U.S. patent application number 12/291983 was filed with the patent office on 2009-06-04 for carbon-based waterlock with attached heat-exchanger for cooling of electronic devices.
This patent application is currently assigned to Watronx, Inc. (aka OnScreen Technologies, Inc.). Invention is credited to Stanley Robinson.
Application Number | 20090139698 12/291983 |
Document ID | / |
Family ID | 40674553 |
Filed Date | 2009-06-04 |
United States Patent
Application |
20090139698 |
Kind Code |
A1 |
Robinson; Stanley |
June 4, 2009 |
Carbon-based waterlock with attached heat-exchanger for cooling of
electronic devices
Abstract
A cooling device for an electric component or components,
includes a coolant liquid circulation system, a carbon-based heat
intake block for transferring heat from said electrical component
or components, a top layer on the carbon block for increasing
thermal inertia during heat transfer via said layer by system
coolant, and means whereby the heated coolant transfers heat to a
heat remover.
Inventors: |
Robinson; Stanley; (Vista,
CA) |
Correspondence
Address: |
WILLIAM W. HAEFLIGER
201 S. LAKE AVE, SUITE 512
PASADENA
CA
91101
US
|
Assignee: |
Watronx, Inc. (aka OnScreen
Technologies, Inc.)
|
Family ID: |
40674553 |
Appl. No.: |
12/291983 |
Filed: |
November 17, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61005012 |
Dec 3, 2007 |
|
|
|
Current U.S.
Class: |
165/104.31 ;
165/104.33 |
Current CPC
Class: |
H01L 2924/0002 20130101;
F28F 1/32 20130101; F28D 15/00 20130101; F28F 3/12 20130101; H01L
23/473 20130101; F28F 21/02 20130101; H01L 2924/0002 20130101; H01L
2924/00 20130101 |
Class at
Publication: |
165/104.31 ;
165/104.33 |
International
Class: |
F28D 15/00 20060101
F28D015/00 |
Claims
1. In a cooling device for an electrical component or components,
the combination of: a) a coolant liquid cooling system, b) a
carbon-based heat intake block for transferring heat from said
electrical component or components, c) a top layer on the carbon
block for increasing thermal inertia during heat transfer via said
layer to system coolant, and d) means whereby the heated coolant
transfers heat to a heat remover.
2. The combination of claim 1 wherein the liquid cooling system is
self contained and hermetically sealed.
3. The combination of claim 1 including a diaphragm in contact with
the coolant for thermal expansion compensation
4. The device of claims 2 or 3 including a fan to move air over
heat removing radiator fins, the fan located in alignment with the
block.
5. The device of claim 4 where the fan is a centrifugal fan in
alignment with the block and said top layer.
6. The device of any of the preceding-claims where additional
cooling means are provided and ported to a cooler.
7. A method for cooling electric components, comprising in
combination: passing liquid through a cooling system having a
carbon-based heat transfer block, wherein the carbon-based block
has a top layer of a different material for increasing thermal
inertia; and a plumbing system in which coolant to which heat is
transferred via said layer and is pumped by a pump through pipes
thermally coupled to heat radiator fins.
8. The method of claim 7 wherein the liquid cooling system is self
contained and hermetically sealed.
9. The method of claim 8 wherein the thermal expansion of the
coolant is compensated for by an expansion chamber.
10. The method of claim 9 wherein the expansion chamber is formed
at least in part by a flexible diaphragm.
11. The method of claim 9 wherein air is moved in cooling relation
across the fins by a fan, in alignment with the block.
12. The method of claim 11 wherein the fan is a centrifugal
fan.
13. The method of claim 9 wherein the expansion chamber, pump and
diaphragm are in alignment with said carbon block, providing a
compact assembly.
14. The method of claim 7-12 wherein additional cooling means are
operatively attached to a main cooler defined by said system.
15. Cooling apparatus for an electrical component or components,
comprising in combination: a) a housing defining first and second
liquid coolant flow chambers, in communication, b) pyrolytic carbon
structure association with the housing to transfer heat from said
component or components to coolant flowing in the first chamber,
thereby heating the coolant, c) thermal inertion means in the path
of heat transfer from said block to the coolant in the first
chamber, said means having a composition different from that of
said structure, d) other means for flowing heated coolant from the
second chamber to heat removal means and for returning said coolant
to the first chamber.
16. The combination of claim 15 including an elastic diaphragm
forming a wall of the second chamber, to deflect in response to
pressure increase of the coolant.
17. The combination of claim 15 wherein said thermal inertia means
has the forms of a layer on the carbon structure, said layer having
an irregular surface exposed to coolant in the first chamber.
