Title of Invention

HIGH PERFORMANCE COOLING DEVICE WITH HEAT SPREADER

Abstract A low-cost, fan assisted cooling device 10 is disclosed. The cooling device 10 includes a heat mass 11 with a taper bore 14 therein adapted to receive a heat spreader 40 that has a shape that complement the taper bore 14. The heat mass 11 and the heat spreader 40 are made from dissimilar materials. A fastener 45 or the like can be used to urge the heat spreader 40 and the heat mass 11 into contact with each other. A plurality of vanes 21 are connected with the heat mass 11 and an inside surface 26 of the vanes define a chamber 30 that surrounds the heat mass 11. A portion of each vane 21 is split into a plurality of fins 23 and both the vanes and the fins (21, 23) have a surface area that increase in a radially outward direction r from an axis Z-Z of the heat mass 11.
Full Text HIGH PERFORMANCE COOLING DEVICE WITH HEAT SPREADER
FIELD OF THE INVENTION
The present invention relates generally to a cooling device including a heat
spreader for removing heat from a component connected with the cooling device.
More specifically, the present invention relates to a cooling device that includes a heat
spreader made from a dissimilar material with a higher thermal conductivity than a
material of a heat mass of the cooling device so that heat in a component connected
with the cooling device is efficiently removed.
BACKGROUND OF THE INVENTION
It is well known in the electronics art to place a heat sink in contact with an
electronic device so that waste heat generated by operation of the electronic device is
thermally transferred to the heat sink thereby cooling the electronic device. With the
advent of high clock speed electronic devices such as microprocessors (uP), digital
signal processors (DSP), and application specific integrated circuits (ASIC), the
amount of waste heat generated by those electronic devices and the operating
temperature of those electronic devices are directly proportional to clock speed.
Therefore, higher clock speeds result in increased waste heat generation which in turn
increases the operating temperature of the electronic device. However, efficient
operation of the electronic device requires that waste heat be continuously and
effectively removed.
Heat sink devices have become commonplace as a means for dissipating
waste heat from electronic devices such as the types described above. In a typical
application, a component to be cooled is carried by a connector that is mounted on a
PC board. A heat sink is mounted on the component by attaching the heat sink to the
connector using a clip or fasteners, for example. Alternatively, the heat sink is mounted

to a PC board that carries the electronic device and fasteners or the like are used to
connect the heat sink to the PC board via holes that are drilled in the PC board.
The need to drill holes can be one disadvantage to using fasteners because the
fasteners or other mounting hardware used for connecting the heat sink to the PC
board are usually electrically conductive and there is a risk of an electrical short due to
contact between a PC board trace and the mounting hardware. Moreover, to avoid
electrical shorts, the PC board traces can be routed around the hole, but that routing
requires keep out zones that can complicate the routing of the traces.
Typically, a heat sink used in conjunction with a modem high clock speed
electronic device will use an electrical fan mounted on top of the heat sink or within a
cavity formed by cooling fins/vanes of the heat sink. The cooling fins increase the
surface area of the heat sink and maximize heat transfer from the heat sink to ambient
air that surrounds the heat sink. The fan causes air to circulate over and around the
cooling fins thereby transferring heat from the cooling fins into the ambient air.
As mentioned previously, with continuing increases in clock speed, the amount
of waste heat generated by electronic devices has also increased. Accordingly, to
adequately cool those electronic devices, larger heat sinks and/or larger capacity fans
(i.e. in CFM) are required. Increasing the size of the heat sink results in a greater
thermal mass and a greater surface area from which the heat can be dissipated.
Increases in fan capacity provide for more air flow through the cooling fins.
There are disadvantages to increased fan and heat sink size. First, if the size of
the heat sink is increased in a vertical direction (i.e. in a direction transverse to the PC
board), then the heat sink is tall and may not fit within a vertical space in many
applications, such as the chassis of a desktop computer. Second, if the PC board has
a vertical orientation, then a heavy and tall heat sink can mechanically stress the PC
board and/or the electronic device resulting in a device or PC board failure.

Third, a tall heat sink will require additional vertical clearance between the heat
sink and a chassis the heat sink is contained in to allow for adequate air flow into or out
of the fan. Fourth, if the heat sinks size is increased in a horizontal direction, then the
amount of area available on the PC board for mounting other electronic devices is
limited. Fifth, when the heat sink has a cylindrical shape formed by the fins it is often
not possible to mount several such heat sinks in close proximity to each other because
air flow into and out of the fins is blocked by adjacent heat sinks with a resulting
decrease in cooling efficiency.
Finally, increases in fan size to increase cooling capacity often result in
increased noise generation by the fan. In many applications such as the desktop
computer or a portable computer, it is highly desirable to minimize noise generation. In
portable applications that depend on a battery to supply power, the increased power
drain of a larger capacity fan is not an acceptable solution for removing waste heat.
In the above mentioned heat sink with cooling fins there are additional
disadvantages to mounting the fan within a cavity formed by the fins. First, a substantial
portion of a heat mass of the heat sink is partially blocked by the fan because the fan is
mounted directly on the heat mass and therefore blocks a potential path for heat
dissipation from the heat mass because air from the fan does not circulate over the
blocked portion of the heat mass.
Second, without the fan, a depth of the fins could extend all the way to a center of
the heat mass; however, the depth and surface area of the fins is reduced by a
diameter of the fan because the fan is mounted in a cavity having a diameter that is
slightly larger than the fans diameter to provide clearance for the fan blades.
Consequently, the heat mass of the heat sink must be made broader to compensate for
the reduced surface area of the fins. The broader heat mass increases the size, cost,
and weight of the heat sink.
Third, the reduced depth of the fins makes it easier for the fins to be bent if
damaged. One possible consequence of a bent fin is that it will contact and damage

the fan blades and/or cause the fan to stall thereby damaging the fan or causing the fan
to fail. Fourth, because the fan is mounted in the cavity formed by the fins, power leads
for the fan must be routed through a space between the fins. Sharp edges on the fins
can cut the power leads or cause an electrical short. In either case, the result is that the
fan will fail. Fifth, glue is typically used to mount the fan to the heat sink and the glue can
get into the fan and cause the fan to fail. Any of the above mentioned fan failure modes
can lead to a failure of the electronic device the heat sink was designed to cool
because air circulation generated by the fan is essential to effectively dissipate waste
heat from the electronic device.
Some prior heat sinks attempt to overcome the aforementioned disadvantages
of a larger heat mass or increased fin area by using a metal heat spreader that is
joined with the heat sink. Typical processes for joining the heat spreader with the heat
sink include brazing, soldering, heat shrink fitting, vacuum brazing, micro forging and
shrink fitting.
One disadvantage of those processes is that they are very expensive resulting in
a higher cost for the heat sink. Another disadvantage is that the above processes are
limited in their ability to join dissimilar metals for the heat sink and the heat spreader,
particularly if the metal for the heat spreader has superior thermal conductivity
properties over the metal for the heat sink. A disadvantage of the shrink fitting process
is that a thermal resistance between the heat spreader and the heat sink is high due to
micro gaps between the heat spreader and the heat sink. Finally, depending on the
application, another potential disadvantage to the above processes is that once joined,
the heat sink and the heat spreader cannot be easily removed for servicing or for a field
upgrade to a better material for the heat spreader.
Consequently, there is a need for a cooling device with a heat spreader that
allows for the use of dissimilar materials that are optimized for efficient thermal
conduction and heat dissipation. There is also a need for a cooling device with a heat
spreader that eliminates micro gaps between the heat spreader and a heat mass so
that there is a low thermal resistance between the heat spreader and the cooling

device. There is a need for a cooling device with a heat spreader that provides an
inexpensive processes for joining the heat spreader with the cooling device. There
exists a need for a cooling device with dissimilar materials for the heat mass and the
heat spreader that allows the heat spreader to be fixedly connected with the heat mass
to prevent the heat mass and the heat spreader from separating from each other.
Finally, there exists a need for a cooling device with a heat spreader that allows for
easy disassembly and in field servicing.
SUMMARY OF THE INVENTION
Broadly, the present invention is embodied in a cooling device for dissipating
waste heat from a component to be cooled. The cooling device includes a heat mass
made from a first material and including a base, an arcuate boss that is surrounded by
an arcuate groove, a taper bore extending from the base to the boss, and an aperture
extending from the boss to the taper bore. A fastener including a head and a threaded
shaft is inserted through the aperture with the head in contact with the boss. A heat
spreader made from a second material that is dissimilar to the first material includes a
taper wall that complements the taper bore of the heat mass, a mounting surface
adapted to thermally connect with the component, a threaded aperture adapted to
receive the threaded shaft of the fastener. Optionally, a thermal sealant is connected
with the taper wall and/or the taper bore.
The heat spreader is inserted into the taper bore and the threaded shaft is
threaded into the threaded aperture and the head of the fastener is turned to urge the
taper wall into contact with the taper bore. The optional thermal sealant is operative to
seal micro gaps between the taper bore and the taper wall so that a thermal resistance
between the heat mass and the heat spreader is reduced.
Extending from the heat mass are a plurality of vanes that are spaced apart from
each other to define a primary slot between adjacent vanes and extending to the heat
mass. The vanes have a surface area that increases in a radially outward direction

