U.S. patent application number 09/946798 was filed with the patent office on 2003-03-06 for integrated cooling system.
This patent application is currently assigned to Microelectronic & Computer Technology Corporation. Invention is credited to Nelson, Richard D., Somadder, Anjan.
Application Number | 20030043544 09/946798 |
Document ID | / |
Family ID | 25485001 |
Filed Date | 2003-03-06 |
United States Patent
Application |
20030043544 |
Kind Code |
A1 |
Nelson, Richard D. ; et
al. |
March 6, 2003 |
INTEGRATED COOLING SYSTEM
Abstract
Systems and methods are described for integrated cooling system.
A method includes: circulating a liquid inside a flexible
multi-layer tape; and transporting heat between a heat source that
is coupled to the flexible multi-layer tape and a heat sink that is
coupled to the flexible multi-layer tape. A method includes
installing a flexible multi-layer tape in an electrical system,
wherein the flexible multi-layer tape includes a top layer; an
intermediate layer coupled to the top layer; and a bottom layer
coupled to the intermediate layer, the intermediate layer defining
a closed loop circuit for a circulating fluid. An apparatus
includes a flexible multi-layer tape, including: a top layer; an
intermediate layer coupled to the top layer; and a bottom layer
coupled to the intermediate layer, wherein the intermediate layer
defines a closed loop circuit for a circulating fluid.
Inventors: |
Nelson, Richard D.; (Austin,
TX) ; Somadder, Anjan; (Fremont, CA) |
Correspondence
Address: |
FULBRIGHT & JAWORSKI L.L.P.
SUITE 2400
600 CONGRESS AVENUE
AUSTIN
TX
78701
US
|
Assignee: |
Microelectronic & Computer
Technology Corporation
|
Family ID: |
25485001 |
Appl. No.: |
09/946798 |
Filed: |
September 5, 2001 |
Current U.S.
Class: |
361/690 ;
165/104.33; 257/714; 257/E23.098 |
Current CPC
Class: |
Y10T 29/4935 20150115;
F28F 2250/08 20130101; H01L 2924/0002 20130101; A61K 31/00
20130101; H01L 23/473 20130101; H01L 2924/0002 20130101; G06F 1/20
20130101; H01L 2924/00 20130101; G06F 1/203 20130101 |
Class at
Publication: |
361/690 ;
165/104.33; 257/714 |
International
Class: |
H05K 007/20 |
Claims
What is claimed is:
1. A method, comprising: circulating a liquid inside a flexible
multi-layer tape; and transporting heat between a heat source that
is coupled to the flexible multi-layer tape and a heat sink that is
coupled to the flexible multi-layer tape.
2. The method of claim 1, wherein circulating the liquid inside the
flexible multi-layer tape includes circulating the liquid inside
the flexible multi-layer tape via a closed loop circuit.
3. The method of claim 1, wherein circulating the liquid inside the
flexible multi-layer tape includes pumping the liquid inside the
flexible multi-layer tape.
4. The method of claim 1, wherein circulating the liquid inside the
flexible multi-layer tape includes circulating the liquid inside
the flexible multi-layer tape in a preferred direction around the
closed loop circuit via a plurality of valves.
5. The method of claim 1, wherein circulating the liquid includes
circulating water.
6. The method of claim 1, wherein exchanging heat between the heat
source and the heat sink includes flowing the liquid over a
plurality of fins.
7. A method, comprising installing a flexible multi-layer tape in
an electrical system, wherein the flexible multi-layer tape
includes a top layer; an intermediate layer coupled to the top
layer; and a bottom layer coupled to the intermediate layer, the
intermediate layer defining a closed loop circuit for a circulating
fluid.
8. The method of claim 7, further comprising providing a liquid
within the closed loop circuit.
9. The method of claim 7, wherein the flexible multi-layer tape
includes a heat extraction region, a pumping region, and a heat
rejection region and installing includes: attaching the heat
extraction region to an electronic component; attaching the heat
rejection region to a heat sink; and coupling a pump to the pumping
region.
10. The method of claim 9, further comprising bending the
multi-layer flexible tape.
