U.S. patent application number 09/964476 was filed with the patent office on 2003-04-03 for radial base heatsink.
Invention is credited to Guarnero, Richard F., Stapleton, Michael A., Wei, Wen.
Application Number | 20030063439 09/964476 |
Document ID | / |
Family ID | 25508578 |
Filed Date | 2003-04-03 |
United States Patent
Application |
20030063439 |
Kind Code |
A1 |
Wei, Wen ; et al. |
April 3, 2003 |
RADIAL BASE HEATSINK
Abstract
A radial base heatsink is provided to dissipate heat from a heat
source. Such a heatsink comprises a cylindrical core; and a
plurality of cooling fins projecting outwardly from the cylindrical
core and defining a series of channels in a substantially radial
pattern with a fin orientation relative to a center line of the
cylindrical core, for dissipating heat generated from a heat
source, via the cylindrical core.
Inventors: |
Wei, Wen; (Beaverton,
OR) ; Stapleton, Michael A.; (Portland, OR) ;
Guarnero, Richard F.; (Scappose, OR) |
Correspondence
Address: |
ANTONELLI TERRY STOUT AND KRAUS
SUITE 1800
1300 NORTH SEVENTEENTH STREET
ARLINGTON
VA
22209
|
Family ID: |
25508578 |
Appl. No.: |
09/964476 |
Filed: |
September 28, 2001 |
Current U.S.
Class: |
361/703 ;
257/722; 257/E23.099 |
Current CPC
Class: |
H01L 2924/0002 20130101;
H01L 23/467 20130101; H01L 2924/3011 20130101; Y10T 29/4935
20150115; H01L 2924/0002 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
361/703 ;
257/722 |
International
Class: |
H05K 007/20 |
Claims
What is claimed is:
1. A heatsink comprising: a cylindrical core; and a plurality of
cooling fins projecting outwardly from the cylindrical core and
defining a series of channels in a substantially radial pattern
with a fin orientation relative to a center line of the cylindrical
core, for dissipating heat generated from a heat source, via the
cylindrical core.
2. The heatsink as claimed in claim 1, wherein the cylindrical core
includes a substantially planar top surface adapted to accommodate
a fan hub, a substantially planar base surface adapted to contact
the heat source, and a peripheral outer wall extended from the top
surface to the base surface.
3. The heatsink as claimed in claim 1, wherein the cylindrical core
and the cooling fins are made of a single aluminum (Al) piece.
4. The heatsink as claimed in claim 1, wherein the cooling fins
extending from the cylindrical core in the substantially radial
pattern are cut and spaced-apart along a horizontal direction
relative to the center line of the cylindrical core.
5. The heatsink as claimed in claim 2, wherein the cooling fins
extending from the cylindrical core in the substantially radial
pattern are straight fins in which all cooling fins have a
predetermined length, width, pattern and shape arranged uniformly
along the peripheral outer wall of the cylindrical core at a
predetermined angle.
6. The heatsink as claimed in claim 2, wherein the cooling fins
extending from the cylindrical core in the substantially radial
pattern are angled fins in which all cooling fins have a
predetermined length, width, pattern and shape arranged uniformly
along the peripheral outer wall of the cylindrical core at a
predetermined angle.
7. The heatsink as claimed in claim 1, wherein the cooling fins
extending from the cylindrical core in the substantially radial
pattern are angled fins in which cooling fins are tapered from the
planar top surface to the planar base surface at a predetermined
angle.
8. The heatsink as claimed in claim 1, wherein the cooling fins
extending from the cylindrical core in the substantially radial
pattern are elongated conical fins, pin-type fins or pre-fabricated
bonded fins.
9. The heatsink as claimed in claim 1, wherein the cooling fins
extending from the cylindrical core in the substantially radial
pattern are airfoil fins in which cooling fins are curved along a
direction of a fan swirl.
10. The heatsink as claimed in claim 1, wherein the cylindrical
core and the cooling fins are made of a single metallic piece that
is light weight and has a high thermal conductivity, including a
copper-tungsten alloy, aluminum nitride, beryllium oxide or
copper.
11. The heatsink as claimed in claim 1, wherein the cooling fins
are mounted onto the cylindrical core by way of solder, adhesive or
other low thermal resistance material.
12. The heatsink as claimed in claim 1, wherein the heat source
corresponds to a microprocessor.
13. A heatsink assembly for dissipating heat from a heat source,
comprising: a radial base heatsink including a cylindrical core;
and a plurality of cooling fins projecting outwardly from the
cylindrical core in a substantially radial pattern with a fin
orientation relative to a center line of the cylindrical core; and
a fan shroud and heatsink retention mechanism including a fan
housing having an air shroud and an airflow duct, and a fan
structure to secure the radial base heatsink over the heat
source.
14. The heatsink assembly as claimed in claim 13, wherein the fan
structure comprises: a fan hub positioned substantially coaxially
with a top surface of the cylindrical core and having substantially
the same diameter as the top surface of the cylindrical core for
rotation about a fan rotation axis; and a plurality of fan blades
extending radially from the fan hub for forcing air in an axial
direction past a substantial portion of the blades.
15. The heatsink assembly as claimed in claim 14, wherein the
cylindrical core of the radial base heatsink includes a
substantially planar top surface adapted to accommodate the fan
hub, a substantially planar base surface adapted to contact the
heat source, and a peripheral outer wall extended from the top
surface to the base surface.
16. The heatsink assembly as claimed in claim 14, wherein the
cylindrical core and the cooling fins of the radial base heatsink
are made of a single aluminum (Al) piece.