from an axis of the heat mass and a portion of the surface area of the vanes also
increase in a direction that is along the axis. The vanes include a top face upon which a
fan can be mounted, an aerodynamically profiled inner wall that defines a chamber that
surrounds the boss and the groove, and an outer wall including a surface profile that
widens from the base to the top face and includes a smooth curved portion, a draft
portion, and a smooth radially outward portion. Furthermore, the surface area of the
vanes is increased by a plurality of fins formed in each vane by a secondary slot
extending through a portion of the vane.
An air flow entering the chamber creates a three-dimensional air flow that
dissipates heat from the cooling device. First, the air flow exits through the vanes and
a portion of the fins in an exhaust flow that dissipates heat from the vanes and the fins.
Second, the exhaust flow creates a low pressure region within the chamber that induces
an intake flow into the chamber through a major portion of the fins and a top portion of
the vanes thereby dissipating heat from the fins and the vanes. Third, the low pressure
region induces a surface flow along the inner wall so that the surface flow wets the
groove and the boss as it passes over the groove and the boss to dissipate heat from
the heat mass.
The cooling device of the present invention solves the aforementioned
disadvantages of prior heat sinks. The cooling device can be mounted to a component
to be cooled by using a clip to connect the cooling device with a connector that carries
the component. Therefore, holes need not be drilled in a PC board to mount the
cooling device. The cooling device employs vanes that extend deep within the heat
mass and the surface area of the vanes increases from a bottom of the cooling device
to a top of the cooling device and in a radially outward direction from the heat mass.
Furthermore, each vane is split into at least two fins thus further increasing the surface
area available for cooling. As a result, the codling device need not be made taller to
increase vane surface area and the cooling device need not be made wider to
increase the size of the heat mass.

The top of the cooling device is adapted to mount a fan so that the heat mass is
not blocked by the fan and air can circulate over the heat mass thus further dissipating
heat from the cooling device. The fan can include a shroud that surrounds the blades
unlike the fans that are mounted in a cavity formed by fins of prior heat sink devices.
However, the cooling device can also mount a fan without a shroud using a clip or
space frame to mount the fan to the top of the cooling device. Because the fan is
mounted on top of the cooling device, the wires of the power leads for the fan are not
routed through the vanes or fins thereby eliminating the risk of the wires being cut or
short circuited.
The shape of the cooling device (wider at the top than at the bottom) allows for
several of the cooling devices to be placed adjacent to each other without blocking air
flow into and out of the vanes and fins.
The vanes of the cooling device can be tangentially oriented with a circle
centered on an axis of the heat mass and the vanes can be inclined at an angle with
respect to the axis such that the angle of inclination substantially matches or closely
approximates a pitch angle of the blades of a fan. The tangential orientation and the
inclination of the vanes reduces fan noise due to air shock losses.
The heat spreader can be mounted with the heat mass using a fastener or the
like thereby eliminating the problems and costs associated with the prior welding or
brazing of dissimilar metals to each other. Additionally, the use of the fastener allows
for easy in field servicing, repairs, and upgrades to the cooling device. Furthermore, if
necessary, the heat spreader can be fixedly connected with the heat mass by
preventing removal of the fastener and/or by welding, brazing, soldering the heat
spreader to the heat mass.
Moreover, a second material for the heat spreader can be selected for its
superior thermal conductivity properties for efficient conduction and dissipation of
waste heat from the component connected with the mounting surface of the heat
spreader. Furthermore, the optional thermal sealant of the present invention solves the

aforementioned problems caused by micro gaps between prior heat spreaders and
heat sinks by sealing those micro gaps thereby reducing a thermal resistance between
the heat spreader and the heat mass.
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 present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1a is a cross-sectional view along line A-A of FIG. 2a of a cooling device
with a heat mass and a taper bore according to the present invention.
FIG. 1b is a cross-sectional view along line A-A of FIG. 2a of a cooling device
with a heat spreader inserted into a taper bore of a heat mass according to the present
invention.
FIGS. 2a and 2b are top plan views of a cooling device according to the present
invention.
FIGS. 2c is detailed view of a portion E-E of the top plan view of FIG. 2b that
depicts in greater detail features a fin and a vane of a cooling device according to the
present invention.
FIG. 3a is a cross-sectional view along line A-A of FIG. 3b of an air flow into and
out of a cooling device according to the present invention.
FIG. 3b is a top plan view of an air flow into and out of a cooling device
according to the present invention.

FIG. 4a is a top profile view of a chamber of a cooling device and a fastener
connected with a boss of a heat mass according to the present invention.
FIG. 4b is a bottom profile view of a base of a heat mass and a mounting
surface of a heat spreader according to the present invention.
FIG. 4c is a bottom profile view of a base and a taper bore of a heat mass
according to the present invention.
FIG. 4d is a top profile view of a heat mass including a boss with an aperture
therein for receiving a fastener according to the present invention.
FIGS. 5a and 5b are side views of a cooling device with vanes inclined at an
angle according to the present invention.
FIG. 6 is a top plan view depicting a cooling device having vanes with a
tangential orientation according to the present invention.
FIG. 7a is a bottom profile view of a mounting surface of a heat spreader
according to the present invention.
FIG. 7b is a top profile view of a heat spreader including a threaded aperture
according to the present invention.
FIGS. 7c and 7d are cross-sectional views depicting a heat spreader with an
arcuate profile according to the present invention.
FIG. 8 is a side view of a fan mounted to a cooling device according to the
present invention.
FIG. 9 is a cross-sectional view illustrating various dimensional relationships
between a fan, fan blades, and a cooling device according to the present invention.

FIG. 10 is a side view of a space frame for mounting a fan to a cooling device
according to the present invention.
FIG. 11 is a side view of a cooling device with a mounting surface that includes
projections that protect a thermal interface material according to the present invention.
FIGS. 12a is a side plan view of a cooling device according to the present
invention.
FIGS. 12b is a cross-sectional view along a line A-A of FIG. 12a and depicts a
heat spreader connected with a taper bore by a fastener according to the present
invention.
FIG. 12c is a top plan view of a head of a fastener connected with a boss of a
heat mass according to the present invention.
FIG. 12d is cross-sectional view of a heat spreader with a thermal sealant
connected with a taper wall and a thermal interface material and projections connected
with a mounting surface according to the present invention.
FIG. 13 is a side view of a system for dissipating heat according to the present
invention.

DETAILED DESCRIPTION
In the following detailed description and in the several figures of the drawings,
like elements are identified with like reference numerals.
As shown in the drawings for purpose of illustration, the present invention is
embodied in a cooling device for dissipating heat from a component that is in thermal
communication with a heat spreader of the cooling device. The thermal communication
can be by direct contact between the heat spreader and the component or by an
intermediate material (e.g a thermal interface material) positioned between the cooling
device and the component as will be described below. The component can be any
heat source, such as an electrical component, for example.
The cooling device includes a heat mass made from a first material and
including a base, a boss surrounded by a groove with the groove and the boss
symmetrically positioned about an axis of the heat mass, a taper bore extending from
the base to the boss, and an aperture extending from the boss to the taper bore. The
boss has a convex arcuate surface profile and the groove has a concave arcuate
surface profile.
A fastener including a head and a threaded shaft is inserted through the aperture
with the head in contact with the boss. A heat spreader made from a second material
that is dissimilar to the first material includes a taper wall that complements the taper
bore of the heat mass, a mounting surface adapted to thermally connect with the
component, and a threaded aperture adapted to receive the threaded shaft of the
fastener. Optionally, a thermal sealant that can be connected with the taper wall, the
taper bore, or both the taper wall and the taper bore as will be described below.
The heat spreader is inserted into the taper bore and the threaded shaft is
threaded into the threaded aperture and the head of the fastener is turned to urge the
taper wall into contact with the taper bore. The optional thermal sealant is operative to
seal micro gaps between the taper bore and the taper wall so that a thermal resistance

