U.S. patent application number 10/209981 was filed with the patent office on 2004-02-05 for adjustable pedestal thermal interface.
Invention is credited to Belady, Christian L., Boudreaux, Brent A., Fraker, Stacy, Peterson, Eric C..
Application Number | 20040020634 10/209981 |
Document ID | / |
Family ID | 31187183 |
Filed Date | 2004-02-05 |
United States Patent
Application |
20040020634 |
Kind Code |
A1 |
Boudreaux, Brent A. ; et
al. |
February 5, 2004 |
ADJUSTABLE PEDESTAL THERMAL INTERFACE
Abstract
A heat sink is constructed including at least one thermally
conductive pedestal, allowing configuration of the heat sink to
make contact with a plurality of heat-generating electronic devices
where the devices may not be co-planar due to tolerance stack-up.
The pedestals may be raised and lowered and tilted as needed to
match the heights and tilts of the electronic devices. Within the
heat sink is a cavity above the pedestal that may be filled with a
thermally conductive material, such as solder, or a thermally
conductive liquid, during construction to create a low thermal
resistance contact between the pedestal and the heat sink fins.
Also, thermally conductive material, such as thermal paste or a
thermal pad, may be used between the heat generating device and the
pedestal to create a low thermal resistance contact.
Inventors: |
Boudreaux, Brent A.;
(Highland Village, TX) ; Fraker, Stacy; (Allen,
TX) ; Peterson, Eric C.; (McKinney, TX) ;
Belady, Christian L.; (McKinney, TX) |
Correspondence
Address: |
HEWLETT-PACKARD COMPANY
Intellectual Property Administration
P. O. Box 272400
Fort Collins
CO
80527-2400
US
|
Family ID: |
31187183 |
Appl. No.: |
10/209981 |
Filed: |
July 31, 2002 |
Current U.S.
Class: |
165/104.33 ;
165/104.21; 257/E23.094; 29/890.032 |
Current CPC
Class: |
H01L 21/4882 20130101;
H01L 23/4338 20130101; H01L 2924/0002 20130101; H01L 2924/0002
20130101; F28F 13/00 20130101; H01L 2924/3011 20130101; Y10T
29/49353 20150115; F28F 2013/006 20130101; H01L 2924/00
20130101 |
Class at
Publication: |
165/104.33 ;
165/104.21; 29/890.032 |
International
Class: |
F28D 015/00; B23P
006/00 |
Claims
What is claimed is:
1. A heat sink comprising: a heat sink body, including a cavity; a
thin plate including an opening, mechanically attached to said heat
sink body covering said cavity; and a pedestal, inserted into the
opening of said thin plate.
2. A heat sink as claimed in claim 1, wherein said cavity is a
solder cavity.
3. A heat sink as claimed in claim 1, wherein said pedestal
includes threads and is configured to thread into the opening of
said thin plate.
4. A heat sink as claimed in claim 1, wherein said pedestal
includes teeth and is configured to push into the opening of said
thin plate.
5. A heat sink as claimed in claim 1, wherein said pedestal
includes a drive socket; and wherein said heat sink body includes a
drive access hole into said cavity, configured to allow access
through said heat sink body to the drive socket in said
pedestal.
6. A heat sink as claimed in claim 1, wherein said heat sink body
includes an overflow vent into said cavity.
7. A heat sink as claimed in claim 1, wherein said heat sink body
includes heat sink fins.
8. A heat sink comprising: a heat sink body, including a cavity; a
plate mechanically attached to said heat sink body; a thin plate
including an opening, mechanically attached to said heat sink body
covering said cavity; and a pedestal, inserted into the opening of
said thin plate.
9. A heat sink as claimed in claim 8, wherein said cavity is a
solder cavity.
10. A heat sink as claimed in claim 8, wherein said pedestal
includes threads and is configured to thread into the opening of
said thin plate.
11. A heat sink as claimed in claim 8, wherein said pedestal
includes teeth and is configured to push into the opening of said
thin plate.
12. A heat sink as claimed in claim 8, wherein said pedestal
includes a drive socket; and wherein said plate includes a drive
access hole into said cavity, configured to allow access through
said plate to the drive socket in said pedestal.
13. A heat sink as claimed in claim 8, wherein said plate includes
an overflow vent into said cavity.
14. A heat sink as claimed in claim 8, wherein said heat sink body
includes heat sink fins.
15. A heat sink as claimed in claim 8, further comprising: heat
sink fins attached to said plate.
