U.S. patent application number 12/919260 was filed with the patent office on 2011-01-06 for heat sink device.
Invention is credited to Arthur K. Farnsworth, Shailesh N. Joshi.
Application Number | 20110000649 12/919260 |
Document ID | / |
Family ID | 41016382 |
Filed Date | 2011-01-06 |
United States Patent
Application |
20110000649 |
Kind Code |
A1 |
Joshi; Shailesh N. ; et
al. |
January 6, 2011 |
HEAT SINK DEVICE
Abstract
A heat sink is provided. The heat sink contains a first vapor
chamber section having a top surface and a bottom surface that is
in thermal contact with a heat source, a second vapor chamber
section that extends vertically from the top surface of the first
vapor chamber section, and heat-dissipating fins that are attached
to the second vapor chamber section. The first and second vapor
sections are connected to each other forming a continuous vapor
chamber space.
Inventors: |
Joshi; Shailesh N.;
(Houston, TX) ; Farnsworth; Arthur K.; (Cypress,
TX) |
Correspondence
Address: |
HEWLETT-PACKARD COMPANY;Intellectual Property Administration
3404 E. Harmony Road, Mail Stop 35
FORT COLLINS
CO
80528
US
|
Family ID: |
41016382 |
Appl. No.: |
12/919260 |
Filed: |
February 27, 2008 |
PCT Filed: |
February 27, 2008 |
PCT NO: |
PCT/US08/55126 |
371 Date: |
August 25, 2010 |
Current U.S.
Class: |
165/104.26 ;
165/185 |
Current CPC
Class: |
H01L 23/467 20130101;
F28F 1/32 20130101; H01L 23/427 20130101; H01L 2924/0002 20130101;
F28F 3/02 20130101; F28D 15/0233 20130101; F28D 15/0266 20130101;
H01L 2924/0002 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
165/104.26 ;
165/185 |
International
Class: |
F28D 15/04 20060101
F28D015/04; F28F 7/00 20060101 F28F007/00 |
Claims
1. A heat sink comprising: a first vapor chamber section having an
upper surface and a lower surface; a second vapor chamber section
extending vertically fro the upper surface of said first vapor
chamber section; and heat-dissipating fins extending horizontally
from said second vapor chamber section, wherein said lower surface
is in thermal contact with a heat source and wherein said first and
second vapor sections are connected to each other, forming a
continuous vapor chamber space.
2. The heat sink of claim 1, wherein said second vapor chamber
section is in the form a hollow-centered sidewall.
3. The heat sink of claim 1, wherein said second vapor chamber
section is in the form a hollow-centered center column.
4. The heat sink of claim 3, wherein said hollow-centered center
column is in the form of a free-standing column.
5. The heat sink of claim 3, wherein said hollow-centered center
column is in the form of a center wall.
6. The heat sink of claim 1, wherein said first and second vapor
chambers comprise a porous material.
7. The heat sink of claim 6, wherein said porous material comprises
sintered powder wick.
8. The heat sink of claim 7, wherein said sintered powder wick
comprises a material selected from the group consisting of carbon,
tungsten, copper, aluminum, magnesium, nickel, gold, silver,
aluminum oxide, and beryllium oxide.
9. The heat sink of claim 8, wherein said sintered powder wick is
sintered copper wick.
10. The heat sink of claim 1, wherein said first and second vapor
chambers comprise a material of high thermal conductivity.
11. The heat sink of claim 10, wherein the material of high thermal
conductivity comprises copper or aluminum.
12. The heat sink of claim 1, wherein said heat dissipating fins
are planar-shaped and are attached in horizontal arrangement to
said second vapor chamber section.
13. The heat sink of claim 12, wherein said heat dissipating fins
comprises a material of high thermal conductivity,
14. The heat sink of claim 13, wherein the material of high thermal
conductivity comprises copper or aluminum.
15. The heat sink of claim 1, wherein said first vapor chamber
section contains a working fluid.
16. The heat sink of claim 15, wherein said working fluid is
water.
17. A heat sink comprising: a hollow-centered base having a top
surface and a bottom surface, wherein said bottom surface is in
thermal contact with a heat source; two hollow-centered sidewalls
located on two opposite sides of the base and extending upwardly
from the top surface of the base; and one or more hollow-centered
center columns located between the two sidewalls and extending
upwardly from the top surface of the base, wherein the hollow
centers of said base, said sidewalls and said one or more center
columns are connected to each other forming a continuous vapor
chamber space, and wherein said sidewalls and said center columns
comprise fins for heat dissipation.
18. The heat sink of claim 16, wherein said fins have a planar
shape and extend in directions parallel to said top surface of said
hollow-centered base.