17. The heatsink assembly as claimed in claim 14, wherein the
cooling fins of the radial base heatsink extending from the
cylindrical core in the substantially radial pattern are cut and
spaced-apart along a horizontal direction relative to the center
line of the cylindrical core.
18. The heatsink assembly as claimed in claim 14, wherein the
cooling fins of the radial base heatsink extending from the
cylindrical core in the substantially radial pattern straight fins
in which all cooling fins have a predetermined length, width,
pattern and shape arranged uniformly along the peripheral outer
wall of the cylindrical core at a predetermined angle.
19. The heatsink assembly as claimed in claim 14, wherein the
cooling fins of the radial base heatsink extending from the
cylindrical core in the substantially radial pattern are angled
fins in which cooling fins are tapered from the planar top surface
to the planar base surface at a predetermined angle.
20. The heatsink assembly as claimed in claim 14, wherein the
cooling fins of the radial base heatsink extending from the
cylindrical core in the substantially radial pattern are angled
fins in which all cooling fins have a predetermined length, width,
pattern and shape arranged uniformly along the peripheral outer
wall of the cylindrical core at a predetermined angle.
21. The heatsink assembly as claimed in claim 14, wherein the
cooling fins of the radial base heatsink extending from the
cylindrical core in the substantially radial pattern are elongated
conical fins, pin-type fins or airfoil fins in which cooling fins
are curved along a direction of a fan swirl.
22. The heatsink assembly as claimed in claim 14, wherein the
cylindrical core and the cooling fins of the radial base heatsink
are made of a single metallic piece that is light weight and has a
high thermal conductivity, including a copper-tungsten alloy,
aluminum nitride, beryllium oxide or copper.
23. A method of removing heat from a heat source, comprising:
providing a heatsink having a cylindrical core, and a plurality of
cooling fins projecting outwardly from a peripheral outer wall of
the cylindrical core in a substantially radial pattern with a fin
orientation relative to a center line of the cylindrical core;
providing a fan shroud and heatsink retention mechanism having a
fan housing with an air shroud and an airflow duct, and a fan
structure with a fan hub and a plurality of fan blades; securing
the heatsink over the heat source, via the fan shroud and heatsink
retention mechanism, such that the cylindrical core of the heatsink
is positioned between the heat source and the fan hub; transferring
heat generated from the heat source to the cooling fins of the
heatsink, via the cylindrical core of the heatsink; and causing
airflow generated by the fan blades to move away from the cooling
fins of the heatsink, via the air shroud and the airflow duct of
the fan housing, to dissipate heat from the heat source.
24. The method as claimed in claim 23, wherein the cylindrical core
and the cooling fins of the heatsink are made of a single metallic
piece, and the cooling fins of the heatsink extending from the
cylindrical core in the substantially radial pattern are straight
fins in which all cooling fins have a predetermined length and
width.
25. The method as claimed in claim 23, wherein the cooling fins of
the heatsink extending from the cylindrical core in the
substantially radial pattern are angled fins in which cooling fins
are tapered from the top surface to the base surface at a
predetermined angle.
26. The method as claimed in claim 25, wherein the cooling fins of
the radial base heatsink extending from the cylindrical core in the
substantially radial pattern are elongated conical fins, pin-type
fins, airfoil fins in which cooling fins are curved along a
direction of a fan swirl, or pre-fabricated bonded fins in which
cooling fins are mounted on an outer wall of the cylindrical core.
Description
TECHNICAL FIELD
[0001] The present invention relates to heatsinks for electronic
components, and more particularly, relates to an advanced radial
base heatsink comprising a cylindrical core with a conduction
enhanced base and a series of cooling fins extended therefrom in a
substantial radial pattern with a fin orientation relative to a
center line optimized to provide a low thermal resistance
connection to the base and minimize air flow impedance.
BACKGROUND
[0002] Modern electronic appliances such as computer systems have
not only microprocessor chips, including Intel.RTM. i386, i486,
Celeron.TM. or Pentium.RTM. processors, but also many hundreds of
integrated circuits (ICs) and other electronic components, most of
which are mounted on printed circuit boards (PCBs). Many of these
components generate heat during normal operation. Components that
have a relatively small number of functions in relation to their
size, as for example individual transistors or small scale
integrated circuits (ICs), usually dissipate all their heat without
a heat sink. However, as these components become smaller and
smaller to the extent that many thousands are now combined into a
single integrated circuit (IC) chip or an electronic package, and
operate faster and faster to provide the computing power that is
increasingly required, the amount of heat which the components
dissipated increasingly require the assistance of external cooling
devices such as heatsinks.
[0003] Heatsinks are typically passive devices, for example an
extruded aluminum plate with a plurality of fins, that is thermally
coupled to a heat source, i.e., an electronic package such as a
microprocessor to absorb heat from the electronic component. The
heatsinks dissipate this heat into the air by convection. Generally
there are several types of heatsinks available for dissipating heat
from an electronic package.
[0004] Typical heatsinks are copper (Cu) or aluminum (Al) based
heatsinks with either folded fins or skived fins with no fan or an
active fan on top to promote airflow efficiency. A retention
mechanism such as a clip is required to secure the heatsink onto an
electronic package across the heat dissipation path. An active fan
is often mounted on top of the heatsinks to transfer heat, during
operation, from a heat source (electronic package) to the ambient
air, via the folded or skived fins. For copper based heat sinks
with folded fins, the retention mechanism may be elaborate and
often interfere with the heat dissipation path directly over a heat
source. In addition, copper based heatsinks can be heavy and
expensive to manufacture. Moreover, the fin surface area can be
limited with high airflow resistance or heat sink impedance.
