U.S. patent application number 11/749444 was filed with the patent office on 2007-09-20 for integrated circuit coolant microchannel assembly with targeted channel configuration.
Invention is credited to Je-Young Chang, Chia-Pin Chiu, Gregory M. Chrysler, Eric DiStefano, Chuan Hu, Rajiv K. Mongia, Himanshu Pokharna, Ravi S. Prasher, Ioan Sauciuc.
Application Number | 20070217147 11/749444 |
Document ID | / |
Family ID | 37082421 |
Filed Date | 2007-09-20 |
United States Patent
Application |
20070217147 |
Kind Code |
A1 |
Chang; Je-Young ; et
al. |
September 20, 2007 |
INTEGRATED CIRCUIT COOLANT MICROCHANNEL ASSEMBLY WITH TARGETED
CHANNEL CONFIGURATION
Abstract
A microchannel structure has microchannels formed therein. The
microchannels are to transport a coolant and to be proximate to an
integrated circuit to transfer heat from the integrated circuit to
the coolant. At least one of the microchannels has a length extent
and has a first section at a first location along the length extent
and a second section at a second location along the length extent.
The first section of the microchannel has a first aspect ratio and
the second section is divided into at least two sub-channels. Each
sub-channel has a respective second aspect ratio that is greater
than the first aspect ratio.
Inventors: |
Chang; Je-Young; (Phoenix,
AZ) ; Sauciuc; Ioan; (Phoenix, AZ) ; Hu;
Chuan; (Chandler, AZ) ; Chiu; Chia-Pin;
(Tempe, AZ) ; Chrysler; Gregory M.; (Chandler,
AZ) ; Prasher; Ravi S.; (Phoenix, AZ) ;
Mongia; Rajiv K.; (Fremont, CA) ; Pokharna;
Himanshu; (San Jose, CA) ; DiStefano; Eric;
(Livermore, CA) |
Correspondence
Address: |
BUCKLEY, MASCHOFF & TALWALKAR LLC
50 LOCUST AVENUE
NEW CANAAN
CT
06840
US
|
Family ID: |
37082421 |
Appl. No.: |
11/749444 |
Filed: |
May 16, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11101061 |
Apr 7, 2005 |
|
|
|
11749444 |
May 16, 2007 |
|
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|
Current U.S.
Class: |
361/689 ;
257/E23.098 |
Current CPC
Class: |
H01L 2924/0002 20130101;
H01L 2924/00 20130101; F28F 2260/02 20130101; F28F 3/12 20130101;
H01L 23/473 20130101; H01L 2924/0002 20130101 |
Class at
Publication: |
361/689 |
International
Class: |
H05K 7/20 20060101
H05K007/20 |
Claims
1-7. (canceled)
8. An apparatus comprising: a microchannel structure having
microchannels formed therein, said microchannels to transport a
coolant and to be proximate to an integrated circuit to transfer
heat from the integrated circuit to the coolant; a cover positioned
on the microchannel structure; and a plate mounted on said cover,
said plate having formed therein a right-angle passage to provide
fluid communication between a first port on a lower horizontal
surface of said plate and a second port on a vertical surface of
said plate.
9. The apparatus of claim 8, wherein said first port is aligned
with an inlet formed in said cover.
10. The apparatus of claim 9, wherein said right-angle passage is a
first right-angle passage; said plate also having formed therein a
second right-angle passage to provide fluid communication between a
third port on said lower horizontal surface of said plate and a
fourth port on a vertical surface of said plate; wherein said third
port is aligned with an outlet formed in said cover.
11. An apparatus comprising: a microchannel structure having
microchannels formed therein, said microchannels to transport a
coolant and to be proximate to an integrated circuit to transfer
heat from the integrated circuit to the coolant; a cover positioned
on the microchannel structure and having formed therein a
right-angle passage to provide fluid communication between a first
port on a lower horizontal surface of said cover and a second port
on a vertical surface of said cover.
12. The apparatus of claim 11, wherein said right-angle passage is
a first right-angle passage; said cover also having formed therein
a second right-angle passage to provide fluid communication between
a third port on said lower horizontal surface of said cover and a
fourth port on said vertical surface of said cover.
13. The apparatus of claim 11, wherein said right-angle passage is
a first right-angle passage and said vertical surface is a first
vertical surface; said cover also having formed therein a second
right-angle passage to provide fluid communication between a third
port on said lower horizontal surface of said cover and a fourth
port on a second vertical surface of said cover, said second
vertical surface being different from said first vertical
surface.
14. A microchannel assembly comprising: a first member having a
base and parallel walls extending normally from said base; and a
second member having a base and parallel walls extending normally
from said base of said second member; said second member bonded to
said first member such that said parallel walls of said second
member cooperate with said parallel walls of said first member to
define microchannels, said microchannels to transport a coolant and
to be proximate to an integrated circuit to transfer heat from the
integrated circuit to the coolant.
15. The microchannel assembly of claim 14, wherein: each of said
parallel walls of said first member has a respective outer end;
each of said parallel walls of said second member has a respective
outer end; and the respective outer end of each of said parallel
walls of said first member is bonded to the respective outer end of
a respective one of said parallel walls of said second member.