11. An apparatus, comprising a flexible multi-layer tape,
including: a top layer; an intermediate layer coupled to the top
layer; and a bottom layer coupled to the intermediate layer,
wherein the intermediate layer defines a closed loop circuit for a
circulating fluid.
12. The apparatus of claim 11, wherein the top layer includes a
metal layer.
13. The apparatus of claim 11, wherein the intermediate layer
includes a polymer layer.
14. The apparatus of claim 11, wherein the bottom layer includes a
metal layer.
15. The apparatus of claim 11, wherein the intermediate layer
defines a closed loop circuit.
16. The apparatus of claim 11, wherein the intermediate layer
defines a plurality of internal cavities coupled together via the
closed loop circuit.
17. The apparatus of claim 16, wherein the plurality of internal
cavities include a plurality of heat exchange devices.
18. The apparatus of claim 17, wherein the plurality of heat
exchange devices include at least one member selected from the
group consisting of: a longitudinal fin, a pin fin, a folded metal
fin, a metal mesh, and a liquid impingement jet plate.
19. The apparatus of claim 15, wherein the closed loop circuit
includes a heat extraction region, a pumping region and a heat
rejection region.
20. The apparatus of claim 19, further comprising a pump coupled to
the pumping region.
21. The apparatus of claim 20, wherein the pump includes at least
one member selected from the group consisting of: a bellows pump, a
rotary pump, a diaphragm pump, a micromechanical gear pump, and an
electrokinetic pump.
22. The apparatus of claim 20, wherein the pump is located in a
cavity defined by the intermediate layer.
23. The apparatus of claim 11, further comprising a heat source
coupled to the flexible multi-layer tape.
24. The apparatus of claim 23, wherein the heat source includes a
plurality of electronic components.
25. The apparatus of claim 11, further comprising a heat sink
coupled to the flexible multi-layer tape.
26. The apparatus of claim 25, wherein the heat sink includes a
heat exchange unit.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates generally to the field of cooling and
heat sinking. More particularly, the invention relates to an
integrated liquid cooling system of flexible structure.
[0003] 2. Discussion of the Related Art
[0004] It has been apparent for at least the past 15 years that, as
performance improves, there is a growing need for efficient heat
dissipation of electronic devices and systems. This trend has
remained within the capabilities of air cooling until recently.
However, some of today's typical desktop and mobile electronic
systems can easily outstrip the cooling capability of existing air
cooling techniques. Portable computers have begun challenging
traditional thermal management systems.
[0005] Air cooling has shown limitations in certain
high-power/high-dissipation applications mostly due to the fact
that, in a typical situation, heat must be completely removed from
an electronic system's enclosure.
[0006] On-chip and near-chip refrigeration techniques, such as
thermo-electrics, reject a great amount of localized heat, which
must also be transported out of the electronic package and its
neighborhood. Furthermore, even though air cooling advances will
continue to appear, it is known to one skilled in the art that
liquid cooling technologies have a much greater capacity (than air
cooling technologies) to handle large quantities of heat in small
spaces.
[0007] A few techniques for integration of liquid cooling with
chips have been available since the early 80's. The microchannel
cooling techniques of Tucherman and Pease were shown to be capable
of handling high heat flux levels, at least 50 watts per square
centimeter at the chip, with only small water flow requirements.
Later work has confirmed and reproduced these heat sinks, but
commercial applications have not been made. This results from
limitations imposed by the integration itself. The micro-channels
must be machined in the backside of the wafer or chip to be cooled,
and the technique does not provide for integrated liquid packaging
and delivery systems.
[0008] A recent report describes micro-channels formed in aluminum
nitride to cool a multichip module (MCM). However, the assembly
terminates with conventional tubing fittings at the fluid manifold
ends. Thus, using this technique would require the electronic
system to include external tubing and pumps.
[0009] Heretofore, the mass flow capability of air cooling is
incompatible with densely packed or high power dissipation
electronics, and the "plumbing requirement" and potential for leaks
and spills associated with liquid cooling has restricted its
utility.
