U.S. patent application number 09/742919 was filed with the patent office on 2002-06-27 for cavity plate and jet nozzle assemblies for use in cooling an electronic module, and methods of fabrication thereof.
This patent application is currently assigned to INTERNATIONAL BUSINESS MACHINES CORPORATION. Invention is credited to Agonafer, Dereje, Chu, Richard C., Ellsworth, Michael J. JR., Simons, Robert E..
Application Number | 20020079088 09/742919 |
Document ID | / |
Family ID | 24986778 |
Filed Date | 2002-06-27 |
United States Patent
Application |
20020079088 |
Kind Code |
A1 |
Agonafer, Dereje ; et
al. |
June 27, 2002 |
CAVITY PLATE AND JET NOZZLE ASSEMBLIES FOR USE IN COOLING AN
ELECTRONIC MODULE, AND METHODS OF FABRICATION THEREOF
Abstract
Cavity plate and jet nozzle assemblies are presented for use in
cooling an electronic module. The assemblies include a cavity plate
having one or more blind holes formed therein and one or more jet
nozzles each configured to reside within a respective blind hole of
the cavity plate. A lower surface of the blind hole and/or jet
nozzle is curved to facilitate the flow of fluid from the blind
hole after impinging upon the lower surface of the blind hole.
Various jet nozzle configurations are also provided which employ
pedestals or radially extending fins. Further, the radially
extending fins may interdigitate with inwardly extending fins on
the inner sidewall of a respective blind hole in the cavity plate.
Methods of fabricating the cavity plate and jet nozzle assemblies
are also presented.
Inventors: |
Agonafer, Dereje; (Grand
Prairie, TX) ; Chu, Richard C.; (Poughkeepsie,
NY) ; Ellsworth, Michael J. JR.; (Lagrangeville,
NY) ; Simons, Robert E.; (Poughkeepsie, NY) |
Correspondence
Address: |
Kevin P. Radigan, Esq.
HESLIN & ROTHENBERG, P.C.
5 Columbia Circle
Albany
NY
12203
US
|
Assignee: |
INTERNATIONAL BUSINESS MACHINES
CORPORATION
Armonk
NY
|
Family ID: |
24986778 |
Appl. No.: |
09/742919 |
Filed: |
December 21, 2000 |
Current U.S.
Class: |
165/80.4 ;
257/E23.1 |
Current CPC
Class: |
F28D 7/12 20130101; H01L
2924/0002 20130101; Y10S 165/908 20130101; H01L 2924/0002 20130101;
H01L 23/4735 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
165/80.4 |
International
Class: |
F28F 007/00 |
Claims
1. A cooling assembly for an electronic module, said cooling
assembly comprising: a thermally conductive cavity plate having a
first main surface and a second main surface with at least one
blind hole formed in said second main surface extending towards
said first main surface, wherein each blind hole has a lower
surface and a side surface, said lower surface and said side
surface connecting at a non-orthogonal angle to facilitate the flow
of fluid therealong; and at least one jet nozzle, each jet nozzle
being sized to reside within a respective blind hole of said at
least one blind hole in said cavity plate, wherein fluid introduced
into said cavity plate through a jet nozzle of said at least one
jet nozzle impinges upon said lower surface of said respective
blind hole and flows outward through a space defined between said
side surface of said blind hole and a side surface of said jet
nozzle, wherein said non-orthogonal angle between said lower
surface and said side surface of said blind hole facilitates fluid
flow, after impinging upon said lower surface, outward through said
space defined between said side surface of said blind hole and said
side surface of said jet nozzle.
2. The cooling assembly of claim 1, wherein within each blind hole
said lower surface and said side surface thereof connect via a
curved surface which facilitates outward transfer of fluid to said
space between said side surface of said blind hole and said side
surface of said jet nozzle after said fluid has impinged upon said
lower surface.
3. The cooling assembly of claim 2, wherein each jet nozzle further
comprises a lower surface, said lower surface meeting said side
surface of said jet nozzle at a non-orthogonal angle to facilitate
the flow of fluid delivered through said jet nozzle from said blind
hole after impinging upon said lower surface of said blind
hole.
4. The cooling assembly of claim 3, wherein said side surface and
said lower surface of each jet nozzle have a surface shape
conforming to an opposing surface shape of said side surface and
said lower surface of said respective blind hole, with a uniform
space being defined between said side surface of said blind hole
and said side surface of said jet nozzle and between said lower
surface of said blind hole and said lower surface of said jet
nozzle.
5. The cooling assembly of claim 3, wherein said side surface and
said lower surface of each jet nozzle connect via a curved surface
which further facilitates the flow of fluid delivered through said
jet nozzle from said blind hole after impinging upon said lower
surface of said blind hole.
6. The cooling assembly of claim 3, wherein said lower surface of
each jet nozzle comprises a curved surface.
7. The cooling assembly of claim 1, wherein each said jet nozzle
includes radially extending pedestals which are sized to physically
contact said side surface of said respective blind hole when said
jet nozzle is disposed therein, wherein said radially extending
pedestals define said space between said side surface of said blind
hole and said side surface of said jet nozzle.