16. A method for constructing a heat sink, comprising the steps of:
a) providing a heat sink body including a cavity; b) creating an
overflow vent in said heat sink body into said cavity; c) attaching
a thin plate to said heat sink body under said cavity, wherein said
thin plate includes an opening; d) inserting a pedestal into the
opening of said thin plate.
17. A method for constructing a heat sink as claimed in claim 16,
further comprising the steps of: e) adjusting said pedestal to
match a height of a electrical device; f) filling said cavity with
molten solder; and g) mechanically attaching said heat sink to a
substrate.
18. A method for constructing a heat sink as claimed in claim 16,
further comprising the steps of: e) adjusting said pedestal to
match a height of a electrical device; f) filling said cavity with
a thermally conductive liquid; g) sealing said thermally conductive
liquid inside said cavity; and h) mechanically attaching said heat
sink to a substrate.
19. A method for constructing a heat sink as claimed in claim 16,
further comprising the step of: e) attaching heat sink fins to said
heat sink body.
20. A method for constructing a heat sink as claimed in claim 16,
further comprising the step of: e) creating a drive access hole in
said heat sink body into said cavity; and f) creating a drive
socket in a top surface of said pedestal.
21. A method for constructing a heat sink as claimed in claim 16,
further comprising the step of: e) placing a thermally conductive
material between said pedestal and the electrical device.
22. A method for constructing a heat sink as claimed in claim 16,
wherein said pedestal includes threads and is configured to thread
into the opening of said thin plate.
23. A method for constructing a heat sink as claimed in claim 16,
wherein said pedestal includes teeth and is configured to push into
the opening of said thin plate.
24. A method for constructing a heat sink, comprising the steps of:
a) providing a heat sink body including a cavity; b) attaching a
plate to a top surface of said heat sink body, covering said
cavity; c) creating an overflow vent in said plate into said
cavity; d) attaching a thin plate to said heat sink body under said
cavity, wherein said thin plate includes an opening; e) inserting a
pedestal into the opening of said thin plate.
25. A method for constructing a heat sink as claimed in claim 24,
further comprising the steps of: f) adjusting said pedestal to
match a height of an electrical device; g) filling said cavity with
molten solder; and h) mechanically attaching said heat sink to a
substrate.
26. A method for constructing a heat sink as claimed in claim 24,
further comprising the steps of: f) adjusting said pedestal to
match a height of an electrical device; f) filling said cavity with
a thermally conductive liquid; g) sealing said thermally conductive
liquid inside said cavity; and i) mechanically attaching said heat
sink to a substrate.
27. A method for constructing a heat sink as claimed in claim 24,
further comprising the step of: f) attaching heat sink fins to said
heat sink body.
28. A method for constructing a heat sink as claimed in claim 24,
further comprising the step of: f) attaching heat sink fins to said
plate.
29. A method for constructing a heat sink as claimed in claim 24,
further comprising the step of: f) creating a drive access hole in
said plate into said cavity; and g) creating a drive socket in a
top surface of said pedestal.
30. A method for constructing a heat sink as claimed in claim 24,
further comprising the step of: f) placing a thermally conductive
material between said pedestal and the electrical device.
31. A method for constructing a heat sink as claimed in claim 24,
wherein said pedestal includes threads and is configured to thread
into the opening of said thin plate.
32. A method for constructing a heat sink as claimed in claim 24,
wherein said pedestal includes threads and is configured to thread
into the opening of said thin plate.
33. A heat sink comprising: a heat sink body, including means for
placing liquid solder into a cavity within said heat sink body; a
thin plate mechanically attached to said heat sink body covering
said cavity, including means for moveably capturing a pedestal; and
a pedestal, moveably captured within said thin plate.
34. A heat sink as claimed in claim 33, wherein said pedestal
includes threads and is configured to thread into the opening of
said thin plate.
35. A heat sink as claimed in claim 33, wherein said pedestal
includes teeth and is configured to push into the opening of said
thin plate.
36. A heat sink comprising: a heat sink body, including means for
placing a thermally conductive liquid into a cavity within said
heat sink body; a thin plate mechanically attached to said heat
sink body covering said cavity, including means for moveably
capturing a pedestal; and a pedestal, moveably captured within said
thin plate.
37. A heat sink as claimed in claim 36, wherein said pedestal
includes threads and is configured to thread into the opening of
said thin plate.
