U.S. patent application number 09/366153 was filed with the patent office on 2001-11-08 for stackable heat sink for electronic components.
This patent application is currently assigned to Andrea L. Mays. Invention is credited to GUERRERO, FRED.
Application Number | 20010037875 09/366153 |
Document ID | / |
Family ID | 23291979 |
Filed Date | 2001-11-08 |
United States Patent
Application |
20010037875 |
Kind Code |
A1 |
GUERRERO, FRED |
November 8, 2001 |
STACKABLE HEAT SINK FOR ELECTRONIC COMPONENTS
Abstract
A stackable heat sink having a core shaft in heat-engaging
relation with a semiconductor device and a plurality of individual
thin fins having an opening for receiving the core shaft in press
fit relation so that a plurality of the fins, when mounted on the
shaft, define a plurality of air passageways and the fins and shaft
efficiently transfer heat away from the semiconductor device and
into the surrounding atmosphere. In an improved version of the heat
sink, the heat-dissipating fins may be corrugated so as to increase
the surface area of each individual fin without increasing its
perimeter. A heat pipe may be used in conjunction with the core
shaft or base of the heat sink so as to facilitate heat transfer
away from the electronic component. An improved heat sink may also
include a base having a plurality of openings and a small fan
connected to the portion of the base with the openings, so as to
direct air across and between adjacent fins.
Inventors: |
GUERRERO, FRED; (OXNARD,
CA) |
Correspondence
Address: |
PEACOCK MYERS AND ADAMS P C
P O BOX 26927
ALBUQUERQUE
NM
871256927
|
Assignee: |
Andrea L. Mays
|
Family ID: |
23291979 |
Appl. No.: |
09/366153 |
Filed: |
August 3, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09366153 |
Aug 3, 1999 |
|
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09330946 |
Jun 11, 1999 |
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6199625 |
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Current U.S.
Class: |
165/80.3 ;
165/104.33; 165/182; 257/E23.103; 361/700 |
Current CPC
Class: |
H01L 2924/00 20130101;
H01L 23/3672 20130101; H01L 2924/0002 20130101; H01L 2924/0002
20130101 |
Class at
Publication: |
165/80.3 ;
165/104.33; 165/182; 361/700 |
International
Class: |
F28F 007/00; F28D
015/00; F28F 001/30; H05K 007/20 |
Claims
What is claimed is:
1. An improved stackable heat sink for electronic components
comprising: a base with an opening; a core shaft secured in the
base; and a plurality of corrugated thin heat-dissipating fins
mounted on said shaft so as to form a plurality of parallel air
passages between adjacent fins.
2. The heat sink of claim I wherein the direction of the
corrugations are parallel with the airflow between adjacent
fins.
3. The heat sink of claim 1 wherein each fin has at least several
thin separators near the outer peripheral edge to maintain spacing
between adjacent fins.
4. The heat sink of claim 3 wherein each separator comprises a
dimple formed in the fin.
5. The heat sink of claim 4 wherein the dimple height is at least
twice the thickness of the fin thickness.
6. The heat sink of claim 5 wherein said dimple is formed by
coining.
7. A stackable heat sink for electronic components comprising: a
base with an opening; a core shaft secured in the base and having a
cylindrical opening and a heat pipe press fit into said opening;
and a plurality of thin heat dissipating fins mounted on said shaft
so as to form a plurality of parallel air passages between adjacent
fins.
8. The heat sink of claim 7 wherein the end of the core shaft
secured in the base is in heat conducting contact with an
electronic component and said heat pipe permits heat transfer from
the portion of the core shaft in contact with the electronic
component toward the free end thereof.
9. The heat sink of claim 8 wherein the heat pipe comprises a
sealed metallic container containing a liquid.
10. The heat sink of claim 9 wherein said heat pipe has a low
coefficient of thermal expansion.
11. An improved stackable heat sink for electronic components
comprising: a base with an opening for receiving a core shaft
aligned perpendicular to the plane of said base, said base having a
slot opening extending from one end of said base to the opposite
end, and a heat pipe of generally rectangular cross section press
fit in said slotted opening; a core shaft secured in the base; and
a plurality of thin heat-dissipating fins mounted on said shaft so
as to form a plurality of parallel air passages between adjacent
fins.