8. The cooling assembly of claim 7, wherein for each said jet
nozzle, said radial pedestals extend at least partially
longitudinally along said jet nozzle within a region of said jet
nozzle disposed within said respective blind hole.
9. The cooling assembly of claim 1, wherein said at least one blind
hole comprises a plurality of blind holes formed in said second
main surface extending toward said first main surface of said
cavity plate, and wherein said at least one jet nozzle comprises a
plurality of jet nozzles, each jet nozzle being sized to reside
within a respective blind hole of said plurality of blind holes in
said cavity plate.
10. The cooling assembly of claim 9, wherein at least one jet
nozzle of said plurality of jet nozzles has a side surface with a
plurality of radial channels disposed therein, said radial channels
comprising said space defined between said side surface of said
blind hole and said side surface of said jet nozzle, wherein fluid
delivered through said at least one jet nozzle impinges upon said
lower surface of said respective blind hole and flows outward
through said plurality of radial channels.
11. The cooling assembly of claim 9, further comprising a jet
nozzle support plate, wherein each jet nozzle of said plurality of
jet nozzles resides at least partially within said cavity plate and
at least partially within said jet nozzle support plate, and
wherein said plurality of jet nozzles are secured to said jet
nozzle support plate, said jet nozzle support plate facilitating
maintenance of said space between said side surface of each blind
hole and said side surface of said respective jet nozzle.
12. The cooling assembly of claim 11, further comprising an inlet
plenum for providing fluid to said plurality of jet nozzles and an
outlet plenum for removing fluid from said plurality of blind holes
after fluid delivered through said plurality of jet nozzles has
impinged upon said lower surfaces of said blind holes.
13. The cooling assembly of claim 1, wherein said first main
surface of said thermally conductive cavity plate is configured to
thermally couple to an electronic module for dissipating heat
received therefrom, and wherein at least one of said lower surface
of each blind hole and a lower surface of said respective jet
nozzle disposed therein, is at least partially curved to facilitate
the flow of fluid from said blind hole and thereby enhance heat
transfer from said electronic module to said fluid when said
cooling assembly is thermally coupled to said electronic
module.
14. The cooling assembly of claim 8, wherein said side surface of
said at least one blind hole has inwardly extending fins and said
side surface of said respective jet nozzle has outwardly extending
fins, and wherein said inwardly extending fins of said blind hole
interdigitate with said outwardly extending fins of said net
nozzle, with said space for removing fluid comprising a gap between
said interdigitated fins.
15. The cooling assembly of claim 14, further comprising multiple
physical contacts between said inwardly extending fins of said at
least one blind hole and said outwardly extending fins of said
respective jet nozzle, wherein said multiple physical contacts
comprise multiple thermal contacts for facilitating heat transfer
from said inwardly extending fins of said blind hole to said
outwardly extending fins of said jet nozzle.
16. The cooling assembly of claim 14, further comprising at least
one interference fit key structure disposed between said at least
one blind hole and said respective jet nozzle for ensuring said gap
between said interdigitated fins.
17. A cooling assembly for an electronic module, said cooling
assembly comprising: a thermally conductive cavity plate having a
first main surface and a second main surface with at least one
blind hole formed in said second main surface extending towards
said first main surface, wherein each blind hole has a lower
surface and a side surface; at least one jet nozzle, each jet
nozzle being sized to reside within a respective blind hole in said
cavity plate, wherein fluid introduced into said cavity plate
through a jet nozzle of said at least one jet nozzle impinges upon
said lower surface of said respective blind hole and flows outward
through a space defined between said side surface of said blind
hole and a side surface of said jet nozzle; and wherein a jet
nozzle of said at least one jet nozzle comprises a side surface
having a plurality of radial channels disposed therein, wherein
said space defined between said side surface of said blind hole and
said side surface of said jet nozzle comprises said plurality of
radial channels, and wherein fluid delivered through said jet
nozzle impinges upon said lower surface of said respective blind
hole and flows outward from said blind hole at least partially
through said plurality of radial channels disposed within said jet
nozzle.
18. The cooling assembly of claim 17, wherein said jet nozzle
having said radial channels is sized and configured with said side
surface to be in physical contact with said side surface of said
respective blind hole when said jet nozzle is disposed therein,
wherein said fluid delivered through said jet nozzle impinges upon
said lower surface of said blind hole and is removed from said
blind hole through said plurality of radial channels disposed
within said jet nozzle.
19. The cooling assembly of claim 17, wherein said plurality of
radial channels are defined by a plurality of outwardly extending
fins on said side surface of said jet nozzle, and wherein said
respective blind hole further comprises a plurality of inwardly
extending fins sized and configured such that said outwardly
extending fins of said jet nozzle interdigitate with said inwardly
extending fins on said side surface of said blind hole, with a gap
being defined between fins, wherein said space defined between said
side surface of said blind hole and said side surface of said jet
nozzle comprises said gap defined between said interdigitated
fins.
20. The cooling assembly of claim 19, wherein said thermally
conductive cavity plate comprises a laminate structure having a
plurality of cavity plate layers secured together.