16. The microchannel assembly of claim 14, wherein: each of said
parallel walls of said first member has a respective outer end;
each of said parallel walls of said second member has a respective
outer end; the outer ends of the parallel walls of said first
member are bonded to said base of said second member; and the outer
ends of the parallel walls of said second member are bonded to said
base of said first member.
17. A method comprising: providing a first member having a base and
parallel walls extending normally from said base; providing a
second member having a base and parallel walls extending normally
from said base of said second member; and bonding said first member
to said second member to form a microchannel assembly.
18. The method of claim 17, wherein: each of said parallel walls of
said first member has a respective outer end; each of said parallel
walls of said second member has a respective outer end; and said
bonding includes bonding the respective outer end of each of said
parallel walls of said first member to the respective outer end of
a respective one of said parallel walls of said second member.
19. The method of claim 18, wherein: each of said parallel walls of
said first member has a respective outer end; each of said parallel
walls of said second member has a respective outer end; and said
bonding includes: bonding the respective outer end of each of said
parallel walls of said first member to the base of said second
member; and bonding the respective outer end of each of said
parallel walls of said second member to the base of said first
member.
20. A method comprising: supplying a microchannel assembly having
at least one microchannel formed therein, said at least one
microchannel to transport a coolant and to be proximate to an
integrated circuit to transfer heat from the integrated circuit to
the coolant; and flowing a coolant from opposite ends of said at
least one microchannel to a central location of said at least one
microchannel.
21. The method of claim 20, wherein the coolant is flowed into said
microchannel assembly via two inlets, including a first inlet
located at a first end of the microchannel assembly and a second
inlet located at a second end of the microchannel assembly, said
second end opposite said first end.
22. The method of claim 21, wherein the coolant is flowed out of
said microchannel assembly via a plenum that is centrally located
relative to said microchannel assembly.
23. A method comprising: supplying a microchannel assembly having
at least one microchannel formed therein, said at least one
microchannel to transport a coolant and to be proximate to an
integrated circuit to transfer heat from the integrated circuit to
the coolant; and flowing a coolant from a central location of said
at least one microchannel to opposite ends of said at least one
microchannel.
24. The method of claim 23, wherein the coolant is flowed out of
said microchannel assembly via two outlets, including a first
outlet located at a first end of the microchannel assembly and a
second outlet located at a second end of the microchannel assembly,
said second end opposite said first end.
25. The method of claim 24, wherein the coolant is flowed into said
microchannel assembly via a plenum that is centrally located
relative to said microchannel assembly.
26. A microchannel assembly having microchannels formed therein,
said microchannels to transport a coolant and to be proximate to an
integrated circuit to transfer heat from the integrated circuit to
the coolant, said microchannel assembly having two inlets to allow
coolant to flow into said microchannel assembly, said two inlets
including a first inlet located at a first end of said microchannel
assembly and a second inlet located at a second end of said
microchannel assembly, said second end opposite said first end,
said microchannel assembly also having an outlet to allow coolant
to flow out of said microchannel assembly.
27. The microchannel assembly of claim 26, wherein said outlet is
between and substantially equidistant from said inlets.
28. The microchannel assembly of claim 27, further comprising a
plenum which extends across and above said microchannels at a
central location of said microchannels to allow coolant to flow
from said microchannels to said outlet.
29. The microchannel assembly of claim 27, wherein said
microchannels are formed in a microchannel structure, said assembly
further comprising: a cover positioned on the microchannel
structure, said cover having at least one right-angle passage
formed therein to allow fluid to flow to one of said inlets or from
said outlet.
30. A microchannel assembly having microchannels formed therein,
said microchannels to transport a coolant and to be proximate to an
integrated circuit to transfer heat from the integrated circuit to
the coolant, said microchannel assembly having two outlets to allow
coolant to flow out of said microchannel assembly, said two outlets
including a first outlet located at a first end of said
microchannel assembly and a second outlet located at a second end
of said microchannel assembly, said second end opposite said first
end, said microchannel assembly also having an inlet to allow
coolant to flow into said microchannel assembly.
31. The microchannel assembly of claim 30, wherein said inlet is
between and substantially equidistant from said outlets.
32. The microchannel assembly of claim 31, further comprising a
plenum which extends across and above said microchannels at a
central location of said microchannels to allow coolant to flow
from said inlet to said microchannels.
33. The microchannel assembly of claim 30, wherein said
microchannels are formed in a microchannel structure, said assembly
further comprising: a cover positioned on the microchannel
structure, said cover having at least one right-angle passage
formed therein to allow fluid to flow from one of said outlets or
to said inlet.
Description
BACKGROUND
[0001] As microprocessors advance in complexity and operating rate,
the heat generated in microprocessors during operation increases
and the demands on cooling systems for microprocessors also
escalate. A particular problem is presented by so-called "hotspots"
at which circuit elements at a localized zone on the microprocessor
die raise the temperature in the zone above the average temperature
on the die. Thus it may not be sufficient to keep the average
temperature of the die below a target level, as excessive heating
at hotspots may result in localized device malfunctions even while
the overall cooling target is met. This issue may be applicable to
proposed cooling systems in which a coolant such as water is
circulated through narrow channels (known as "microchannels") which
are close to or formed in the die.
