U.S. patent application number 10/977860 was filed with the patent office on 2006-05-04 for thin film evaporation heat dissipation device that prevents bubble formation.
Invention is credited to Ioan Sauciuc.
Application Number | 20060090882 10/977860 |
Document ID | / |
Family ID | 36260466 |
Filed Date | 2006-05-04 |
United States Patent
Application |
20060090882 |
Kind Code |
A1 |
Sauciuc; Ioan |
May 4, 2006 |
Thin film evaporation heat dissipation device that prevents bubble
formation
Abstract
Apparatus for removing heat from a heat generating device
comprising a two-phase heat dissipation device having a dispersion
device disposed within the heat dissipation device. The heat
dissipation device includes a sealed housing having a vaporization
region within the sealed housing and a condensation region within
the sealed housing, a working fluid disposed within said seal
housing; and the dispersion device being adapted to disperse said
working fluid toward the sealed housing vaporization region. The
heat dissipation device may further include a divider plate dispose
within the sealed housing, wherein the divider plate substantially
divides the sealed housing into a vapor path chamber and a liquid
path chamber.
Inventors: |
Sauciuc; Ioan; (Phoenix,
AZ) |
Correspondence
Address: |
BLAKELY SOKOLOFF TAYLOR & ZAFMAN
12400 WILSHIRE BOULEVARD
SEVENTH FLOOR
LOS ANGELES
CA
90025-1030
US
|
Family ID: |
36260466 |
Appl. No.: |
10/977860 |
Filed: |
October 28, 2004 |
Current U.S.
Class: |
165/104.26 ;
257/E23.088 |
Current CPC
Class: |
F28D 15/04 20130101;
H01L 2924/0002 20130101; H01L 2924/0002 20130101; F28D 15/0233
20130101; F28D 2015/0291 20130101; F28D 15/06 20130101; H01L
2924/00 20130101; H01L 23/427 20130101; F28F 13/125 20130101 |
Class at
Publication: |
165/104.26 |
International
Class: |
F28D 15/00 20060101
F28D015/00 |
Claims
1. A heat dissipation device, comprising: a sealed housing having a
vaporization region within said sealed housing and a condensation
region within said sealed housing; a working fluid disposed within
said seal housing; and a dispersion device disposed within said
sealed housing, said dispersion device being adapted to disperse
said working fluid.
2. The heat dissipation device of claim 1, wherein said dispersion
device disperses said working fluid toward said sealed housing
vaporization region.
3. The heat dissipation device of claim 1, further including a
divider plate dispose within said sealed housing, wherein said
divider plate substantially divides said sealed housing into a
vapor path chamber and a liquid path chamber.
4. The heat dissipation device of claim 3, wherein said divider
plate abuts said dispersion device.
5. The heat dissipation device of claim 1, further including at
least one wick structure.
6. The heat dissipation device of claim 5, wherein said at least
one wick structure abuts an interior surface of said sealed
housing.
7. The heat dissipation device of claim 6, wherein said at least
one wick structure extends from at least a position proximate said
condensation region to at least a position proximate said
dispersion device.
8. The heat dissipation device of claim 1, a thermally insulative
material on at least a portion of an exterior surface of said
sealed housing.
9. The heat dissipation device of claim 1, a heat sink on an
exterior of said sealed housing proximate the condensation
region.
10. An assembly, comprising: a heat generating device; a sealed
housing having a vaporization region within said sealed housing and
a condensation region within said sealed housing, wherein said heat
generating mechanism abuts an exterior surface of said sealed
housing proximate said vaporization region; a working fluid
disposed within said seal housing; and a dispersion device disposed
within said sealed housing, said dispersion device being adapted to
disperse said working fluid.
11. The assembly of claim 10, wherein said heat generating device
comprises a microelectronic device.
12. The assembly of claim 10, wherein said dispersion device
disperses said working fluid toward said sealed housing
vaporization region.