21. The cooling assembly of claim 19, further comprising multiple
physical contacts disposed between said inwardly extending fins of
said at least one blind hole and said outwardly extending fins of
said respective jet nozzle, wherein said multiple physical contacts
comprise multiple thermal contacts which facilitate heat transfer
from said inwardly extending fins of said blind hole to said
outwardly extending fins of said jet nozzle.
22. The cooling assembly of claim 19, further comprising at least
one interference fit key structure disposed between said at least
one blind hole and said respective jet nozzle for ensuring said gap
between said interdigitated fins.
23. The cooling assembly of claim 17, wherein at least one of said
lower surface of each said blind hole and a lower surface of said
respective jet nozzle is at least partially curved to facilitate
flow of fluid delivered through said jet nozzle from said blind
hole after impinging upon said lower surface of said blind
hole.
24. The cooling assembly of claim 17, wherein said at least one
blind hole comprises a plurality of blind holes in said cavity
plate formed in said second main surface extending toward said
first main surface, and wherein said at least one jet nozzle
comprises a plurality of jet nozzles, each jet nozzle being sized
to reside within a respective blind hole of said plurality of blind
holes in said cavity plate.
25. The cooling assembly of claim 24, further comprising a jet
nozzle support plate, wherein each jet nozzle of said plurality of
jet nozzles resides at least partially within said cavity plate and
at least partially within said jet nozzle support plate, and
wherein said plurality of jet nozzles are secured to said jet
nozzle support plate, and wherein said assembly further comprises
an inlet plenum for providing fluid to said plurality of jet
nozzles and an outlet plenum for removing fluid from said plurality
of blind holes after fluid delivered through said plurality of jet
nozzles has impinged upon said lower surfaces of said blind
holes.
26. A method of fabricating a cooling assembly for an electronic
module, said method comprising: providing a thermally conductive
cavity plate having a first main surface and a second main surface
with a plurality of blind holes formed in said second main surface
extending toward said first main surface, wherein each blind hole
has a lower surface and side surface; providing a plurality of jet
nozzles, at least one jet nozzle including radially extending
pedestals on a side surface thereof which are sized to physically
contact said surface of said respective blind hole when said at
least one jet nozzle is disposed at least partially therein; and
interference fitting said at least one jet nozzle of said plurality
of jet nozzles into a respective blind hole of said plurality of
blind holes, wherein fluid introduced into said cavity plate
through said at least one jet nozzle of said plurality of jet
nozzles impinges upon said lower surface of said respective blind
hole and flows outward through a space defined between said side
surface of said blind hole and said side surface of said jet
nozzle, and wherein said radially extending pedestals physically
contacting said side surface of said blind hole define a size of
said space between said side surface of said blind hole and said
side surface of said jet nozzle.
27. The method of claim 26, further comprising providing a jet
nozzle support plate, with each jet nozzle of said plurality of jet
nozzles being sized to reside at least partially within said jet
nozzle support plate, and wherein said method further comprises
securing each jet nozzle of said plurality of jet nozzle to said
jet nozzle support plate.
28. The method of claim 27, wherein said securing of each jet
nozzle to said jet nozzle support plate comprises soldering each
said jet nozzle to said jet nozzle support plate after said jet
nozzle has been interference fit within said respective blind hole
of said thermally conductive cavity plate.
29. The method of claim 28, wherein each jet nozzle of said
plurality of jet nozzles includes radially extending pedestals on a
side surface thereof, said pedestals being sized to physically
contact a side surface of a respective blind hole when the jet
nozzle is disposed therein, and wherein said method further
comprises interference fitting each jet nozzle of said plurality of
jet nozzles into its respective blind hole of said cavity plate,
and thereafter soldering each said jet nozzle to said jet nozzle
support plate.
30. The method of claim 26, wherein said radially extending
pedestals define a plurality of radial channels therebetween, and
wherein when said at least one jet nozzle is interference fit into
said respective blind hole, fluid delivered through said jet nozzle
impinges upon said lower surface of said blind hole and moves
outward from said blind hole through said plurality of radial
channels defined between said radially extending pedestals of said
jet nozzle.
31. A method of fabricating a cooling assembly for an electronic
module, said method comprising: providing a thermally conductive
cavity plate having a first main surface and a second main surface
with a plurality of blind holes formed in said second main surface
extending toward said first main surface, wherein each blind hole
has a lower surface and a side surface, and radially inwardly
extending fins disposed along said side surface; providing a
plurality of jet nozzles, each jet nozzle including radially
outwardly extending fins on a side surface thereof configured to
interdigitate with said inwardly extending fins on said side
surface of a respective blind hole when said jet nozzle is disposed
within said blind hole, with a gap being defined between said
interdigitated fins; and disposing each jet nozzle of said
plurality of jet nozzles within said respective blind hole of said
plurality of blind holes, wherein fluid introduced into said cavity
plate through each jet nozzle of said plurality of jet nozzles
impinges upon said lower surface of said respective blind hole and
flows outward through said gap defined between said interdigitated
fins of said side surface of said blind hole and said jet
nozzle.