[0002] Another issue that may be encountered in microchannel
cooling systems is the total pressure drop experienced by the
coolant through its circulation path. The higher the pressure drop,
the greater the demands on the pump that circulates the coolant. If
higher pumping capacity is required, it may be necessary to include
a larger and/or more expensive and/or less reliable pump. Pump size
may be especially critical, since space may be at a premium, as is
the case in notebook computers and other portable computer
systems.
[0003] Still another issue that may be encountered in microchannel
cooling systems is potential difficulty in connecting tubes for the
coolant path to the potentially delicate cover of a microchannel
assembly.
[0004] Yet another issue relates to fabricating microchannels that
have a high aspect ratio (ratio of height to width). Generally
speaking, higher aspect ratios in microchannels provide higher heat
transfer rates and lower pressure drops. However, the production
processes that may be employed in accordance with known practices
to form high-aspect-ratio microchannels may be more expensive than
other production processes that produce microchannels having
smaller aspect ratios.
[0005] Another issue is how to reduce pressure drop by shortening
the flow length without changing the geometry of the channels
(i.e., to keep parallel flow geometry channels). This may allow for
improved manufacturability.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a schematic side cross-sectional view of a
system.
[0007] FIG. 2 is a schematic view taken in horizontal cross-section
of a microchannel assembly according to some embodiments.
[0008] FIG. 3 is a view similar to FIG. 2 of a microchannel
assembly according to some other embodiments.
[0009] FIG. 3A is a view similar to FIGS. 2 and 3 of a microchannel
assembly according to other embodiments.
[0010] FIG. 4 is a schematic side cross-sectional view of a system
according to still other embodiments.
[0011] FIG. 5 is a view similar to FIG. 4 of a system according to
other embodiments.
[0012] FIG. 6 is a schematic side cross-sectional view of a
microchannel assembly according to further embodiments.
[0013] FIG. 7 is a schematic side cross-sectional view showing two
members from which a microchannel assembly may be constructed in
accordance with some embodiments.
[0014] FIG. 8 is a schematic side cross-sectional view showing the
microchannel assembly constructed from the members shown in FIG.
7.
[0015] FIG. 9 is a schematic side cross-sectional view showing two
members from which a microchannel assembly may be constructed in
accordance with some other embodiments.
[0016] FIG. 10 is a schematic side cross-sectional view showing the
microchannel assembly constructed from the members shown in FIG.
9.
[0017] FIG. 11 is a schematic plan view of a microchannel assembly
according to still further embodiments.
[0018] FIG. 12 is a schematic vertical sectional view taken along
line XII-XII in FIG. 1.
[0019] FIG. 13 is view similar to FIG. 12, showing an alternative
embodiment.
[0020] FIG. 14 is a schematic vertical sectional view taken along
line XIV-XIV in FIG. 11.
[0021] FIG. 15 is a block diagram showing a die with additional
components of a cooling system according to some embodiments.
[0022] FIG. 16 is a block diagram of a computer system according to
some embodiments that includes an example of an integrated circuit
die associated with a cooling system as in one or more of FIGS.
2-14.
DETAILED DESCRIPTION
[0023] FIG. 1 is a schematic side cross-sectional view of a system
100 including an Integrated Circuit (IC) 110. The IC 110 may be
associated with, for example, an INTEL.RTM.PENTIUM IV processor. To
help remove heat generated by the IC 110, a liquid coolant (not
separately shown) may be circulated through a microchannel cold
plate 120. The microchannel cold plate 120 may be located proximate
to the IC 110 to facilitate the removal of heat from the system
100. The microchannel cold plate 120 may, for example, be thermally
coupled to the IC 110 by a thermal interface material (TIM) 130.
(In some cases, the TIM 130 may be omitted and the microchannel
cold plate 120 may be directly thermally coupled to the IC 110. In
some cases a rear side of the IC 110 may be thinned to reduce
thermal resistance between the IC 110 and the microchannel cold
plate 120, which may be coupled to the rear side of the IC 110.)
Heat may be transferred from the IC 110 to the coolant, which may
then leave the system 100. For example, the coolant may exit from
the microchannel cold plate 120 via an outlet port 140 and may be
circulated to a heat exchanger (not shown) and then to a pump (not
shown). The heat exchanger may for example include a length of tube
with heat-conductive fins (not shown) mounted thereon and a fan
(not shown) to direct air through the fins. Heat transferred to the
coolant in the microchannel cold plate 120 may be dissipated at the
heat exchanger. After passing through the heat exchanger and the
pump, the coolant may flow back to the microchannel cold plate 120
via an inlet port 150.
[0024] The coolant may be water, or a liquid antifreeze compound
that has a lower freezing point than water, or an aqueous solution
of such a compound.