12. An improved stackable heat sink for electronic components
comprising: a generally L-shaped base member, the longer portion of
said base member having an opening for receiving a core shaft, and
the smaller portion of said L-shaped base member having a plurality
of louvers for the passage of air; a core shaft secured in the
longer portion of the base; and a plurality of thin
heat-dissipating fins mounted on said shaft so as to form a
plurality of parallel air passages between adjacent fins.
13. The heat sink of claim 12 wherein said openings are formed by
stamping louvers in the smaller portion of said L-shaped base
member.
14. The heat sink of claim 12 wherein said louvers are stamped so
as to control the direction of airflow through the openings.
15. The heat sink of claim 14 wherein said louvers are formed so as
to project toward said plurality of fins.
16. The heat sink of claim 12 wherein a cooling fan may be mounted
on the smaller portion of said L-shaped base member for directing
air through said openings and across said fin.
Description
RELATED APPLICATIONS
[0001] This application is a continuation-in-part application of
U.S. patent application Ser. No. 09/330,946, entitled "Stackable
Heat Sink for Electronic Components", filed on Jun. 11, 1999, and
the specification thereof is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to cooling of electronic components
and assemblies through the provision of a heat sink.
BACKGROUND OF THE INVENTION
[0003] Integrated circuits or other electronic components are
generally mounted on printed circuit boards which are then
installed in an enclosure for the electronic equipment. A personal
computer would be a typical electronic device that houses printed
circuit boards having such electronic components. There has been
since the advent of the integrated circuit a steady progression of
larger and larger devices capable of performing more functions
within a single component package. At the same time, there has been
a trend toward the packing of a larger number of components onto a
printed circuit board and within a given volume of an enclosure.
The result of these two trends and others, has resulted in an
increasing requirement for low-cost, efficient, heat-dissipating
devices for use within the electronic equipment.
[0004] One type of heat-dissipating device is a simple fan mounted
within the enclosure and designed to circulate air through the
enclosure, removing the hot air and introducing cooler air so as to
dissipate the heat generated by the electronic components. Another
method of removing heat is the use of a heat sink. The term "heat
sink" is here used in its normal dictionary definition: "a
substance or device for the absorption or dissipation of unwanted
heat (as from a process or an electronic device)." Webster's Ninth
New Collegiate Dictionary, p. 560 (1983). A typical heat sink used
in the electronics industry for dissipating heat from components
will comprise a base and a plurality of fins. The heat sink base is
secured in firm heat-transfer engagement with the electronic
component so as to absorb the heat from the component, passing it
into the plurality of fins, which in turn radiate the heat into the
surrounding air. Heat sinks are normally constructed from high
heat-conducting material, such as metal, including aluminum and
copper. Heat sinks may be used in combination with a fan.
[0005] A typical heat sink may be formed from an aluminum extrusion
in which the base and fins are integral. The extrusion is then cut
off in sections, each section forming an individual heat sink.
Since the extrusion process results in fins that are in parallel
planes, the fins form a plurality of passages between the fins
extending in one direction. When a heat sink is formed with
passages in one direction, it is desirable to have the fan and heat
sink located relative to one another so that the air flow of the
fan is parallel with the air passages between the fins. That is of
course not always possible or desirable for other reasons. It has
therefore been common to machine passages in a perpendicular
direction to the extruded air passages, resulting in a series of
spike-like fins, as shown in U.S. Pat. No. 5,600,540. In that
manner, the positioning of the heat sink relative to the fan offers
greater design flexibility.
[0006] One of the shortcomings in the heat sinks described above is
that they have a fixed heat-dissipating area for a given size
determined by the height of the extruded fins. In many electronic
assemblies, the electronic components are mounted on the printed
circuit board in close relation to one another. Therefore, mounting
a heat sink on a particular electronic device is more or less
circumscribed by the area (width and length) of the electronic
component. Generally speaking, the space in which the heat sink may
be mounted is unrestricted as to height as opposed to the area of
the component. However, since the height of the fins is
predetermined by the extrusion, it is not possible to change the
heat-dissipating area of a particular extruded heat sink without
infringing upon the air space of adjacent components. The thermal
designer for the electronic assembly is therefore faced with
specifying a custom-made extruded heat sink of a particular height
for a particular application, or attempting to accommodate the
limited heat sink dissipation capability by selection of a more
powerful fan. Thus, a heat sink with a fixed heat-dissipating area
presents the thermal designer with a design restriction that is
undesirable.