18. The combination of claim 17 wherein said layer consists
primarily of a material selected from the group that includes
aluminum, copper, silver and gold.
19. The combination of claim 17 wherein the carbon consists of a
block of carbon having molecular cleavage planes that extend toward
said layer.
20. The combination of claim 14 including said heat removal means
that comprises one of the following structures: x.sub.1) a
centrifugal fan in alignment with the block, heat radiating fins
extending about the fan, and said other means including coolant
ducting extending in heat transfer relation with the fins, x.sub.2)
a heat radiator spaced from said housing, said other means
including coolant ducting extending between said radiator and said
second chamber.
21. The combination of claim 19 wherein said other means includes a
cover over said second chamber and defining flow paths
communicating between said ducting and said second chamber.
22. The combination of claim 17 wherein said irregular surface
faces toward a pump delivering coolant toward and through an
opening in an enclosure extending about the pump, and flowing
toward and against said irregular surface.
23. The combination of claim 12 wherein said layer is metallic and
forms said irregular surface, said layer engaging the side of a
carbon block having cleavage planes extending toward the metallic
block.
24. The combination of claim 23 wherein said layer consists of a
metal selected from the group consisting of aluminum, copper,
silver and gold.
25. The combination of claim 22 including coolant passages in
housing and housing cover structure enclosing the pump, there being
cooling fins spaced above the cover and coolant pipes extending
through the fins and communicating with said passages, and a
centrifugal fan located between banks of said fins.
Description
[0001] This application claims priority from provisional
application Ser. No. 61/005,012, filed Dec. 3, 2007.
FIELD OF THE INVENTION
[0002] The evolution of electronic devices to more compact form
factors and, specifically, the migration of semiconductor
manufacturing to smaller design processes have increased the power
density of modern semiconductors orders of magnitude above that of
older designs. Some of the areal power density increase is offset
by reduced supply voltages and concurrent reduction in operating
current. However, modern semiconductors also operate at much higher
frequencies than their predecessors, which counteracts the savings
stemming from lower voltages. Power density is equivalent to areal
heat dissipation; as a result, the trend towards compact, high
speed integrated circuits (ICs) results in higher thermal load and,
by extension, increasing challenges for cooling solutions.
[0003] The ideal situation for any cooling device is to maintain a
uniform temperature distribution across the entire surface. Uniform
temperature distribution is also known as isothermicity and the
only way of approaching this is to move heat as quickly and
efficiently as possible from the source to any other part of the
cooler. Compared to passive heat transfer through any solid
material, active transport provides much higher efficacy of heat
transport. A well-established example is the liquid cooling system
of combustion engines where heat is taken up by water, which is
pumped away from the engine to a remote radiator where the heat is
then released into the environment. In the case of electronic
devices, liquid cooling has been used in specialty designs but
never received general acceptance in mainstream consumer devices.
Primary reasons for the lack of general acceptance comprise among
other factors the inherent risk for spills, life expectancy of
pumps, the cost overhead, the complexity of installation which
includes routing of tubing and the configuration of more or less
bulky radiators.
[0004] Any cooling system can only be as efficient as the primary
interface responsible for the removal of thermal energy from the
source. In the case of electronics, it appears as if the highest
efficiency could be achieved by direct immersion of the
semiconductor into the coolant. However, for all practical
purposes, in the consumer space, this may not be a viable solution
because of the reasons mentioned above. A more feasible solution
necessarily entails a self-contained, sealed system. Sealed
systems, on the other hand rely on the efficiency of the thermal
interface between the semiconductor die and the coolant. In that
particular area, many different solutions have been proposed, based
on waterblocks machined from copper or silver. However, even copper
or silver have a relatively low thermal conductivity compared to
carbon structures, for example diamonds. Diamonds, on the other
hand are not only too expensive for mainstream cooling devices,
they are also close to impossible to machine into a suitable form.
Carbon nano tubes (CNT) and carbon nano fibers (CNF) have been
discussed as possible thermal conductors but at the present time
obtaining pure CNT structures is still cost prohibitive. A superbly
thermally conductive material is pyrolytic carbon, which is a
carbon material similar to graphite but with additional covalent
bonding between the individual graphene sheets. The specific
bonding arrangement in form of sheets with additional cross-linking
between the sheets results in unique heat transfer distribution
characteristics that can be used to increase net thermal transfer
from any source.