[0025] FIG. 2 is a schematic view taken in horizontal cross-section
of a microchannel assembly 200 according to some embodiments. The
microchannel assembly 200 may be employed as a microchannel cold
plate in a system such as that shown in FIG. 1. The microchannel
assembly may have microchannels 202-1, 202-2, 202-3, 202-4, 202-5
and 202-6 formed therein, as well as other microchannels which are
shown although not associated with reference numerals. (The number
of microchannels in the microchannel assembly may be more or fewer
than the number illustrated in FIG. 2. Also, the drawing is not
necessarily to scale. It will be appreciated by those who are
skilled in the art that an inlet plenum may be provided upstream
from the microchannels and an outlet plenum may be provided
downstream from the microchannels, in the embodiment of FIG. 2 and
in other embodiments, although these plenums are not shown, in some
cases, so as to simplify the drawings.) The microchannels are
defined, in part, by side walls including those indicated by
reference numerals 204-1, 204-2, 204-3, 204-4 and 204-5. At least
some of the side walls separate adjacent microchannels from each
other. It will be appreciated that each microchannel has a length
extent which corresponds to a direction in which coolant flows
through the microchannel.
[0026] The ovals 206, 208 shown in FIG. 2 are indicative of the
loci of hotspots in an IC (not shown in FIG. 2) to which the
microchannel assembly 200 may be coupled to cool the IC. In
accordance with some embodiments, microchannels located on or near
the hotspots may be divided into sub-channels at the loci of the
hotspots. Such microchannels, including for example microchannel
202-6, may have a first, undivided section 210 at one location
along the length extent of the microchannel, and a second, divided
section 212 at another location along the length extent of the
microchannel. The divided section 212 may include dividing walls
214 (e.g., three dividing walls in the example illustrated, to
define four sub-channels) to separate the sub-channels from each
other to define the sub-channels along a relatively short portion
of the microchannel at or near the locus of the hotspot. It will be
noted that the dividing walls are oriented parallel to the length
extent of the microchannels in which they are provided. The
dividing walls may extend normal to the floor (not shown) of the
microchannels.
[0027] The microchannels exhibit a first aspect ratio in their
undivided portions. The aspect ratio is defined as the ratio of
height to width, where the height is the vertical dimension and the
width is the horizontal dimension that is transverse to the
direction of coolant flow. (As a matter of convention the vertical
direction will be taken to be the direction from the microchannel
assembly to the IC die which it cools.) It will be understood that
the sub-channels share the same height as the undivided portions of
the microchannels, but have a much narrower width, and therefore
the sub-channels have a much greater aspect ratio than the
undivided portions of the microchannels. Because of the greater
aspect ratios of the sub-channels, the divided portions of the
microchannels provide substantially greater heat transfer
capability than the undivided portions, thereby providing targeted
improvements in cooling ability at the hotspots. There may be an
increased pressure drop at the divided portions of the
microchannels, but since the divided portions run for only a
relatively short distance along the microchannels, the total
pressure drop caused by the dividing of the microchannels may be
rather small, so that the targeted dividing of the microchannels
may lead to an improved trade-off between heat transfer capability
and pressure drop. The use of targeted division of the
microchannels may satisfy cooling requirements while allowing use
of a relatively reliable centrifugal pump rather than a higher
capacity but less reliable positive displacement pump. As an
alternative to either of these types of pump, an electrokinetic
pump may be employed. With any type of pump, the relatively small
pressure drop associated with the targeted division of
microchannels may allow for savings in terms of the power
requirements for the pump and/or the size and capacity of the
pump.
[0028] The number of sub-channels into which a microchannel is
divided may be more or fewer than the four sub-channels shown in
the exemplary embodiment of FIG. 2, and the number of sub-channels
may vary from microchannel to microchannel. The microchannels need
not be straight. Exemplary dimensions of the microchannels (in the
undivided sections) may be 150 microns wide by 300 microns high,
although these dimensions may be varied as appropriate. The
microchannels may be formed in a conventional material, such as
silicon or copper, and by a conventional process, such as dry
etching. Although not shown in the drawings, the microchannel
assembly 200 may also include, in accordance with conventional
practices, an inlet reservoir or manifold at one end of the
microchannels and an outlet reservoir or manifold at the other end
of the microchannels.
[0029] FIG. 3 is a view similar to FIG. 2 of a microchannel
assembly 300 according to some other embodiments. The microchannel
assembly 300 may be the same as the microchannel assembly 200 of
FIG. 2, except that at least some of the microchannels (e.g.,
microchannels 302-1, 302-2) which are not subdivided and do not
pass over hotspots may have a narrower width than the width
exhibited at undivided portions of the microchannels (e.g., 304-1,
304-2) that pass over and are subdivided at hotspots. The provision
of narrow channels that do not cool hotspots may help to balance
the pressure drop among all microchannels and to allow for adequate
coolant flow into the divided microchannels that cool hotspots. As
in the prior example, the wider microchannels may, in their
undivided sections, be 150 microns wide by 300 microns high, and
the narrower microchannels may be 50 microns wide by 300 microns
high. Again, the dimensions may be varied as appropriate.
