U.S. patent application number 10/084138 was filed with the patent office on 2002-10-10 for laminated heat transfer device and method of producing thereof.
Invention is credited to Siu, Wing Ming.
Application Number | 20020144809 10/084138 |
Document ID | / |
Family ID | 23080377 |
Filed Date | 2002-10-10 |
United States Patent
Application |
20020144809 |
Kind Code |
A1 |
Siu, Wing Ming |
October 10, 2002 |
Laminated heat transfer device and method of producing thereof
Abstract
A laminated heat transfer device for cooling or thermal energy
transport applications and a method of manufacture thereof. In
various implementations, the laminated heat transfer device
provides complex duct channels for efficient cooling. The various
implementations are compatible and integrateable with each other.
The method of producing a laminated heat transfer device includes
specifying a three-dimensional structure as a plurality of laminae,
producing the laminae from sheets of working material, stacking the
laminae according to a predetermined sequence with a guiding
structure, and connecting the laminae.
Inventors: |
Siu, Wing Ming; (Kowloon
City, HK) |
Correspondence
Address: |
FISH & RICHARDSON P.C.
1425 K STREET, N.W.
11TH FLOOR
WASHINGTON
DC
20005-3500
US
|
Family ID: |
23080377 |
Appl. No.: |
10/084138 |
Filed: |
February 28, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60282170 |
Apr 9, 2001 |
|
|
|
Current U.S.
Class: |
165/185 ;
165/80.3; 257/E23.103; 29/890.03 |
Current CPC
Class: |
Y10T 29/4935 20150115;
F28F 3/02 20130101; B23P 2700/10 20130101; B21D 53/04 20130101;
B23P 15/26 20130101; H01L 2924/00 20130101; H01L 23/3672 20130101;
H01L 2924/0002 20130101; H01L 2924/0002 20130101; B23P 2700/12
20130101 |
Class at
Publication: |
165/185 ;
165/80.3; 29/890.03 |
International
Class: |
F28F 007/00; B21D
053/02 |
Claims
What is claimed is:
1. A laminated heat transfer device, comprising a base; and a vane
formed from a plurality of laminae, each lamina having a plurality
of fins and a conduction core, wherein the laminae are stacked
together according to a predetermined sequence.
2. The laminated heat transfer device of claim 1, further
comprising: at least one guide rod to guide the stacking of
laminae.
3. The laminated heat transfer device of claim 1, further
comprising: an alignment fixture to guide the stacking of
laminae.
4. The laminated heat transfer device of claim 1, wherein the
laminae are of equal size or varying size.
5. The laminated heat transfer device of claim 1, wherein the
laminae are shaped like spokes of a wheel.
6. The laminated heat transfer device of claim 1, wherein at least
one of the laminae is shaped like a web.
7. The laminated heat transfer device of claim 1, wherein the fins
of the heat sink form a spiral.
8. The laminated heat transfer device of claim 1, wherein the heat
sink is a ducting-type heat sink.
9. A laminated heat transfer device, comprising a base; and a
porous structure formed from a plurality of first and second
laminae, each lamina having a plurality of shaped openings, wherein
the laminae are stacked together according to a predetermined
sequence.
10. The laminated heat transfer device of claim 9, wherein the
first and second laminae are alternately stacked and wherein the
laminae are stacked horizontally or vertically.
11. The laminated heat transfer device of claim 9, wherein the
shaped openings of each laminae are uniformly spaced or
non-uniformly spaced.
12. The laminated heat transfer device of claim 9, wherein the
shaped openings of each laminae are uniformly sized or
non-uniformly sized.
13. The laminated heat transfer device of claim 9, wherein the
shaped openings of each laminae comprise the shapes of a rectangle,
an oval, or a circle.
14. The laminated heat transfer device of claim 9, wherein the
laminae are of equal size or varying size.
15. The laminated heat transfer device of claim 9, wherein the
laminated heat transfer device is a heat sink.