between the heat mass and the heat spreader is reduced.
A plurality of vanes are in contact with the heat mass and surround the heat
mass. The vanes are spaced apart from one another to define a primary slot between
adjacent vanes that extends to the heat mass. The vanes have a surface area that
increases in a radially outward direction from the axis and in a direction along the axis.
A plurality of fins are formed in each vane by a secondary slot extending through a
portion of each vane.
The vanes include a top face and an aerodynamically profiled inner wall that
includes a first portion extending from the groove and terminating at a second portion
that extends to the top face. The inner wall defines a chamber that surrounds the
groove. The vanes also include an outer wall having a surface profile that widens from
the base to the top face. The surface profile includes a smooth curved portion, a draft
portion, and a smooth radially outward portion.
An air flow entering the chamber creates a three-dimensional air flow that
dissipates heat from the cooling device. First, the air flow exits the primary slots and a
bottom portion of the secondary slots in an exhaust flow that dissipates heat from the
vanes and the fins. Second, the exhaust flow creates a low pressure region within the
chamber that induces an intake flow into the chamber through a major portion of the
secondary slots and a top portion of the primary slots thereby dissipating heat from the
fins and the vanes. Third, the low pressure region induces a surface flow along the first
and second portions of the inner wall so that the surface flow wets the groove and the
boss as it passes over the groove and the boss to dissipate heat from the heat mass.
The heat spreader is operative to increase a thermal conductivity of the cooling
device by effectively spreading waste heat from the component to a larger surface area
on the heat mass to reduce a heat concentration at an interface between the heat
spreader and the heat mass. The second material of the heat spreader is dissimilar to
the first material of the heat mass and is selected based on properties for superior heat
conduction and heat dissipation as compared with similar properties for the first

material of the heat mass.
As an example, a component having a surface of 30.0 mm x 30.0 mm is in
contact with the mounting surface of the heat spreader such that a thermal contact area
of 30.0 mm * 30.0 mm = 900.0 mm2 is established between the component and the
heat spreader. Because the second material of the heat spreader makes the heat
spreader a better thermal conductor than the heat mass, the waste heat from the
component is conducted through the heat spreader and is then transferred to the heat
mass. However, the contact area between the taper bore of the heat mass and the
taper walls of the heat spreader is greater than the aforementioned thermal contact
area of 900.0 mm2 at the mounting surface. Therefore, the heat is spread out over a
larger surface area and heat concentration per unit of area is reduced when compared
to the heat concentration at the thermal contact area.
If the component generates 80.0 W of waste heat, then heat concentration on the
surface is 80.0 = 900.0 mm2 = 0.0889 W/mm2. If that waste heat is conducted more
efficiently through the heat spreader due to a higher thermal conductivity of its second
material, then the heat spreader can absorb more heat than the heat mass. Assuming
for the purpose of this example, that the heat spreader conducts all of the heat from the
component, then if the heat spreader has a diameter of 40.0 mm at the mounting
surface, a diameter of 25.0 mm at the top, and a height of 20.0 mm, then a surface area
of the heat spreader that is in contact with the heat mass is: (3.14) * (s) * ® + r) = 3.14
* 21.31 (20 + 12.5) = 2174.68 mm2. Hence, heat concentration at the heat mass will
be 80.0 W -r 2174.68 = 0.03678 W/ mm2. Accordingly, 0.03678 W/ mm2 at the heat
mass is significantly less than the 0.0889 W/mm2 at the mounting surface of the heat
spreader.
In FIGS. 1a, 1b and 2a through 2c, a cooling device 10 for dissipating heat from
a component (not shown) includes a heat mass 11, a boss 13, and a groove 15 that
completely surrounds the boss 13. The boss 13 and the groove 15 are symmetrically
positioned about an axis Z-Z of the heat mass 11. The boss 13 has a convex arcuate

surface profile and the groove 15 has a concave arcuate surface profile. The arcuate
profiles of the boss and the groove (13,15) blend into each other as illustrated by a
dashed line a. The cooling device 10 further includes a base 17. The heat mass 11
also includes a tape bore 14 extending from the base 17 to the boss 13 and an
aperture 14a extending from the boss 13 to the taper bore 14. The aperture 14a is a
through hole that is adapted to receive a shaft of a fastener (see FIG. 1b) as will be
described below. The heat mass 11 is made from a first material. Optionally, a
thermal sealant can be applied to the taper bare 14 as depicted by dashed arrows 44.
In FIG. 1b, the cooling device 10 includes a heat spreader 40 that includes a
mounting surface 19 adapted to thermally connect the heat spreader 40 with the
component (not shown), a taper wall 41 having a profile (see reference numeral 41 p in
FIGS. 7a and 7b) that complements the taper bore 14 of the heat mass 11, and a
threaded aperture 43. A fastener 45 including a head 47 and a threaded shaft 49 is
inserted through the aperture 14a with the head 47 in contact with the boss 13. The
threaded shaft 49 is threaded into the threaded aperture 43 and the head 47 is turned
(e.g. using a wrench, nut driver, Allen wrench,;hex driver, TORX® driver, etc.) to thread
the fastener 45 into the heat spreader 40 thereby urging the taper wall 41 into contact
with the taper bore 14.
The heat spreader 40 is made from a second material that is dissimilar to the
first material of the heat mass 11. The heat spreader 40 must be a better thermal
conductor than the heat mass 11. Accordingly, the dissimilarity between the first and
second materials can be accomplished using different materials for the heat mass 11
and the heat spreader 40 or by using different alloys of the same material (e.g. copper
(Cu) for the heat mass 11 and a copper alloy for the heat spreader 40) for the heat
mass 11 and the heat spreader 40. As another example, aluminum (Al) or an
aluminum alloy can be used for the heat mass 11 and copper (Cu) or a copper alloy for
the heat spreader 40.

The first material for the heat mass 11 can be a material including but not limited
to aluminum (Al), an aluminum alloy, copper (Cu), a copper alloy, and a ceramic
material.
The second material for the heat spreader 40 can be a material including but not
limited to copper (Cu), a copper alloy, silver (Ag), a silver alloy, silicon (Si), gold (Ag),
graphite, a carbon fiber material, a carbon fiber reinforced material, and a gold alloy.
Preferably, the fastener 45 should be made from a high tensile strength material
so that a pulling load resulting from the tightening of the head 47 will not damage the
fastener 45 or the threaded shaft 49. Furthermore, it is preferable for the material for
the fastener 45 to be rust resistant. For example, a stainless steel material can be
used to accomplish the tensile strength requirement and the rust resistance
requirement. Preferably, the head 47 includes either an Allen key slot or a Hex/Square
head slot in order to withstand an assembly torque required to tighten the fastener 45.
The torque required to adequately tighten the fastener 45 will be application and
material dependent; however, the torque can be in a range including but not limited to
6.0 lbs-inch to about 500.0 lbs-inch.
In some applications it may be desirable to prevent the fastener 45 from being
removed after it has been tightened. For instance, to prevent loosening of the fastener
45 which could result in a higher thermal resistance between the taper wall 41 of the
heat spreader 40 and the taper bore 14 of the heat mass 11 because the taper wall 41
is no longer urged into firm thermal contact with the taper bore 14. To that end, as one
example, the fastener 45 can have a sealant/adhesive such as LOCTITE® applied to
the threaded shaft 49 prior to insertion and tightening. Consequently, after the
sealant/adhesive has set, the fastener 45 is fixedly connected with the heat mass 11,
the heat spreader 40, or both the heat mass 11 and the heat spreader 40.
Alternatively, the fastener 45 can be fixedly connected using a process including
but not limited to welding, friction stir welding, soldering, or brazing to the head 47 to the

boss 13 of the heat mass 11, for example.
In FIG. 4a, a seam S between the head 47 and the boss 13 can be welded,
soldered, or brazed to fixedly connect the heat spreader 40 to the heat mass 11 and/or
to prevent removal of the fastener 45. As another alternative, a spring or lock washer
can be used to secure the fastener 45 thereby preventing removal. The above are only
examples and the present invention is not limited to the above means for preventing the
fastener 45 from being removed after insertion into the threaded aperture 43.
Depending on the type of material selected for the second material of the heat
spreader 40, the material for the fastener 45 can be selected to be identical to the
second material or it can be an alloy of the second material so that a thermal mass of
the heat spreader 40 is increased and a contact area between the heat spreader 40
and the heat mass 11 is also increased due the fastener 45 being in thermal contact
with the threaded aperture 43, the aperture 14a, and the boss 13. As described herein,
a thermal sealant can be applied to the head 47 and/or the threaded shaft 49 to seal
micro voids and to reduce thermal resistance between the fastener 45, the heat mass
11 and the heat spreader 40.
In one embodiment of the present invention, to prevent removal of the heat
spreader 40 from the heat mass 11, the heat spreader 40 is fixedly connected with the
heat mass 11 using a process including but not limited to brazing, soldering, friction stir
welding (FSW), or welding a portion of the heat spreader 40 to the heat mass 11. For
example, in FIGS. 1b and 4b, a seam S between the mounting surface 19 and the
base 17 can be welded, soldered, or brazed to fixedly connect the heat spreader 40
with the heat mass 11. Another advantage to fixedly connecting the heat spreader 40
to the heat mass 11 is that taper wall 41 and the taper bore 14 are held in thermal
contact with each other thereby reducing thermal resistance. The fastener 45 can also
be fixedly connected as described above.