38. A heat sink as claimed in claim 36, wherein said pedestal
includes teeth and is configured to push into the opening of said
thin plate.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to the field of heat
sinks and more specifically to the field of heat sinks configured
to maximize thermal conduction with heat generating devices that
may not be co-planar with the heat sink.
BACKGROUND OF THE INVENTION
[0002] Modern electronics have benefited from the ability to
fabricate devices on a smaller and smaller scale. As the ability to
shrink devices has improved, so has their performance.
Unfortunately, this improvement in performance is accompanied by an
increase in power as well as power density in devices. In order to
maintain the reliability of these devices, the industry must find
new methods to remove this heat efficiently.
[0003] By definition, heat sinking means that one attaches a
cooling device to a heat-generating component and thereby removes
the heat to some cooling medium, such as air or water.
Unfortunately, one of the major problems in joining two devices to
transfer heat through a common surface is that a thermal interface
is created at the junction. This thermal interface is characterized
by a thermal contact impedance. Thermal contact impedance is a
function of contact pressure, surface finish, and gap size.
[0004] As the power density of electronic devices increases, heat
transfer from the heat generating devices to the surrounding
environment becomes more and more critical to the proper operation
of the devices. Many current electronic devices incorporate heat
sink fins to dissipate heat to the surrounding air moving over the
fins. These heat sinks are thermally connected to the electronic
devices by a variety of techniques. Some devices use a thermally
conductive paste in an attempt to lower the contact resistance.
Others may use solder between the two elements both for mechanical
strength and thermal conductance. However, these two solutions
require additional cost and process steps that would not be
necessary except for presence of the contact resistance.
[0005] Many present electronic modules include a plurality of
heat-generating electronic devices on a single substrate. Often
these devices to not have a co-planer upper surface which would
allow a single heat sink to be thermally coupled to the plurality
of devices. Thermal paste and other thermally conductive materials
may be used to fill any gaps between the heat-generating electronic
devices and the single heat sink, however large gaps, caused by
tolerance stack-up issues between the heat-generating devices, are
often not capable of being filled by a paste. Thermal gap pads are
capable of filling gaps on the order of 20 to 200 mils, however,
they have relatively low thermal conductivity, and may not be
usable with high performance devices that generate large amounts of
heat. In such cases, multiple heat sinks may be used, however, this
adds cost and reduces the efficiency of the heat dissipation.
SUMMARY OF THE INVENTION
[0006] A heat sink is constructed including at least one thermally
conductive pedestal, allowing configuration of the heat sink to
make contact with a plurality of heat-generating electronic devices
where the devices may not be co-planar due to tolerance stack-up.
The pedestals may be raised and lowered and tilted as needed to
match the heights and tilts of the electronic devices. Within the
heat sink is a cavity above the pedestal that may be filled with a
thermally conductive material, such as solder, or a thermally
conductive liquid, during construction to create a low thermal
resistance contact between the pedestal and the heat sink fins.
Also, thermally conductive material, such as thermal paste or a
thermal pad, may be used between the heat generating device and the
pedestal to create a low thermal resistance contact.
[0007] Other aspects and advantages of the present invention will
become apparent from the following detailed description, taken in
conjunction with the accompanying drawings, illustrating by way of
example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a cross-sectional view of an example embodiment of
a heat sink according to the present invention.
[0009] FIG. 2 is a cross-sectional view of an example embodiment of
a heat sink including three threaded pedestals according to the
present invention.
[0010] FIG. 3 is a cross-sectional view of an example embodiment of
a heat sink according to the present invention.
[0011] FIG. 4 is a top view of an example embodiment of a heat sink
according to the present invention.
[0012] FIG. 5 is a flow chart of an example method of constructing
a heat sink according to the present invention.
[0013] FIG. 6 is a cross-sectional view of an example embodiment of
a heat sink according to the present invention.
DETAILED DESCRIPTION
[0014] FIG. 1 is a cross-sectional view of an example embodiment of
a heat sink according to the present invention. A heat-generating
electronic device 100 is attached to a substrate 102. A thermally
conductive threaded pedestal 104 is thermally coupled with the
electronic device 100 on a side opposite to that of the substrate
102. A heat sink including a heat sink base 108, a plate 112, fins
120 and a thin plate 110 is attached to the threaded pedestal 104.