16. The laminated heat transfer device of claim 15, wherein the
heat sink is a porous-type heat sink.
17. The laminated heat transfer device of claim 9, further
comprising: two end plates, and wherein the openings of the primary
and secondary laminae are different sizes in order to form
capillary grooves when the laminae are stacked together.
18. The laminated heat transfer device of claim 17, wherein the
primary and secondary laminae are perforated so that the
perforations form capillary channels across the laminae toward the
end plates when the laminae are stacked together.
19. The laminated heat transfer device of claim 17, further
comprising: two plates, each plate being formed with a plurality of
slits and positioned before the respective end plate.
20. The laminated heat transfer device of claim 17, wherein the
laminated heat transfer device is a heat pipe.
21. A laminated heat transfer device, comprising a base; and a
plurality of laminae formed with thermo-electric junctions, wherein
a first group of laminae are attached to the base and a second
group of laminae are thermally isolated, and the laminae are
stacked together according to a predetermined sequence.
22. The laminated heat transfer device of claim 21, wherein the
laminated heat transfer device is a split-body Peltier device.
23. A laminated heat transfer device, comprising the laminated heat
transfer device as claimed in claim 1 formed integrally with the
laminated heat transfer device as claimed in claim 17.
24. A laminated heat transfer device, comprising the laminated heat
transfer device as claimed in claim 9 formed integrally with the
laminated heat transfer device as claimed in claim 17.
25. A laminated heat transfer device, comprising the laminated heat
transfer device as claimed in claim 17 formed integrally with the
laminated heat transfer device as claimed in claim 21.
26. A method of producing a laminated heat device, comprising
specifying a three-dimensional structure as a plurality of laminae;
producing the laminae from sheets of working material; stacking the
laminae according to a predetermined sequence with a guiding
structure; and connecting the laminae.
27. The method of producing a laminated heat transfer device of
claim 26, wherein the laminated heat transfer device is a heat
sink.
28. The method of producing a laminated heat transfer device of
claim 26, wherein the laminated heat transfer device is a heat
pipe.
29. The method of producing a laminated heat transfer device of
claim 26, wherein the laminated heat.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 USC .sctn. 119(e)
to U.S. patent application Ser. No. 60/282,170, filed on Apr. 9,
2001, the entire contents of which are incorporated by
reference.
TECHNICAL FIELD
[0002] This invention relates to a laminated heat transfer device
for cooling or thermal energy transport applications.
BACKGROUND
[0003] Heat is a by-product of electronic systems and the efficient
removal of heat is key to preventing failure of electronics. For
electronics, the most common methods of heat removal are of heat
sinks, heat-pipes, and Peltier devices.
[0004] Heat sinks (also known as heat-fins) are
conduction-convection devices that remove heat by conducting heat
away from a given source and then rejecting the heat into a working
fluid through convection. A heat sink balances the conduction and
the convection processes so that the conduction resistance is not
too large, while the convection resistance is small. In general,
the conduction resistance will increase as the fin's design is
changed to yield a smaller convection resistance. Heat sinks can be
either a ducting type or a porous type. A ducting-type heat sink
channels the flow from a source so that the fluid flows over a
maximum area of the heat sink. This is particularly important, for
example, where the size of the heat sink is larger than the fan,
and without the channeling function, less surface undergoes
forced-convective cooling. In contrast, a porous-type heat sink
does not channel the flow, but instead allows the fluid to flow
through from three directions. One example is porous metallic foam,
where the fluid flow can come from any of the three orthogonal
directions, and as such, these heat sinks are useful in situations
where the flow area is larger than the heat sink.