19. A heat sink comprising: a planar-shaped first vapor chamber
having a first surface and a second surface, wherein said first
surface is opposite to said second surface and is in contact with a
heat source; a second vapor chamber formed on said second surface,
said second vapor chamber is connected to said first vapor chamber
thus forming a continuous vapor chamber space; and a plurality of
planar-shaped heat dissipating fins extending from said second
vapor chamber.
20. The heat sink of claim 19, wherein said second vapor chamber is
a wall-like vapor chamber.
Description
TECHNICAL FIELD
[0001] The technical field relates generally to cooling systems for
electronics, and more particularly to a heat sink with vapor
chambers and thermal dissipating fins.
BACKGROUND
[0002] Increasing levels of component power and power density from
electronic devices such as integrated circuits and memory are
creating an increased demand for thermal management solutions. For
example, hid blade servers have been in great demand in recent
years due to their outstanding performance. This high density
computing power, however, comes with very limited space in the
server enclosure. Accordingly, high performance heat sinks are
necessary for efficient cooling. The heat sinks in use today have
reached their limit in dissipating the heat generated by power
chips. A need for more efficient cooling exists to expand the
thermal dissipation performance envelope.
SUMMARY
[0003] A heat sink is disclosed. The heat sink comprises a first
vapor chamber section having an upper surface and a lower surface,
a second vapor chamber section extending vertically from said upper
surface of said first vapor chamber section, and heat dissipating
fins extending horizontally from said second vapor chamber section,
wherein said lower surface is in thermal contact with a heat source
and wherein said first and second vapor sections are connected to
each other, forming a continuous vapor chamber space.
[0004] Also disclosed is a heat site comprising: a hollow-centered
base having a top surface and a bottom surface, wherein said bottom
surface is in thermal contact with a heat source; two
hollow-centered sidewalls located on two opposite sides of the base
and extending upwardly from the top surface of the base; and one or
more hollow-centered center columns located between the two
sidewalls and extending upwardly from the top surface of the base,
wherein the hollow centers of said base, said sidewalls and said
one or more center columns are connected to each other forming a
continuous vapor chamber space, and wherein said sidewalls and said
center columns comprise fins for heat dissipation.
[0005] Also disclosed is a heat sink comprising: a planar-shaped
first vapor chamber having a first surface and a second surface,
wherein said first surface is opposite to said second surface and
is in contact with a heat source; a second vapor chamber formed on
said second surface, said second vapor chamber is connected to said
first vapor chamber thus forming a continuous vapor chamber space;
and a plurality of planar-shaped heat dissipating fins extending
from said second vapor chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Embodiments of the invention will be readily understood by
the following detailed description in conjunction with the
accompanying drawings. To facilitate this description, like
reference numerals designate like structural elements. Embodiments
of the invention are illustrated by way of example and not by way
of limitation in the figures of the accompanying drawings.
[0007] FIG. 1 is a cross-sectional view of a prior art heat
sink.
[0008] FIGS. 2A and 2B are schematic representations of two
embodiments of a heat sink with innovative vapor chamber
configuration;
[0009] FIG. 3 is a composite of schematic representations of a heat
sink with free-standing center column configuration with (upper
panel) or without (lower panel) fins;
[0010] FIGS. 4A-4C are results of computational fluid dynamics
(CFD) analysis of the heat sink configuration shown in FIG. 3;
[0011] FIGS. 5A and 5B are results of CFD analysis of the airflow
in the heat sink configuration shown in FIG. 3;
[0012] FIG. 6 is a schematic representation of a heat sink with
wall-like center column configuration;
[0013] FIGS. 7A and 7B are results of CFD analysis of the heat sink
configuration shown in FIG. 6;
[0014] FIGS. 8A and 8B are results of CFD analysis of the airflow
in the heat sink configuration shown in FIG. 6.
DETAILED DESCRIPTION OF THE INVENTION
[0015] In the following detailed description, reference is made to
the accompanying drawings which form a part hereof wherein like
numerals designate like parts throughout, and in which is shown by
way of illustration embodiments in which the invention may be
practiced. It is to be understood that other embodiments may be
utilized and structural or logical changes may be made in alternate
embodiments. Therefore, the following detailed description is not
to be taken in a limiting sense, and the scope of embodiments in
accordance with the present invention is defined by the appended
claims and their equivalents.