[0030] FIG. 3A is a view similar to FIGS. 2 and 3 of a microchannel
assembly 320 according to other embodiments. The microchannel
assembly has relatively wide or sparse microchannels 322-1, 322-2,
322-3 at the locus of a cache area (indicated by dashed-line
rectangle 324 and being a portion of a microprocessor which
generally is not shown), which requires a relatively small cooling
efficiency. The microchannels 322 are divided into relatively
narrow or dense sub-channels 326 at the locus of a core area
(indicated by dashed-line rectangle 328), which is a part of the
microprocessor that requires a greater cooling efficiency. In the
particular example shown in FIG. 3A, each microchannel 322 is
divided into five sub-channels 326 at the core area 328. It will be
appreciated that the sub-channels 326 have a greater aspect ratio
than the undivided portions of the microchannels 322. (The number
of microchannels and/or the number of sub-channels may be more or
fewer than the number illustrated in FIG. 3A, and the drawing is
not necessarily to scale.)
[0031] Coolant (not shown) flows to the sub-channels 326 via an
inlet 330 and an inlet plenum 332. The coolant flows out of the
microchannels 322 via an outlet plenum 334 and an outlet 336. (It
will be appreciated that the direction of coolant flow may be
reversed in some embodiments.)
[0032] FIG. 4 is a schematic side cross-sectional view of a system
400 according to still other embodiments. The system 400 includes
an IC 402 (e.g. a microprocessor or "CPU" die) and a microchannel
assembly 404 thermally coupled to the IC 402 by a TIM 406. The
microchannel assembly 404 includes a microchannel structure 408
which has microchannels (not shown in detail) formed therein. In
particular, the microchannel structure 408 may define bottom and
side walls of microchannels in which coolant is to be transported
in proximity to the IC 402 for heat to be transferred to the
coolant from the IC 402. The microchannel structure 408 may be
provided in accordance with conventional practices or may be
configured as in one of the microchannel assemblies illustrated in
FIGS. 2 and 3. Other variations in the microchannel layout are
possible.
[0033] The microchannel assembly 404 also includes a cover plate
410 positioned on (e.g., bonded to) the microchannel structure 408
to define top walls of the microchannels. The cover plate 410 may
be provided in accordance with conventional practices and may have
formed therein an inlet port 412 and an outlet port 414. The inlet
port 412 is to allow coolant to flow into the microchannel
structure 408 and the outlet port 414 is to allow coolant to flow
out of the microchannel structure 408.
[0034] In addition, the microchannel assembly 404 includes a
manifold plate 416 that is mounted on the cover plate 410 to
facilitate connection to the microchannel assembly of tubing (not
shown) for the coolant. The manifold plate 416 may, for example, be
adhered to the top surface of the cover plate 410 by solder or by a
sealant 418 such as epoxy or silicone. The manifold plate 416 has a
lower horizontal surface 420, a left side vertical surface 422 and
a right side vertical surface 424. (As used herein and in the
appended claims, a "vertical surface" should be understood to
include any surface that departs substantially from the horizontal;
and "horizontal" refers to any direction normal to the direction
from the microchannel assembly to the IC.)
[0035] The manifold plate 416 has formed therein an inlet passage
426. The inlet passage 426 provides fluid communication between a
port 428 on the lower horizontal surface 420 of the manifold plate
416 and a port 430 on the left side vertical surface 422. The inlet
passage 426 is a right-angle passage in that it is formed of a
vertical course 432 and a horizontal course 434 that joins the
vertical course 436 at a right angle. (More generally, as used
herein and in the appended claims, "right-angle passage" refers to
any passage that supports at least an 85.degree. change in flow
direction therethrough.) The manifold plate 416 is adhered to the
cover plate 410 in such a manner that the port 428 of the manifold
plate 416 is aligned with the inlet port 412 of the cover plate
410. Advantageously, the sealant 418 (or alternatively solder, as
the case may be) is deployed in such a manner that coolant flows
from the port 428 to the inlet port 412 without leakage.
[0036] The manifold plate 416 also has formed therein an outlet
passage 436. The outlet passage 436 provides fluid communication
between a port 438 on the lower horizontal surface 420 of the
manifold plate 416 and a port 440 on the right side vertical
surface 424. The outlet passage 436 is a right-angle passage in
that it is formed of a vertical course 442 and a horizontal course
444 that joins the vertical course at a right angle. The port 438
of the manifold plate 416 is aligned with the outlet port 414 of
the cover plate 410. Sealant 418 (or solder, as the case may be)
may be deployed in such amanner that coolant flows from the outlet
port 414 to the port 438 without leakage.
[0037] A clamp (not shown) or the like may apply a downward force
to the upper surface 446 of the manifold plate 416 to retain the
manifold plate 416 in position on the cover plate 410.
[0038] The manifold plate 416 may be formed of a suitable material
such as copper, ceramic or polymer. Each passage 426, 436 may be
formed with two drilling operations--one from the horizontal
surface 420 and one from the vertical surface 422 or 424 as the
case may be. It is not critical as to the order in which the two
drilling operations are performed for a given one of the passages
426, 436. In some embodiments a molding process may performed as an
alternative to drilling. For example, the manifold plate may have
suitable fittings incorporated therein and may be formed by molding
around metal tubes that constitute the right angle passages and the
fittings.