[0005] A heat-pipe is a heat-transfer device that relies on the
evaporation and condensation of a working liquid. Normally, the
liquid evaporates from the hot-side (called evaporator side) and
travels as a vapor to the cold-side where it condenses back into
liquid (called condenser side). The liquid must then be carried
back to the evaporator side so that the cycle can start anew, which
is typically done by using a porous wick and the capillary action
of the liquid. As the heat of vaporization is typically very large,
the heat-pipe is generally capable of a relatively large heat
transfer rate. Indeed, heat-flux as high as 20 W/sq-cm has been
reported for complex wicking structures.
[0006] A Peltier device is a thermoelectric device where heat is
absorbed and rejected as an electric current flows through
dissimilar conductors. Current Peltier devices have thermal
back-diffusion.
SUMMARY
[0007] A laminated heat transfer device maybe a laminated
ducting-type heat sink, a laminated porous-type heat sink with an
integrated base, a laminated heat-pipe, a laminated split-body
Peltier device, or any combination of these.
[0008] A laminated ducting-type heat sink includes ducting channels
to allow for efficient air-flow. In one implementation, naturally
convecting heat sinks include chimneys with varying cross-sectional
areas for flow-acceleration to provide fanless solutions. In
another implementation, a ducting-type heat sink includes
cross-linkages to better utilize the spaces between the guiding
vanes. This device is a cost-effective alternative to complex heat
sinks, such as the radially ducting type. Additionally, this device
is compatible and integrateable with the laminated heat-pipe and/or
laminated split-body Peltier devices, described below.
[0009] A laminated porous-type heat sink contains an integrated
base structure, which minimizes the contact resistance. The depth
of the base and its footprint can be changed to suit the specific
thermal requirement. This device accommodates a spatially varying
porous structure to better balance the convective and conductive
thermal resistances. This device is also compatible and
integrateable with the laminated heat-pipe and/or laminated
split-body Peltier devices, described below.
[0010] A laminated heat-pipe provides a low-cost heat-pipe
solution. This laminated heat-pipe can be made in different sizes
and can have different wicking structures without using a sintering
process. The wicking structure is an integral part of the overall
heat-pipe to minimize thermal resistances, by stacking multiple
laminae such that the final product is a hollow enclosure with the
wicking structure coming from either the stacking arrangement of
the laminae and/or by using perforated laminae. This device is
compatible and integrateable with the laminated heat sinks and/or
the laminated split-body Peltier devices.
[0011] A laminated split-body Peltier device is a low-cost vehicle
to implement a split-body Peltier device. This implementation
stacks multiple laminae such that each layer is an electrically
conducting element consisting of P-type and N-type materials. This
device is also compatible and integrateable with the laminated heat
sinks and/or the laminated heat-pipe.
[0012] A method to produce the different implementations of a
laminated heat transfer device is also provided. The method
includes: designing a three-dimensional structure into series of
planar elements (laminae), which may or may not be self-repeating
depending on the three-dimensional requirements; producing the
laminae from sheets of working material by stamping, punching,
etching, cutting, plating or other material forming process that
are known in the art; stacking the laminae together according to a
predetermined sequence; and functionally connecting the parts of
each lamina by diffusive bonding, welding, weaving, plating,
bonding with inter-connective material, or any inter-connective
method, or combination of inter-connective method and material
forming process, or any combination thereof. Alternatively, the
laminae can be formed from laminated working materials. The
stacking process is accomplished with the usage of a guiding
structure, which may or may not be integrated with the final
product. The attachment process is accomplished through thermal,
pressure, sonic, chemical driven process, or any combination
thereof. The attachment process may also involve additional
interfacial material, and may occur at the same time or after the
stacking of some or all laminae.
[0013] The details of one or more implementations are set forth in
the accompanying drawings and the description below. Other features
and advantages will be apparent from the description and drawings,
and from the claims.