[0010] Another typical problem with liquid cooling technology has
been miniaturization. Only one aspect of liquid cooling systems has
been miniaturized or integrated to the scale of microelectronics,
namely the heat exchanger at a hot chip. The prospect of assembling
macro-scale pumps, tubes, and fittings, along with their potential
for leaks, has stopped most efforts in liquid cooling technology
development. What is needed is an integrated, liquid cooling system
with micro-scale components based on flexible circuitry materials
technology that solves these problems.
[0011] Heretofore, the requirement of providing an integrated
liquid cooling system, with micro-scale components based on
flexible circuitry materials technology for heat dissipation of
high power, densely packaged electronic systems as referred to
above have not been fully met. What is needed is a solution that
addresses this requirement.
SUMMARY OF THE INVENTION
[0012] There is a need for the following embodiments. Of course,
the invention is not limited to these embodiments.
[0013] According to an aspect of the invention, a method comprises:
circulating a liquid inside a flexible multi-layer tape; and
transporting heat between a heat source that is coupled to the
flexible multi-layer tape and a heat sink that is coupled to the
flexible multi-layer tape. According to another aspect of the
invention, a method comprises installing a flexible multi-layer
tape in an electrical system, wherein the flexible multi-layer tape
includes a top layer; an intermediate layer coupled to the top
layer; and a bottom layer coupled to the intermediate layer, the
intermediate layer defining a closed loop circuit for a circulating
fluid. According to another aspect of the invention, an apparatus
comprises a flexible multi-layer tape, including: a top layer; an
intermediate layer coupled to the top layer; and a bottom layer
coupled to the intermediate layer, wherein the intermediate layer
defines a closed loop circuit for a circulating fluid.
[0014] These, and other, embodiments of the invention will be
better appreciated and understood when considered in conjunction
with the following description and the accompanying drawings. It
should be understood, however, that the following description,
while indicating various embodiments of the invention and numerous
specific details thereof, is given by way of illustration and not
of limitation. Many substitutions, modifications, additions and/or
rearrangements may be made within the scope of the invention
without departing from the spirit thereof, and the invention
includes all such substitutions, modifications, additions and/or
rearrangements.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The drawings accompanying and forming part of this
specification are included to depict certain aspects of the
invention. A clearer conception of the invention, and of the
components and operation of systems provided with the invention,
will become more readily apparent by referring to the exemplary,
and therefore nonlimiting, embodiments illustrated in the drawings,
wherein like reference numerals (if they occur in more than one
view) designate the same elements. The invention may be better
understood by reference to one or more of these drawings in
combination with the description presented herein. It should be
noted that the features illustrated in the drawings are not
necessarily drawn to scale.
[0016] FIG. 1 is a block diagram of an integrated cooling system,
representing an embodiment of the invention.
[0017] FIG. 2 is an exploded perspective view of a flexible
integrated cooling system, representing an embodiment of the
invention.
[0018] FIG. 3 is a perspective view of a flexible integrated
cooling system, representing an embodiment of the invention.
[0019] FIG. 4 is a section view of a heat transfer system,
representing an embodiment of the invention.
[0020] FIG. 5 is a diagram of a gear pump with magnetic coupling,
representing an embodiment of the invention.
[0021] FIGS. 6A-6D are section views of heat transfer regions,
representing an embodiment of the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0022] The invention and the various features and advantageous
details thereof are explained more fully with reference to the
nonlimiting embodiments that are illustrated in the accompanying
drawings and detailed in the following description. Descriptions of
well known components and processing techniques are omitted so as
not to unnecessarily obscure the invention in detail. It should be
understood, however, that the detailed description and the specific
examples, while indicating preferred embodiments of the invention,
are given by way of illustration only and not by way of limitation.
Various substitutions, modifications, additions and/or
rearrangements within the spirit and/or scope of the underlying
inventive concept will become apparent to those skilled in the art
from this detailed description.
[0023] The invention relates to an integrated liquid cooling
system, and provides a method of liquid cooling and chip-level heat
dissipation. An embodiment of the invention utilizes flexible
circuitry materials technology. Flexible micro-channels and ducts
are used to transport a cooling liquid, which extracts heat from a
chip, moves it some distance out of the densely packed electronics
area, and dumps it to the environment (usually room air). Liquids,
especially water, have high enough specific heat and density to
efficiently move the heat generated by electronic components.