The method and compounds used for welding, soldering, or brazing will depend
on the materials for the heat mass 11 and the heat spreader 45. For example, EN
Plating is essential for soldering copper (Cu) to aluminum (Al).
In FIG. 12d, an optional thermal sealant 44 is connected with the taper walls 41
and can cover the top and side surfaces of the taper walls 41 as depicted by the
dashed circles 44 in FIGS. 7a and 7b. The thermal sealant 44 is connected with the
taper walls 41 prior to the above step of inserting the heat spreader 40 in the taper
bore 14 and tightening the fastener 45. Alternatively, the thermal sealant 44 can be
connected with the taper bore 14 (see FIG. 1a) or connected with both the taper bore
14 and the taper walls 41. However, it may be easier to coat, deposit, or connect the
thermal sealant 44 on the taper walls 41.
Suitable materials for the thermal sealant 44 include but are not limited to a
thermally conductive paste, a thermally conductive grease, silicone, paraffin, a phase
transition material, graphite, a coated aluminum foil, and carbon fiber. The thermal
sealant 44 can be screen printed, pasted, dip coated, dispensed by a tool, or applied
with a brush to the taper walls 41 of the heat spreader 40, for example.
In FIG. 1a, a plurality of vanes 21 are in contact with the heat mass 11 and the
vanes 21 are spaced apart from one another tp define a primary slot P (see FIGS. 2a
and 2c) between adjacent vanes 21. The vanes 21 have a surface area that increases
in a radially outward direction from the axis Z-Z as indicated by the dashed arrow r. At
least a portion of the vanes 21 have a surface area that increases in a direction along
the axis Z-Z as shown by dashed arrow y.
Preferably, the primary slot P extends to the heat mass 11 and the primary slot P
includes a first arcuate surface profile 21a along the heat mass 11. The first arcuate
profile 21a terminates on a plane H-H (see FIG. 1a). It is also preferable that the vanes
21 are equidistantly spaced apart from each another. By extending the primary slot P
to the heat mass 11, air flow through the vanes 21 also wets the heat mass 11 to

dissipate heat therefrom. The first arcuate surface profile 21a can be an arc having a
radius from about 38.0 millimeters to about 45.0 millimeters.
One advantage of the cooling device 10, is that a fan (not shown) for generating
an air flow is not mounted on the heat mass 11. Consequently, the vanes 21 can extend
deep into the heat mass 11 (as illustrated by arrow e) and the depth of the vanes 21
provides a large surface area for efficient dissipation of waste heat and exposes the
heat mass 11 to an air flow (see FIGS. 3a and 3b) that wets over the boss 13 and the
groove 15 so that additional waste heat can be dissipated from the heat mass 11.
The vanes 21 also include a top face 29, an aerodynamically profiled inner wall
26 including a first portion 25 that extends from the groove 15 and terminates at a
second portion 27 that extends to the top face 29. The first portion 25 blends with the
arcuate profile of the groove 15 as illustrated by dashed line b and the first portion 25
blends with the second portion 27 as illustrated by dashed line C. The second portion
27 blends with the top face 29 as illustrated by dashed line d. The inner wall 26 can
include additional portions and the present invention is not to be construed as being
limited to the first and second portions (25,27). The inner wall 26 defines a chamber
30 that surrounds the groove 15.
In one embodiment of the present invention, as illustrated in FIGS. 1a, 1b, and
2c, the first portion 25 of the inner wall 26 is a slope surface and the second portion 27
of the inner wall 26 is a concave arcuate surface. The sloped and concave arcuate
surfaces aerodynamically interact with an air flow into the chamber 30 so that the air
flows along the first and second portions (25,27) of the inner wall 26 and wet over the
groove and the boss (15,13) to dissipate heat from the heat mass 11 as will be
described below in reference to FIGS. 3a and 3b.
The first portion 25 can be inclined at an angle ψ with respect to the axis Z-Z as
illustrated in FIG. 1a. The angle ψ can be in a range from about 15.0 degrees to about

75.0 degrees. If the vanes 21 have a tangential orientation with a circle about the axis
Z-Z as will be discussed below in reference to FIG. 6, then the first portion 25 will have
a tangential orientation with the groove 15. The angle ψ will vary based primarily on an
output of a fan (not shown) in cubic feet per minute (CFM).
In FIG. 1b, the vanes 21 further include an outer wall 32 having a surface profile
that widens from a bottom 11a of the heat mass 11 to the top face 29 and includes a
smooth curved portion 33, a draft portion 35, and a smooth radially outward portion 37.
The draft portion 35 an be substantially parallel to the axis Z-Z or the draft portion 35
can be inclined at an angle A.
In FIGS. 2a through 2c, the vanes 21 include at least one secondary slot S that
extends through a portion of each vane 21 to define a plurality of fins 23 (two are
shown) in each vane 21. By splitting at least a portion of each vane 21 into a plurality of
fins 23, the available surface area for dissipating waste heat is increased and the
secondary slot S provides an additional air flow path between the fins 23 that further
increases waste heat dissipation.
In another embodiment of the present invention, the secondary slot S extends to
the heat mass 11 and the secondary slot S includes a second arcuate profile 23a (see
dashed line in FIG. 1a) along the heat mass 11. The second arcuate profile 23a
terminates on the plane H-H. By extending the secondary slot S to the heat mass 11,
the airflow through the fins 23 also wets the heat mass 11 to dissipate heat therefrom.
The second arcuate profile 23a can be an arc having a radius from about 31.0
millimeters to about 38.0 millimeters.
Reference points for a center of the above mentioned radiuses (i.e. for 21a and
23a) will be positioned outside the cooling device 10 and the actual location of the
center will depend on the arcs radius. However, the position of the center of the radius
will be at least about 5.0 millimeters out side of the cooling device 10 to accommodate
a cutting tool used in a machining process for making the cooling device 10. The

position of the center of the radius is a limitation imposed by a machining process that
uses cutting wheels to form the vanes 21 and the fins 23. If the vanes 21 and the fins 23
can be diecasted or impact forged, then the arc radius could be reduced and the
position of the center of the radius could come inside the cooling device 10. The
cooling device 10 can be made amendable to a diecasted or impact forged process
by reducing the number of vanes 21.
In FIGS. 3a and 3b, heat dissipation by an air flow F entering the chamber 30 is
illustrated. A portion of the air flow F exits the chamber 30 through the primary slots P
and a bottom portion of the secondary slots S (not shown) in an exhaust flow E. The
exhaust flow E passes over the vanes 21 and the fins 23 and dissipates heat therefrom.
A low pressure region AP is created within the chamber 30 by the exhaust flow E.
Consequently, the low pressure region AP induces an intake flow I into the chamber 30
through a major portion of the secondary slots S and a top portion of the primary slots P
(not shown) thereby dissipating heat from the fins 23 and the vanes 21. The low
pressure region AP also induces a surface flow B along the aerodynamically shaped
first and second portions (25,27) of the inner wall 26. The surface flow B passes over
the arcuate profiles of the groove and boss (15,13) thereby dissipating heat from the
heat mass 11 as the surface flow B circulates back towards (i.e. it is a balancing air
flow) the low pressure region AP. Therefore, another advantage of the cooling device
10 is that waste heat is efficiently dissipated by a three-dimensional air flow
(comprising E, I, and B) through the vanes 21 and the fins 23, and passing over the
groove and boss (15,13).
In one embodiment of the present invention, the arcuate surface profile of the
boss 13 includes but is not limited to a profile of a sphere, a frustum of a sphere, a
cone, and a frustum of a cone. In FIG. 1a, the boss 13 has a conical surface profile. On
the other hand, the surface profile could also be spherical. In FIG. 1b, the boss 13 has
a surface profile that is a frustum of a cone due to a substantially flat head 47 of the
fastener 45. However, depending on the shape of the head 47, the combined shape of
the head 47 and the boss 13 can result in a conical surface profile. The boss 13 could