[0007] A related problem with the extruded heat sink is that even
after the designer selects a heat sink of a given surface area and
therefore heat-dissipating capacity, the use of the component in a
particular printed circuit board configuration and in a specific
electronic enclosure may change the thermal conditions in which the
component and its associated extruded heat sink will be used,
requiring redesign of the extruded heat sink or again resorting to
removal of heat through a more powerful fan. Even after the
manufacturing stage is reached, thermal testing may show that the
theoretical calculations did not properly accommodate the heat
generated and still further modifications to the heat sink
dissipation surface area or fan must be designed.
[0008] In short, the thermal designer of electronic equipment is
continually faced throughout the design and manufacturing process
with the limitation of the surface area of an extruded heat sink
because the size of the base is restricted by the crowded "real
estate" on the printed circuit board and the height of the extruded
heat sink is predetermined. Of course, heat sinks may be made with
fins of different height, but that requires stocking of heat sinks
of different heights to accommodate changes during the design
process that results in different thermal conditions. It also
complicates the inventory stocking of heat sinks in manufacturing
as well as in customer service.
[0009] It is therefore a primary object of the present invention to
provide a heat sink in which the heat-dissipating capacity may be
varied at any point during design, manufacturing or use.
[0010] Another object of this invention is to provide a heat sink
in which a plurality of fins may be manually added so as to
increase the heat-dissipating surface capacity.
[0011] One other object of the present invention is to provide a
construction whereby the heat is rapidly and efficiently dispersed
to the fins where the heat is dissipated.
[0012] Still another object of the present invention is to provide
a heat sink in which the air passages are in a plane parallel to
the plane of the printed circuit board on which the electronic
component is mounted and to which the heat sink is attached so as
to accommodate air flow in any direction.
[0013] All of the objects of the invention may be accomplished
through the provision of a stackable heat sink that includes a
plurality of fins which are mounted generally parallel to the
electronic component and printed circuit board on a core shaft one
end of which is in heat conducting relation with the electronic
component, and a base with an opening for receiving the core
shaft.
[0014] In an improved stackable heat sink, the problem of the
limited area available for the fins may be partially solved without
increasing the perimeter of the fin by forming a corrugated, rather
than a flat, fin. One of the limitations in a stackable heat sink
is the ability of the core shaft to transfer heat from one end in
contact with the heat source to the other end and thus to the
individual fins. It is an object of this invention to promote or
facilitate the heat transfer from the heat source to the fins by
the use of a heat pipe inserted into an axial opening in the core
shaft that supports the fins. Still another problem overcome by the
improved stackable heat sink is to form the base with an opening in
which the core shaft is press fit and/or including a portion on
which a small cooling fan may be mounted so as to move air directly
between adjacent fins and in a general direction of the fin
corrugation, where the fins are so formed.
[0015] Yet another object of the present invention is to provide a
heat sink that is of low cost, simple construction, made from
common materials, and constructed using machine tools in common
use.
SUMMARY OF THE INVENTION
[0016] The present invention comprises a heat sink for use with
electronic components that includes a base of heat-conducting
material for engaging a surface of the electronic component from
which the heat is to be dissipated, a core shaft secured in the
base, and a plurality of heat-dissipating fins mounted on the shaft
forming a plurality of parallel air passages. More particularly, in
the improved invention, the plurality of heat-dissipating fins may
be formed with corrugations so as to increase the area of the fin
without increasing its perimeter. An additional improvement is the
use of a heat sink in conjunction with the base and/or core shaft
of the invention so as to rapidly transfer heat from the portion of
the base and/or shaft in heat-conducting contact with the
electronic component (heat source) to other portions of the core
shaft and/or base so as to more rapidly dissipate the heat. Still
another improved aspect of the invention is to provide, integral
with the base, a support for a small cooling fan which may be
positioned so as to effectively move air to the passages between
adjacent fins.
BRIEF DESCRIPTION OF THE DRAWINGS OF THE INVENTION
[0017] One embodiment of a heat sink constructed in accordance with
the present invention in shown in perspective view in FIG. 1;
[0018] FIG. 2 is a side elevation view of the embodiment shown in
FIG. 1;
[0019] FIG. 3 is an end elevation view of the embodiment of the
heat sink shown in FIG. 1;
[0020] FIG. 4 is another perspective view of the embodiment of the
heat sink shown in FIG. 1, showing the lower portion of the heat
sink;
[0021] FIG. 5 is a detailed view of the shaft of the heat sink
embodiment shown in FIG. 1;
[0022] FIG. 6 is a detailed view of one of the typical fins
included in the first embodiment of the heat sink shown in FIG.