[0016] This description is intended to be read in connection with
the accompanying drawings, which are to be considered pan of the
entire written description of this invention. The drawing figures
are not necessarily to scale and certain features of the invention
may be shown exaggerated in scale or in somewhat schematic form in
the interest of clarity and conciseness, in the description,
relative terms such as "horizontal," "vertical," "up," "'down,"
"top" and "bottom" as well as derivatives thereof (e.g.,
"horizontally," "downwardly," "upwardly," etc.) should be construed
to refer to the orientation as been described or as shown in the
drawing figure under discussion. These relative terms are for
convenience of description and normally are not intended to require
a particular orientation. Terms including "inwardly" versus
"outwardly," "upwardly" versus "downwardly," "longitudinal" versus
"lateral" and the like are to be interpreted relative to one
another or relative to an axis of elongation, or an axis or center
of rotation, as appropriate. Terms concerning attachments, coupling
and the like, such as "connected" and "interconnected," refer to a
relationship wherein structures are secured or attached to one
another either directly or indirectly through intervening
structures, as well as both movable or rigid attachments or
relationships, unless expressly described otherwise. The term
"operatively connected" is such an attachment, coupling or
connection that allows the pertinent structures to operate as
intended by virtue of that relationship.
[0017] FIG. 1 is a conceptual illustration of a prior art heat sink
with a vapor chamber. The vapor chamber is confined in a base plate
having a lower surface and an upper surface. The lower surface is
in thermal contact with a heat source and the upper surface
comprises planar fins extending vertically from the upper surface
for heat dissipation.
[0018] FIG. 2A illustrates an embodiment of a heat sink with
innovative vapor chamber configuration. Heat sink 10 comprises a
vapor chamber base 20, vapor chamber sidewalls 30 and optionally
one or more vapor chamber center columns 40. Each of the vapor
chamber base 20, vapor chamber sidewalls 30 and vapor chamber
center columns 40 is a hollow-centered structure that comprises a
vapor chamber space enclosed by surrounding walls. In one
embodiment, the vapor chamber base 20, the sidewalls 30 and the
center columns 40 are operatively connected to each other to form a
continuous vapor chamber space.
[0019] The base 20 contains a bottom surface 22 that is in thermal
contact with a heat source, and a top surface 24 on which the
sidewalls 30 and/or center columns 40 are formed. The base 20 is
made of a material having a high thermal conductivity, such as a
metal or alloy. In one embodiment, the base 20 is made of copper or
aluminum. The base 20 is filled or partially filled with an
evaporable working fluid, such as water.
[0020] The sidewalls 30 are formed only on selected sides of the
base 20 so as to maintain an unobstructed airflow between the
sidewalk 30. In the embodiment shown in FIG. 2A, two sidewalk 30
are formed on the opposite sides of the base 20. It should be noted
that the sidewalk 30 do not need to be formed on the edges of the
base 20. As shown in FIG. 2B, the two sidewalls 30 are formed at
locations near the edges of the base 20.
[0021] The center column 40 is formed between the sidewalls 30 to
further facilitate heat dissipation from the base 20. In one
embodiment, the center column 40 is in the form of a free-standing
column that serves as a heat pipe, Multiple free-standing center
columns 40 may be used to facilitate heat transfer from the base 20
to fins 60. In another embodiment, the center column 40 is in the
form of a center will that is parallel to the sidewalls 30 and
extends from one side of the base 20 to the other side of the base
20. Multiple center walls may be formed between the sidewalk 30 to
facilitate heat transfer from the base 20 to fins 60. A person
skilled in the art would also understand that efficient heat
dissipation may be achieved with the sidewalls 30 alone, the center
columns 40 alone, or a combination of the sidewalk 30 and the
center columns 40. The sidewalls 30 and center columns 40 are made
of a material having a high thermal conductivity, such as a metal
or alloy. In one embodiment, the sidewalk 30 and center columns 40
made of copper or aluminum.
[0022] In one embodiment, the vapor chamber base 20, sidewalls 30
and center columns 40 are filled with a porous material 50. The
porous material 50 has a porosity that allows vapor transport from
the base 20, where evaporation takes place, to sidewalk 30 and
center columns 40, where condensation of the vapor takes place. The
capillary forces created by the porous material also facilitate the
return of condensed working fluid to the base 20. Examples of the
porous material 50 include, but are not limited to, sintered powder
wick which can be attached to the vapor chamber base 20, sidewalls
30 and/or center columns 40 by solder.
[0023] The sintered powder may be selected from any of the
materials having high thermal conductivity and that are suitable
for fabrication into porous structures, e.g., carbon, tungsten,
copper, aluminum, magnesium, nickel, gold, silver, aluminum oxide,
beryllium oxide, or the like, and may comprise either substantially
spherical, arbitrary or regular polygonal, or filament-shaped
particles of varying cross-sectional shape. In one embodiment, the
porous material 50 comprises sintered copper wick. Other wick
materials, such as aluminum-silicon-carbide or
copper-silicon-carbide may be used with equal effect.