[0005] Another common example is a Mushroom based Arctic heatsink
with either machined or extruded fins. Typically, a fan is
installed inside the housing, i.e., a generally cylindrically
shaped fan chamber of the Mushroom based Arctic heatsink. The
housing surrounding the fan is constructed of a series of cooling
vanes (fins) which have elongated openings therebetween allowing
air to pass between and cool the vanes (fins). The vanes are angled
in an approximately opposite manner to the angle of the fan blades
in order to reduce operation noise while improving heat
dissipation. However, the Mushroom based Arctic heatsink tends to
be more expensive to manufacture as the design is far more complex
to house an internal fan. Moreover, the thermal resistance and heat
transfer efficiency may not be maximized since the mushroom base is
limited with less contact with extending vanes (fins) and less
cooling surface area for heat transfer.
[0006] Accordingly, there is a need to provide a lower cost and
thermal resistance alternative to flat, rectangular folded fin or
skived fin heatsinks, Mushroom based Arctic heatsinks and other
active coolers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] A more complete appreciation of exemplary embodiments of the
present invention, and many of the attendant advantages of the
present invention, will become readily apparent as the same becomes
better understood by reference to the following detailed
description when considered in conjunction with the accompanying
drawings in which like reference symbols indicate the same or
similar components, wherein:
[0008] FIG. 1 illustrates an example copper (Cu) or aluminum (Al)
based heatsink with folded fins;
[0009] FIG. 2 illustrates an example copper (Cu) or aluminum (Al)
based heatsink with skived fins;
[0010] FIG. 3 illustrates an airflow simulation result of the
copper (Cu) or aluminum (Al) based heatsink with skived fins shown
in FIG. 2.
[0011] FIGS. 4A-4B illustrate an example Mushroom based Arctic
heatsink with an active fan mounted internal to fins;
[0012] FIG. 5 illustrates an airflow simulation result of the
Mushroom based Arctic heatsink with an active fan mounted internal
to fins shown in FIGS. 4A-4B;
[0013] FIGS. 6A-6D illustrate an example advanced radial base
heatsink with straight fins according to an embodiment of the
present invention;
[0014] FIGS. 7A-7D illustrate an example advanced radial base
heatsink with angled fins according to an embodiment of the present
invention;
[0015] FIG. 8 illustrates an example advanced radial base heatsink
with conical fins according to an embodiment of the present
invention;
[0016] FIG. 9 illustrates an example advanced radial base heatsink
with pin type fins according to an embodiment of the present
invention;
[0017] FIG. 10 illustrates an example advanced radial base heatsink
with airfoil fins according to an embodiment of the present
invention;
[0018] FIG. 11 illustrates an example advanced radial base heatsink
with pre-fabricated bonded fins according to an embodiment of the
present invention;
[0019] FIG. 12 illustrates a cross-sectional view of an example
radial base heatsink according to an embodiment of the present
invention;
[0020] FIGS. 13A-13B illustrate an airflow direction of an example
radial base heatsink with straight fins or angled fins according to
an embodiment of the present invention;
[0021] FIGS. 14A-14C illustrate an example fin angle and fin
pattern of an example radial base heatsink with straight fins or
angled fins according to an embodiment of the present
invention;
[0022] FIGS. 15A-15D illustrate example fin shapes of an example
radial base heatsink with straight fins or angled fins according to
an embodiment of the present invention;
[0023] FIG. 16 illustrates an airflow simulation result of an
example radial base heatsink according to an embodiment of the
present invention;
[0024] FIGS. 17A-17B illustrate an advanced heatsink assembly
including an example radial base heatsink and a fan shroud and
heatsink retention mechanism according to an embodiment of the
present invention; and
[0025] FIGS. 18A-18B illustrate an example fan shroud and heatsink
retention mechanism according to an embodiment of the present
invention.
DETAILED DESCRIPTION
[0026] The present invention is applicable for use with all types
of electronic packages and IC devices such as Intel.RTM. i386,
i486, Celeron.TM. or Pentium.RTM. processors, including new
microprocessor chips which may become available as computer
technology develops in the future. Further, the present invention
is not limited to use in computer systems, but is suitable for
applications in many industries and/or environments such as
automotive, telecommunications, etc. However, for the sake of
simplicity, discussions will concentrate mainly on exemplary use of
a heatsink assembly to be mounted onto a system board of a computer
system, although the scope of the present invention is not limited
thereto.
[0027] Attention now is directed to the drawings and particularly
to FIG. 1, an example copper (Cu) or aluminum (Al) based heatsink
with folded fins for is illustrated. As shown in FIG. 1, the copper
(Cu) or aluminum (Al) based heatsink 100 may include a heat
spreader base 110 with a flat bottom surface and a large number of
cooling (radiation) fins 112A-112N extending perpendicularly or
projecting upwardly from the heat spreader base 110. The heat
spreader base 110 may generally be a rectangular plate and its size
may be co-extensive with the size of an electronic packet (not
shown). In addition, the heatsink 100 may also include a channel
120 in a central region extending across the heat spreader base 110
for purposes for accommodating a separate retention mechanism such
as a retainer clip 130 to secure the heatsink 100 and the
electronic package onto a socket (not shown).
[0028] Usually, the heat spreader base 110 and fins 112A-12N may be
integrally formed from a strip of metal foil, such as copper (Cu)
or aluminum (Al) sheet material. The fins 112A-112N comprise folded
portions of the metal foil, having two adjacent portions joined at
a fold 114 at the edge of the fins 112A-112N. Often times the
folded fins 112A-112N may be bonded in a thermally conductive way
onto the heat spreader base 110, by way of adhesive for
example.