13. The assembly of claim 10, further including a divider plate
dispose within said sealed housing, wherein said divider plate
substantially divides said sealed housing into a vapor path chamber
and a liquid path chamber.
14. The assembly of claim 13, wherein said divider plate abuts said
dispersion device.
15. The assembly of claim 10, further including at least one wick
structure.
16. The assembly of claim 15, wherein said at least one wick
structure abuts an interior surface of said sealed housing.
17. The assembly of claim 16, wherein said at least one wick
structure extends from at least a position proximate said
condensation region to at least a position proximate said
dispersion device.
18. The assembly of claim 10, a thermally insulative material on at
least a portion of an exterior surface of said sealed housing.
19. The assembly of claim 10, a heat sink on an exterior of said
sealed housing proximate the condensation region.
20. An electronic system, comprising: a substrate within a housing;
at least one microelectronic device attached to said substrate; a
heat dissipation device, comprising: a sealed housing having a
vaporization region within said sealed housing and a condensation
region within said sealed housing; a working fluid disposed within
said seal housing; and a dispersion device disposed within said
sealed housing, said dispersion device being adapted to disperse
said working fluid; and an input device interfaced with said
substrate; and a display device interfaced with said substrate.
21. The electronic system of claim 20, wherein said dispersion
device of said heat dissipation device disperses said working fluid
toward said sealed housing vaporization region.
22. The electronic system of claim 20, wherein said heat
dissipation device further includes a divider plate dispose within
said sealed housing, wherein said divider plate substantially
divides said sealed housing into a vapor path chamber and a liquid
path chamber.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] Embodiments of the present invention relate to heat
dissipation devices. In particular, an embodiment of the present
invention relates to a two-phase (liquid/vapor), forced convection
heat dissipation device that disperses a working fluid, which
results in the prevention of bubble formation and/or creation of a
thin film of the working fluid on an evaporation region for
improved evaporation thereof.
[0003] 2. State of the Art
[0004] The microelectronic device industry continues to see
tremendous advances in technologies that permit increased circuit
density and complexity, and equally dramatic decreases in package
sizes. Such high density and high functionality in these
microelectronic devices has resulted in an increase in the density
of the power consumption by the integrated circuit components in
the microelectronic device, which, in turn, increases the average
junction temperature of the microelectronic device. If the
temperature of the microelectronic device becomes too high, the
integrated circuits within the microelectronic device may be
damaged or destroyed.
[0005] Various apparatus and techniques have been used and are
presently being used for removing heat from microelectronic
devices. One known method of removing heat from a microelectronic
device is the use of a heat pipe 300, as shown in FIG. 6. A heat
pipe 300 is a simple device that can quickly transfer heat from one
point to another without the use of electrical or mechanical energy
input. The heat pipe 300 is generally formed by evacuating air from
a sealed pipe 302 that contains a "working fluid" 304, such as
water or alcohol. The sealed pipe 302 is usually constructed from a
thermally conductive material, such as copper, copper alloys,
aluminum, aluminum alloys, and the like, and oriented with a first
end 306 proximate a heat source 308. The working fluid 304, which
is in a liquid phase proximate the heat source 308, increases in
temperature and evaporates to form a vapor phase of the working
fluid 304, which moves (shown by arrows 312) toward a cooler,
second end 314 of the sealed pipe 302. As the vapor phase moves
toward the sealed pipe second end 314, it condenses to again form
the liquid phase of the working fluid 304, thereby releasing the
heat absorbed during the evaporation of the liquid phase of the
working fluid 304. The liquid phase returns, usually by capillary
action, gravity (thermosiphon), or a wick 316 to the sealed pipe
first end 306 proximate the heat source 308 (shown by arrows 318),
wherein the process is repeated. Thus, the heat pipe 300 is able to
rapidly transfer heat away from the heat source 308 and requires no
external driving force other than a temperature differential.