also have a surface profile that is a frustum of a sphere.
In another embodiment of the present invention, the arcuate surface profile of the
groove 15 includes but is not limited to a semi-circular profile as illustrated in FIGS. 1a
and 1b. Preferably, the boss 13 has a diameter dB (see FIG. 1a) that is less than a
diameter of a hub 79 of a fan 70 (see FIG. 9). The groove 15 should have a radius rG
(see FIG. 9) that provides a smooth change in air flow direction for the surface flow B
as it transitions from the first portion 25 to the groove 15 so that the surface flow B flows
over the groove 15 and onto the boss 13 (see FIG. 3a). As mentioned previously, the
boss 13, the groove 15, and the inner wall 26 (i.e. 25 and 27) can be formed by forging,
machining, or diecasting.
In FIGS. 5a and 5b, the vanes 21 can be inclined at angle with respect to the
axis Z-Z. In FIG. 5a, the vanes 21 are inclined at an angle β measured between a line
21c and the axis Z-Z. The line 21c is measured along the primary slot P of the fins 23.
The inclination of the angle β includes but is not limited to a range from about 0 (zero)
degrees to about 25.0 degrees. In another embodiment of the present invention as
illustrated in FIG. 5b, the angle at which the vanes 21 are inclined with respect to the
axis Z-Z includes a first angle δ1 measured between a line 21 d and the axis Z-Z and a
second angle δ2 measured between a line 21 e and the axis Z-Z. The first angle δ1 is
measured along the smooth radially outward portion 37 of the fins 23. The inclination of
the first angle δ1 includes but is not limited to a range from about 0 (zero) degrees to
about 25.0 degrees. The second angle δ2 is measured along the smooth curved
portion 33 of the fins 23. The inclination of the second angle δ2 includes but is not
limited to a range from about 5.0 degrees to about 18.0 degrees. Because the fins 23
are defined by the vanes 21, the fins 23 and the vanes 21 are inclined at the angles (β,
δ1 and δ2) as described above.
In one embodiment of the present invention as illustrated in FIG. 6, the vanes 21
have a tangential orientation with respect to a circle Ct (shown in dashed line) centered

about the axis Z-Z (shown as a "+") and having a predetermined diameter. In FIG. 6, an
example of the tangential orientation of the vanes 21 is illustrated by a plurality of the
vanes 21 having tangent lines t drawn through their primary slots P and tangentially
crossing a perimeter of the circle Ct. A line M through the axis Z-Z (shown as a M+")
and a parallel line N that also is tangential to the circle Ct define a radius R
therebetween and the predetermined diameter of the circle Ct is two times the radius
R (that is: Ct = 2 * R). The predetermined diameter includes but is not limited to a
range from about 3.0 millimeters to about 12.0 millimeters.
In FIGS. 5a, 5b, and 6, at least a portion of the top face 29 of the vanes 21
includes a substantially planar portion 29a (shown as a dashed line). Preferably the
substantially planar portion 29a covers the entirety of the top face 29 as illustrated in
FIG. 6. One advantage of the substantially planar portion 29a of the top face 29 is that
a fan can be mounted on the substantially planar portion 29a.
In FIGS. 4a and 4b the cooling device 10 is depicted with the heat spreader 40
already connected with the taper bore 14 and the fastener 45 inserted in the aperture
14a with the head 47 in contact with the boss 13. The head 47 of the fastener can be
substantially flat as illustrated or the head 47 can have a profile that complements the
shape of the boss 13 in order to streamline the air flow F through the chamber 30.
In FIG. 4b, the mounting surface 19 of the heat spreader 40 is illustrated as
being substantially flush with the base 17 of the heat mass 11. However, the mounting
surface 19 need not be flush with the base 17. For example, the mounting surface 19
can be inset from the base 17 or the mounting surface 19 can extend outward of the
base 17.
In FIGS. 4c and 4d, the heat spreader is not mounted to the taper bore 14 of the
heat mass 11. The taper bore 14 includes an upper portion denoted as 14t where the
aperture 14a terminates. As illustrated, the portion 14t is substantially planar (i.e. flat);
however, the portion 14t can be arcuate or sloped and an actual shape of the portion

14t will depend on the shape of the heat spreader 40 because the shape of the taper
bore 14 and the taper walls 41 of the heat spreader 40 should be complementary in
order to facilitate mating the heat spreader 40 to the taper bore 14 and to increase a
contact area between the heat spreader 40 and the heat mass 11. A larger contact
area increases heat transfer from the heat spreader 40 to the heat mass 11 and
distributes the transferred heat over a larger surface area.
in FIGS. 7a and 7b, the heat spreader 40 includes a taper wall 41 having a
profile 41 p that is a sloped profile such that the heat spreader has a shape of a cone.
In FIG. 1b and 7b, the shape of the heat spreader 40 is that of a frustum of a cone
because a top surface 411 is flat. The top surface 411 complements the portion 14t of
the taper bore 14 and the taper wall 41 complements the taper bore 14 (see FIG. 4c).
However, the shape of the heat spreader 40 and the taper bore 14 are not
limited to the shapes illustrated herein. In FIG. 7c, the heat spreader 40 includes a
taper wall 41 with an arcuate profile and a top surface 411 that is flat. In FIG. 7d, the
heat spreader 40 includes a taper wall 41 with an arcuate profile. In either case, the
taper bore 14 would include a complementary arcuate profile.
In FIG. 8, a fan 70 is positioned to be mounted on the substantially planar portion
29a of the top face 29. The fan 70 generates an air flow (see reference letter F in FIG.
3a) into the chamber 30 of the cooling device 10 in a direction indicated by dashed
arrow af. A shroud 73 houses a rotor hub 79 having a plurality of fan blades 77. The
rotor hub 79 is rotatably mounted on a stator 71 and the fan blades 77 rotate in a
direction indicated by arrow IT. Several holes 75 through the shroud 77 are adapted to
receive a fastener 89.
A mounting ring 80 including a frame 81 and several mounting fixtures 83 is
abutted against a surface 37a of the smooth radially outward portion 37. The diameter
of the smooth radially outward portion 37 at the surface 37a is greater than an inside
diameter of the frame 81 of the mounting ring 80 so that the frame 81 can be urged into
snug contact with the smooth radially outward portion 37 without sliding off of the vanes

and fins (21,23). The only way to slide the mounting ring 80 off of the vanes and fins
(21,23) is in the direction of the base 17 because the diameter of the vanes and fins
(21,23) narrows in that direction.
The mounting fixtures 83 receive the fastener 89 and optionally an additional
fastener 87 such that the fan 70 is firmly connected with the top face 29 as illustrated in
FIG. 8. The fasteners (87, 89) can be a nut and bolt as shown or another type of
fastener. Preferably, a rotational axis B-B of the fan 70 is colinear with the axis Z-Z of
the cooling device 10 when the fan 70 is connected with the mounting ring 80.
Examples of suitable materials for the mounting ring 80 include but are not limited to
metals, plastics, or ceramics. The mounting ring 80 can be produced by machining,
casting, molding, and pressure diecasting.
Although the previous discussion has focused on fasteners as one means of
connecting the mounting ring 80 with the fan 70, the present invention is not to be
construed as being limited to fasteners only. For instance, a latch on the fan could mate
with a complementary latching profile on the mounting ring 80. Because the mounting
ring 80 can be formed by an injection molding process, many possibilities exist for
effectuating the mounting of the fan 70 to the mounting ring 80 and fasteners are an
example of one of those many possibilities.
In FIG. 8, the fan 70 is shown mounted on the substantially planar portion 29a of
the top face 29. For purposes of illustration, only one set of fasteners (87,89) are
shown installed through the holes 75 and the mounting fixtures 83. A power lead 72 of
the fan 70 is positioned so that it is not necessary for the power lead 72 to be routed
through or to come into contact with the vanes or fins (21, 23). Although shown with only
two wires (+ and -) the power lead 72 can include additional wires such as one or more
additional wires for communicating with a circuit that controls the fan 70 (e.g turning fan
70 on or off, or controlling fan speed) or for determining if the fan 70 is operating
properly.