BRIEF DESCRIPTION OF DRAWINGS
[0014] Exemplary implementations are depicted in the attached
figures, in which:
[0015] FIG. 1a illustrates an implementation of a laminated
ducting-type heat sink;
[0016] FIG. 1b is an exploded perspective view of the individual
lamina of FIG. 1a;
[0017] FIG. 1c shows illustrates an implementation of a laminated
ducting-type heat sink with cross-linkages;
[0018] FIG. 2a illustrates a laminated porous-type heat sink with
an integrated base;
[0019] FIG. 2b is a cross-sectional view of the porous structure of
FIG. 2a;
[0020] FIG. 2c is an exploded perspective view of the individual
lamina of FIG. 2a;
[0021] FIG. 2d is another exploded perspective view of the
individual lamina of FIG. 2a;
[0022] FIG. 2e is another exploded perspective view of the
individual lamina of a porous-type heat sink with varying
pores;
[0023] FIG. 3a illustrates an implementation of a laminated
ducting-type heat sink for natural convection applications;
[0024] FIG. 3b is an exploded perspective view of the individual
lamina of FIG. 3a;
[0025] FIG. 4a illustrates a laminated heat-pipe;
[0026] FIG. 4b is an exploded perspective view of the individual
lamina of the laminated heat-pipe with an integrated wicking
structure;
[0027] FIG. 4c is another exploded perspective view of the
laminated heat-pipe with another integrated wicking structure;
[0028] FIG. 4d is a close-up view of laminae of the heat-pipe with
a wicking structure;
[0029] FIG. 5a illustrates a laminated split-body Peltier
device;
[0030] FIG. 5b is an exploded perspective view of the individual
lamina of the device of FIG. 5a;
[0031] FIG. 6a illustrates an implementation of a porous heat sink
with an integrated heat-pipe; and
[0032] FIG. 6b illustrates an implementation of a split-body
Peltier device with an integrated heat-pipe.
[0033] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION
[0034] FIG. 1a illustrates an implementation of a laminated
ducting-type heat sink 100. Alternatively, the heat sink could have
a spiral-vane configuration. The heat sink 100 includes a base 110
and the vanes 130. The base 110 conducts heat from the source (not
shown), such as an electronic device, to the vanes 130. The base
110 is made out of thermally-conductive materials, such as copper,
and its thickness is a function of the applied heat-flux and the
airflow over the vanes. In general, the larger the applied
heat-flux, the thicker the base needs to be in order to assure that
the heat spreads over most of the base. Typically, the base 110 is
approximately 5 mm.
[0035] FIG. 1b shows two guiding rods 111, which are functionally
attached to the base 110 through interference fitting, chemical
bonding, soldering, brazing, or any other similar techniques known
in the art. The guiding rods 111 are made of metals or polymers,
and guide the stacking of the laminae 120 through the guiding holes
121. Each lamina has fins 122 and a conduction core 123, so that
the heat conducts from the base 110 through the conduction core 123
toward the fins 122. As the conduction core 123 reduces the overall
thermal resistance, its diameter needs to be sufficiently large to
enable the heat to effectively from the base 110 to the top-most
lamina with minimal resistance. While the exact diameter will
depend on the flow rate impinging on the structure, the diameter of
the conduction core 123 is generally between 5 and 20 mm.
[0036] The fins 122 eject heat into the working fluid. The width of
the fins is in the range of 0.5 to 2 mm. The base of the fins 122
may touch at the conduction core 123 or may be spaced apart. In
addition to ejecting heat, the fins 122 of the laminae 120 form the
vanes 130 of the final product 100 to provide radial ducting of the
working fluid. The laminae 120 may be identical in shape or
different depending on the requirement of the final product 100.
Each lamina 120 is a thermal conductor and should preferably be
made out of metal. The laminae 120 can be obtained by stamping,
punching, etching, and/or plating processes from sheets of working
materials. The thickness of each lamina is determined by the lamina
production process. For example, a stamping process is applied for
copper material with a thickness of approximately 1 mm or less.