32. The method of claim 31, wherein said disposing comprises
interference fitting each jet nozzle of said plurality of jet
nozzles into said respective blind hole of said plurality of blind
holes, said interference fitting comprising providing at least one
interference fit key structure disposed between each said jet
nozzle and said respective blind hole for ensuring said gap between
said interdigitated fins.
33. The method of claim 31, wherein said disposing comprises
interference fitting each jet nozzle of said plurality of jet
nozzles into said respective blind hole of said plurality of blind
holes, said interference fitting comprising providing multiple
physical contacts disposed between said inwardly extending fins of
each said blind hole and said outwardly extending fins of said
respective jet nozzle, wherein said multiple physical contacts
comprise multiple thermal contacts which facilitate heat transfer
from said inwardly extending fins of said blind hole to said
outwardly extending fins of said jet nozzle.
Description
TECHNICAL FIELD
[0001] The present invention relates to heat transfer mechanisms,
and more particularly, to heat transfer mechanisms and cooling
assemblies for removing heat generated by an electronic circuit
module.
BACKGROUND OF THE INVENTION
[0002] The efficient extraction of heat from electronic circuit
modules for very large scale integrated circuit packages has
presented a significant limitation on the design and use of such
electronic modules. The power consumed in the integrated circuits
generates heat which must in turn be removed from the package.
Lacking an efficient heat transfer mechanism, the speed,
reliability and power capabilities of the electronic circuit
modules are limited. As the density of circuitry within very large
scale integrated circuit chips has increased, the need for improved
heat extraction has become even more acute since more densely
packed chips tend to have a higher need for heat dissipation per
unit area. It is also known that runaway thermal conditions and
excessive heat generated by chips is a leading cause for failure of
chip devices. Furthermore, it is anticipated that demand for heat
removal from these devices will continue to increase indefinitely.
Accordingly, it is seen that there is a significant need to
continue to further improve upon cooling mechanisms for electronic
devices.
DISCLOSURE OF THE INVENTION
[0003] Briefly summarized, the present invention comprises in one
aspect a cooling assembly for an electronic module. The cooling
assembly includes a thermally conductive cavity plate and at least
one jet nozzle. The cavity plate has a first main surface and a
second main surface with at least one blind hole formed in the
second main surface extending towards the first main surface. Each
blind hole has a lower surface and a side surface. The lower
surface and the side surface connect at a non-orthogonal angle to
facilitate the flow of fluid therealong. Each jet nozzle is sized
to reside within a respective blind hole of the cavity plate. Fluid
is introduced into the cavity plate through the at least one jet
nozzle, and impinges upon the lower surfaces of the respective
blind hole and flows outward through space defined between the side
surface of the blind hole and the side surface of the jet nozzle.
The non-orthogonal angle between the lower surface and the side
surface of the blind hole facilitate fluid flow, after impinging
upon the lower surface, outward through the space defined between
the side surface of the blind hole and the side surface of the jet
nozzle.
[0004] In another aspect, the present invention comprises a cooling
assembly for an electronic module, wherein the cooling assembly
includes a thermally conductive cavity plate and at least one jet
nozzle. The cavity plate has a first main surface and a second main
surface with at least one blind hole formed in the second main
surface extending towards the first main surface. Each blind hole
has a lower surface and side surface. Each jet nozzle is sized to
reside within a respective blind hole of the cavity plate. Fluid
introduced into the cavity plate through a jet nozzle impinges upon
the lower surface of the respective blind hole and flows outward
through a space defined between the side surface of the blind hole
and a side surface of the jet nozzle. At least one jet nozzle
includes a side surface having a plurality of radial channels
disposed therein. The space defined between the side surface of the
blind hole and the side surface of this jet nozzle includes the
plurality of radial channels. Fluid delivered through the jet
nozzle impinges upon the lower surface of the respective blind hole
and flows outward from the blind hole at least partially through
the plurality of radial channels disposed within the jet
nozzle.
[0005] In still another aspect, a method of fabricating a cooling
assembly for an electronic module is presented. The method
includes: providing a thermally conductive cavity plate having a
first main surface and second main surface with a plurality of
blind holes formed in the second main surface extending towards the
first main surface, wherein each blind hole has a lower surface and
a side surface; providing a plurality of jet nozzles, at least one
jet nozzle including radially extending pedestals on a side surface
thereof which are sized to physically contact the sidewall of the
respective blind hole when the jet nozzle is disposed at least
partially therein; and interference fitting the at least one jet
nozzle into a respective blind hole, wherein fluid introduced into
the cavity plate through the jet nozzle impinges upon the lower
surface of the blind hole and flows outward through the space
defined between the side surface of the blind hole and the side
surface of the jet nozzle, wherein the radially extending pedestals
physically contacting the side surface of the blind hole define the
size of the space between the side surface of the blind hole and
the side surface of the jet nozzle.