[0029] However, the copper (Cu) or aluminum (Al) based heat sink
with folded fins can be heavy and expensive to manufacture. In
addition, an elaborate retainer clip 130 is required and often
interfere with the heat dissipation path directly over a heat
source, i.e., an electronic package. Moreover, the fin surface area
can be limited with high airflow resistance or heat sink
impedance.
[0030] FIG. 2 illustrates an example copper (Cu) or aluminum (Al)
based heatsink with skived fins. As shown in FIG. 2, the skived
heatsink 200 may include a longitudinally extending heat spreader
base 210 and a large number of skived fins 212A-212N extending
perpendicularly or projecting upwardly from the heat spreader base
210. The heat spreader base 210 may also be a rectangular plate and
its size may be co-extensive with the size of an electronic packet
(not shown). The fins 212A-212N may be created using a process
which "skives"the fins from extruded sheets of metal, such as
copper (Cu) or aluminum (Al), with a high production
throughput.
[0031] Typically, a sharpened tool may be brought into angular
contact with the surface of the copper (Cu) or aluminum (Al) sheet
to repeatedly form fins which are spaced very close together.
Aspect ratios (e.g. height/gap) of greater than 8, and nominally
10, are generally necessary to adequately dissipate heat from an
electronic package. Each fin 212A-212M may identically match the
thermal coefficient of the underlying surface of base 210 because
the fin is a carved part of the base surface 210.
[0032] In either folded fin or skived fin heatsinks as described
with reference to FIGS. 1-2, a fan structure 220 including an
active fan installed on a fan hub 222 may be mounted on top of the
heatsink 200, for example, in order to promote heat transfer and
airflow efficiency, during operation, from an electronic component
to the ambient air, via the folded or skived fins.
[0033] Skived fin heatsinks may typically lower in cost than
conventional folded fin heatsinks which require individual fins to
be bonded in a thermally conductive way to the base. However, the
skived fin heatsinks can still be heavy and expensive to
manufacture. In addition, the fin surface area can also be limited
with high airflow resistance or heat sink impedance and low
heatsink efficiency as described with reference with FIG. 3
hereinbelow.
[0034] FIG. 3 illustrates an airflow simulation result of the
copper (Cu) or aluminum (Al) based heatsink 200 with skived fins
212A-212N shown in FIG. 2. When the heatsink 200 with skived fins
212A-212N is secured on top of an electronic package (not shown),
the cylindrical base is under a fan hub 222 where a heat stagnation
region is present. Heat will be removed by the airflow under the
fan blade area. However, the heat stagnation region leads to lower
fin efficiency.
[0035] FIGS. 4A-4B illustrate another common heatsink, known as a
Mushroom based Arctic heatsink 300 with machined or extruded fins
312A-312N positioned on top of a socket 410 supporting a heat
source, i.e., an electronic package such as a microprocessor. The
heatsink 300 may include a Mushroom base 310 and a series of
cooling vanes (fins) 312A-312N extending outwardly and then
projecting upwardly from the Mushroom base 310 to form a housing
320, i.e., a generally cylindrically shaped fan chamber of the
Mushroom based Arctic heatsink 300.
[0036] Typically, a fan structure 330 including an active fan 332
may be installed inside the housing 320 of the Mushroom based
Arctic heatsink 300. The series of cooling vanes (fins) 312A-312N
may contain elongated openings (slots) therebetween for allowing
air to pass between and cool the vanes (fins). The vanes (fins)
312A-312N may be angled in an approximately opposite manner to the
angle of the fan blades in order to reduce operation noise while
improving heat dissipation. However, the Mushroom based Arctic
heatsink 300 tends to be more expensive to manufacture as the
design is far more complex to house an internal fan. Moreover, the
thermal resistance and heat transfer efficiency may not be
maximized since the Mushroom base is limited with less contact with
extending vanes (fins) and less cooling surface area for heat
transfer.
[0037] FIG. 5 illustrates an airflow simulation result of the
Mushroom based Arctic heatsink with an active fan mounted internal
to fins shown in FIGS. 4A-4B. As can be seen from the arrows shown
in FIG. 5, the airflow may be recirculated within the housing 320
of the Mushroom based Arctic heatsink 300 and eventually exited via
the elongated openings of the vanes (fins) 312A-312N. Airflow
recirculation within the housing (chamber) 320 of the Mushroom
based Arctic heatsink 300 may cause air pressure to drop, resulting
in relatively high airflow loss and low heatsink efficiency.
[0038] Turning now to FIGS. 6A-6D, 7A-7D and 8-12, a variety of
lower cost and thermal resistance alternative solutions to flat,
rectangular folded fin or skived fin heatsinks as described with
reference to FIGS. 1-2, Mushroom based Arctic heatsinks as
described with reference to FIGS. 4-5 and other active coolers
according to an embodiment of the present invention are
illustrated. Radial base heatsinks with a substantially solid
cylindrical core having a conduction enhanced cylindrical base and
different cooling fins configurations extending from the
cylindrical core are advantageously provided to produce up to twice
the thermal performance of typical rectangular folded fin or skived
fin heatsinks or Mushroom based Arctic heatsinks heatsinks in the
same or smaller volume. Cooling fins may be attached to or mounted
onto (by way of solder, adhesive or other low thermal resistance
material), extruded from or machined from the cylindrical core in a
substantial radial pattern with a fin orientation relative to a
center line of the cylinder optimized (i.e., straight or angled to
match fan swirl). Each of the cooling fins can have its height
optimized in accordance with its location on the cylindrical core,
and its length optimized in accordance with its location on the
cylindrical core separated by cuts. Likewise, the cylindrical core
can also have its dimension optimized (straight or tapered) to
spread heat uniformly and more efficiently from a heat source,
i.e., an electronic package such as a microprocessor to all the
cooling fins. A typical size of a radial base heatsink may be
approximately 3 inches with the cylindrical core exhibiting a
relatively small diameter of, for example, 1.125 inches, and the
cooling fins exhibiting a length of, for example, 1.875 inches.