[0006] However, with the ever increasing temperature, simple heat
pipes are not capable of removing sufficient heat from
microelectronic device, as current heat pipe designs suffer from
low critical heat flux and high evaporator resistance, as will be
understood to those skilled in the art. Improvements to heat pipes,
such as forced convection with pumps and/or microchannels, can be
implemented. However, these improvements have not been entirely
successful. Pumps are not sufficiently reliable and microchannels
can develop liquid slugs in the vapor portion of the microchannel
which blocks the vapor flow to the condensation end of microchannel
causing partial or total dry-out condition resulting in heat
transfer failure. Furthermore, using more complex cooling methods,
such cryogenic cooling or refrigeration cooling are too expensive
for use in high volume commercial electronic devices.
[0007] Therefore, it would be advantageous to develop heat
dissipation device designs having an improved critical heat flux
and lower evaporator resistance, while still having using simple
components.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] While the specification concludes with claims particularly
pointing out and distinctly claiming that which is regarded as the
present invention, the advantages of this invention can be more
readily ascertained from the following description of the invention
when read in conjunction with the accompanying drawings to
which:
[0009] FIG. 1 is a side cross-sectional view of an embodiment of a
thin film evaporation heat dissipation device, according to the
present invention;
[0010] FIG. 2 is a side cross-sectional view of another embodiment
of a thin film evaporation heat dissipation device, according to
the present invention;
[0011] FIG. 3 is a side cross-sectional view of a thermosiphon
configuration of a thin film evaporation heat dissipation device,
according to the present invention;
[0012] FIG. 4 is a side cross-sectional view of another embodiment
of a thin film evaporation heat dissipation device, according to
the present invention;
[0013] FIG. 5 is an oblique view of a computer system having a heat
dissipation device of the present integrated therein, according to
the present invention; and
[0014] FIG. 6 is a side cross-sectional view of a heat pipe/vapor
chamber, as known in the art.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
[0015] In the following detailed description, reference is made to
the accompanying drawings that show, by way of illustration,
specific embodiments in which the invention may be practiced. These
embodiments are described in sufficient detail to enable those
skilled in the art to practice the invention. It is to be
understood that the various embodiments of the invention, although
different, are not necessarily mutually exclusive. For example, a
particular feature, structure, or characteristic described herein,
in connection with one embodiment, may be implemented within other
embodiments without departing from the spirit and scope of the
invention. In addition, it is to be understood that the location or
arrangement of individual elements within each disclosed embodiment
may be modified without departing from the spirit and scope of the
invention. The following detailed description is, therefore, not to
be taken in a limiting sense, and the scope of the present
invention is defined only by the appended claims, appropriately
interpreted, along with the full range of equivalents to which the
claims are entitled. In the drawings, like numerals refer to the
same or similar functionality throughout the several views.
[0016] An embodiment of the present invention comprises a two-phase
(liquid/vapor) heat dissipation device to remove heat from a heat
generating device, wherein the heat dissipation device has an
internal dispersion device (e.g., a rotating device, such as a fan)
and is adapted to decrease boiling resistance and increase the
critical heat flux.
[0017] FIG. 1 illustrates a heat dissipation device 100 according
to the present invention. The heat dissipation device 100 may
comprise a sealed housing 102, which may be constructed of
conductive material including, but not limited to, copper, copper
alloys, aluminum, aluminum alloys, and the like. A first external
portion 104 of the sealed housing 102 thermally contacts a heat
generating device 106, such as a microelectronic device (e.g.,
central processing units (CPUs), chipsets, memory devices, ASICs,
and the like). A dispersion device 108 (e.g., a rotating device,
such as a fan) may be positioned within the sealed housing 102
proximate the heat generating device 106.
[0018] A working fluid 112 within the sealed housing 102, when in a
liquid phase, is a dispersed by the dispersion device 108 as a
liquid spray toward a vaporization region 114, within the sealed
housing 102, proximate the heat generating device 106. The working
fluid 112 liquid spray is dispersed substantially uniformly to form
a thin layer on the vaporization region 114. Thus, the vaporization
region should be substantially continuously wetted with the working
fluid 112. Furthermore, the dispersion device 108 "flattens"
substantially all working fluid bubbles before they can form. If
such working fluid bubbles form, they impede the working fluid from
wetting the vaporization region 114, which greatly reduces the
efficiency of the heat dissipation device 100.