Although only one fan 70 is shown in FIG. 8, two or more fans 70 can be
stacked one upon the other with the holes 75 aligned so that a longer fastener 89 can
be inserted through the holes 75 an into the mounting fixtures 83 of the mounting ring
80. Therefore, another advantage of the cooling device 10 of the present invention is
that a plurality of fans can be used to generate the air flow F into the chamber 30. The
use of more than one fan 70 allows for redundant cooling if one or more fans should fail.
In contrast, prior fan assisted heat sinks in which the fan is mounted in a cavity formed
by the fins, it is very difficult to mount more than one fan in the cavity. Moreover,
because the fan 70 is not mounted in the chamber 30, the risks associated with routing
the power lead 72 through the vanes 21 is eliminated because the fan 70 is mounted on
the top face 29.
An additional advantage to mounting the fan 70 on the top face is that if one or
more of the vanes and fins (21,23) are damaged, the blades 77 will not come into
contact with a damaged vane or fin (21,23); therefore, potential damage to the blades
77 or the fan 70 is eliminated. In FIGS. 2a, 2b and 3b, a notch 31 can be formed in the
fins 23. The notch 31 can have a shape the complements an indexing tab (not shown)
on the shroud 73 so that when the fan 70 is mounted on the top face 29 the indexing tab
mates with the notch 31. The notch 31 can be used to ensure proper orientation of the
fan 70 with respect to the cooling device 10 and/or to prevent relative movement
between the shroud 73 and the cooling device 10.
In FIG. 9, the tangential orientation of the vanes 2, as was described above in
reference to FIG. 61 can be determined by two factors. A first factor is a height h1 from
the top of the boss 13 to the top face 29. For example, when the height h1 is about 7.5
millimeters, the vanes 21 can be tangential to the circle C, having a diameter of about
6.5 millimeters. On the other hand, a second factor is a height h2 from the top of the
boss 13 to a bottom 76 of the fan blades 77. For instance, the diameter of the circle
Ct can be from about 3.0 millimeters to about 12.0 millimeters when the height h2
varies from about 2.0 millimeters to about 8.5 millimeters. The above are examples
only and the heights (h1, h2) are not to be construed as being limited to the ranges set

forth above.
The angle (β, δ1 and δ2) at which the vanes 21 are inclined relative to the axis
Z-Z as described above can be set to substantially match or closely approximate a
pitch angle θ of the fan blades 77 as illustrated in FIG. 9. On the other hand, the angles
(β, δ1, and δ2) can be set so that they are within a predetermined range of the pitch
angle θ. For example, the pitch angle 0 can be about 15.0 degrees and the angle β
can be about 17.0 degrees or the pitch angle θ can be about 12.0 degrees and the
angle δ1 can be about 10.0 degrees and the angle δ2 can be about 8.0 degrees.
Another advantage of the cooling device 10 of the present invention is that the
aforementioned tangential orientation and inclination of the vanes 21 and the
aerodynamically profiled first and second portions (25,27) of the inner wall 26 provide
a low resistance path to the air flow F thereby reducing airflow shock noise.
Additionally, because of the low resistance path, the fan 70 can be a lower RPM fan
which produces lower noise levels and can be operated on less power than a higher
RPM fan.
The cross-sectional view of the cooling device 10 in FIG. 9 also depicts
radiuses for the arcuate shapes of the boss 13, the groove 15, the second portion 27,
the first arcuate surface profile 21a, and the second arcuate surface profile 23a.
The arcuate profile of the boss 13 can have a radius rB that is dependent in part
on a desired thermal mass for the boss 13. For instance, for a thermal mass of about
50.0 grams, the radius rB for the boss 13 is about 15.0 millimeters. Similarly, the
arcuate profile of the groove 15 has a radius rG of about 2.5 millimeters. The actual
values for rB and rG will be application dependent and the above values are examples
only. The present invention is not to be construed as being limited to the values set
forth above.

Furthermore, the arcuate surface profiles for the first and second arcuate surface
profiles (21a, 23a) have a radius of rv and rF respectively. For example, the radius rv
can be from about 38.0 millimeters to about 45.0 millimeters and the radius rF can be
from about 31.0 millimeters to about 38.0 millimeters. The second portion 27 of the
inner wall 26 has a radius rc. The radius rc can be about 20.0 millimeters, for
example. The actual values for rv, rF and rG will be application dependent and the
above values are examples only. The present invention is not to be construed as being
limited to the values set forth above.
The above mentioned radiuses can be determined by a machining process
used to form the cooling device 10. Reference points for the radiuses need not be
relative to a point on the cooling device 10. The radiuses rB, rG and rc can be formed
by a forging process. They can also be machined or produced using a diecasting
process. The radiuses rv and rF can be formed by machining after forging the cooling
device 10 from a blank or material.
In one embodiment of the present invention as illustrated in FIG. 10, a fan 74
without a shroud (i.e. it lacks the shroud 73 of FIGS. 7 and 8) is positioned over the top
face 29 of the cooling device 10 by a space frame 90. A stator 71 of the fan 74 is
connected with the space frame 90 and a plurality of arms 91 span the width of the top
face 29 and fingers 93 at the ends of the arms 91 clamp the space frame 90 to the
cooling device 10 approximately at the surface 37a of the smooth radially outward
portion 37. Consequently, a hub 79 and blades 77 of the fan 74 are positioned over the
chamber 30 so that an air flow from the fan 74 can enter the chamber 30 as was
described above. Moreover, power leads 72 from the fan 74 can be routed away from
the fins and vanes (21, 23) of the cooling device 10 and away from the fan blades 77.
The space frame 90 can be integrally formed with the stator 71 or the space
frame 90 can be made from a metal or plastic material, preferably plastic because it is
electrically non-conductive.

In another embodiment of the present invention as illustrated in FIG. 13, the base
17 of the cooling device 10 includes at least two projections 22 that extend outward of
the base 17. A thermal interface material 24 is in contact with the mounting surface 19
of the heat spreader 40 and is positioned between the projections 22. The projections
22 protect the thermal interface material 25 from damage when the mounting surface
19 is in contact with a component 50. The projections 22 can also protect the thermal
interface material from damage during manufacturing, transit, and/or handling. The
thermal interface material 24 is in contact with a component face 51 of the component
50 and the thermal interface material 24 provides a thermally conductive path for waste
heat from the component face 51 to be communicated through the mounting surface 19
and into the heat mass 11. The projections 22 prevent the thermal interface material 24
from being crushed, deformed, or otherwise damaged when the cooling device 10 is
mounted on the component 50 and/or during manufacturing, transit, and handling.
The projections 22 extend outward of the base 17 by a distance dp The distance
dp will be application dependent and will depend on among other things a thickness of
the thermal interface material 24. The distance dp can be from about 0.2 millimeters to
about 1.0 millimeters. Preferably, the mounting surface 19 is a substantially planar
surface (i.e. it is substantially flat) and the mounting surface 19 is substantially
perpendicular to the axis Z-Z (i.e. about 90.0 degrees, see angle α in FIG. 10).
Additionally, the thermal interface material 24 seals micro voids (i.e. gaps)
between the mounting surface 19 and the component face 51 thereby enhancing
thermal transfer from the component 50 to the cooling device 10. Suitable materials for
the thermal interface material 24 include but are not limited to a thermally conductive
paste, a thermally conductive grease, silicone, paraffin, a phase transition material,
graphite, a coated aluminum foil, and carbon fiber. The thermal interface material 24
can be screen printed or pasted to the mounting surface 19 of the heat spreader 40, for
example.

In another embodiment of the present invention, as illustrated in FIGS. 11 and
12d, the mounting surface 19 of the heat spreader 40 can include the above mentioned
projections 22 that extend outward of the mounting surface 19 by the distance dp and
are operative to protect the thermal interface material 24 from damage as described
above. Preferably, either the base 17 or the mounting surface 19 include the
projections 22.
In FIG. 13, a system for dissipating heat 100 includes the cooling device 10 as
described above, a fan 70 connected with the top face 29 as described above, a
component 50 to be cooled by the cooling device 10, and a base mount 300. A
component face 51 of the component 50 is in contact with the mounting surface 19, or
as described above in reference to FIG. 11, a thermal interface material 24 may be
positioned intermediate between the component face 51 and the mounting surface 19.
In either case, waste heat is thermally communicated through the component
face 51 into the mounting surface 19 either by direct contact between the component
face 51 and the mounting surface 19 or via the thermal interface material 24. The base
mount 300 urges the mounting surface 19 and the component face 51 into contact with
each other so that heat from the component is thermally communicated into the cooling
device 10.
In one embodiment of the present invention, the mounting surface 19 of the heat
spreader includes the projections 22 that extend outward of the mounting surface 19
and the thermal interface material 24 is positioned intermediate between the
projections 22 as described above in reference to FIGS. 11 and 12d. Alternatively, the
base 17 can include the projections 22 that extend outward of the base 17 and the
thermal interface material 24 can be connected with the mounting surface 19 and
positioned intermediate between the projections 22 as described above.
In another embodiment of the present invention, the component 50 is carried by
a support unit 99. The support unit includes but is not limited to a socket, a substrate,
and a PC board. The socket can be mounted to a PC board in a manner that is well