[0024] In its integrated form, the flexible cooler includes
miniature pumps, valves, piping, and cooling fins, resulting in a
completely sealed, flexible liquid cooling system. The components
utilized in this system are integrated with flexible metal and
polymer laminates, in the form of a laminated tape. Used in
conjunction with a local heat exchange component, the flexible
liquid cooler completes the cooling chain required to dissipate the
heat originated from a source.
[0025] Using flexible channels to transport a liquid, the invention
can be advantageously employed in a variety of high power
dissipation and space-constrained applications. In particular, the
integrated cooling system and method can be utilized in electronic
applications with high power dissipation and confined to close
quarters (e.g. optical emitters, server forms, etc.). The
micro-sized heat exchange apparatus generally provides a liquid
handling assembly which could be readily bent and twisted on route
to the final heat rejection area. A flexible, laminated
metal/polymer/metal tape can be formed to provide the embodiments
describer here.
[0026] An embodiment of the invention is represented by a closed
loop liquid micro-cooling system based on mini-scale components,
integrated and fully sealed. The closed liquid micro-cooling system
comprises a flexible laminated metal/polymer/metal liquid loop
piping, an external heat sink, an internal heat exchanger, and an
internal mini-pump to enable the use of known micro-channel and
micro-impingement techniques at the chip level. A suitable
micro-fabrication technology, in a known manner, is generally
employed to fabricate the chip-scale or miniature device of the
invention useful for a variety of electronic and opto-electronic
applications. The geometric features or materials used for these
various components can be readily devised to suite a particular
specification using a conventional micro-fabrication process from
3M corporation of Minneapolis/St. Paul, Minn. The invention should,
however, not be restricted to the field of these applications,
geometric features or materials, as will be readily evident.
[0027] A patterned and laminated copper sheet with a polyimide web
can be produced with techniques already used in the production of
flexible circuitry and TAB tape, and specially "multi-layer" tape.
These include die cutting for the polyimide and subtractive etching
of the copper. Small features can be produced in the polyimide by
laser ablation. While flexible circuitry employs flat copper
sheets, the particular needs of these cooling components may
benefit from adding dimples, ridges, or bends to the copper in a
forming step. Also, since there may be top and bottom layers of
copper (with a polyimide layer in between), it may be desirable to
join them at certain points by soldering or by plating via holes in
the metal/polyimide/metal stack. All of these structures and
processes are within the capability of the state of the art.
[0028] Fins may be required on the copper layers at heat exchange
regions, either where heat is to be absorbed at a package, or where
it is to be rejected to external cooling air. Both longitudinal
fins and pin fins can be produced by plating through openings in
the polyimide web. They can also be produced by plating through
openings formed in photoresist. Several other methods exist for
adding pin fins, for instance in a pick-and-place "surface mount"
operation followed by solder reflow.
[0029] In general, the fin thickness or diameter and the fin
spacing is desired to be relatively small on the order of 50
microns (micro-channels) to 500 microns (milli-channels). Use of
such small fins and channel dimensions inherently increases the
heat transfer coefficient on the exposed surfaces. As a result,
coolant flow rates may be expected to be relatively small on the
order of a few cubic centimeters per second.
[0030] Many factors such as design specifications, balancing liquid
flow, pressure drop, heat load, and temperature rise may determine
optimal fin and channel dimensions for a particular application. An
integrated pumping system may move fluids at the rate of a few
cubic centimeters per second or higher. The total pressure
requirement ranges from a fraction of a pound per square inch to 20
pounds per square inch.
[0031] Inside the flexible piping system, the cooling liquid may be
desired to flow in a particular direction, and valves can be used
for that purpose. Miniature flow-operated check valves can be
devised using simple ball-checks, diaphragm operated poppets, or
flappers created in the polyimide web. Magnetically driven valves
can be used as an alternative.
[0032] A micro-pump can include a small rotor in a rotor housing
created in the polyimide web. For instance, a micro-mechanical gear
pump can be implemented, using externally rotating magnetic fields
to couple the driving energy to the gears. Lubrication, sealing,
and micro-mechanical bearings may be also provided.