[0024] The sidewalls 30 and/or center columns 40 thriller comprise
a plurality of stacked fins 60 for efficient heat dissipation. The
fins 60 are attached in horizontal arrangement to the sidewalls 30
and center columns 40. Each fin 60 has a planar-shaped main body
having a top surface 62 and a bottom surface 64 opposite to the top
surface 62. The top surface 62 of one fin and the bottom surface 64
of the neighboring fin are parallel to each other. The distance (d)
between the two neighboring fins 60 may be determined
experimentally to allow for efficient cooling of the fins 60 by
airflow. In one embodiment, the distance (d) is in the range of
0.5-5 mm. The fins 60 are typically made of a material having high
thermal conductivity, such as a metal or an alloy. In one
embodiment, the fins 60 are made of aluminum.
[0025] The heat sink 10 may be used to cool a heat-generating
device which may be an electronic component such as, but not
limited to, an integrated circuit, as memory module,
Micro-Electro-Mechanical System (MEMS), a sensor, a resister, or a
capacitor. The heat sink 10 may be positioned directly on the
electronic component, or on a thermal solution including, but not
limited to, a heat pipe, a heat spreader, a heater block, and a
thermal transfer plate. A fan may be complementarily positioned to
accelerate airflow between fins 60 and increase the rate of heat
dissipation. The exact complementary positioning is application
dependent, and may be affected by a number of factors, including
but not limited to, the amount of heat to be removed, the volume
and velocity of the airflow, and so forth. The optimal
complementary positioning for a particular application of flow
provider and flow modifier may be determined empirically.
[0026] During operation, the base 20 of the heat sink 10 absorbs
heat generated by the heat-generating device. The working fluid
that is contained in the inner side of the base 20 absorbs the heat
and evaporates substantially and moves to the sidewalls 30 and/or
center columns 40. Evaporated working fluid is cooled and condensed
in the sidewalls 30 and center columns 40. The heat is released
through fins 60. Finally, the condensed working fluid flows back to
the base 20 to begin another cycle. In this way, the working fluid
can absorb/release amounts of heat. The heat generated by the
heat-generating electronic device is thus transferred from the base
20 to the fins 60 almost immediately.
EXAMPLES
Example 1
CFD Analysis of Heat Sink with Free-Standing Center Column
Configuration
[0027] FIGS. 3-5B show results of a CFD analysis of a heat sink
with free-standing center column configuration. As shown in FIG. 3,
the heat sink device contains six free-standing center columns 40
that are attached to the vapor chamber base 20. The free-standing
center columns 40 serve as heat pipes to transfer heat from the
base 20 to fins 60. Heat dissipation was achieved by eighteen
aluminum plate fins 60 attached to the center columns 40. In this
embodiment, the fins have a thickness of 0.5 mm, a surface area of
80.times.85 mm, and a fin-to-fin gap of 1.1 mm. FIGS. 4A-4C show
heat distribution on the center columns 40 (FIG. 4A) and fins 60
(FIG. 4B) and the base plate 20 (FIG. 4C). FIGS. 5A and 5B show the
airflow generated by fins 60.
Example 2
[0028] CFD Analysis of Heat Sink with Wall-Like Center Column
Configuration
[0029] FIGS. 6A-8B show results of a CFD analysis of a heat sink
with wall-like center column configuration. As shown in FIGS.
6A-6C, the heat sink device contains a base vapor chamber, two
sidewalls and a wall-like center column. The sidewalls 30 and the
center column 40 are operatively connected to base 20 and form a
continuous vapor chamber space. Heat dissipation was achieved by
eighteen aluminum plate fins attached to the center columns. The
fins have a thickness of 0.5 mm, a surface area of 80.times.85 mm,
and a fin-to-fin gap of 1.1 mm. FIGS. 7A-7B show heat distribution
on the base plate 20 (FIG. 7A) and fins 60 (FIG. 7B). FIGS. 8A and
8B show the airflow generated by fins 60.
[0030] Under the same heat generation and air flow rate settings,
the heat sink with wall-like center column configuration was able
to achieve a 11.degree. C. improvement over the heat sink with
five-standing center column configuration, i.e., having a source
temperature of 45.degree. C. (FIG. 7B) vs. 56.degree. C. (FIG.
4C).
[0031] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not
limited to the disclosed embodiments, but, on the contrary, is
intended to accommodate various modifications and equivalent
arrangements. It will be appreciated by those of ordinary skill in
the art that a wide variety of alternate and/or equivalent
embodiments or implementations calculated to achieve the same
purposes may be substituted for the embodiments shown and
described. This application is intended to cover any adaptations or
variations of the embodiments discussed herein. Therefore, it is
manifestly intended that embodiments in accordance with the present
invention be limited only by the claims and the equivalents
thereof.
* * * * *