1;
[0023] FIG. 7 is an end elevation view of the fin shown in FIG.
6;
[0024] FIG. 8 is a perspective view of a second embodiment of the
heat sink in accordance with the present invention;
[0025] FIG. 9 is a side elevation view of the heat sink shown in
FIG. 8;
[0026] FIG. 10 is an end elevation view of the embodiment shown in
FIG. 8;
[0027] FIG. 11 is a detailed view of the shaft of a heat sink
embodiment shown in FIG. 8;
[0028] FIG. 12 is an assembly of fins for use in the second
embodiment of the heat sink shown in FIG. 8;
[0029] FIG. 13 is a third embodiment of a heat sink constructed in
accordance with the present invention;
[0030] FIG. 14 is a side elevation view of an improved stackable
heat sink;
[0031] FIG. 15 is a perspective view of one of the corrugated fins
of the improved stackable heat sink of FIG. 14;
[0032] FIG. 16 is a top view of FIG. 14;
[0033] FIG. 17 is a cross sectional view of a core shaft and heat
pipe;
[0034] FIG. 18 is an exploded view of the heat pipe and core
shaft;
[0035] FIG. 19 is an alternate embodiment of the use of a heat pipe
in the base of the improved stackable heat sink;
[0036] FIG. 20 is an exploded view of an improved stackable heat
sink including a base on which may be mounted a fan;
[0037] FIG. 21 is a side elevation view of the improved stackable
heat sink of FIG. 20; and
[0038] FIG. 22 is a perspective exploded view of the improved
stackable heat sink of FIG. 20.
DETAILED DESCRIPTION OF SELECTED EMBODIMENTS OF THE INVENTION
[0039] A first embodiment of the present invention is shown
completely assembled in FIGS. 1 through 4. The invention comprises
base 10, shaft 30, and plurality of fins 50 that comprise a
stackable heat sink for electronic components. Base 10 may comprise
plate 12 of heat-dissipating material, such as metal. Other types
of material with good heat-conducting capability are also suitable
for use in the invention. The particular configuration of base 10
is adapted to the electronic component and component mounting
assembly and may be of any size or shape. The specific mounting
plate 12 shown is for use in connection with the Intel S.E.C.
cartridge. However, the present invention can be configured for use
with many different cartridges and processors. Base 10 provides the
means for securing the heat sink to the cartridge thermal plate as
will be described below. The base or plate 12 has an opening for
receiving shaft 30. Plate 12 may be attached to a cartridge
containing the semiconductor device through plastic pins.
[0040] Shaft 30 is shown in detail in FIG. 5. In the embodiments
disclosed, shaft 30 is generally cylindrical in shape, although it
should be understood that the shaft cross-section could be square,
rectangular, elliptical or other cross-section as may be selected
for the particular manufacturing process and the intended use of
the heat sink. Shaft 30 has three sections. The lowermost section
comprises annular lip 32 which as seen best in FIGS. 2 and 4,
provides a stop or shoulder 33 for limiting the insertion of shaft
30 into base plate 12. A second section 34 has a slightly smaller
diameter than annular lip 32. The diameter of section 34 is only
slightly less than the diameter of the opening in the base plate
12. When shaft 30 is assembled with base plate 12, the section 34
of the shaft is press fit into the opening of the base. The height
of the section 34 is greater than the thickness of base plate 12
and forms a shoulder at its upper end indicated at 36. As seen best
in FIG. 2, the shoulder 36 functions as a stop for the lowermost
fin of the fin assembly 50. The third section of shaft 30 is of yet
smaller diameter, as shown at 38, and extends from shoulder 36 to
the upper end of shaft 30. As seen best in FIG. 1, when all of the
fins, as will be described below, are assembled onto shaft 30, the
upper end may be coined so as to increase the diameter of the top
edge of the shaft section 38, thereby preventing the uppermost fin
from disengaging with the shaft.