[0019] The working fluid 112 may include, but is not limited to
water, Freon, acetone, alcohol, and the like. The heat from the
heat generating device 106 is transferred through the sealed
housing 102 by conductive heat transfer. This heat vaporizes the
working fluid 112 liquid film into a vapor phase within the
vaporization region 114. The vapor phase of the working fluid 112
substantially follows along a path illustrated by arrows 116 in
FIG. 1 to a cooler, condensation region 122 within the sealed
housing 102. The vapor phase of the working fluid 112 condenses in
the condensation region 122 to form a liquid phase. During the
condensation process, the heat absorbed during the evaporation of
the liquid phase of the working fluid 112 is released and the
released heat is transferred to the sealed housing 102 proximate
the condensation region 122. The sealed housing 102 may be
evacuated to at or near vacuum condition. The pressure condition
within the sealed housing 102 is, of course, dependant on the
working fluid 112 used. For example, if the working fluid 112 is
water, the sealed housing 102 may have a pressure between about
10-50 kPa. If the working fluid is Freon (i.e., R134a), the
pressure can be between about 600-700 kPa.
[0020] In a heat pipe or vapor chamber configuration of the heat
dissipation device 100, the liquid phase of the working fluid 112
is absorbed by at least one wick structure 124, which can abut an
interior surface 120 of the sealed housing 102. The wick structure
124 may be any appropriate material including, but not limited to,
sintered porous structures (such as porous copper structures),
gauzes (such as bronze mesh), wires, and the like. The liquid phase
of the working fluid 112 is then transported from the condensation
region 122 by the wick structure 124 in the direction illustrated
by arrows 126 to an area proximate the dispersion device 108. The
liquid phase of the working fluid 112 returns to the dispersion
device 108, which disperses the working fluid 112 as a liquid spray
toward the heat generating device 106 perpetuating the
evaporation/condensation cycle described.
[0021] In an embodiment of the present invention, the heat
dissipation device 100 is oriented such that the liquid phase
working fluid drips onto the dispersion device 108 (shown as arrows
118), such as shown in FIG. 1. It is understood that the heat
dissipation device can be placed in any position with respect to
gravity. However, for alternate orientations, it is preferred that
the wick structure 124 lines the sealed housing interior surface
120 (shown in FIG. 2 as heat dissipation device 150) to ensure
effective operation. As shown in FIG. 3, it is also understood that
a heat dissipation device 160, can be oriented in a vertical
configuration such that the liquid phase 152 of the working fluid
112 moves along arrows 152 substantially in the direction of
gravitational pull 130. The vapor phase of the working fluid 112
moves substantially in the direction shown as arrows 154. No wick
structure is used with such a thermosiphon configuration, except
that in some cases a boiling structure 156 may be required, as will
be understood by those skilled in the art.
[0022] In an embodiment of the present invention, a heat sink (such
as a plurality of high surface area, thermally conductive
projections 128) may extend from a second external portion 132 of
the sealed housing 102 proximate the condensation region 122. Thus,
the heat absorbed by the sealed housing 102 proximate the
condensation region 122 is conductively transferred to the
conductive projections 128. The high surface area thermally
conductive projections 128 allow heat to be convectively dissipated
from the projections 128 into the air surrounding the heat
dissipation device 100 (referring back to FIG. 1). High surface
area conductive projections 128 are generally used because the rate
at which heat is dissipated is substantially proportional to the
surface area of the high surface area conductive projections 128.
The conductive projections 128 may be constructed of highly
conductive material including, but not limited to, copper, copper
alloys, aluminum, aluminum alloys, and the like. It is, of course,
understood that the high surface area conductive projections 128
may include, but are not limited to, elongate planar fin-like
structures and columnar/pillar structures.