[0006] In a further aspect, the invention comprises a method of
fabricating a cooling assembly for an electronic module. This
method includes: providing a thermally conductive cavity plate
having a first main surface and a second main surface with a
plurality of blind holes formed in the second main surface
extending toward the first main surface, wherein each blind hole
has a lower surface and a side surface, and radially inwardly
extending fins disposed along the side surface; providing a
plurality of jet nozzles, each jet nozzle including radially
inwardly extending fins on a side surface surface configured to
interdigitate with the inwardly extending fins on the side surface
of a respective blind hole when the jet nozzle is disposed within
the blind hole, with a gap being defined between the interdigitated
fins; and disposing each jet nozzle of the plurality of jet nozzles
within the respective blind hole, wherein fluid introduced into the
cavity plate through a jet nozzle impinges upon the lower surface
of the respective blind hole and flows outward through the gap
defined between the interdigitated fins of the side surfaces of the
blind hole and the jet nozzle.
[0007] To restate, various enhanced cavity plate and jet nozzle
assemblies are disclosed herein to facilitate the removal of heat
from a structure, such an electronic circuit module. These
assemblies enhance the ability to remove a large amount of heat
with a low temperature difference. Further, the assemblies
presented provide a low coolant pressure drop, and are compact and
modular in design.
[0008] Additional features and advantages are realized through the
techniques of the present invention. Other embodiments and aspects
of the invention are described in detail herein and are considered
a part of the claimed invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The above-described objects, advantages and features of the
present invention, as well as others, will be more readily
understood from the following detailed description of certain
preferred embodiments of the invention, when considered in
conjunction with the accompanying drawings in which:
[0010] FIG. 1 illustrates a schematic of a hybrid air--closed loop
coolant system to employ a cooling plate assembly in accordance
with the principles of the present invention;
[0011] FIG. 2 is a cross-sectional elevational view of one
embodiment of a jet cavity plate with a jet nozzle disposed within
a blind hole formed therein, and depicting the basic fluid flow
concept of a jet cavity cold plate;
[0012] FIGS. 3A-3D depict various cross-sectional elevational
embodiments of jet nozzles and blind hole cavity plates formed in
accordance with one aspect of the present invention;
[0013] FIG. 4A is a perspective view of one embodiment of a jet
nozzle having multiple radially extending pedestals disposed along
a side surface thereof in accordance with another aspect of the
present invention;
[0014] FIG. 4B is an elevational view of the jet nozzle embodiment
of FIG. 4A;
[0015] FIG. 4C is a top plan view of the jet nozzle embodiment of
FIG. 4A;
[0016] FIG. 4D is a top plan view of the jet nozzle embodiment of
FIG. 4A interference fit within a blind hole of a cavity plate in
accordance with the principles of the present invention;
[0017] FIG. 5 is an exploded view of one embodiment of a cooling
plate assembly employing a plurality of jet nozzles and a cavity
plate in accordance with the principles of the present
invention;
[0018] FIG. 6 is a plan view of the assembled cavity plate and jet
nozzles of the cooling assembly of FIG. 5 in accordance with the
principles of the present invention;
[0019] FIG. 7 is a cross-sectional elevational view of one
embodiment of the assembled cooling assembly of FIG. 5;
[0020] FIG. 8 is a top plan view of an alternative embodiment of a
jet nozzle in accordance with another aspect of the present
invention;
[0021] FIG. 9A is a top plan view of still another embodiment of a
jet nozzle in accordance with a further aspect of the present
invention;
[0022] FIG. 9B is a plan view of one embodiment of a blind hole in
a cavity plate for use with the jet nozzle embodiment of FIG. 9A in
accordance with the principles of the present invention;
[0023] FIG. 9C is a top plan view of the jet nozzle of FIG. 9A
disposed within the blind hole of FIG. 9B showing the outwardly
projecting fins of the jet nozzle interdigitated with the inwardly
projecting fins of the cavity plate in accordance with one aspect
of the present invention;
[0024] FIG. 10A is a cross-sectional elevational view of one
embodiment of the cavity plate and blind hole depicted in FIG. 9B
taken along line B-B;
[0025] FIG. 10B is a cross-sectional elevational view of an
alternate embodiment of the blind hole and cavity plate of FIG. 9B
taken along line B-B;
[0026] FIG. 11 is a top plan of a further embodiment of a jet
nozzle and blind hole cavity plate in accordance with the
principles of the present invention, wherein multiple physical
contacts are provided between the interdigitated fins of the jet
nozzle and the blind hole cavity; and
[0027] FIG. 12 is a top plan view of an alternate embodiment of a
jet nozzle and blind hole cavity in accordance with the principles
of the present invention, wherein spacing between the
interdigitated fins of the jet nozzle and the blind hole cavity
wall is maintained by multiple interference fit key structures
disposed therebetween.
BEST MODE FOR CARRYING OUT THE INVENTION
[0028] As noted above, computers continue to increase both in speed
and function. Dissipated heat increases accordingly, even for
complementary metal oxide semiconductor (CMOS) circuitry that was
once considered a low power technology. The limits of existing
cooling medium for large server processors are quickly being
approached using conventional direct air cooling technologies (air
cooled heat sinks) as heat dissipation rises. One possible
extension to direct air cooling is a hybrid/closed loop coolant
system 10 such as depicted in FIG. 1. With this system, heat is
transferred from an electronic module 12 to the coolant (for
example, water) via a cold plate 14 which is thermally coupled to
the module 12. Coolant is pumped 16 through an air/coolant heat
exchanger 18 for dissipation of the heat to the surrounding
environment. The present invention is directed in one aspect to an
enhanced cold plate 14 for use within a cooling structure, such as
depicted in FIG. 1. Those skilled in the art, however, will note
that the present invention can be applied to other cooling
applications, and work with a multitude of coolant fluids.