[0039] In addition, the cylindrical core can be provided with an
option for an integrated heat pipe, a vapor camber of high thermal
conductivity material. For example, a heat pipe (generally a
cylindrical structure constructed of a conductive material, such as
copper) may be disposed within a central portion of the cylindrical
core to enhance the conduction or spreading efficiency inside the
base to further dissipate the heat received from a heat source.
[0040] Referring now to FIGS. 6A-6D, an example radial base
heatsink with straight fins according to an embodiment of the
present invention is illustrated. More specifically, FIG. 6A
illustrates an isometric view of an advanced radial base heatsink
with straight fins according to an embodiment of the present
invention. FIGS. 6B-6D illustrate orthographic views of the same
radial base heatsink according to an embodiment of the present
invention. As will be described with reference to FIGS. 6A-6D
herein below, the radial base heatsink according to an embodiment
of the present invention advantageously provides a low cost, quiet,
lightweight heatsink solution that can provide up to twice the
thermal performance of typical heatsinks in the same or smaller
volume.
[0041] As shown in FIG. 6A, an advanced heatsink 600 comprises a
substantially solid cylindrical core 610 and a series of cooling
fins 620A-620N projecting outwardly or extending from the
cylindrical core 610 and defining a series of channels 630A-630N in
a substantial radial pattern with a fin orientation relative to a
center line of the cylindrical core 610 as shown in FIG. 6B in
order to dissipate heat from a heat source, i.e., an electronic
package (not show) while providing a low thermal resistance
connection to the base and minimizing air flow impedance.
[0042] In an embodiment of the present invention, the cooling fins
620A-620N may be machined from the cylindrical core 610 of the same
material to provide a low resistance thermal path from the base
surface 614 to cooling fins 620A-620N. For example, the radial base
heatsink 600 including the cylindrical core 610 and the cooling
fins 620A-620N can be machined or constructed from a single
metallic conduction based material, such as aluminum (Al). The
radial base heatsink 600 may also be constructed of any metallic
material that is light weight and has a high level of thermal
conductivity, such as a copper-tungsten alloy, aluminum nitride,
beryllium oxide or copper. Separately, the cooling fins 620A-620N
may alternatively be attached to or mounted onto (by way of solder,
adhesive or other low thermal resistance material) the cylindrical
core 610 of the same or different high thermal conduction
material.
[0043] As shown in FIG. 6D, the cylindrical core 610 includes a
substantially planar top surface 612, a substantially planar base
(bottom) surface 614 adapted to contact a heat source, i.e., an
electronic package such as a microprocessor, and a peripheral outer
wall 616 extended from the top surface 612 to the base (bottom)
surface 614. The cylindrical core 610 may have a small uniform
diameter at the heat exchange base surface 614 adapted to contact a
heat source and at the top surface 612 adapted to accommodate a fan
hub (not shown) to reduce turbulent airflow. The cylindrical core
610 may exhibit a high level of conductivity if enhanced using a
vapor chamber, a heat pipe, and high thermal conductive
material.
[0044] In addition, the cooling fins 620A-620N extending from the
cylindrical core 610 in a radial pattern may be cut several times
and separated by cut lines 622 along a horizontal direction
relative the center line of the cylindrical core 610, to a
peripheral outer wall 616 of the cylindrical core 610 as shown in
FIGS. 6C-6D. This way individual cooling fins 620A-620N can be
uniformly arranged along vertical and horizontal directions on a
peripheral outer wall surface of the cylindrical core 610. The cuts
on cooling fins 620A-620N, and cut lines separating the cooling
fins 620A-620N in the horizontal direction relative to the center
line of the cylindrical core 610 are intended to reduce the
pressure drop as a function of air flow rate and thereby obtaining
higher fin efficiency.
[0045] As described with reference to FIGS. 6A-6D, radial mounting
of the cooling fins 620A-620N advantageously allows high fm density
at the cylindrical core 610 with greater spacing (channels) between
the fins 620A-620N further out, thereby allowing more than twice
the fin surface area in the same volume and less airflow
restriction. High fin efficiency may be obtained by providing a low
resistance thermal path from the small diameter base surface 614 of
the cylindrical core 610 to the cooling fins 620A-620N where heat
is removed by concentrated airflow under a fan blade area.
[0046] FIGS. 7A-7D illustrate an example radial base heatsink with
angled fins according to an embodiment of the present invention.
More specifically, FIG. 7A illustrates an isometric view of an
advanced radial base heatsink with angled fins according to an
embodiment of the present invention. FIGS. 7B-7D illustrate
orthographic views of the same radial base heatsink with angled
fins according to an embodiment of the present invention.
[0047] As shown in FIG. 7A, an advanced heatsink 700 also comprises
a substantially solid cylindrical core 710 and a series of cooling
fins 720A-720N projecting outwardly or extending from the
cylindrical core 710 and defining a series of channels 730A-730N in
a substantial radial pattern with a fin orientation relative to a
center line of the cylindrical core 710 as shown in FIG. 7B. The
cylindrical core 710 and cooling fins 720A-720N can also be
machined or constructed from any light weight conduction based
material, such as aluminum (Al).