[0033] Referring to FIG. 1, a block diagram of an integrated
cooling system 50 is depicted. The integrated cooling system 50
integrates liquid pumping, delivery, and heat exchange
functionality to transmit heat generated form a problem area at a
particular location to a heat rejection area. For example, the
integrated cooling system 50 could be coupled to a heat source 80
for transporting heat generated to a substantially spaced apart
location in the heat rejection area. To integrate liquid cooling in
a flexible manner, the integrated cooling system 50 may comprise a
flexible liquid conduit 60, an integrated pumping unit 70, and an
integrated heat-exchanging unit 55.
[0034] In operation, the flexible liquid conduit 60 may provide
liquid ducting and manifolding between the integrated pumping unit
70 and the integrated heat exchanging unit 55. The integrated
pumping unit 70 may provide fluid circulation within the integrated
cooling system 50. A liquid 90 such as a coolant or water can flow
in a closed loop path 95 for dissipating heat generated in the heat
source 80.
[0035] Referring to FIG. 2, an exploded perspective view of a
flexible integrated cooling system 300 is depicted. The flexible
integrated cooling system 300 may comprise three layers including a
top metal layer 305A, a bottom metal layer 305B, and a center layer
305C that is generally disposed therebetween. The top and bottom
metal layers 305A, 305B can be made of copper, which is a good
thermal conductor. The center layer 305C may be a spacer such as a
plastic core of an appropriate thickness. For example, a polyimide
core on the order of from 5 mils to as much as 50 mils may be
utilized. Alternatively, the center layer 305C comprising a foamed
material is also contemplated.
[0036] Among other characteristics, flexibility and patternability
are primary characteristics for the center layer 305C. As can be
seen, the center layer 305C may be patterned on a first distal end
310A to provide a left cavity 315A and on a second distal end 310B
with a right cavity 315B. Furthermore, one or more micro-channels
may couple the left and right cavities 315A and 315B. For example,
a first tube 320A may be patterned to connect the left cavity 315A
to the right cavity 315B. Likewise, a second tube 320B connecting
the right cavity 315B to the left cavity 315A may be utilized. The
first and second tubes 320A, 320B form a closed loop circuit for a
liquid to flow when the center layer 305C is suitably enclosed at
the top and bottom utilizing the top and bottom metal layers 305A,
305B, respectively. Accordingly, the three layers 305A through 305C
may be glued together to form a multi-layer metal tape which
provides a flexible cooling interconnect for the integrated system
300 to handle an encapsulated liquid while exchanging heat in a
self-contained manner.
[0037] In order to enhance heat transfer within the left and right
cavities 315A, 315B, a first set of fins 330 and a second set of
fins 335 may be incorporated therein, respectively. The first and
second sets of fins 330 and 335 are equally spaced from each other
and separated by intermediate channels. Accordingly, for heat
dissipation within the left cavity 315A, a plurality of fins 330A
through 330I may be suitably incorporated. Likewise, for heat
extraction within the right cavity 315B, a plurality of fins 335A
through 335H may be appropriately included. If the cavities 315A,
315B are spaced significantly proximal to each other and if the
center layer 305C is relatively thin, fins 330 and 335 may be
discarded.
[0038] An external pump 340 can be attached to the top metal layer
305A. The external pump 340 may comprise a pair of bellows
including, a first bellow 345A and a second bellow 345B to provide
a push-full action for guiding the encapsulated liquid to flow
through the closed loop circuit. Such oscillatory push-pull action
generally causes a net fluid flow of the encapsulated liquid in a
desired direction. Alternatively, the left cavity 315A may include
an internal pump such as a rotary pump, a diaphragm pump, or an
electrokinetic pump. It is to be understood that a variety of
pumping means may be readily devised. Optionally, to reject heat to
atmosphere, an external heat sink 350 may be attached proximal to
the left cavity 315A. As the fluid is desired to flow from one
cavity to the other and back, to control such flow one or more
valves may be deployed. For example, a pair of flapper valves 360A
and 360B may allow flow of the encapsulated liquid in a desired
direction.
[0039] The foregoing describes only one embodiment of the present
invention, however, many variations of this embodiment will be
obvious to a person skilled in the art of semiconductor or
micro-electromechanical fabrication. Certainly, various other
materials and techniques can be utilized in the construction of the
various layers.