[0041] Fin assembly 50 comprises a plurality of individual fins 52,
one of which is shown in FIGS. 6 and 7. Fin 52 is shown in the
embodiments disclosed as having a square or rectangular shape,
although it will be appreciated that the shape of the fin could be
round, oval, or some other geometric shape. Each fin is formed from
a suitable heat-conducting material, such as metal, more
specifically, aluminum. In the embodiment shown in FIG. 1, the
fin's material stock is 0.015 inches and is made from 1100-H18
Aluminum. Fin 52 has an opening 54 which is shown located centrally
in the fin, although it will be understood that the opening need
not be centered within the geometric shape although that may be
preferable for maximizing the heat conduction from the core shaft
to all portions of the fin.
[0042] Opening 54 is initially machined, such as by stamping, with
a dimension that is less than the dimension of the third section 38
of shaft 30. The hole is then coined or swaged so as to create a
flange shown at 55 in FIG. 7a. In the process of deforming the
materials so as to create the flange 55, the surface area,
indicated at 56, will be greater than the surface area of the
opening before coining. Thus, by coining the opening 54, and
producing flange 55, the heat transfer area between the fin and the
shaft section 38 will be increased, thus more effectively
transferring heat from the core shaft to each individual fin.
Furthermore, creation of the flange and increase of the engaging
surface area between the fin and shaft will produce greater
structural stability. Additionally, because the process of coining
or swaging will create a radius in the material, as shown at 57,
the opening on the bottom of the fin is slightly larger than the
opening at the top of the fin, resulting in a funnel-shaped opening
that facilitates positioning of the fin on the core shaft and
forcing the fin down onto the shaft, as explained more fully
below.
[0043] Each fin also includes at least several separators,
indicated at 58, four of which are shown in this particular
embodiment. As seen best in FIG. 7, the separators project above
the surface of the fin and, as seen best in FIG. 2, will contact
the adjacent fin, thereby preventing the fins from being
inadvertently bent, or if a fin is not flat when originally
manufactured, or any other condition that may result in restricting
the air flow through passage 60 between adjacent fins. A separator
may have a variety of configurations. A separator could be a
separate element that is attached to the fin by adhesive,
soldering, or other means. If the separator is a separate element
from the fin, it is preferably made of the same material. However,
the preferable manner of forming the separators is to coin the
material of the fin so as to create a dimple, protrusion, or other
raised area. Such construction is extremely inexpensive and is
extremely simple, as is desirable for purposes of cost, resisting
detachment in the event of vibration or shock, or similar reasons.
In the particular embodiment shown in FIGS. 1 through 7, if the fin
has a material stock of 0.015 inches as indicated above, the height
of the fin from the lower surface of the fin to the upper surface
of the dimple would be 0.065 plus or minus 0.005 inches. It is
desirable that the dimple have a height which is at least twice
that of the thickness of the fin so as to assure continued
maintenance of an air passageway between adjacent fins.
[0044] The outer surface of the core shaft is roughened so as to
resist movement of the fins after assembly on the shaft. Such
roughening may be in the nature of physically scoring the outer
surface of the portions of the shaft, or more particularly by
knurling the outer surface. Such knurling is shown at 40 on FIG. 5.
It will be noted that both the upper or top or third section 38 is
knurled, as well as the center or second portion 34. The shaft is
constructed of a high heat transfer material, such as copper, to
rapidly move the heat from the portion of the shaft closest to the
heat source to the fins that are spaced apart on the shaft.
[0045] The stackable heat sink shown in the first embodiment may be
built at the appropriate time to accommodate the heat generated in
the component to which the heat sink is attached. Typically, the
thermal engineer will determine the total heat dissipation surface
area required for the application and thus specify for
manufacturing personnel the number of fins that must be assembled
onto the core shaft. The manufacturing operation can then pre-build
heat sinks as required for production needs by assembling the
complete heat sink. Such assembly involves insertion of the
smallest diameter end of the core shaft into the opening in the
base and forcing the entire shaft through the opening until annular
lip 32 contacts the bottom surface of base plate 12. This press fit
will normally keep the two parts in sufficient engagement during
use of the heat sink. However, it would also be possible to secure
the shaft to the base by other means, including adhesive, or
mechanically by clips, threading the opening and second section of
the shaft, or the like. Lip 32 also prevents shaft 30 from being
forced upwardly out of the opening in plate 12 when the assembly is
subject to vibration or shock in the plane perpendicular to the
plane of plate 12. The method or means for attaching the shaft to
base plate 12 does not form a critical part of the present
invention. Once shaft 30 and base 10 are assembled, then the
specified number of fins may be assembled by aligning the opening
54 in each fin over the upper end of the shaft 30 and manually
forcing the fin onto the shaft individually, or in a gang.
