also comprise electrical
connectors carried by at least one of the first pair of opposing
major surfaces and the third pair of opposing end surfaces.
[0012] The package may comprise a base and a lid connected thereto
defining a cavity receiving the at least one integrated circuit.
The micro-fluidic cooler may comprise at least one micro-fluidic
passageway extending through the base and directed toward the at
least one integrated circuit. In addition, the at least one
integrated circuit may comprise an active surface comprising active
devices therein, and the at least one integrated circuit may be
positioned so that the active surface is adjacent the at least one
micro-fluidic passageway. In this arrangement, the droplets of the
cooling fluid may be delivered directly onto the active surface of
the integrated circuit to efficiently remove heat therefrom. Also,
using such flip chip bonding, a plurality of bodies, such as solder
balls, may connect the at least one integrated circuit to the base
in spaced apart relation therefrom so that cooling fluid also flows
adjacent the bodies and into the cavity. Heat is also removed from
the solder balls, and cooling efficiency is further enhanced.
[0013] The package may comprise low temperature co-fired ceramic
(LTCC) material. This material offers advantages in terms of
ruggedness, and an ability to form recesses and passageways
therein.
[0014] Another aspect of the invention relates to a method for
cooling at least one integrated circuit in a package also including
a micro-fluidic cooler therein. The micro-fluidic cooler may also
include a cooling fluid. The method preferably comprises
controlling the micro-fluidic cooler so that the cooling fluid
provides evaporative cooling. The controlling may further comprise
sensing power consumption of the at least one integrated circuit
and controlling the micro-fluidic cooler responsive thereto.
Controlling may alternately comprise sensing a temperature of the
at least one integrated circuit and controlling the micro-fluidic
cooler responsive thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a perspective view of the electronic device in
accordance with the invention.
[0016] FIG. 2 is a schematic cross-sectional view of the electronic
device as shown in FIG. 1 with the heat sinks removed for
clarity.
[0017] FIG. 3 is a transparent perspective view of the electronic
device as shown in FIG. 1 with the heat sinks removed for
clarity.
[0018] FIG. 4 is a transparent top plan view of the electronic
device as shown in FIG. 1.
[0019] FIG. 5 is a graph illustrating comparisons of the
evaporative cooling efficiency of the present invention versus
various convective cooling approaches.
[0020] FIG. 6 is a perspective view of a plurality of the
electronic devices as shown in FIG. 1 assembled in stacked
relation.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] The present invention will now be described more fully
hereinafter with reference to the accompanying drawings in which
preferred embodiments of the invention are shown. This invention
may, however, be embodied in many different forms and should not be
construed as limited to the illustrated embodiments set forth
herein. Rather, these embodiments are provided so that this
disclosure will be thorough and complete, and will fully convey the
scope of the invention to those skilled in the art. Like numbers
refer to like elements throughout.
[0022] Referring initially to FIGS. 1-5, the electronic device 20
in accordance with the invention is now initially described. The
electronic device 20 includes a package 21 surrounding an
integrated circuit 22. The package 21 includes a base 21a and a lid
21b connected thereto. The package 21 may comprise low temperature
co-fired ceramic (LTCC) material, for example. This material offers
advantages in terms of ruggedness, and an ability to form recesses
and small stable passageways therein, as well as to provide
electrical paths therethrough. Of course, other similar materials
may be used as well. Also, in other embodiments, two or more
integrated circuits 22 may be carried by the package 21 as will be
appreciated by those skilled in the art.
[0023] The electronic device also includes a micro-fluidic cooler
25 in the package 21, and a controller schematically illustrated by
block 30 in FIG. 2 for controlling the micro-fluidic cooler so that
the cooling fluid provides evaporative cooling as will be described
in greater detail below. The evaporative cooling may be based upon
droplet impingement to provide yet greater heat removal capacity as
will be appreciated by those skilled in the art and as explained in
greater detail below. The controller 30 may be provided by
circuitry on the integrated circuit 22, or may be a separate
circuit within the package 21. Alternately, the controller 30 may
also be provided external to the package 30 in some other
embodiments. In yet other embodiments, portions of the controller
30 may be provided both inside and outside the package 21.
[0024] The electronic device 20 may comprise a power consumption
sensor schematically illustrated by block 31 in FIG. 2 that is
connected to the integrated circuit 22 to sense its power
consumption. Typically such a sensor would sense current flow
through the one or more power supply leads to the integrated
circuit 22. Accordingly, the controller 30 may control the
micro-fluidic cooler 25 responsive to the power consumption sensor.
Alternately, a temperature sensor schematically illustrated by the
dashed block 32 in FIG. 2 may be connected to the integrated
circuit 22, and the controller 30 may control the micro-fluidic
cooler 25 responsive to the sensed temperature. Of course, in other
embodiments, a combination of these sensors 31, 32 may be used.
[0025] The micro-fluidic cooler may comprise at least one droplet
generator for generating and impinging droplets of cooling fluid
onto the integrated circuit. More particularly, the at least one
droplet generator comprises at least one micro-electromechanical
(MEMs) pump. In the illustrated embodiment, a series of MEMs pumps
35 are provided within a pump cavity 36 in the base 21. The MEMs
pumps 35 are connected at their inlets to the micro-fluidic
passageways or channels 37.
[0026] As will be appreciated by those skilled in the art, the term
MEMs pump 35 is used herein to denote any MEMs type device which
can cause the movement of cooling fluid. It will be recognized that
a typical MEMs pump may include a MEMs actuator and one or more
valves associated therewith to control fluid flow.