[0040] In operation, the encapsulated liquid is generally confined
to flow through micro-channels including the first and second tubes
320A and 320B formed in the polyimide core of center layer 305C,
which is generally bounded by the two opposing copper sheets of the
first and second layers 305A and 305B. The exploded view of FIG. 2
shows the flexible integrated cooling system 300 with flexible
micro-channels, generally bent to carry the encapsulated liquid
between a hot area on a second distal end 310B and a cooled area on
a first distal end 310A. Known die cutting, chemical etching, and
laser ablation techniques can be readily employed to cut out
regions in the polyimide core to define plenums or pipes, including
the depicted first and second tubes 320A and 320B. Also, a variety
of known techniques including plating techniques could be utilized
to form fins 330, 335 on the lower copper plane of the bottom layer
305B.
[0041] While the pair of flapper valves 360A and 360B are shown as
spot-welded, numerous alternate techniques could be used such as
adhesively bonding assemblies. Further, the bellows pair of the
external pump 340 may be soldered on the top layer 305A for
externally actuating first and second bellows 345A and 345B in a
push-pull mode to move fluid in the direction permitted by internal
flappers valves 360A and 360B. Using suitable geometry for the fins
330 and 335, liquid flows of a desired level could be contemplated,
such as liquid flows of a few cubic centimeters per second may be
provided. Heat is generally rejected to external air by convection
on the metal surfaces of the top and bottom layers 305A, 305B and,
additionally or optionally through the attached heat sink 350.
[0042] Referring to FIG. 3, a perspective view, partially in cross
section of an exemplary embodiment of an integrated flexible liquid
cooler is depicted. With reference to FIG. 1 and FIG. 3, for
dissipating heat generated in a package 105, an integrated flexible
liquid cooler 100 may comprise a first cavity 180A to contain a
pump for providing circulation of the liquid 90, and a heat
exchanger 120 disposed adjacent to the package 105 in a heat
conducting relationship for extracting heat therefrom. For
providing transpiration for the liquid 90, an integrated flexible
liquid cooler 100 may further include a flexible housing 125 having
a first pipe 130A and a second pipe 130B. The first and second
pipes 130A and 130B may comprise respective first ends 135A, 135B
and respective second ends 140A, 140B. The first ends 135A, 135B
may be securely coupled to the first cavity 180A and the second
ends 140A, 140B could be coupled to the heat exchanger 120 to form
the closed loop path 95 for circulating the liquid 90.
[0043] The integrated flexible liquid cooler 100 may further
comprise a heat sink 150 coupled to the first cavity 180A in a heat
conducting relationship for dissipating the heat generated in the
package 105. The package 105 may comprise one or more electronic
components having substantially high power dissipation. While the
package 105 may be disposed at a location having substantially
constrained airflow, heat generated by the package 105 could be
readily transferred for dissipation from the heat exchanger 120 to
the heat sink 150 via a fluid flow through the flexible housing
125. The invention is particularly advantageous when the first
cavity 180A is integrated with heat sink 150, which can be located
away from the package 105 so that the extracted heat may be
remotely dissipated.
[0044] The flexible housing 125 may comprise a first layer 155, an
intermediate layer 165, and a second layer 185. The intermediate
layer 165 may include a first and a second opposing portions 175A,
175B, respectively. It may also include the first cavity 180A at
the first portion 175A, and a second cavity 180B at the second
portion 175B. Moreover, the intermediate layer 165 is tightly
coupled to the first major surface 170 of the first layer 155. The
intermediate layer 165 is also coupled to the second surface 171 of
the second layer 156.
[0045] The first layer 155 and the second layer 156 may be made of
a metal such as copper. Moreover, the intermediate layer 165 is
flexible, patternable, and may comprise a foamed polymer or a
polyimide layer. The first and second pipes 130A and 130B may
couple the first cavity 180A to the second cavity 180B, and may be
formed by appropriately patterning the intermediate layer 165. The
cavity 180A may contain a pump to provide the circulation of a
liquid, routing it through a closed loop path. As shown in FIG. 3,
the first cavity 180A can contain a pump to be integrated with the
flexible housing 125. Likewise, the heat exchanger 120 can be
internally located at the second cavity 180B.