Note that in some embodiments of the present invention, the heat
sink base 108, plate 112, and fins 120 may all be constructed as
integral parts of a heat sink, instead of being constructed
separately and assembled into a heat sink. In some embodiments of
the present invention, the thin plate 110 will be configured such
that the threaded pedestal 104 may be threaded into it at a small
angle to match a tilt in the upper surface of the heat-generating
electronic device 100. Note that the threads shown in FIG. 1 are
exaggerated in size for purposes of illustration. Many embodiments
of the present invention will use threads proportionally smaller
than those shown in this figure. In some embodiments of the present
invention the plate 112 may be formed as a contiguous portion of
the heat sink base 108, as shown in FIG. 2. Other embodiments of
the present invention may construct the plate 112 separately from
the heat sink base 108 and physically connect them together to form
a surface for the attachment of the heat sink fins 120, as shown in
FIG. 1. The plate 112 includes a drive access hole 114 and a solder
overflow vent 116. The threaded pedestal 104 includes a drive
socket 106.
[0015] FIG. 2 is a cross-sectional view of an example embodiment of
a heat sink including three threaded pedestals according to the
present invention. In an example embodiment of the present
invention, a plurality of thermally conductive threaded pedestals
may be used with a single heat sink, allowing heat dissipation from
a plurality of heat-generating electronic devices with
non-co-planar upper surfaces. In the example embodiment of the
present invention shown in FIG. 2 three heat-generating electrical
devices with different heights are thermally coupled with a single
heat sink body 220 and a single set of heat sink fins 240. A first
heat-generating electrical device 202 having a first height is
attached to a substrate 200, along with a second heat-generating
electrical device 208 having a second height and a third
heat-generating electrical device 214 having a third height. The
first, second, and third heights may all be different as shown in
the example embodiment of the present invention of FIG. 2. A heat
sink body 220 is constructed including a first solder cavity 222, a
second solder cavity 228, and a third solder cavity 234. A first
thin plate 242 including an opening 248 sized to fit a first
pedestal 204 is attached to the heat sink body 220 under the first
solder cavity 222. A second thin plate 244 including an opening 250
sized to fit a second pedestal 210 is attached to the heat sink
body 220 under the second solder cavity 228. A third thin plate 246
including an opening 252 sized to fit a third pedestal 216 is
attached to the heat sink body 220 under the third solder cavity
234. A first solder overflow vent 226 and a first drive access hole
224 are included in the portion of the heat sink body 220 above the
first solder cavity 222. A second solder overflow vent 232 and a
second drive access hole 230 are included in the portion of the
heat sink body 220 above the second solder cavity 228. A third
solder overflow vent 238 and a third drive access hole 236 are
included in the portion of the heat sink body 220 above the third
solder cavity 234. A first threaded pedestal 204 including a first
drive socket 206, a second threaded pedestal 210 including a second
drive socket 212, and a third threaded pedestal 216 including a
third drive socket 218 are provided. In use of the example
embodiment of the present invention shown in FIG. 2, the three
threaded pedestals 204, 210, and 216 are adjusted by a drive tool
through the three drive access holes 224, 230, and 236 to match the
differing heights of the three heat-generating electrical devices
202, 208, and 214. Other embodiments of the present invention may
not require the use of a drive socket and drive access hole. The
threaded pedestals may be threaded into the heat sink to a known
depth before the assembled heat sink is placed over the substrate,
eliminating the need for a drive socket and drive access hole. A
thermally conductive material, such as a solder paste, thermal
grease, or a thermal pad, may be applied between the three
heat-generating electrical devices 202, 208, and 214 and the three
threaded pedestals 204, 210, and 216. The three solder cavities
222, 228, and 236 may be filled with melted solder to create a low
resistance thermal connection between the three threaded pedestals
204, 210, and 216 and the heat sink body 220. The three solder
cavities 222, 228, and 236 may be filled either before or after the
heat sink is mechanically attached to the substrate 200. Upon
filling of the three solder cavities 222, 228, and 236 excess
solder may escape via the three solder overflow vents 226, 232, and
238. The presence of solder at the three solder overflow vents 226,
232, and 238 may be used as a visual indication that the three
solder cavities 222, 228, and 236 are full.
[0016] FIG. 3 is a cross-sectional view of an example embodiment of
a heat sink according to the present invention. In some embodiments
of the present invention it may be desirable to simplify the heat
sink body 308 by attaching a plate 312 between the heat sink body
308 and the heat sink fins 320. Note that in some embodiments of
the present invention, the heat sink base 308, plate 312, and fins
320 may all be constructed as integral parts of a heat sink,
instead of being constructed separately and assembled into a heat
sink. In this embodiment, the solder overflow vent 316 and the
drive access hole 314 may be created in the plate 312 instead of
into the heat sink body 308. A thin plate 310 is attached to the
bottom of the heat sink body 308 below a solder cavity 318. A
heat-generating electrical device 300 is attached to a substrate
302 and a thermally conductive threaded pedestal 304 including a
drive socket 306 is threaded into the thin plate 310. Other than
the addition of the plate 312 this example embodiment of the
present invention is similar to that shown in FIG. 1.