[0027] The electronic device 20 may also include at least one heat
exchanger carried by the package 21 and connected in fluid
communication with the micro-fluidic cooler 25. In one particularly
advantageous class of embodiments and as shown in the illustrated
electronic device 20, the package 21 may have a parallelepiped
shape with a first pair of opposing major surfaces 24a, 24b (see
FIG. 2) a second pair of opposing side surfaces 24c, 24d (see FIGS.
2 and 3) and a third pair of opposing end surfaces 24e, 24f (see
FIG. 3).
[0028] In the illustrated embodiment of the electronic device 20,
the at least one heat exchanger comprises a pair of heat exchangers
40a, 40b, each being coupled to a respective one of the second pair
of opposing side surfaces 24c, 24d. As perhaps best shown in FIG.
4, each heat exchanger 40, 41, in turn, includes a respective body
portion 42, 43. Each body portion 42, 43 includes microfluidic
passageways 44, 45 therein. In addition, each body portion 42, 43
also carries a set of respective cooling fins 46, 47.
[0029] In other embodiments, the heat exchangers 40, 41 may include
additional liquid passageways, not shown, for providing a
liquid-to-liquid exchange of heat rather that the liquid-to-air
exchange as shown in the illustrated embodiment.
[0030] The package 21, as best shown in FIG. 1, may carry
electrical connectors 29 on at least one of the first pair of
opposing major surfaces and the third pair of opposing end
surfaces. As shown in the illustrated device 20, connectors 29 may
be provided on both pairs of surfaces. In other embodiments, edge
connectors may be provided to connect to a ribbon type cable, for
example, as will be appreciated by those skilled in the art.
[0031] The base and lid 21, 21b of the package 21 may be configured
to define a cavity 28 receiving the integrated circuit 22. The
micro-fluidic cooler 25 also illustratively includes a series of
spaced apart micro-fluidic passageways 50 extending through the
base 21b and directed toward the integrated circuit 22.
[0032] As will be appreciated by those skilled in the art, the
integrated circuit 22 may comprise an active surface 22a with
active devices therein. As shown in the illustrated embodiment, the
integrated circuit 22 is mounted using flip chip technology so that
the active surface 22a is adjacent the outlet ends of the
micro-fluidic passageways 50. Accordingly, the droplets of the
cooling fluid may be delivered directly onto the active surface 22a
of the integrated circuit 22 to efficiently remove heat
therefrom.
[0033] In accordance with flip chip bonding techniques, a plurality
of bodies, such as solder balls 52, are used to mount and
electrically connect the integrated circuit 22 to corresponding
electrical traces, not shown, carried by the base 24b. The
integrated circuit 22 is thereby positioned in spaced apart
relation from the base 24b so that cooling fluid also flows
adjacent the solder balls 52 and into the cavity 28 surrounding the
integrated circuit 22. Accordingly, heat is also removed from the
solder balls 52, and cooling from the active surface 22a of the
integrated circuit 22 is further enhanced. Heat may also be removed
from the back surface of the integrated circuit 22 as cooling fluid
flows through the cavity 28.
[0034] As will be appreciated by those skilled in the art, in other
embodiments, the integrated circuit 22 may be attached with its
bottom surface connected to the base 24b. Accordingly, the cooling
fluid may be directed to the bottom surface to still provide
efficient cooling, or the cooling fluid can be directed to the
exposed active surface using a shower type arrangement.
[0035] Turning now more particularly to the graphs of FIG. 5, the
advantages of using a controller 30 to control the micro-cooler 25
to provide evaporative cooling is now described in further detail.
The top two plots 60, 61 provide values of heat transfer
coefficients in Btu/Hr Ft.sup.2 F for free convective cooling using
air and FLUORINERT vapor, respectively. The next three plots from
the top 62, 63 and 64 provide similar values for silicone oil,
FLUORINERT liquid and water, respectively, for free convective
cooling. FLUORINERT materials are heat transfer materials available
from 3M as will be appreciated by those skilled in the art.
[0036] Forced convective cooling using air and FLUORINERT vapor are
given by plots 65 and 66. Forced convective cooling values using
silicone oil, FLUORINERT liquid, and water are given by plots 70,
71 and 72. As can be seen forced convective cooling provides
greater heat transfer than free convective cooling, and liquids are
generally superior to gases.
[0037] Plots 73 and 74 are for FLUORINERT liquid and water,
respectively, operating at their boiling points. The plot portion
indicated by reference numeral 73a, is for flow boiling along with
subcooling, and the plot portion 73b is for droplet impingement
evaporative cooling. As will be readily appreciated, evaporative
cooling provides very efficient cooling, especially when the
micro-cooler is operated at the regime using droplet impingement
evaporative cooling.
[0038] Turning now additionally to FIG. 6, an assembly of stacked
devices 20' is now described. Because of the parallelepiped shape
of each electronic module or device 20', a series of such devices
may be stacked on top of each other. In addition, in the
illustrated embodiment, each of the electronic devices 20' may
include an edge connector 76.
[0039] Many modifications and other embodiments of the invention
will come to the mind of one skilled in the art having the benefit
of the teachings presented in the foregoing descriptions and the
associated drawings. Accordingly, it is understood that the
invention is not to be limited to the embodiments disclosed, and
that other modifications and embodiments are intended to be
included within the spirit and scope of the appended claims.
* * * * *