However, the thinner the working material is, the larger the number
of laminae to complete one product. The balance between tool-life,
production rate, and product quality is an operational issue
determined on the production floor. The laminae 120 are stacked and
functionally joined together to yield the final product 100. The
joining between the laminae 120 and with the base 110 can be
accomplished with soldering, brazing, welding, plating, chemical
bonding, diffusion bonding, or any similar process known in the
art. The stacking process can be performed through the
aforementioned guiding rods 111 or through an appropriate alignment
fixture (not shown). Furthermore, the stacking and joining can be
accomplished in one or multiple processes.
[0037] Another implementation of the laminated ducting-type heat
sink includes cross-linkages between the guiding vanes. As shown in
FIG. 1c, laminae 140 with cross-linkages 141 are introduced
periodically to render a structure that effectively utilizes the
space between the guiding vanes. These cross-linkages 141 increase
the number of heat conduction paths and the amount of convective
surface area.
[0038] FIG. 2a illustrates a laminated porous-type heat sink with
an integrated base. This heat sink 200 includes a base 210 and a
porous structure 220. As shown in FIG. 2b, the porous structure
allows the working fluid to pass through in three directions. As
shown in FIG. 2c, this is obtained by stacking together primary
laminae 221 and secondary laminae 222 having different opening
designs, so that the base 210 is formed as an integral part of the
assembly 200. Alternatively, the primary and secondary laminae 221,
222 can be stacked perpendicular to the base (FIG. 2d). The
openings in the laminae are rectangular, but can be oval, circular,
or any other convenient shape. In addition, the openings on the
individual laminae can be non-uniform in space in order to render a
final heat sink with spatially varying porosity (FIG. 2e). This
configuration allows optimization of the heat-conduction path
relative to the fluid flow. In general, the thickness, materials
and process of stacking and joining the laminae are similar to
those described above.
[0039] One alternative, shown in FIG. 3a, is a laminated
ducting-type heat sink 300 for natural convection applications.
This heat sink 300 includes a base 310, an air intake 320, a
converging duct 330, guiding vanes 340 and a conduction rod 350. In
operation, a heat source (not shown) is applied to the bottom of
the base 310, which conducts the heat to the guiding vanes 340 and
the conduction rod 350. This conduction rod 350 should be
sufficiently large in diameter to allow heat to conduct upwards,
but sufficiently small to yield a large surface area to volume
ratio. In general, the conduction rod 350 is approximately 3 to 5
mm in diameter, and this rod may be straight or ribbed (not shown)
in order to maximize the heat transfer efficiency to the
surrounding air. The conduction rod 350 is situated directly above
the heat-source so most of the heat will travel up this conduction
rod 350 and to the adjacent air, which then rises due to the
buoyancy force. As the air rises, it is accelerated by the
converging duct 330, which then entrains air at the intake 320 by
creating a low-pressure condition. The guiding vanes 340 serve the
dual purpose of radially directing air inward, while conducting
heat from the base 310 to the converging duct 330, which further
heats the air and increases the flow-rate within. The converging
duct 330 should be a thermally conducting material, preferably a
metal, such as copper or aluminum. In addition, a fan (not shown)
can be placed on top of the heat sink to provide forced convective
cooling, in which case, the guiding vanes 340 also serve the
function of heat fins. As described above, the heat sink 300 is
obtained by stacking and joining together the inlet laminae 321 and
the duct laminae 331 shown in FIG. 3b. By stacking together the
inlet laminae 321, the air intake 320 and the guiding vanes 340 are
created, and above these inlet laminae 321, the duct laminae 331
are stacked and functionally joined to render the converging duct
structure 330. In general, the thickness, materials and process of
stacking and joining the laminae are similar to those described
above, with the exception that the duct laminae 331 need to be
sufficiently thin to render a smooth curvature. In general, these
laminae are approximately 0.5 mm in thickness, although thicker
laminae can be accommodated by the appropriate use of chamfers. As
before, the stacking process can be performed through guiding rods
311 or through an appropriate alignment fixture (not shown).