[0017] FIG. 4 is a top view of an example embodiment of a heat sink
according to the present invention. Cross-section A is the
cross-section used in FIG. 1 and FIG. 3. Heat sink fins 400 are
shown attached to a heat sink body 408, as in the embodiment of the
present invention shown in FIG. 2. In the example embodiments of
the present invention shown in FIG. 1 and FIG. 3, the heat sink
body 408 of FIG. 4 would show instead a plate. A solder overflow
vent 406 and a drive access hole 402 are shown in the heat sink
body 408. A drive socket 404 may be seen through the drive access
hole 402.
[0018] FIG. 5 is a flow chart of an example method of constructing
a heat sink according to the present invention. In a step 500 a
heat sink body including a solder cavity is provided. In an
optional step 502 heat sink fins are attached to the heat sink
body. In other example embodiments of the present invention, heat
sink fins may be formed as an integral part of the heat sink body,
or may not be needed at all. In a step 504 a solder overflow vent
into the solder cavity is formed in the heat sink body. In an
optional step 506 a drive access hole into the solder cavity is
formed in the heat sink body. In a step 508 a thin plate including
an opening sized to fit a thermally conductive pedestal is
mechanically attached to the heat sink body under the solder
cavity. In a step 510 a thermally conductive pedestal is threaded
into the opening in the thin plate. In a step 512 the pedestals are
adjusted to correspond to the height of a heat-generating
electrical device on a substrate. In a step 514 the solder cavity
is filled with molten solder. In an optional step 516 a thermally
conductive material, such as a thermal paste is placed between the
thermal pedestal and the electrical device. In an optional step 518
the heat sink assembly is mechanically attached to a substrate.
Some embodiments of the present invention may not require the heat
sink assembly to be mechanically attached to a substrate. They may
use other techniques to prevent the heat sink from shifting within
the scope of the present invention. Still other embodiments of the
present invention may attach the heat sink assembly to a substrate
before filling the solder cavity with molten solder.
[0019] FIG. 6 is a cross-sectional view of an example embodiment of
a heat sink according to the present invention. A heat-generating
electronic device 600 is attached to a substrate 602. A thermally
conductive toothed pedestal 604 is thermally coupled with the
electronic device 600 on a side opposite to that of the substrate
602. Instead of spiral threads, the toothed pedestal 604 has a
series of circular saw-tooth cuts about the outside of the
pedestal. A heat sink including a heat sink base 608, a plate 612,
fins 620 and a thin plate 610 is attached to the push-in pedestal
604. In assembly, the toothed pedestal 604 is simply forced into an
appropriately sized opening in the thin plate 610 and the saw-teeth
in the surface of the toothed pedestal 604 keep it from backing out
of the heat sink. Note that the teeth shown in FIG. 6 are
exaggerated in size for purposes of illustration. Many embodiments
of the present invention will use teeth proportionally smaller than
those shown in this figure. The thin plate 610 is configured to
allow the toothed pedestal 604 to fit snugly, but also allow the
toothed pedestal 604 to fit into the plate at an angle, allowing
for use over heat-generating devices 600 that are not parallel to
the thin plate 610. In some embodiments of the present invention
the plate 612 may be formed as a contiguous portion of the heat
sink base 608, as shown in FIG. 2. Other embodiments of the present
invention may construct the plate 612 separately from the heat sink
base 608 and physically connect them together to form a surface for
the attachment of the heat sink fins 620, as shown in FIG. 6. The
plate 612 includes a drive access hole 614 and a solder overflow
vent 616. The push-in pedestal 604 includes a drive socket 606.
[0020] The foregoing description of the present invention has been
presented for purposes of illustration and description. It is not
intended to be exhaustive or to limit the invention to the precise
form disclosed, and other modifications and variations may be
possible in light of the above teachings. The embodiments were
chosen and described in order to best explain the principles of the
invention and its practical application to thereby enable others
skilled in the art to best utilize the invention in various
embodiments and various modifications as are suited to the
particular use contemplated. It is intended that the appended
claims be construed to include other alternative embodiments of the
invention except insofar as limited by the prior art.
* * * * *