DESCRIPTION OF RELATED ART
Carbon-Based Interfaces
[0005] Current approaches to heat transfer away from electronic
components have employed a variety of materials, mostly copper or
aluminum based as the primary interface. Carbon-based solutions
have been used in experimental designs but have not gained wide
acceptance. Reasons for the failure in acceptance of carbon
materials are found in the lack of three-dimensional transfer of
heat, resulting in excellent laminar conduct through the sheets but
an almost complete lack of dissipation into the environment. As a
result, the surface area at the back end of a graphene-based cooler
is essentially the same size as the surface area at the front end,
namely the cross sectional surface of each sheet and does not offer
any advantage with respect to facilitation of heat dissipation to
the environment. Another drawback of carbon-based-solutions is the
very low heat capacitance or buffering capability that can cause
adverse side effects such as temporary, local boiling of any liquid
cooling media on the back end of the carbon interface.
Expansion Reservoir
[0006] Most liquid cooling systems used with electronic components
rely on a remote reservoir, a pump and more or less elaborate tube
connections between the individual components. The reservoir also
serves to compensate for the temperature-dependent expansion of the
coolant in order to avoid building up of pressure that could
eventually break the seals of the system. Expansion reservoirs are
usually rather simple, in some closed systems, the plenum is simply
not filled completely but contains air bubbles that are compressed
with increasing temperature and associated thermal expansion of the
liquid coolant. However, any air in the system can cause a
breakdown of the cooling efficiency. Within a self-contained
compact cooling system partial fills would have the same
disadvantages, on the other hand, pressure changes can cause
mechanical stress and should be avoided at all means.
Carbon-Based Waterblock with Heat Exchanger
[0007] The combination of carbon interface machined to contain
microchannels with a hermetically sealed, self-contained
fluid-cooling system has been disclosed in an earlier patent
application (Robinson, 2007). However, the invention described does
not address the buffering of fast temperature transients on the
fluid back-end of the cooling system, nor does it address the issue
of pressure compensation within the closed system. The above
mentioned limitations of existing coolers underscore the need for
more advanced solutions for the use with high power density
electronic components.
SUMMARY OF THE INVENTION
[0008] The present invention provides a cooling device utilizing
the thermal transfer characteristics of pyrolytic carbon for
enhanced heat removal from a semiconductor. The high thermal
conductivity along the X and Y axes of the sheets can be used to
expand the initial contact area towards the heat source (heat
absorption area) at least in one dimension. That is, the cleavage
plane is typically positioned in normal orientation to the chip
interface surface whereas optimal conductance is found in any
direction within the sheets parallel to the cleavage plane. This
orientation allows for expanding the "release" interface surface
area for thermal energy depending on the thickness of the carbon
interface block. For the addition of thermal inertia on the release
surface, a layer of thermally conductive material is bonded to the
carbon block, which also allows for standard processes of machining
of any surface increasing structures such as micro or macro
channels into the metal layer. The metal layer itself serves as an
interface to the liquid coolant that is pumped across its surface.
The coolant may then be ducted into a system of pipes that are
thermally connected to a cooling fin array. A pump moves the fluid
through the channel and pipe system. The entire system may be
hermetically sealed, and typically contains a diaphragm to allow
for expansion of the fluid as it increases in temperature. In one
embodiment, a squirrel cage type fan moves air through the fin
array to take up heat and dissipate it into the environment.
Because of the high efficiency of the cooler, it is possible to add
additional cooling blocks to the main cooler, these satellite
coolers can then be ported to the coolant and serve for thermal
management of additional components such as chipsets, voltage
regulators, power supply transistors or even discrete graphics
processors.
UTILITY OF THE INVENTION
[0009] In short, the advantages of the current invention can be
summarized as follows: [0010] a) Highest possible heat uptake from
the heat source by the carbon interface. [0011] b) Expansion of the
heat dissipation area compared to the heat uptake through use of
pyrolytic carbon. [0012] c) Combination of carbon with metal
increases thermal inertia of the interface to prevent local hot
spots on the coolant side. [0013] d) Liquid coolant provides
efficient removal of heat from the source. [0014] e) Expansion
diaphragm accommodates thermal expansion of the coolant without
pressure changes or air in the system. [0015] f) Self-contained
cooling system is user-friendly and easy to install. [0016] g) High
efficiency of the main cooler allows porting of satellite cooling
blocks for additional components.
DETAILED INITIAL DESCRIPTION OF THE INVENTION
[0017] The present invention provides a self-contained cooling
system having extreme efficiency. The self contained, hermetically
sealed configuration ensures ease of installation, along with a
maintenance free use for the lifespan of the cooling device. The
efficiency of the cooling performance stems from a variety of
features, each of which is important by itself and which, in
combination, work synergistically to remove heat from high power
density devices and dissipate it at a high rate into the
environment.