[0023] In an embodiment of the present invention, a divider plate
134 may positioned within the sealed housing, which substantially
separates the vapor phase of the working fluid 112 from the liquid
phase of the working fluid 112, thereby essentially dividing the
sealed housing 102 into a vapor path chamber 136 and a liquid path
chamber 138. The divider plate 134 assists the vapor phase of the
working fluid 112 move toward the condensation region 122 and
assists the liquid phase of the working fluid 112 move toward the
dispersion device 108. The divider plate 134, in one embodiment,
separates an inlet side 142 of the dispersion device 108 from an
outlet side 144 of the dispersion device 108 in order to prevent
the vapor phase of the working fluid 112 circulating through the
dispersion device 108. In one embodiment, the divider plate 134 can
substantially abut the wick structure 124, so that the pressure
differential created by the dispersion device 108 assists in
pulling the liquid phase of the working fluid 112 through the wick
structure 124 toward the dispersion device 108.
[0024] The dispersion device 108 may be a water-proof or
"liquid"-proof, flat rotary fan with no hub or at least a very
small hub and separates at least a portion of the vapor path
chamber 136 from a portion of the liquid path chamber 138. A flat
rotary fan has its motor located the fan periphery. The dispersion
device 108 may comprise a rotor consisting of two flat washers with
a magnet therebetween and a stator comprising a printer circuit
board placed in a gap between the washers of the rotor. Power for
the dispersion device 108 is delivered from an external source (not
shown). As previously discussed, the dispersion device 108
distributes the working fluid 112 as a substantially uniform film
on the vaporization region 114. A substantially uniform spray
distribution of the working fluid 112 assists in having the
vaporization region 114 substantially "wet" during operation,
suppression of bubble formation, and having only a thin liquid film
collecting in the vaporization region 114.
[0025] A thermally insulation material 146 may be placed abutting
at least a portion of an outside surface 148 of the sealed housing
102. The thermally insulation material 146 assists in preventing
the condensation of the vapor phase of the working fluid 112 on the
sealed housing 102 walls within the vapor path chamber 136 and from
vaporizing within the liquid path chamber 138 (from potential
external heat).
[0026] Although the dispersion device 108 is described as "blowing"
the liquid phase of the working fluid 112 toward the vaporization
region 114, it has been found that the dispersion device 108 can
spin in the opposite direction and still be effective, as shown in
FIG. 4. The working fluid 112 is vaporized in the vaporization
region 114. The vapor phase of the working fluid 112 substantially
follows the direction shown as arrows 162 to the condensation
region, where is condenses into the liquid phase of the working
fluid 112. The wick 124 transports the liquid phase of the working
fluid 112 from the condensation region 122 substantially along the
direction of arrows 164 to the vaporization region 114.
[0027] It is, of course, understood that although the present
detailed description discusses the heat generating device 106 in
terms of a microelectronic device, it may be anything which
generates heat. Furthermore, although the heat dissipation devices
100, 150, 160, and 170 are shown with a specific configuration in
FIGS. 1, 2, 3, and 4, respectively, it is, of course, understood
that all of the components of the heat dissipation devices 100,
150, 160, and 170 may take on any appropriate configuration and
shape.
[0028] The microelectronic device assemblies formed by the present
invention may also be used in a computer system 210, as shown in
FIG. 5. The computer system 210 may comprise an substrate or
motherboard 220 with at least one heat dissipation device 100, 150,
160, and 170 as described above, abutting a microelectronic device
(not shown), including but not limited to, a central processing
units (CPUs), chipsets, memory devices, ASICs, and the like, within
a housing or chassis 240. The external substrate or motherboard 220
may be attached to various peripheral devices including inputs
devices, such as a keyboard 250 and/or a mouse 260, and a display
device, such as a CRT monitor 270.
[0029] Having thus described in detail embodiments of the present
invention, it is understood that the invention defined by the
appended claims is not to be limited by particular details set
forth in the above description, as many apparent variations thereof
are possible without departing from the spirit or scope
thereof.
* * * * *