[0039] The presence of the manifold plate 416 as part of the
microchannel assembly 404 may facilitate connection of tubing (for
coolant circulation) to the microchannel assembly 404. A tube (not
shown) leading from the heat exchanger and the pump (both not
shown) may be connected at the port 430 of the inlet passage 426 of
the manifold plate 416.
[0040] Another tube (not shown) leading to the heat exchanger and
the pump may be connected at the port 440 of the outlet passage 436
of the manifold plate 416. The manifold plate 416 may be more
robust than a typical cover plate for a micro channel assembly and
may reduce the possibility of breakage of the cover plate, and may
help to insure reliable tube connection. In general, the presence
of the manifold plate may facilitate high volume manufacturing
(HVM) with regard to the system.
[0041] Moreover, the horizontal-facing ports 430, 440 of the
passages 426, 436, respectively, may allow for improvements in form
factor for the cooling system as a whole. Also, if it is desired to
modify the configuration of the tubing and/or manner of connection
of tubing to the microchannel assembly, such a modification may be
accommodated by a manifold plate having a different configuration,
without requiring modification of the cover plate. In other words,
the manifold plate may be tailored to match the desired orientation
of inlet/outlet tubes, while keeping the cover plate and
microchannel structure unchanged.
[0042] FIG. 5 is a view similar to FIG. 4 of a system 500 according
to other embodiments. The system 500 may include all of the
constituent parts of the system 400 (FIG. 4) as described above,
but in the system 500 the manifold plate 416 is integrated with the
package 502 for the IC 402. In particular, the manifold plate may
form the upper wall of the package 502, which may also be formed of
(a) side walls 504, 506 joined to the manifold plate 416 at
respective ends of the manifold plate 416, and (b) a package
substrate 508 on which the IC 402 is mounted, and which is joined
to the lower ends of the side walls 504, 506.
[0043] In the system 500, with the microchannel assembly
effectively integrated with the IC package, it may not be necessary
to apply an external retaining force to keep the manifold plate 416
in place on the cover plate 410.
[0044] FIG. 6 is a schematic side cross-sectional view of a
microchannel assembly 600 according to further embodiments. The
microchannel assembly 600 may include a microchannel structure 602
which is like the microchannel structure 408 described above in
connection with FIG. 4. In addition, the microchannel assembly 600
may include a cover plate 604 positioned on the microchannel
structure 600. The cover plate 604 may be formed in similar manner
to the manifold plate 416 described above in connection with FIG.
4. In particular, the cover plate 604 may have formed therein two
right-angle passages 606, 608 like the inlet passage 426 and the
outlet passage 436 described above in connection with FIG. 4. Thus,
in this microchannel assembly 600, the cover plate and manifold
plate of previously described embodiments may effectively be
integrated together to form a plate which defines upper walls of
the microchannels while facilitating connection of tubing to the
microchannel assembly.
[0045] In the manifold plate 416 and cover plate 604 illustrated
above, the horizontal course of the outlet passage is formed at the
opposite vertical surface from the horizontal course of the inlet
passage. However, in alternative embodiments, the horizontal
courses of both the inlet passage and the outlet passage may be
formed at the same surface or at respective vertical surfaces that
are oriented 900 apart from each other (i.e., at adjoining vertical
surfaces).
[0046] FIG. 7 is a schematic side cross-sectional view showing two
members 702, 704 from which a microchannel assembly may be
constructed in accordance with some embodiments. FIG. 8 is a
schematic side cross-sectional view showing the resulting
microchannel assembly 802 constructed from the members 702, 704. In
both drawings, the cross-section is taken transversely to the
direction of flow of the coolant. Each of the members 702, 704 may
be generally in the form of a conventional microchannel structure
(which would be covered by a flat lid if conventional practice were
to prevail). Alternatively, varying microchannel widths and/or
subdividing of microchannels at hotspots, as described above, may
be implemented in the members 702, 704. The members 702, 704 may be
identical to each other in over-all form, except, e.g., for
features such as inlet/outlet holes (not shown) in one of the
members 702, 704. Thus each member may have a base 706 and parallel
walls 708 each extending normally from the base 706. The walls 708
are for defining side walls of the microchannels 804 (FIG. 8) in
the resulting microchannel assembly 802. Each of the walls 708 has
a respective outer end 710.
[0047] In assembling the microchannel assembly 802 from the members
702, 704, the members 702, 704 may be bonded to each other by
bonding the respective outer end 710 of each of the parallel walls
708 of the member 702 to the respective outer end 710 of a
respective parallel wall 708 of the member 704 in a mirror-image
configuration as shown in FIG. 8. In this arrangement, the walls
708 of member 702 cooperate with walls 708 of member 704 to define
the side walls of the microchannels 804. In particular, in this
arrangement, the walls 708 of member 702 provide half the height of
the microchannels 804 while the walls 708 of member 704 provide the
other half of the height of the microchannels 804.