[0046] One skilled in the art will realize that a variety of pumps
could be deployed including, but are not limited to a rotary pump
or a diaphragm pump. Such rotary or diaphragm pump circulate a
liquid, thereby causing a net flow thereof through a closed loop
path between the first cavity 180A and the second cavity 180B.
[0047] Referring to FIG. 4, a heat transfer system is depicted. A
pumping region 410 is coupled to a heat rejection region 420 via a
fluid micro-channel 400. The heat rejection region 420 is coupled
to a heat extraction region 430 via the fluid micro-channel 400.
The heat extraction region 430 is coupled to a heat source 440.
[0048] Still referring to FIG. 4, three general regions are shown:
the heat extraction region 430, the heat rejection region 420, and
the pumping region 410. These are created and interconnected by
fluid micro-channel 400 in the tape core. The heat extraction 430
region will generally be remote and separate from the heat
rejection region 420 and the pumping region 410. However, the
latter two may be in the order shown, reversed in order, or
combined into a single region.
[0049] Referring to FIG. 5, a gear pump with magnetic coupling is
depicted. A fluid channel 500 in the tape core allows liquid to
circulate in the flexible tape. A ferromagnetic gear 510 is coupled
to a gear 505 inside the fluid channel 500 in the tape core. An
external coil 520 drives the ferromagnetic gear 510.
[0050] Still referring to FIG. 5, pump systems of this type are
well known, but have not been integrated with a tape based cooling
system in the prior art. One of the gears is ferromagnetic, or made
of a permanent magnetic material, and is driven by a rotating
magnetic field created by the external coil 520 (shown below the
tape itself). FIG. 5 is a view of the tape with the top copper
sheet removed. The gears have holes in their centers and are simply
placed on bearing posts created in the tape core (polyimide) by
laser ablation.
[0051] Referring to FIGS. 6A-6D, various heat transfer regions of
different types of flexible tape are depicted. Several fin
structures are shown, which enhance heat transfer to the fluid
passing through them.
[0052] Referring to FIG. 6A, a fluid micro-channel 600A is
patterned in a foam layer 630A. A polyimide layer 610A is coupled
to the foam layer 630A via an adhesive layer 620A. The foam layer
630A is coupled to a metal layer 650A via an adhesive layer
640A.
[0053] Still referring to FIG. 6A, a heat transfer region of a
copper/foam/polyimide flexible tape with adhesive between layers is
depicted. If heat transfer is desired only through the bottom
surface, the upper surface need not be copper and can be another
material, such as polyimide. This makes the assembly even more
flexible.
[0054] Referring to FIG. 6B, a fluid micro-channel 600B is
patterned in a thermoplastic layer 620B. A metal layer 610B is
coupled to the thermoplastic layer 620B. The thermoplastic layer
620B is coupled to a metal layer 630B. A set of fins 640 is plated
to the metal layer 630B, inside the fluid micro-channel 600B.
[0055] Still referring to FIG. 6B, a heat transfer region of a
copper/thermoplastic/copper flexible tape is depicted. Melting the
thermoplastic provides the bond to the copper. Also shown is a
possible heat transfer structure using micro-fins plated on one of
the copper layers.
[0056] Referring to FIG. 6C, a fluid micro-channel 600C is
patterned in a polyimide layer 630C. A metal layer 610C is coupled
to the polyimide layer 630C via an adhesive layer 620C. The
polyimide layer 630C is coupled to a metal layer 650C via an
adhesive layer 640C. A set of folded metal fins 660C is attached to
the metal layer 650C via welding, gluing or soldering, inside the
fluid micro-channel 600C.
[0057] Referring to FIG. 6D, a fluid micro-channel 600D is
patterned in a polyimide layer 620D. A metal layer 610D is coupled
to the polyimide layer 600D. The polyimide layer 620D is coupled to
a metal layer 630D. A metal mesh 640D partially fills the fluid
micro-channel 600D.