Obviously, various types of automatic or semi-automatic tools could
be used for forcing the fins onto the shaft where the number of
heat sinks being constructed would warrant the expense of such
non-manual assembling device. Finally, to secure all of the fins
onto the shaft, the upper surface of the shaft, 42, may be coined,
as shown at 44 in FIG. 1, resulting in a slight increase in the
diameter of the shaft due to deformation of the material which will
prevent the fin from working loose on the shaft such as may
otherwise occur if the heat sink is being used in electronic
equipment subjected to vibration or shock.
[0046] It will be appreciated that one of the advantages of the
stackable heat sink is that should it be found in the manufacture
of the equipment that thermal conditions were higher than
originally designed for, or that a design computation failed to
include all of the sources of heat generation, or for various other
reasons, that the total heat-dissipating surface area of the heat
sink may be easily changed by simply adding another fin. Moreover,
it will also be appreciated that the base plate and core shaft
provide the foundation for building heat sinks of various capacity.
For example, if heat sinks are required of different dissipating
capacity within the same piece of equipment, it would be
unnecessary to inventory different physical heat sinks. Working
with the foundation, and the specified number of fins required for
the particular component, a single basic heat sink could be adapted
for various types of components with different amounts of generated
heat.
[0047] Referring now to FIGS. 8 through 12, a second embodiment of
a heat sink constructed in accordance with the present invention is
shown. In this heat sink, as shown best in FIG. 9, fins 52 have a
rectangular configuration wherein the long ends of the fin project
beyond the edges of the base plate 12. Furthermore, as seen best in
FIG. 11, core shaft 80 has two sections, including the annular ring
82 and roughened surface 84 of the second section of the shaft,
which is of less diameter than portion 82. In this embodiment,
there are no separators to maintain the air passageways between
adjacent fins. Moreover, the fins are pre-assembled and are
inserted onto the section 84 of shaft 80 as a pre-assembled unit.
The pre-assembly may attach individual fins to one another through
various means such as an epoxy or the like. Furthermore, without
the middle section 34, as shown in FIG. 5, the lowermost fin may be
inserted all the way down the shaft until it contacts the upper
surface of base plate 12. As in the first embodiment, the upper
surface of shaft 80 may be coined so as to retain all of the fins
on the shaft during use of the heat sink.
[0048] As shown in FIG. 13, there are alternative configurations if
it is desired to pre-assemble the fins prior to insertion onto the
shaft. In the embodiment shown in FIG. 13, fins 90 have a central
opening 92 for accommodating a shaft, such as shaft 30. The
individual fins are held in place with at least several pins such
as shown at 94 which are inserted through suitable holes made in
the peripheral portions of each fin, thereby performing the dual
function of creating a sub-assembly unit while simultaneously
spacing the fins from one another so as to assure the maintenance
of air passageway between adjacent fins.
[0049] The invention also contemplates the further extension of the
heat capacity of a stackable heat sink by the provision of a second
shaft similar in configuration to core shaft 30 or 80, but having a
cylindrical opening or inset in the bottom of the shaft with a
diameter approximately equal to the diameter of the upper end of a
first shaft. When it is desired to increase the height of the
stack, this second shaft may be press fit onto the top of the first
shaft, thus effectively elongating the shaft and permitting the
addition of other fins. In addition to securing the second shaft to
the first by a press fit, other types of adhesive or mechanical
fastenings may be used to secure the two shafts together.
[0050] In FIGS. 14 through 16, there is shown an improved stackable
heat sink in which the area of the heat sink may be increased
without increasing the area encompassed by the heat sink in the
plane of the printed circuit board to which the electronic
component, that is, the heat source, for which the heat sink
functions.