[0018] The initial absorption of the heat is achieved through a
carbon interface. Pyrolytic carbon has a thermal conductance of
approximately 1400 W/m/C along the X and Y directions, parallel to
the cleavage plane or planes of the graphite sheets. Since the heat
conductance occurs in two dimensions rather than unidirectionally,
this circumstance can be used to expand the interface area in an
almost lossless manner, which also reduces the power density on the
back face of the carbon block. The pyrolytic carbon interface is
oriented with the cleavage plane or planes substantially normal to
the front and back faces of the carbon block. The expansion of the
back face compared to the front face depends on the thickness of
the carbon block used and will typically have a 3:1 or greater
ratio.
[0019] Pyrolytic carbon has very low thermal capacitance or
buffering capability, therefore, fast thermal transients are
propagated through the block without much attenuation. In the case
of fluid cooling, this can result in boiling of the coolant or else
insufficient dissipation into the coolant and either situation can
cause transient temperature spikes on the heat source. To avoid
these thermal transients, it is of advantage to add a buffer in the
form of, for example, copper or aluminum to the back face of the
carbon block, thereby forming a hybrid interface block. The
increased thermal capacitance results in thermal inertia of the
hybrid block, which greatly reduces the thermal fluctuations at the
heat source. In addition, it is very easy to machine copper or
aluminum to add surface extensions in the form of fins or spikes
that facilitate heat transfer to the coolant.
[0020] The cooling apparatus disclosed is typically a single, self
contained structure that is mounted onto a standard processor,
examples being central processing units as currently manufactured
by Advanced Micro Devices (AMD) or Intel, or else graphics
processors as manufactured by AMD or nVidia. Those processors have
standard mounting brackets associated with each design to allow
interchangeable equipment with original and after market cooling
devices. In most cases it is a clip that is engaged, alternatively,
pegs or screws are commonly employed. Often, a back plate serves to
reinforce the printed circuit board in order to avoid flexing of
the board caused by the weight of the cooler in situations where
the system is transported and possibly subjected to bumps or
impacts.
[0021] Because of the self-contained, hermetically sealed nature of
the cooler, it is necessary to accommodate the thermal expansion of
the coolant that occurs if the processor gives off heat. Different
designs are possible to achieve this goal, for example a flexible
expansion reservoir can be used with unusual advantage. A variation
of this type of reservoir is a concave diaphragm that can flip in
or out, depending on the pressure of the coolant in the system.
Such a flexible diaphragm is easy to manufacture and implement into
the wall of any coolant container.
[0022] The cooler disclosed herein is extremely powerful and scales
with size, meaning that any increase of the radiators will increase
the amount of heat that can be dissipated into the environment.
This allows extension of the cooling apparatus beyond the central
processor, and the use of satellite attachments that are ported to
the same coolant circulation system to provide thermal management
of the voltage regulator modules, the chipset and potentially of
discrete graphics as well. None of the mentioned components require
any further cooling devices beyond the satellites.
[0023] Most coolers currently used employ axial fans, primarily
because of high efficiency and low cost. Axial fans, however, are
usually noisier than centrifugal fans also known as squirrel cage
fans of similar rating. In the case of the cooling device at hand,
a further advantage of the centrifugal fan provided is that there
is very little back pressure and the air passes through the cooling
fins without being redirected. The combination of the centrifugal
fan with a radiator surrounding it results in ultra-quiet operation
at very high levels of air movements.
[0024] Remote radiator apparatus may also be provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 shows a schematic drawing of the integrated liquid
cooler including the carbon interface with the metal overlay for
increased thermal inertia, a pump, water pipes with radiator fins,
a centrifugal fan and the diaphragm for thermal expansion
compensation;
[0026] FIG. 2 is a tilted top view for illustration of the fan
arrangement compared to the radiator fins and water pipes; FIG. 3
shows a tilted bottom view for illustration of the carbon block
interface;
[0027] FIG. 4 shows a functional illustration of the action of a
thermal expansion compensation diaphragm;
[0028] FIG. 5 schematically shows additional satellite coolers for
thermal management of e.g. chipset and voltage regulators connected
to the main cooler;
[0029] FIG. 6 shows an alternate heat radiator and liquid cooler
configuration;
[0030] FIG. 7 is like FIG. 6, but shows a remote radiator; and
[0031] FIG. 8 is a view like FIG. 1, showing a modification.