[0058] Variations of the invention can be devised by one skilled in
the art. For example, micro-channel fins can be machined on a chip
surface. A tape based cooling system may provide piping and
manifolding, and can be soldered or adhesively sealed to the chip
surface to form an integrated package/liquid loop. Another
implementation utilizes two polyimide layers and three metal layers
to provide fluid piping and plenums. The intermediate layer is
perforated at the heat exchange regions to provide liquid jet
impingement cooling. In yet another implementation, the one of the
two polyimide ducts is filled with a wick, the other is a vapor
channel. A plurality of layers may be utilized.
[0059] The context of the invention can include cooling and/or heat
sinking electronic components, subsystems and/or systems. The
context of the invention can also include cooling and/or heat
sinking mechanical, optical, chemical and/or biological components,
subsystems and/or systems.
[0060] The invention can also be included in a kit. The kit can
include some, or all, of the components that compose the invention.
The kit can be an in-the-field retrofit kit to improve existing
systems that are capable of incorporating the invention. The kit
can include software, firmware and/or hardware for carrying out the
invention. The kit can also contain instructions for practicing the
invention. Unless otherwise specified, the components, software,
firmware, hardware and/or instructions of the kit can be the same
as those used in the invention.
[0061] The term approximately, as used herein, is defined as at
least close to a given value (e.g., preferably within 10% of, more
preferably within 1% of, and most preferably within 0.1% of). The
term substantially, as used herein, is defined as at least
approaching a given state (e.g., preferably within 10% of, more
preferably within 1% of, and most preferably within 0.1% of). The
term coupled, as used herein, is defined as connected, although not
necessarily directly, and not necessarily mechanically. The term
deploying, as used herein, is defined as designing, building,
shipping, installing and/or operating. The term means, as used
herein, is defined as hardware, firmware and/or software for
achieving a result. The term program or phrase computer program, as
used herein, is defined as a sequence of instructions designed for
execution on a computer system. A program, or computer program, may
include a subroutine, a function, a procedure, an object method, an
object implementation, an executable application, an applet, a
servlet, a source code, an object code, a shared library/dynamic
load library and/or other sequence of instructions designed for
execution on a computer system. The terms including and/or having,
as used herein, are defined as comprising (i.e., open language).
The terms a or an, as used herein, are defined as one or more than
one. The term another, as used herein, is defined as at least a
second or more.
Advantages of the Invention
[0062] An integrated liquid cooling system of flexible structure,
representing an embodiment of the invention, can be cost effective
and advantageous for at least the following reasons. The invention
allows for a thin, bendable, potentially resilient heat transport
system. The invention improves quality and/or reduces costs
compared to previous approaches.
[0063] All the disclosed embodiments of the invention disclosed
herein can be made and used without undue experimentation in light
of the disclosure. Although the best mode of carrying out the
invention contemplated by the inventors is disclosed, practice of
the invention is not limited thereto. Accordingly, it will be
appreciated by those skilled in the art that the invention may be
practiced otherwise than as specifically described herein.
[0064] Further, the individual components need not be formed in the
disclosed shapes, or combined in the disclosed configurations, but
could be provided in virtually any shapes, and/or combined in
virtually any configuration. Further, the individual components
need not be fabricated from the disclosed materials, but could be
fabricated from virtually any suitable materials.
[0065] Further, although the integrated liquid cooling system of
flexible structure described herein can be a separate module, it
will be manifest that the integrated liquid cooling system of
flexible structure may be integrated into the system with which it
is associated. Furthermore, all the disclosed elements and features
of each disclosed embodiment can be combined with, or substituted
for, the disclosed elements and features of every other disclosed
embodiment except where such elements or features are mutually
exclusive.
[0066] It will be manifest that various substitutions,
modifications, additions and/or rearrangements of the features of
the invention may be made without deviating from the spirit and/or
scope of the underlying inventive concept. It is deemed that the
spirit and/or scope of the underlying inventive concept as defined
by the appended claims and their equivalents cover all such
substitutions, modifications, additions and/or rearrangements.
[0067] The appended claims are not to be interpreted as including
means-plus-function limitations, unless such a limitation is
explicitly recited in a given claim using the phrases(s) "means
for" and/or "step for." Subgeneric embodiments of the invention are
delineated by the appended independent claims and their
equivalents. Specific embodiments of the invention are
differentiated by the appended dependent claims and their
equivalents.
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