[0048] As shown in FIG. 7D, the cylindrical core 710 also includes
a substantially planar top surface 712 adapted to accommodate a fan
hub, a substantially planar base (bottom) surface 714 adapted to
contact a heat source, i.e., an electronic package such as a
microprocessor, and a peripheral outer wall 716 extended from the
top surface 712 to the base (bottom) surface 714.
[0049] The cooling fins 720A-720N extending from the cylindrical
core 710 in a substantially radial pattern may be tapered at the
top of the cylindrical core 710 at a predetermined angle (for
example, .alpha.=0 to 25.degree.) to reduce airflow impedance or
resistance, and thereby increasing airflow efficiency. This is
because cooling fins farthest away from the heat source are
generally less efficient and, hence, can be reduced in size for
efficiency purposes. In addition, the cooling fins 720A-720N may
also be cut several times and separated by cut lines 722 along a
horizontal direction relative the center line of the cylindrical
core 710, to a peripheral outer wall 716 of the cylindrical core
710 as shown in FIGS. 7C-7D. This way individual cooling fins
720A-720N can be uniformly arranged along vertical and horizontal
directions on a peripheral outer wall surface of the cylindrical
core 710. The cuts on cooling fins and cut lines separating the
cooling fins are intended to reduce the pressure drop as a function
of air flow rate and thereby higher fin efficiency. As a result,
the length and height of the cooling fins 720A-720N can be
optimized depending on the location on the cylindrical core
710.
[0050] FIGS. 8-11 illustrate an example radial base heatsink with a
different type of fins, such as conical fins, pin type fins,
airfoil fins and pre-fabricated bonded fins, optimized for
increased fin surface area, fin efficiency and airflow according to
the present invention. For radial base heatsinks with conical fins,
pin-type fins and airfoil fins, the fin shape, fin orientation, fin
length, fin width and base shape can all be varied. In addition,
the radial base heatsinks can be machined or constructed from a
single metallic conduction based material. However, for radial base
heatsinks with pre-fabricated bonded fins, optimization
opportunities such as the fin shape, fin orientation, fin length,
fin width and base shape may not be as easily varied since the
pre-fabricated bonded fins may need to be mounted onto or attached
to the cylindrical core using a thermally resistive barrier such as
a solder or pressure.
[0051] For example, FIG. 8 illustrates an example radial base
heatsink with conical fins according to an embodiment of the
present invention. As shown in FIG. 8, the radial base heatsink 800
comprises a substantially solid cylindrical core 810 and a series
of elongated conical fins 820A-820N projecting outwardly or
extending from the cylindrical core 810 and defining a series of
channels 830A-830N in a substantial radial pattern with a fin
orientation relative to a center line of the cylindrical core 810
in order to dissipate heat from a heat source, i.e., an electronic
package (not show). The conical fins 820A-820N may have edges 822
at the distal end of the base to minimize airflow impedance.
[0052] Similarly, FIG. 9 illustrates an example advanced heatsink
with pin type fins according to an embodiment of the present
invention. As shown in FIG. 9, the radial base heatsink 900
comprises a substantially solid cylindrical core 910 and a series
of elongated pin-type fins 920A-920N projecting outwardly or
extending from the cylindrical core 910 and defining a series of
channels 930A-930N in a substantial radial pattern with a fin
orientation relative to a center line of the cylindrical core 910
in order to dissipate heat from a heat source, i.e., an electronic
package (not show). The pin-type fins 920A-920N may also have edges
922 at the distal end of the base to minimize airflow
impedance.
[0053] Likewise, FIG. 10 illustrates an example radial base
heatsink with airfoil fins according to an embodiment of the
present invention. As shown in FIG. 10, the radial base heatsink
1000 comprises a substantially solid cylindrical core 1010 and a
series of elongated airfoil fins 1020A-1020N projecting outwardly
or extending from the cylindrical core 1010 and defining a series
of channels 1030A-1030N in a substantial radial pattern with a fin
orientation relative to a center line of the cylindrical core 1010
in order to dissipate heat from a heat source, i.e., an electronic
package (not show). The airfoil fins 1020A-1020N may also have
edges 1022 at the distal end of the base to minimize airflow
impedance, and may be bent in the general direction of the fan
swirl.
[0054] FIG. 11 illustrates an example radial base heatsink with
pre-fabricated bonded fins according to an embodiment of the
present invention. As shown in FIG. 11, the radial base heatsink
1100 comprises a substantially solid cylindrical core 1110 and a
series of elongated bonded fins 1120A-1120N projecting outwardly or
extending from the cylindrical core 1110 and defining a series of
channels 1130A-1130N in a substantial radial pattern with a fin
orientation relative to a center line of the cylindrical core 1110
in order to dissipate heat from a heat source, i.e., an electronic
package (not show). The pre-fabricated bonded fins 1120A-1120N may
be mounted along vertical lines of the cylindrical core 1110. Each
fin may be an elongated strip of a metallic sheet material such as
aluminum (Al) or copper (Cu) having a thickness in the range, for
example, of about 0.025 mm to 0.25 mn. The metallic sheet may be
folded, and adjacent portions joined at a fold at the edge of the
fins.
[0055] In all embodiments of the present invention as shown in
FIGS. 6A-6D, 7A-7D and 8-11, the cylindrical core of the radial
base heatsink with straight fins, angled fins, conical fins, pin
type fins, airfoil fins or pre-fabricated bonded fins can also be
tapered.