Circulating water systems or the evaporator/cold head of a
refrigeration system are examples.
[0029] Disclosed herein are novel cooling assemblies, and methods
of manufacture thereof, for high thermal performance cold plates in
which a fluid impinges upon lower surfaces of cavities within a
plate in thermal contact with an electronics module. In addition to
the heat that is transferred to the fluid at the lower surface of
the cavity, heat is also transferred across the cavity walls by
virtue of a very small annular gap formed between each cavity wall
and the fluid impinging jet nozzle. Heat is also conducted into the
jet nozzle, in certain embodiments, through physical contact of
each jet nozzle to the side wall of the respective cavity, thus
enhancing the heat transfer into the body from an electronic
module.
[0030] A jet cavity cold plate includes a plurality of cavities
fabricated within a relatively high thermal conductivity material.
FIG. 2 depicts the basic concept for a single cavity 20 within a
jet cavity cold plate 22. A jet nozzle 24 is shown partially
disposed within jet cavity 20. Cavity 20 is referred to herein as a
blind hole, and extends from a first main surface of the cavity
plate into the plate towards a second main surface, i.e., the
surface receiving the heat flux in FIG. 2. Water, or any other
suitable coolant, is directed down the center of nozzle 24 and
impinged onto the lower surface 21 of blind hole 20. The jet
effluent then flows outward and up a very thin annulus formed
between the nozzle 24 and the blind hole sidewall 23. After leaving
the annulus, the effluent is directed out of the cold plate, for
example, through an outlet plenum (not shown). Very high heat
transfer coefficients are established on the cavity surfaces thus
making the structure a very low thermal resistance cold plate.
[0031] Although the basic concept defining the function of the
above-summarized jet cavity cold plate has been established,
specific enhancements are disclosed herein to further improve
thermal performance. In FIG. 2, applicants recognize that there
exists a "dead" fluid zone where lower surface 21 of the blind hole
20 meets side surface 23 of the blind hole. The result of this
orthogonal intersection is a relatively poor heat transfer to the
coolant in this region. The heat transfer characteristics can be
improved by providing curvature to the region as shown in FIG. 3A.
Even greater enhancement may be realized by providing a matching
curvature to the nozzle. See, for example, FIGS. 3B-3D.
[0032] In FIG. 3A, a blind hole 30 is defined within a cavity plate
32, and is shown with a jet nozzle 34a. In this embodiment, lower
surface 31 of blind hole 30 connects to side surface 33 thereof via
a curved portion 35.
[0033] In FIG. 3B, jet nozzle 34b has a side surface and lower
surface interface which is also slightly curved or angled 37 to
further facilitate the transfer of fluid injected into the blind
hole 30 outward. In FIG. 3C, jet nozzle 34c has a curved lower
surface 39, which again facilitates the removal of fluid from the
blind hole after impinging upon the lower surface of the blind
hole. In FIG. 3D, the lower surface and side surface of the jet
nozzle 34d are configured to conform to the lower surface and
sidewall surface, respectively, of blind hole 30 in cavity plate
32. In this embodiment, a uniform spacing is established between
the nozzle and the blind hole surface walls.
[0034] The heat transfer that takes place within the annulus
between the blind hole sidewall and the nozzle surface is inversely
proportional to the annulus width between the two surfaces. It is
therefore preferable to make the annulus width as small as
practical, preferably on the order of 0.1 mm (i.e., 0.004").
However, if this dimension is to vary by as much as 0.001", the
average heat transfer coefficient and annulus could change by 25%.
Thus, the annulus should be formed with very tight tolerance in its
characteristic dimension. This can be accomplished by creating an
interference fit between the blind hole sidewalls and individual
jet nozzles which are to be disposed therein in accordance with the
present invention.
[0035] When two members are inserted into one another (for example,
a shaft into a hole), and there is no resulting clearance between
them, an interference fit is said to be made. The result is a tight
joint which has a finite pressure between the two members where the
common surfaces contact. It is this pressure that "holds" the
pieces together.
[0036] By way of example, interference fits can be made in two
ways. First, they can be made simply by forcing two members
together. This method is usually termed a forced fit or a press
fit. The second method, typically referred to as an expansion fit,
utilizes the principle of thermal expansion. For example, the part
to be inserted is reduced in temperature thus compacting (or
shrinking) the member. Sometimes, the receiving member is heated to
correspondingly expand the hole. The members are then fitted
together and allowed to return to room temperature. In doing so,
the inner part expands and the outer part contracts. The result is
an interference fit with a significantly greater contact pressure
that can be achieved by press fitting alone.