DETAILED DESCRIPTION
[0032] Referring now to preferred cooling apparatus of FIG. 1, it
includes a housing 10 defining first and second laterally extending
liquid coolant flow chambers 11 and 12, in flow communication via a
central passage 13. That passage may be formed by a pump 14 in the
housing and operating to pump fluid centrally from chamber 12 to
chamber 11, as shown by arrows 15. The flow is directed toward the
irregular top surface 16 of a layer 17 to remove or transfer heat
from that surface to the coolant flowing in opposite directions in
passages 18 and 19 in the housing. From those passages, the coolant
flows via pipes 20 and 21 to means indicated generally at 40, such
as fins 41 operating to remove heat from the coolant, and to return
the coolant via pipe 42 and 43 to upper chamber 12, in a highly
compact configuration.
[0033] Upper wall 22 of chamber 12 comprises a diaphragm
peripherally mounted at 23 to the housing ring 10a, so as to allow
upward flexing of the diaphragm in response to coolant fluid
expansion. A housing cover plate 23' extends over the diaphragm and
is attached to housing surface 24, whereby the chambers 11 and 12
and the diaphragm are hermetically sealed.
[0034] An electrical component 124 engages the underside 25a of
pyrolytic carbon block 25 fitted peripherally in the bounded space
formed by housing wall 26, layer 17 also peripherally fitting in
that space. Heat received by block 25, by conduction from the
electrical component, is transferred by conduction to the layer 17
comprising a metal interface block (between water and carbon block
25). Its upper surface has irregularity, as for example is provided
by recesses 28 in the layer, that increase the surface area in
contact with coolant in chamber 12, for enhanced heat transfer. The
structure of block 25 and layer 17, and their functioning, prevent
boiling of the coolant, such as water.
[0035] The planes 30 indicative of molecular cleavage planes in
block 25 are directed toward layer 17, for most efficient heat
transfer operation. A centrifugal fan 32 is shown as located in the
space 33 between banks 41a of fins 41, to displace cooling air
radially in passages 41b between fins, for removing heat from the
fins.
[0036] Pyrolytic carbon is a material similar to graphite, but with
some covalent bonding between its graphene sheets. Generally it is
produced by heating a hydrocarbon nearly to its decomposition
temperature, and permitting the graphite to crystallize
(pyrolysis).
[0037] FIG. 5 shows flow ducts 50 and 51 to circulate coolant from
12 to and from a chips at cooler 54; and ducts 55 and 56 to
circulate coolant from 22 to and from a voltage regulator cooler
57.
[0038] FIG. 6 incorporates plate 23 and all the structure of FIG. 1
below that plate. A cover 70 is provided above plate 23 and
incorporate passages that connect chamber 12 with a hose or duct
71, and passages 18 and 19 with a hose or duct 72. Hoses or ducts
71 and 72 extend to a heat radiator 73. Fan 32 and fins 41 are
eliminated, and the remaining apparatus is simplified.
[0039] FIG. 7 is like FIG. 6, excepting that the radiator is
remotely located, as is made by the breaks at 71a and 72a in the
hoses or ducts 71 and 72.
[0040] Cooling fans 74 may be provided to displace air through the
radiator.
[0041] In FIG. 8 the arrangement of elements is generally like that
in FIG. 1, the same numerals being applied to those elements.
[0042] In FIG. 8, the flow passes from space 12 downwardly through
central opening 80 and then divides due to operation of the pump 14
to flow downwardly at 81 about pump structure 14a. The flow then
passes downwardly through central opening 13, to contact metal
interface/water block 17. The flow then travels laterally at 18 and
19, as described in FIG. 1. Carbon block 25 extends directly
beneath and in surface to surface contact with block 17. Electrical
component 124 engages the underside face of block 25, to transfer
heat thereto. Block 17 is in the form of a layer that consists
primarily of a material selected from the group that includes
aluminum, copper, silver and gold. Carbon block 25 has molecular
cleavage planes that extend toward layer 17. The FIG. 8 apparatus
is preferred.
[0043] Additional compactly arranged elements include: [0044] an
enclosure 10A extending about the pump and forming passage 13
through which coolant flow is delivered by the pump 14 toward and
against the upper irregular surface of block 17, [0045] heat
radiator fins 41A and 41G, spaces 41B between the fins, and heat
exchanger 40, [0046] hot water (coolant) pipes 42 and 43, [0047]
centrifugal fan 32 rotating in a space between inner ends 33 of the
fins, [0048] outer housing 10 extending about the pump and
supporting housing cover 23, there being coolant passages 20 and 21
in the cover and communicating with passages 18 and 19 formed
between 10 and 10A, [0049] diaphragm 22 overlying opening 80, and
underlying the fan 32, the diaphragm carried by the cover 23.
* * * * *