[0048] Each of the members 702, 704 may be made of a conventional
material for a microchannel structure and the gaps between the
parallel walls may be formed by a conventional and relatively
inexpensive process such as dry etching to provide gaps having an
aspect ratio of about five, for example. It will be appreciated
that the microchannels in the resulting microchannel assembly 802
have twice the aspect ratio (ten in this example) of the gaps. In
this way, an advantageous process may be employed to form high
aspect ratio microchannels even though the process if employed in a
conventional manner could only produce lower aspect ratio
microchannels. With the higher aspect ratio for the microchannels,
the pressure drop for the coolant flow through the microchannels
may be reduced, thereby in turn reducing the requirements for the
pump employed in the cooling system. Also, the increased aspect
ratio may promote an improved heat transfer rate and thus more
effective cooling.
[0049] Each of the members 702, 704 may, in some embodiments, be
formed as a unitary body. The bonding of one member to another may
be by diffusion bonding, eutectic bonding or other suitable
process.
[0050] FIG. 9 is a schematic side cross-sectional view showing two
members 902, 904 from which a microchannel assembly may be
constructed in accordance with some other embodiments. FIG. 10 is a
schematic side cross-sectional view showing the resulting
microchannel assembly 1002 constructed from the members 902, 904.
In both drawings, the cross-section is taken transversely to the
direction of flow of the coolant.
[0051] Member 902 may be generally in the form of a conventional
microchannel structure (to be covered by a flat lid if conventional
practice were to prevail), but possibly with deeper and wider gaps
formed between parallel walls 906, which extend normally from base
908 of member 902. Each wall 906 has a respective outer end
910.
[0052] Member 904 may be similar to member 902, and may have a base
912 and parallel walls 914 which extend normally from base 912.
Member 904 may differ from member 902 in that the outermost ones of
the walls 914 may both be recessed from a respective end of the
base 912. In other embodiments, however, the members 904, 902 may
be substantially identical, except possibly for the presence of
inlet and outlet holes in one of the members. Each wall 914 has a
respective outer end 916.
[0053] In assembling the microchannel assembly 1002 from members
902, 904, the walls 906 of member 902 may be interleaved with the
walls 914 of member 904 and the outer ends 910 of walls 906 of
member 902 may be bonded to the base 912 of the member 904, and the
outer ends 916 of walls 914 of member 904 may be bonded to the base
908 of the member 902. In this arrangement, the walls 906 of member
902 cooperate with the walls 914 of the member 904 to define
microchannels 1004 (FIG. 10) in the microchannel assembly 1002. In
particular, in each microchannel, one side wall is defined by a
wall 906 of member 902 and the other side wall is defined by a wall
914 of member 904.
[0054] Each of the members 902, 904 may be made of a conventional
material for a microchannel structure and the gaps between parallel
walls may be formed by a conventional and relatively inexpensive
process such as dry etching to provide gaps having an aspect ratio
of five, for example. It will be appreciated that the microchannels
in the resulting microchannel assembly 1002 have an aspect ratio
that is more than twice the aspect ratio of the gaps in the
individual members. In this way, an advantageous process may be
employed to form high aspect ratio microchannels even though the
process if employed in a conventional manner could only produce a
lower aspect ratio microchannel. With the higher aspect ratio,
lower pressure drops and/or improved heat transfer may be
achieved.
[0055] Each of the members 902, 904 may, in some embodiments, be
formed as a unitary body. The bonding of one member to another may
be by diffusion bonding, eutectic bonding or other suitable
process.
[0056] FIG. 11 is a schematic plan view of a microchannel assembly
1102 according to still further embodiments. FIG. 12 is a schematic
vertical sectional view of the microchannel assembly 1102 taken
along line XII-XII in FIG. 11. FIG. 14 is a schematic vertical
sectional view of the microchannel assembly 1102 taken along line
XIV-XIV in FIG. 11.
[0057] The microchannel assembly 1102 includes a microchannel
structure 1402 (FIG. 14) which has microchannels 1404 formed
therein. The microchannels 1404, as in previous embodiments, are
for transporting a coolant and are to be located proximate to an
integrated circuit (not shown in FIGS. 11, 12, 14) to transfer heat
from the IC to the coolant. The microchannel structure 1402 may be
provided in accordance with conventional practices or alternatively
may be configured as described in connection with FIGS. 2 and
3.
[0058] The microchannel assembly 1102 also includes a lid 1406
(FIG. 14) which is positioned on the microchannel structure 1402 to
define the upper walls of the microchannels 1404. As best seen in
FIG. 11, the lid 1406 has formed therein an inlet 1104 and an inlet
1106. The inlets 1104, 1106 are located at respective opposite ends
of the microchannel assembly 1102 and hence are formed at
respective opposite ends of the lid 1406. The inlets are to allow
coolant to flow into the microchannel assembly 1102.