[0051] In FIG. 14, a simple baseplate 120 is shown having an
opening for core shaft 130 which may be identical to core shaft 30
in the embodiment shown in FIG. 1 through 4. Fin assembly 150
comprises a plurality of individual fins 152 one of which is shown
best in FIG. 15. In the embodiment disclosed fin 152 may have a
square or rectangular shape although it will be appreciated that
the shape of the fin could be round, oval, or some other geometric
shape. In order to increase the area, fins 152 are formed with
corrugations so that the total surface area, as measured if the fin
was flattened, would be greater than the area of a flat fin having
the same perimeter as the corrugated fin. While the corrugations as
shown in FIG. 14 and 15 have relatively sharp angles, it should be
understood that any type of surface forming could be utilized so as
to increase the area of fin 152 without increasing its outer
perimeter. In an embodiment in which the fins have corrugation, the
angle included between adjacent flat sections 154, 156 of the fin
could be acute or obtuse. The surface forming of course could be
performed in a variety of ways such as the formation of raised
areas by creating a plurality of circular indentations, or craters,
or pyramidal shaped indentations, so long as the indentations are
in registry when multiple fins are mounted on a shaft in relatively
close spacing. One advantage of a straight corrugation is the
manufacturing process is simple and in use the troughs between the
corrugations form air passages which may be aligned with the
airflow within the enclosure in which the electronics assembly is
being used which will facilitate the movement of air. Conversely,
the troughs would require the fins to be aligned with the direction
of airflow from, for example, a cooling fan, thus requiring a
particular orientation of the heat sink.
[0052] In another embodiment of an improved stackable heat sink,
core shaft 130 may be formed with a cylindrical opening 131 as
shown in FIG. 17 and 18. In all other respects the core shaft is
identical to that shown in FIG. 14 and in FIG. 1 through 4. FIG. 17
and 18 overcome the problem of slow heat transfer from the portion
of core shaft 132 which is in heat conducting relationship with the
electronic component that is the heat source, toward the free end
of core shaft 134. To facilitate heat transfer along the length of
the shaft, and thus to transfer the heat as rapidly as possible to
the plurality of fins, the improved stackable heat sink includes
heat pipe 140. A heat sink suitable for use in the invention is
that manufactured and sold by Noren Products, Inc., 1010 O'Brien
Drive, Menlo Park, Calif. 94025. The heat pipes manufactured by
this company may be fabricated from metal, such as aluminum or
copper, and contain a liquid and function so as to move heat from
the input to the heat pipe, which in this case is in a cylindrical
configuration, to the output of the heat pipe. Heat pipes have an
effective thermal conductivity that is thousands of time greater
than copper. In this manner, the heat sink will rapidly move heat
from the heat source toward free end 134 of the core shaft thus
distributing the heat rapidly to the fins such as fins 152. It
should be understood that the improvement shown in FIGS. 17 and 18
may be used with any of the embodiments of the invention.
[0053] In FIG. 19 another heat pipe application is shown where base
120 is provided with elongated slotted opening 122 into which
rectangular heat pipe 142 is press fit.
[0054] In FIG. 20 there is shown another embodiment of an improved
heat sink comprising core shaft 230 having enlarged diameter
portion 232 in heat-conducting relationship with the electronic
component. A plurality of fins 250 are shown mounted on core shaft
230 as in previous embodiments described. In this embodiment, base
220 is formed with flat horizontal section 222 and integral
vertical portion 223. Vertical portion 223 is in relatively close
space relationship from the adjacent edges of fins 250. As seen
best in FIG. 21, the vertical portion 223 of base 220 has a
plurality of openings shown at 224 which in this particular
embodiment are oriented in a vertical direction. The openings 224
may be formed by stamping louvers, shown at 225, for directing
airflow. The louvers may also be stamped so as to vary the size of
each air passage or opening 224. As seen best in FIG. 22, there is
provided a small cooling fan indicated generally at 260 of standard
configuration in the industry. Cooling fan 260 has air inlet 262
and the conventional blade assembly (not shown) which will direct
air through openings 224 in portion 223 of base 220. When the
cooling fan 260 is mounted to portion 223 of base 220, the air will
be directed to passages 252 between adjacent fins 250. Thus the
improved heat sink shown in FIGS. 20 through 22, in addition to
comprising the inactive means for dissipating heat, also includes
the active electronic component, cooling fan 260, which will
further increase the heat-dissipating capacity of the improved heat
sink.
[0055] It will therefore be seen that the several embodiments of
the stackable heat sink invention accomplish the objectives as set
forth above and provide a superior heat sink for electronic
components. While various embodiments have been shown, it should
also be obvious to those having ordinary skill in the art that
there are still further variations in the materials,
configurations, methods of attachment, and other features of the
invention which while not disclosed, are encompassed within the
spirit of the invention.
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