[0040] Another implementation is the laminated heat-pipe shown in
FIG. 4a. This heat-pipe 400 includes alternately stacked primary
410 and secondary 420 laminae, and is terminated at the two ends by
the end plates 430. Both the primary and secondary laminae 410, 420
have central openings, and thus rendering these laminae, rings. The
openings may be rectangular, circular, oval, or any other
convenient shape, and the amount of material remaining in the
laminae 411, 421 should be sufficient to enable sealing between the
laminae. In addition, the openings on the primary and secondary
laminae 410, 420 are slightly different in size (approximately 0.2
to 1 mm) so that capillary grooves 440 are formed when the laminae
are stacked together (FIG. 4b). These capillary grooves 440
function as the wick and circulate condensed liquid in the in-plane
direction. The whole unit is sealed by functionally joining the two
laminae 410, 420 along with the end plates 430. The sealing can be
done after, during or before the heat-pipe is charged with liquid,
and in the case of the latter, a valve (not shown) would be needed
on the end plate. The sealing process can be a pressure and/or
temperature activated process involving brazing, soldering,
welding, chemical bonding, diffusion bonding or any other similar
methods known in the art.
[0041] To further improve on the circulation process, the primary
and secondary laminae 410, 420 are perforated 412, 422 so that when
the laminae are stacked together, these perforations 412, 422 form
capillary channels 450 across the laminae and toward the two end
plates 430. This is shown in FIG. 4c where the two additional
plates 460 with slits are added before the end plates 430 to
complete the capillary circuits. The capillary channels 450 should
be sufficiently small to enable flow, but not too small to prevent
the accurate alignment between the laminae. In general, these
channels are approximately 0.1 to 0.5 mm in diameter. In addition,
the perforations, as shown in FIG. 4d, can be increased to further
increase the capillary action. Finally, the thickness, materials
and process of stacking and joining the laminae are similar to
those described in the above implementation.
[0042] FIG. 5a shows another implementation called a laminated
split-body Peltier device. This device 500 includes laminae 510
containing thermoelectric junctions, such that one group of
junctions 511 is functionally attached to the base 520, while the
second group of junctions 512 is thermally isolated by distance to
render a split-body configuration. In operation, the group 512 at
the top is the hot junction, while the group 511 at the base is the
cold junction. Attachment to the base can be accomplished by a
chemical agent (curable adhesive), diffusive bonding, welding,
soldering or any similar methods known in the art. The base 515
should be a thermal conductor and electrically insulated from the
laminae 510 through oxides or polymers (not shown). Each lamina is
approximately 0.2 to 2 mm thick and is formed from a N-type and a
P-type of materials in a "Z" shape, obtained from sheets of
dissimilar electrical conductors (metallic or polymeric) through
stamping, etching, plating, and/or punching. The junctions 511, 512
are formed by functionally joining together the P-type 513 and
N-type 514 materials through welding, plating, soldering, diffusive
bonding, and/or any other similar methods that are known in the
art.
[0043] With the exception of the two ends 516, each individual
lamina is electrically insulated by using an oxide or a polymer
coating (not shown) and are stacked/joined together similar to the
methods discussed for the first embodiment. The two ends 516 of
each lamina are not insulated to enable electric current to pass
through after the laminae are joined together. Two basic stacking
arrangements are possible depending on whether the individual
lamina is electrically connected in series or parallel. Electrical
wires 517 are then functionally attached to the two ends 516 for
connection with an external power source.
[0044] The devices shown in FIGS. 1-5 can be combined together in
different ways to suit the final performance target. For example,
as shown in FIGS. 6a, the laminated heat sink and the laminated
heat-pipe can be produced together as one integral unit.
Alternatively, the laminated heat-pipe and the laminated split-body
Peltier device can be produced together using the same process
(FIG. 6b).
[0045] A number of implementations have been described.
Nevertheless, it will be understood that various modifications may
be made. Accordingly, other implementations are within the scope of
the following claims.
* * * * *