understood in the electronics art. For instance the component can be a micro
processor that is inserted into a socket that is solder onto a PC board. The base
mount 300 is removably connected with the support unit 99.
On the other hand, the support unit can be a PC board on which the component
50 is soldered or otherwise electrically connected with. Although the present invention
has described the cooling device 10 in terms of its usefulness in dissipating waste heat
from electronic components, the cooling device 10 and the system 100 are not to be
construed as being limited to cooling electronic devices exclusively. Accordingly, the
component 50 can be any heat generating device from which it is desirable to remove
heat. To that end, the support unit 99 need not be a PC board or a socket. The support
unit 99 can be a substrate that carries the component 50. The component 50 may or
may not be in electrical communication with the substrate.
In FIG. 13, the base mount 300 is a base plate such as the type used for
mounting a heat sink to a PC board. A plurality of holes 300a formed in the base mount
300 and a plurality of holes 99a formed in the support unit 99 receive fasteners (87,89)
that removably connect the base mount 300 with the support unit 99. Although a nut and
bolt are shown, other fasteners and other fastening methods can be used to removably
connect the base mount 300 with the support unit 99.
In one embodiment of the present invention, the system 100 can include a
shroudless fan 74 as was described above in reference to FIG. 10. The shroudless fan
74 includes the space frame 90 for supporting the fan 74 and for positioning the
shroudless fan 74 adjacent to the top face 29 and over the chamber 30 so that the air
flow af enters the chamber 30. As previously mentioned, the space frame 90 includes
a plurality of arms 91 that span the width of the top face 29 and fingers 93 on the arms
91 clamp the space frame 90 to the smooth radially outward portion 37 of the outer wall
32.
Preferably, the heat mass 11, the base 17, and the vanes 21 are
homogeneously formed. An extrusion process can be used to homogeneously form the

heat mass 11, the base 17, and the vanes 21. The cooling device 10 can be made
from a variety of thermally conductive materials including but not limited to copper,
electrolytic copper, aluminum, and alloys of aluminum and copper, ceramics, and
silicon (Si) substrates. An exemplary material for the cooling device 10 is aluminum
1060 or aluminum 6063. For example, the heat mass 11, the base 17, and the vanes
21 can be homogeneously formed from an extruded rod or from a forged nutshell.
The cooling device 10 can be manufactured by a variety of processes including
but not limited to those listed below. First, the cooling device 10 can completely
machining from an extruded bar stock. Second, a diecasting, forging, or pressing
process can be used to form either one or both of the internal and external features (26,
32) of the cooling device 10, followed by a machining process to form the base 17, the
mounting surface 19, the projections 22, the cylindrical neck 18, and the attachment
groove 18g. Next cutting wheels can be used to form the primary P and secondary S
slots for the vanes 21 and the fins 23 respectively, followed by deburring and
degreasing. Third, impact forging the complete cooling device 10 including the vanes
21 and fins 23. Fourth, pressure diecasting the complete cooling device 10 including
the vanes 21 and fins 23.
An exemplary model of the cooling device 10 was created with a diameter of 65
mm at the top face 29 and a diameter of 50 mm at the bottom surface 11a of the heat
mass 11. The base 17 had a diameter of 40 mm and height of 6.5 mm from the bottom
surface 11a. The cooling device 10 had a total height from the mounting surface 19 to
the top face 29 of about 38 mm. The heat mass 11 had a total height of about 22 mm
from the mounting surface 19 to a top of the boss 13. The smooth curved portion 33
had a radius of about 33 mm and the draft portion 35 had a diameter of about 63 mm.
Moreover, for the fan 70, a Delta® fan, model number EFB0612VHB, and
having dimensions of 60 mm x 60 mm x 15 mm in length, breadth, and height was
mounted to the cooling device 10 as illustrated in FIG. 14. The cooling device 10 was
then mounted on a processor carried by a PGA 370 connector that was soldered onto
a mother board. The processor had a top surface of approximately 9 mm x 11 mm and

a thermal output of 36 watts. The cooling device 10 as described in this paragraph was
capable of maintaining the case temperature of the processor at 38.0 degrees Celsius
at an ambient temperature of 25.0 degrees Celsius. Based on the above
temperatures, a temperature difference of 13.0 degrees Celsius for 36 watts of thermal
power results in an estimated thermal resistance for the cooling device 10 of 0.3611
degrees Celsius per watt (13.0 degrees Celsius / 36 watts = 0.3611).
Although several embodiments of the present invention have been disclosed
and illustrated, the invention is not limited to the specific forms or arrangements of parts
so described and illustrated. The invention is only limited by the claims.

WE CLAIM
1. A cooling device 10 for dissipating heat from a component 50, comprising:
a heat mass 11 made from a first material and including a base 17, a boss 13
including a convex arcuate surface profile and a groove 15 surrounding the boss 13
and having a concave arcuate surface profile, the groove 15 and the boss 13 are
symmetrically positioned about an axis Z-Z of the heat mass 11, a taper bore 14
extending from the base 11 to the boss 13, and an aperture 14a extending from the
boss 13 to the taper bore 14;
a fastener 45 including a head 47 and a threaded shaft 49, the fastener 45 is
inserted through the aperture 14a with the head 17 in contact with the boss 17;
a heat spreader 40 made from a second material that is dissimilar to the first
material, the heat spreader 40 including a taper wall 41 with a profile that complements
the taper bore 14, a mounting surface 19 adapted to thermally connect the heat
spreader 40 with the component 50, and a threaded aperture 43 adapted to receive
the threaded shaft 49; and
a plurality of vanes 21 in contact with the heat mass 11 and spaced apart to
define a primary slot P therebetween that extends to the heat mass 11, the vanes 21
have a surface area that increases in a radially outward direction R from the axis Z-Z,
the vanes 21 including a top face 29, an aerodynamically profiled inner wall 26
including a first portion 25 extending from the groove 15 and terminating at a second
portion 27 that extends to the top face 29, the inner walls 26 of the vanes 21 defining a
chamber 30 that surrounds the groove 15, an outer wall 32 having a surface profile that
widens from the base 17 of the heat mass 11 to the tjop face 29 and includes
therebetween a smooth curved portion 33, a draft portion 35 , and a smooth radially
outward portion 37, and

the vanes 21 including at least one secondary slot S extending through a portion
of each vane 21 to define a plurality of fins 23 in each vane 21, and
wherein an air flow F entering the chamber 30 exits through the primary slots P
and a bottom portion of the secondary slots S in an exhaust flow E that dissipates heat
from the vanes 21 and the fins 23, the exhaust flow E creates a low pressure region AP
within the chamber 30 that induces an intake flow I into the chamber 30 through the
secondary slots S and a top portion of the primary slots P thereby dissipating heat from
the fins 23 and the vanes 21, and the low pressure region AP induces a surface flow B
along the first 25 and second portions 27 of the innet wall 26 so that the surface flow B
passes over the groove 15 and the boss 13 to dissipate heat from the heat mass 11.
2. The cooling device 10 as set forth in Claim 1, wherein the heat mass 11, the
base 17, and the vanes 21 are homogeneously formed.
3. The cooling device 10 as set forth in Claim 1, wherein the first material for the
heat mass 11 is a material selected from the group consisting of aluminum, an
aluminum alloy, copper, a copper alloy, and a ceramic, and
wherein the second material for the heat spreader 40 is a material selected from
the group consisting of copper, a copper alloy, silver, a silver alloy, silicon, gold, a gold
alloy, graphite, a carbon fiber material, and a carbon fiber reinforced material.
4. The cooling device 10 as set forth in Claim 1 and further comprising:
a thermal interface material 24 in contact with the mounting surface 19.
5. The cooling device 10 as set forth in Claim 1 and further comprising at least one
fan 70 positioned adjacent to the top face 29 and positioned over the chamber 30 so
that an air flow generated by the fan 70 produces the air flow F into the chamber 30.

6. The cooling device 10 as set forth in Claim 5 and further comprising a mounting
ring 80 adapted to abut against the smooth radially Outward portion 37 and including a
plurality of mounting fixtures 83 adapted to receive a fastener 89 that connects the fan
70 with the mounting ring 80 such that the fan 70 is fixedly connected with the top face
29.
7. The cooling device 10 as set forth in Claim 6, wherein at least a portion of the
top face 29 is a substantially planar portion 29a and ihe fan 70 is seated on the
substantially planar portion 29a when the fan 70 is connected with the top face 29.
8. The cooling device 10 as set forth in Claim 1, wherein the vanes 21 are
tangentially oriented to a predetermined diameter of a circle Ct centered about the axis
Z-Z.
9. The cooling device 10 as set forth in Claim 8, Where in the predetermined
diameter is from about 3.0 millimeters to about 12.0 millimeters.
10. The cooling device 10 as set forth in Claim 1, wherein the vanes 21 are inclined
at an angle β with respect to the axis Z-Z.
11. The cooling device 10 as set forth in Claim 10. wherein the angle β at which the
vanes are inclined is from about 5.0 degrees to about 25.0 degrees.
12. The cooling device 10 as set forth in Claim 10 wherein the angle at which the
vanes are inclined comprises a first angle δ1 from about 10.0 degrees to about 25.0
degrees, the first angle δ1 measured along the smooth radially outward portion, and a
second angle δ2 from about 5.0 degrees to about 18.0 degrees measured along the
smooth curved portion.