[0037] FIGS. 4A-4D illustrate how an annulus may be defined when a
jet nozzle is interference fitted within a blind hole formed in a
cavity plate. In this embodiment, the jet nozzle 40 has multiple
radially extending pedestals 42 disposed along a side surface
thereof. These pedestals 42 are sized and configured to physically
contact with the inner side surface 43 of a blind hole in a cavity
plate 44 (see FIG. 4D).
[0038] In one fabrication embodiment of nozzle 40, the jet nozzle's
outer side surface can be altered to remove material to a
prescribed depth (e.g., 1 mm over all but a small percentage, for
example 15-20%) of the nozzle surface area. The alteration can be
accomplished through mechanical or chemical means. An example of a
mechanical process would be a skiving operation, and an example of
a chemical operation would be an etching process. The resulting
tolerance on the annuli would be less than 10%.
[0039] In addition to defining a narrow annuli using the above
fabrication/assembly process, the high pressure contact between the
nozzles and the blind hole surface walls will also serve as thermal
conduits for heat to pass into the jet nozzles, i.e., providing the
nozzles are made of a relatively high thermal conductivity material
(e.g., copper). Without heat passage into the nozzles, only the
outer surfaces of the annuli contribute to heat transfer. The inner
surfaces of the annuli can thus contribute to heat transfer when
the nozzles are thermally connected to the blind hole sidewall.
Additionally, by establishing a heat flow on both walls, the
Nusselt number which relates to the heat transfer taking place
between the walls and the fluid is increased. However, the
effectiveness of heat transfer from the inner surface is lower
because, while thermally connected, the conduction path is still
relatively high in thermal resistance. This conduction resistance
may be reduced by increasing the area of contact between the nozzle
and the blind hole sidewall, but it will come at the expense of
reducing the annular surface area for heat transfer into the fluid.
FIGS. 8-12 depict various jet nozzle configurations designed to
further facilitate heat transfer into the coolant.
[0040] Before discussing these configurations, however, FIG. 5-7
depict one embodiment of a completed cooling assembly in accordance
with the principles of the present invention. As shown in FIG. 5,
the assembly includes a cavity plate 50, which is machined with one
or more blind holes that may or may not have a surface curvature at
the lower portion of the cavity in accordance with FIGS. 3A-3D. One
or more individual jet nozzles 52 are sized and configured to
interference fit inside respective blind holes of cavity plate 50.
FIG. 6 illustrates a plan view of one embodiment of a cavity
plate/jet nozzle configuration which comprises an interstitial
array. Alternatively, cavity patterns could be formed within the
cavity plate in any desired configuration, such as an in-line
array. Arrays may also be fashioned with varying diameter cavities.
Once each nozzle is interference fitted into the respective blind
hole, a jet nozzle support plate 54 having openings 56 is brought
down over the upper section of each of the plurality of nozzles.
This support plate 54 has a through-hole pattern that matches the
cavity/nozzle pattern. The upper section of each jet nozzle as a
stepped diameter change in this embodiment which facilitates the
placement of the jet nozzle support plate. Solder or braze ring
pre-forms 58 are then placed over the tips of the jet nozzles and
the subassembly is taken through an appropriate solder/braze reflow
process. This operation provides the needed isolation between the
inlet and outlet reservoirs, which are formed by an inlet plenum
plate 60 and an outlet plenum plate 62. Plates 60 and 62 are
designed to produce the inlet and outlet plenums when assembled as
shown in FIG. 5. A cross-section of one embodiment of the final
assembly is shown in FIG. 7. Not shown in FIGS. 5-7 is the
perimeter sealing which would be required between the stacked
plates. One way to seal the assembly is to concurrently braze or
solder the plates in place. The plates may also be sealed in a
mechanical compressive fashion by bolting the plates together at
the periphery and incorporating conventional compression seals, for
example, O-ring, C-ring, gasket, etc.
[0041] An additional assembly alternative to solder/brazing the
upper sections of the nozzles to the jet nozzle support plate would
be to use an elastomer or epoxy to create the isolating joint.
Either compound can be applied as a liquid to the annulus formed by
the nozzle and jet nozzle support plate and then cured to a solid
with appropriate time and temperature processing. This alternative
allows more flexibility in choosing a less dense material for the
jet nozzle support plate. Furthermore, since the outlet and inlet
plenums do not contribute to the transfer of heat, the plenums may
be fashioned from a less dense material to reduce weight, such as a
light-weight metal or a plastic.
[0042] Additional thermal enhancements may be realized by the
formation of a jet nozzle structure which has a plurality of radial
microchannels as shown in FIG. 8. In this top down embodiment, jet
nozzle 80 has a central channel 82 and an outlet orifice 84 through
which coolant passes to impinge upon a lower surface of a blind
hole (not shown). Jet nozzle 80 further includes a plurality of
closely space, radially extending fins 86 which define therebetween
radial microchannels 87. In one fabrication embodiment, the outer
surface of jet nozzle 80 undergoes a chemical etching process that
produces the radial microchannels with a width on the order of 0.1
mm at an aspect radio (depth/width) of 5-10. Additionally, the
number of channels, plus the spacing of the channels, may be chosen
such that the sum of the channel widths roughly equals a third of
the outer circumference of the nozzle. Both the nozzle/cavity
surface contact (i.e., assuming interference fit) and the surface
area for heat transfer to the coolant fluid is dramatically
increased in this embodiment over that of a more conventional
annulus configuration such as depicted in FIG. 2. The former serves
to maximize the effective heat transfer of the latter.