[0056] For example, FIG. 12 illustrates a cross-sectional view of
the radial base heatsink 600 with straight fins in which the top
portion of the cylindrical core 610 is tapered to reduce airflow
impedance. The core 610 may have a conic shape so that the base
surface 614 may be larger than the top surface 612 to reduce
airflow resistance.
[0057] FIGS. 13A-13B illustrate an airflow direction of an example
radial base heatsink according to an embodiment of the present
invention. For purposes of illustration, the example radial base
heatsink may be provided with angled fins as described with
reference to FIG. 7. As shown in FIGS. 13A-13B, the example radial
base heatsink 700 includes the same cylindrical core 710, and
cooling fins 720A-720N. Individual cooling fins 724 may be
uniformly arranged and separated by respective channels 730A-730N
and cut lines 722 along vertical and horizontal directions on a
peripheral outer wall surface of the cylindrical core 710. When an
airflow is generated from a fan structure (not shown), heat
generated from a heat source (not shown) may be transferred from
the base surface of the cylindrical core 710 to the length of the
cooling fins 720A-720N along the airflow direction shown in FIG.
13B.
[0058] In order to reduce airflow resistance and increase fin
efficiency, the cooling fins 720A-720N of the example radial base
heatsink 700 shown in FIGS. 13A-13B may be arranged in several
patterns, including an aligned pattern shown in FIG. 14A, an offset
pattern shown in FIG. 14B, and an interleaved pattern shown in FIG.
14C. In each of the aligned pattern, the offset pattern, and the
interleaved pattern, the individual cooling fins 720A-720N may also
be arranged at a predetermined angle (.alpha.) for example, from
0.degree. to 25.degree..
[0059] In addition, the cooling fins 720A-720N may also be
configured with different fin shapes as shown in FIGS. 15A-15D. For
example, individual cooling fins 724 may have an rectangular shape
as shown in FIG. 15A, a diamond shape as shown in FIG. 15B, a curve
and/or airfoil shape as shown in FIG. 15C, and an elliptical shape
as shown in FIG. 15D. Fin shapes are not limited hereto as other
fin shapes and configurations may also be available to reduce
airflow resistance and increase airflow efficiency.
[0060] FIG. 16 illustrates an airflow simulation result of an
example radial base heatsink with different fin configurations,
such as straight fins, angled fins, conical fins, pin type fins,
airfoil fins or pre-fabricated bonded fins according to an
embodiment of the present invention. As can be seen from the arrows
shown in FIG. 16, there is no airflow recirculation. The
cylindrical core 710 may be positioned directly underneath a fan
hub 1610 where an airflow stagnation region resides to reduce any
turbulent airflow. Heat dissipated from a heat source (not shown)
can be efficiently transferred from the small base surface 714 of
the cylindrical core 710 to the peripheral outer wall 716 and then
to the length of cooling fins 720A-720N over the fin surface area
1620. Fan blade airflow regions 1640 formed by the fan shroud 1630
around the fan hub 1610 may be used to generate an airflow in an
efficient way to transfer heat from the base surface of the
cylindrical core 710 to the length of the cooling fins
720A-720N.
[0061] The shape of the fin edges and comers, which minimize air
flow impedance, may be coupled with a fan shroud to allow air to
flow over the entire fin surface with maximum mass flow rate at low
fan speed.
[0062] The cooling fins 720A-720N are part of the cylindrical core
710 as shown in FIGS. 13A-13B to provide a low thermal resistance
connection to the base. The cylindrical core thermal performance
can also be improved by adding a vapor chamber, heat-pipe, high
thermal conductive material (such as TC1050), or other similar
method.
[0063] The heatsink cooling capacity may be determined by heat
exchange effective surface area, the airflow over the same and the
heat spreading efficiency inside the cylindrical core and cooling
fins. Adding more cooling fins can increase the total heat exchange
surface area. However, there may be a trade off with airflow
resistance, which determines the overall efficiency of the radial
base heatsink. Similarly, increasing fin height can also increase
the fin surface area but it is also limited by fin efficiency and
manufacturable aspect ratio. The cylindrical core can have up to
twice as many fins (or more) compared to a rectangular based
surface without losing heat transfer convective coefficient and fin
efficiency. Radial fins match the airflow path from an active fan
with maximized airflow efficiency. The cylindrical core can spread
heat uniformly and more efficiently from a heat source, i.e., an
electronic package such as a microprocessor to all the fins.
[0064] Actual dimension of a radial base heatsink may be based on
the size and space on a motherboard supporting a heat source, i.e.,
an electronic package. Similarly, the size of the cylindrical core
may be based on the size of the heat source. For example, if the
size of the heat source is 1.875 inches, then the size of the
cylindrical core of the radial base heatsink may correspond to
1.875 inches with an overall dimension of the heatsink of
approximately 3 inches. However, the dimension of the radial base
heatsink is not limited thereto. The fin height and length may be
optimized based on the number of fins and fin shapes chosen based
on the following equation:
Q=h.times.A.times.(Ts-Tam),
[0065] where Q is a power dissipation from a heat source;
[0066] h is a convection coefficient--a function of airflow rate,
airflow efficiency, heatsink resistance and fin efficiency;
[0067] A is a total heatsink surface area (the number of fins
chosen times the fin surface area);
[0068] Ts is a heatsink temperature; and
[0069] Tam is an ambient temperature for heatsink.
[0070] Typically, the power dissipation (Q) is a known fixed value
based on the heat source. Likewise, the heatsink temperature (Ts)
and the ambient temperature for heatsink (Tam) are also known fixed
values. Then the heatsink surface area (A) which is based on the
number of fins chosen and the fin surface area may have an inverse
relationship with the convection coefficient (h). Therefore, the
number of fins and the fin surface area must be chosen relative to
the convection coefficient (h) to ensure that the fin height and
length optimized.