13. The cooling device 10 as set forth in Claim 1, wherein the arcuate surface profile
of the boss 13 is a profile selected from the group consisting of a sphere, a frustum of a
sphere, a cone, and a frustum of a cone.
14. The cooling device 10 as set forth in Claim 1, wherein the arcuate surface profile
of the groove 15 is a semi-circular profile.
15. The cooling device 10 as set forth in Claim 1, Wherein the primary slot P further
includes a first arcuate profile along the heat mass 11 and the first arcuate profile is a
portion of an arc having a radius from about 38.0 millimeters to about 45.0 millimeters.
16. The cooling device 10 as set forth in Claim 1, wherein the secondary slot S
extends to the heat mass 11 and the secondary slot S further includes a second arcuate
profile 23a along the heat mass 11 and the second arcuate profile 23a is a portion of
an arc having a radius from about 31.0 millimeters to about 38.0 millimeters.
17. The cooling device 10 as set forth in Claim 1,• wherein the first portion 25 of the
inner wall 26 is a sloped surface and the second portion 27 of the inner wall 26 is a
concave arcuate surface.
18. The cooling device 10 as set forth in Claim 1 and further comprising:
a shroudless fan 74 including a space frame 90 for supporting the fan 74 and for
positioning the fan 74 adjacent to the top face 29 and over the chamber 30 so that an
air flow at generated by the fan 74 produces the air flow F into the chamber 30,
the space frame 90 including a plurality of arms 91 that span the top face 29, the
arms 91 include fingers 93 at an end thereof, and the fingers 93 are adapted to clamp
the space frame 90 to the smooth radially outward portion 37 of the outer wall 32.

19. The cooling device 10 as set forth in Claim 1, wherein the taper wall 41 of the
heat spreader 40 has a profile selected from the group consisting of an arcuate profile
and a slope profile.
20. The cooling device 10 as set forth in Claim 1, wherein the heat spreader 40 has
a shape comprising a frustum of a cone.
21. The cooling device 10 as set forth in Claim 1 and further comprising:
a plurality of projections 22 connected with and extending outward of a selected
one of the mounting surface 19 of the heat spreader 40 or the base 17 of the heat mass
11; and
a thermal interface material 24 in contact with the mounting surface 19 and
positioned between the projections 22.
22. The cooling device 10 as set forth in Claim 1, wherein the fastener 45 is fixedly
connected with a selected one of the heat mass 11, the heat spreader 40, or the heat
mass 11 and the heat spreader 40.
23. The cooling device 10 as set forth in Claim 1, wherein the heat spreader 40 and
the heat mass 11 are fixedly connected to each other.
24. The cooling device 10 as set forth in Claim 1 and further comprising:
a thermal sealant 44 in contact with the taper bore 41 and the taper wall and
operative to seal micro gaps between the taper bore 41 and the taper wall 14.


A low-cost, fan assisted cooling device 10 is disclosed. The cooling device 10
includes a heat mass 11 with a taper bore 14 therein adapted to receive a heat
spreader 40 that has a shape that complement the taper bore 14. The heat mass 11
and the heat spreader 40 are made from dissimilar materials. A fastener 45 or the like
can be used to urge the heat spreader 40 and the heat mass 11 into contact with each
other. A plurality of vanes 21 are connected with the heat mass 11 and an inside
surface 26 of the vanes define a chamber 30 that surrounds the heat mass 11. A
portion of each vane 21 is split into a plurality of fins 23 and both the vanes and the fins
(21, 23) have a surface area that increase in a radially outward direction r from an axis
Z-Z of the heat mass 11.

Documents:

595-KOL-2003-(22-03-2012)-CORRESPONDENCE.pdf

595-KOL-2003-(22-03-2012)-PA-CERTIFIED COPIES.pdf

595-KOL-2003-ABSTRACT-1.2.pdf

595-KOL-2003-ABSTRACT.-1.1.pdf

595-kol-2003-abstract.pdf

595-KOL-2003-AMANDED CLAIMS-1.1.pdf

595-KOL-2003-AMANDED CLAIMS.pdf

595-KOL-2003-ASSIGNMENT 1.1.pdf

595-kol-2003-assignment.pdf

595-KOL-2003-CLAIMS.-1.1.pdf

595-kol-2003-claims.pdf

595-KOL-2003-CORRESPONDENCE 1.5.pdf

595-KOL-2003-CORRESPONDENCE-1.1.pdf

595-KOL-2003-CORRESPONDENCE-1.2.pdf

595-KOL-2003-CORRESPONDENCE-1.4.pdf

595-KOL-2003-CORRESPONDENCE.-1.3.pdf

595-KOL-2003-DESCRIPTION (COMPLETE)-1.1.pdf

595-kol-2003-description (complete).-1.1.pdf

595-kol-2003-description (complete).pdf

595-KOL-2003-DRAWINGS-1.1.pdf

595-kol-2003-drawings.pdf

595-KOL-2003-EXAMINATION REPORT REPLY RECIEVED.pdf

595-KOL-2003-EXAMINATION REPORT.pdf

595-KOL-2003-FORM 1-1.2.pdf

595-KOL-2003-FORM 1.-1.1.pdf

595-kol-2003-form 1.pdf

595-KOL-2003-FORM 13 1.1.pdf

595-KOL-2003-FORM 13-1.1.pdf

595-KOL-2003-FORM 13-1.2.pdf

595-kol-2003-form 13.pdf

595-kol-2003-form 18.pdf

595-KOL-2003-FORM 2-1.2.pdf

595-KOL-2003-FORM 2.-1.1.pdf

595-kol-2003-form 2.pdf

595-KOL-2003-FORM 3-1.2.pdf

595-KOL-2003-FORM 3.-1.1.pdf

595-kol-2003-form 3.pdf

595-KOL-2003-FORM 5.-1.1.pdf

595-kol-2003-form 5.pdf

595-KOL-2003-FORM-27-1.pdf

595-KOL-2003-FORM-27.pdf

595-kol-2003-gpa.pdf

595-KOL-2003-GRANTED-ABSTRACT.pdf

595-KOL-2003-GRANTED-CLAIMS.pdf

595-KOL-2003-GRANTED-DESCRIPTION (COMPLETE).pdf

595-KOL-2003-GRANTED-DRAWINGS.pdf

595-KOL-2003-GRANTED-FORM 1.pdf

595-KOL-2003-GRANTED-FORM 2.pdf

595-KOL-2003-GRANTED-LETTER PATENT.pdf

595-KOL-2003-GRANTED-SPECIFICATION.pdf

595-KOL-2003-OTHERS 1.1.pdf

595-KOL-2003-OTHERS 1.4.pdf

595-KOL-2003-OTHERS-1.3.pdf

595-KOL-2003-OTHERS.-1.2.pdf

595-KOL-2003-OTHERS.pdf

595-KOL-2003-PA-1.2.pdf

595-KOL-2003-PA.-1.1.pdf

595-KOL-2003-PA.pdf

595-KOL-2003-PETITION UNDER RULE 137.pdf

595-KOL-2003-PETITION UNDER RULE 138-1.1.pdf

595-KOL-2003-REPLY TO EXAMINATION REPORT.pdf

595-kol-2003-specification.pdf

595-KOL-2003-TRANSLATED COPY OF PRIORITY DOCUMENT 1.1.pdf

595-kol-2003-translated copy of priority document.pdf


Patent Number 249945
Indian Patent Application Number 595/KOL/2003
PG Journal Number 47/2011
Publication Date 25-Nov-2011
Grant Date 23-Nov-2011
Date of Filing 18-Nov-2003
Name of Patentee HEWLETT-PACKARD DEVELOPMENT COMPANY L.P.
Applicant Address 11445 COMPAQ CENTER DRIVE WEST HOUSTON, TX 77070 USA
Inventors:
# Inventor's Name Inventor's Address
1 HEGDE SHANKAR 17-81 KRISHNA NAGAR, ANNASSANDRAPALYA, BANGALORE
PCT International Classification Number F28F7/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10/427,670 2003-04-30 U.S.A.