[0059] The lid 1406 also has a plenum 1108 (FIGS. 11, 12, 14)
formed therein. As indicated in FIG. 14, the plenum 1108 extends
across and above the microchannels 1404 at a central location of
the microchannels. More specifically, and as seen from FIG. 11, the
longitudinal axis of the plenum 1108 is perpendicular to a line
(not shown) drawn from one inlet 1104 to the other inlet 1106 and
is substantially equidistant from, and positioned between, the
inlets 1104, 1106. It will be noted that the plenum 1108 is
centrally located relative to the microchannel assembly. At a
central location along the plenum 1108, an outlet 1110 is formed to
allow coolant to flow out of the microchannel assembly 1102. In
some embodiments, a manifold (not shown) may be positioned on the
lid 1406 to manage distribution of coolant between the inlets 1104,
1106 and to take coolant out from the outlet 1110.
[0060] The lid may, for example, be formed of copper and the plenum
may be formed by a stamping operation.
[0061] In operation, coolant is flowed into the microchannel
assembly 1102 via the inlets 1104, 1106. The coolant flows from the
inlets into opposite ends of the microchannels via reservoirs 1112
(indicated in phantom in FIG. 11). The coolant flows from the
opposite ends of each microchannel to a central location of the
respective microchannel, as indicated in FIG. 12. From the central
location in the microchannel, the coolant flows up into the plenum
1108. In the case of each microchannel not located directly under
the outlet 1110, the coolant from the respective microchannel flows
through the plenum toward the outlet 1110 (i.e., toward the center
of the lid 1406). The coolant then flows out of the microchannel
assembly via the outlet 1110.
[0062] With this arrangement of flowing coolant from both ends of
each microchannel toward a central location along the microchannel,
the path of coolant flow along the microchannel from inlet to
outlet is reduced by one-half relative to a given over-all length
of the microchannel. As a result, the pressure drop along the
coolant path from inlet to outlet may be substantially reduced
(e.g., by about half), thereby reducing the requirements for the
pump needed in the cooling system.
[0063] Instead of flowing the coolant from the ends of the
microchannels toward the center of the microchannel assembly, in
other embodiments the coolant may flow from the center of the
microchannel assembly out toward both ends of the microchannels, as
schematically illustrated in FIG. 13. In this case essentially the
same structure may be used, but the central port is used as an
inlet (labeled 1302 in FIG. 13), and the ports at the ends of the
microchannel are used as dual outlets (labeled 1304, 1306 in FIG.
13).
[0064] The various embodiments described above may be combined in a
variety of ways. For example, the manifold plate (FIGS. 4, 5) or
integrated manifold/lid (FIG. 6) may be used in conjunction with
the microchannel structures of FIGS. 2, 3 or 8, 10 and/or with the
reduced flow length inlet/outlet arrangements of FIGS. 11-14. For
example, a manifold plate or lid may provide right-angle passages
for each of the inlets/outlets shown in the embodiments or FIGS.
11-14. Other combinations of features disclosed herein may also be
implemented.
[0065] FIG. 15 is a block diagram showing an IC die 1510 and
additional components of a cooling system 1500. For purposes of
illustration the microchannel assembly 1540 (which may be any one
of the microchannel assemblies described above) is shown as a
single block. The cooling system 1500 includes a coolant
circulation system 1590 to supply the coolant to the microchannel
assembly 1540. The coolant circulation system 1590 may be in fluid
communication with the microchannel assembly 1540 via one or more
coolant supply channels or lines 1592 and one or more coolant
return channels 1594. Although not separately shown, a pump and a
heat exchanger located remotely from the die 1510 may be included
in the coolant circulation system 1590.
[0066] Coolant supplied by the coolant circulation system 1590 may
flow through the microchannels of the microchannel assembly 1540 at
or above the rear surface of the IC die 1510 to aid in cooling the
IC die 1510. In some embodiments, the coolant is operated with two
phases--liquid and vapor. That is, in some embodiments at least
part of the coolant in the microchannels is in a gaseous state. In
other embodiments, the coolant is single phase--that is, all
liquid.
[0067] The IC die 1510 may be associated with a microprocessor in
some embodiments. FIG. 16 is a block diagram of a system 1600 in
which such a die 1610 may be incorporated. In particular, the die
1610 includes many sub-blocks, such as an Arithmetic Logic Unit
(ALU) 1604 and an on-die cache 1606. The microprocessor on die 1610
may also communicate to other levels of cache, such as off-die
cache 1608. Higher memory hierarchy levels, such as system memory
1611, may be accessed via a host bus 1612 and a chipset 1614. In
addition, other off-die functional units, such as a graphics
accelerator 1616 and a Network Interface Controller (NIC) 1618, to
name just a few, may communicate with the microprocessor on die
1610 via appropriate busses or ports.
[0068] The IC die 1610 may be cooled in accordance with any of the
embodiments described herein. For example, a pump 1690 may
circulate a coolant (e.g., including water) through a cold plate
1640 proximate to the IC die 1610 and having at least one
microchannel to transport the coolant.
[0069] The system architecture shown in FIG. 16 is exemplary; other
system architectures may be employed.
[0070] The several embodiments described herein are solely for the
purpose of illustration. The various features described herein need
not all be used together, and any one or more of those features may
be incorporated in a single embodiment. Therefore, persons skilled
in the art will recognize from this description that other
embodiments may be practiced with various modifications and
alterations.
* * * * *