[0071] As a result, the radial base heatsink designs as described
with reference to FIGS. 6A-6D, FIGS. 7A-7D, FIGS. 8-12, FIGS.
13A-13B, 14A-14C and 15A-15D have a number of advantages over
aluminum (Al) skived fin heatsinks and copper (Cu) base aluminum
(Al) folded fin heatsinks. For example, the radial base heatsink
with its easy machining shape is less expensive since large copper
base material is not required. The radial mounting of the cooling
fins advantageously allows higher fin density at the base with
greater spacing between the fins further out thereby allowing twice
the fin surface area and less airflow restriction. The cylindrical
core may also transfer heat more directly to cooling fins so that
fan hub "dead-zone"does not limit fan performance or require higher
speed fans for less audible noise. As a result, all of the airflow
may flow over the cooling fins to maximize the airflow efficiency.
In addition, different fin configurations, such as straight fins,
angled fins, conical fins, pin type fins, airfoil fins or
pre-fabricated bonded fins with variable length and cut may be
positioned to match the fan swirl to reduce airflow impedance.
[0072] Similarly, there are a number of advantages of the radial
base heatsinks as described with reference to FIGS. 6A-6D, FIGS.
7A-7D, FIGS. 8-12, FIGS. 13A-13B, 14A-14C and 15A-15D over Mushroom
base heatsink with machined or extruded fins. For example, the
cylindrical core may transfer heat more directly to the fins over
greater length so that there is no fan hub "dead-zone" and no air
turbulence. As a result, all of the airflow may flow over the
cooling fins to maximize the airflow efficiency. Larger base height
may allow more options to improve base heat transfer with vapor
chamber, heat pipe, conductive material, etc. In addition, radial
mounting of the cooling fins offers more cooling surface area for
less cost and more heat transfer.
[0073] FIGS. 17A-17B illustrate an advanced heatsink assembly
including a radial base heatsink and a fan shroud and heatsink
retention mechanism according to an embodiment of the present
invention. The heatsink assembly may include an example radial base
heatsink 700 with angled fins as shown, for example, in FIGS. 7 and
13A-13B, positioned on top of a heat source, i.e., an electronic
package 1712 mounted on a motherboard 1710, and a fan shroud and
heatsink retention mechanism including a fan housing 1720, a fan
structure 1730 and a plurality of spring loaded hardware
1736A-1736N used to secure the fan structure 1730 and the fan
housing 1720 onto the motherboard 1710 as shown in FIG. 17B.
[0074] The fan structure 1720 may include a fan hub 1732 positioned
substantially coaxially with the top surface of the cylindrical
core 710 having substantially the same diameter as the top surface
of the cylindrical core 710 for rotation about a fan rotation axis,
and a plurality of fan blades 1734A-1734N extending radially from
the fan hub 1732 for forcing air in an axial direction past a
substantial portion of the blades 1734A-1734N.
[0075] FIGS. 18A-18B illustrate an example fan shroud and heatsink
retention mechanism according to another embodiment of the present
invention. As shown in FIG. 18A-18B, the fan shroud and heatsink
retention mechanism 1800 may include a fan housing 1810 having an
air shroud 1812 and an airflow duct 1814 supported by, for example,
four legs 1820A-1820D to be secured onto a motherboard (not shown),
and a built-in fan structure 1830 having a fan hub 1832 and a
plurality of fan blades 1834A-1834N serving as a swirl regulator to
provide more straight airflow. As a result of the air shroud 1812
and the airflow duct 1814, the airflow exiting at the bottom of the
radial base heatsink with straight fins, angled fins, conical fins,
pin type fins, airfoil fins or pre-fabricated bonded fins according
to an embodiment of the present invention may provide cooling to
other electronic components and the motherboard.
[0076] As described from the foregoing, the advanced heatsink
design with different cooling fins configurations according to the
present invention advantageously provides a low cost, quiet,
lightweight heatsink solution that can provide up to twice the
thermal performance of typical heatsinks in the same or smaller
volume. Cooling fins with smaller fin ratio (ratio between fin
height to fin thickness) can lead to higher fin efficiency. The
radial base heatsink with a greater total surface fin area (the
number of cooling fins times the fin surface area) can lead to a
higher heatsink efficiency, less airflow loss, better airflow path,
and more convection efficiency. Fan shroud and good fin
configuration/design can also result in better airflow.
[0077] While there have been illustrated and described what are
considered to be exemplary embodiments of the present invention, it
will be understood by those skilled in the art and as technology
develops that various changes and modifications may be made, and
equivalents may be substituted for elements thereof without
departing from the true scope of the present invention. For
example, the radial base heatsink may be available in a variety of
size and shapes with different projections. The overall dimensions
of the radial base heatsink may be altered depending upon the
electrical elements used, the desired strength, the structural
rigidity, and the thermal stability. More importantly, a wide
variety of different fins configurations may be used in
substitution of those described with reference to FIGS. 6A-6D,
FIGS. 7A-7D, FIGS. 8-12, FIGS. 13A-13B, 14A-14C and 15A-15D as long
as the cooling fins are extending in a radial pattern from a
cylindrical core. In addition, different sizes and shapes of the
fins may be alternatively used. Many modifications may be made to
adapt the teachings of the present invention to a particular
situation without departing from the scope thereof. Therefore, it
is intended that the present invention not be limited to the
various exemplary embodiments disclosed, but that the present
invention includes all embodiments falling within the scope of the
appended claims.
* * * * *