[0043] Further, it should be noted that the surface curvature
enhancements discussed above in connection with FIGS. 3A-3D are
independent of the annulus formation and its enhancements such as
described in FIGS. 4-8. Thus, the use of radial microchannels as
presented in FIG. 8, for example, could be incorporated together
with one or more of the nozzle/cavity embodiments of FIGS. 3A-3D,
or used separately.
[0044] FIGS. 9A-12 present further jet nozzle and cavity plate
embodiments which, when assembled, provide significantly more
surface area for heat transfer (e.g., 5-10.times.) compared with a
conventional structure such as depicted in FIG. 2, while still
maintaining the small spacing necessary for high heat transfer
coefficients on the opposing surfaces. In the embodiments of FIGS.
9A-12, the jet nozzle and blind hole of the cavity plate have fins
or arms which extend radially and are interdigitated. For example,
FIGS. 9A & 9B depict one embodiment of a jet nozzle 90 and a
corresponding cavity plate 92. As shown, jet nozzle 90 has a
plurality of radially outwardly extending fins 94; and the side
surface defining blind hole 93 has a plurality of radially inwardly
extending fins 95. When assembled as shown in FIG. 9C, fins 94 on
jet nozzle 90 are disposed between fins 95 extending into blind
hole 93 of the cavity plate. In other words, the fins of the cavity
plate wall are interdigitated with the fins of the jet nozzle. This
results in a narrow gap between fins which defines channels 91 for
coolant flow. Depending upon the design, the surface area for heat
transfer can be increased by a factor of up to 10 times the surface
area of a more conventional jet cavity assembly. The geometry
depicted in FIGS. 9A-9C represents a 7.1.times. increase in surface
area for heat transfer over a conventional design such as depicted
in FIG. 2.
[0045] The cavity plate structure of FIG. 9B can be formed, for
example, by etching or skiving to remove material within the blind
hole to define fins 95. By way of example, one technique is to
start with a relatively thick plate (for example, 15-25 mm), drill
through holes, and skive the sidewalls to form the fins. The
finished plate 92a can then be brazed, soldered or diffusion bonded
to a base plate 97 as shown in FIG. 10A (which is a cross-section
of plate 92 taken along line B-B in FIG. 9B) to create the final
cavity configuration. An alternative manufacturing approach is to
pattern relatively thin plates (e.g., 1-1.5 mm) using etching or
stamping techniques, stamp the plates, and then braze, solder or
diffusion bond the plates to form a laminated final structure 92b
as shown in FIG. 10B. As with 10A, the final structure is completed
with a base plate 97 which is bonded to the laminated plates 99
defining cavity plate 92b.
[0046] Positioning a jet nozzle within a blind hole cavity so that
fins interdigitate and the channels for coolant flow are properly
defined can be accomplished in a variety of ways. For example, if
the jet nozzle is metal, then providing a press or shrink fit with
the nozzle 102 contacting the cavity 100 wall at multiple locations
104 as shown in FIG. 11 will position the insert correctly, plus
provide good thermal contact between the blind hole cavity plate
and the jet nozzle so that the nozzle surfaces can contribute to
the overall heat transfer.
[0047] As an alternative, a press/shrink fit with a keying
structure 106 such as shown in FIG. 12 could also be used to
properly position a nozzle 112 within a blind hole cavity plate 110
so as to define a uniform spacing 114 between the interdigitated
fins.
[0048] To summarize, numerous concepts are presented herein for an
enhanced jet nozzle/cavity plate assembly. For example, in
accordance with the present invention, jet nozzles are individually
placed into the cavity plate and then subsequently secured to a jet
nozzle support plate. This allows the formation of annuli between
the cavity sidewall and the jet nozzle on the order of
0.002"-0.004"with a tolerance of +/-10% or better. In addition,
curvature at the base of a blind hole cavity and/or the base of the
jet nozzle facilitates elimination of the conventional "dead" fluid
region where the lower surface of the blind hole meets the side
surface. By matching the jet nozzle surface curvature to that of
the blind hole lower surface and side surface, the surface area
within the cavity/nozzle annulus is increased. Further, a nozzle
with radial microchannels can be provided to maximize the
conductive coupling between a cavity wall and jet nozzle, while
also significantly increasing the surface area for heat transfer
and maintaining a high heat transfer coefficient commensurate with
fluid flows in very narrow channels. Additional concepts are also
disclosed and claimed herein.
[0049] While the invention has been described in detail herein in
accordance with certain preferred embodiments thereof, many
modifications and changes therein may be effected by those skilled
in the art. Accordingly, it is intended by the appended claims to
cover all such modifications and changes as fall within the true
spirit and scope of the invention.
* * * * *