U.S. patent application number 10/676982 was filed with the patent office on 2004-09-09 for thermal transfer interface system and methods.
Invention is credited to Belady, Christian L., Peterson, Eric C..
Application Number | 20040173345 10/676982 |
Document ID | / |
Family ID | 27659925 |
Filed Date | 2004-09-09 |
United States Patent
Application |
20040173345 |
Kind Code |
A1 |
Belady, Christian L. ; et
al. |
September 9, 2004 |
Thermal transfer interface system and methods
Abstract
The invention provides a thermal transfer interface for
dissipating heat from an object to a thermal spreader and/or heat
sink. The spreader forms a plurality of passageways. A spring
element couples with the spreader. A plurality of thermally
conductive pins moves along the passageways, extending outwardly
via the spring element for conformal and thermal contact with the
object. Thermal energy transfers from the object to the spreader
through the collective area defining the interface between the pins
and the spreader. The spring element is preferably thermally
conductive; and thermal grease added to the interface may
beneficially decrease thermal resistances due to microscopic
unevenness at the contact between the object and the pins and/or
spring element. An additional heat sink may couple to the spreader
to dissipate additional thermal energy.
Inventors: |
Belady, Christian L.;
(McKinney, TX) ; Peterson, Eric C.; (McKinney,
TX) |
Correspondence
Address: |
HEWLETT PACKARD COMPANY
P O BOX 272400, 3404 E. HARMONY ROAD
INTELLECTUAL PROPERTY ADMINISTRATION
FORT COLLINS
CO
80527-2400
US
|
Family ID: |
27659925 |
Appl. No.: |
10/676982 |
Filed: |
October 1, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10676982 |
Oct 1, 2003 |
|
|
|
10074642 |
Feb 12, 2002 |
|
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Current U.S.
Class: |
165/185 |
Current CPC
Class: |
F28F 13/00 20130101 |
Class at
Publication: |
165/185 |
International
Class: |
F28F 007/00 |
Claims
What is claimed is:
1. A thermal transfer interface, comprising: a thermal spreader
forming a plurality of passageways; a spring element coupled with
the spreader; and a plurality of thermally conductive pins for the
passageways, each of the pins having a head and a shaft moving with
the spring element, at least part of the shaft being internal to
the passageway and forming a gap with an internal surface of the
passageway, wherein the pin heads collectively and macroscopically
conform to an object coupled thereto to transfer heat from the
object to the spreader through the passageway gap formed between
the spreader and each of the plurality of pins.
2. An interface of claim 1, the spring element forming a layer with
a substantially planar face, each of the pin heads being
substantially flush with the face.
3. An interface of claim 1, the spring element forming a layer with
a substantially planar face, each of the pin heads recessed within
the spring element.
4. An interface of claim 1, the spring element formed of
non-conductive material and forming one or more apertures for
thermal energy transfer between the object and the pin heads.
5. An interface of claim 1, the spreader comprising a ventilated
metal block.
6. An interface of claim 1, the spring element comprising a
plurality of springs disposed with the passageways for biasing the
pins outwardly from the spreader towards the object.
7. An interface of claim 1, the spring element comprising a
plurality of springs disposed between the pin heads and the
spreader for biasing the pins outwardly from the spreader towards
the object.
8. An interface of claim 6, each of the pins forming a shoulder,
and further comprising a retaining element for abutting the
shoulder in defining a maximal extension of pins.
9. An interface of claim 7, each of the pins forming a shoulder,
and further comprising a retaining element for abutting the
shoulder in defining a maximal extension of pins.
10. An interface of claim 1, the thermal spreader comprising at
least one vent coupled with at least one of the passageways, to
vent pressure from the one passageway.
11. An interface of claim 1, one or more of the pin shafts having
non-cylindrical shape, each of the passageways having a
substantially matched non-cylindrical shape to accommodate motion
of the shafts therethrough.
12. An interface of claim 1, the pin heads arranged in a geometric
pattern that covers an area extending beyond a region of contact
between the pin heads and the object.
13. An interface of claim 1, further comprising thermal grease
disposed within the gap.
14. An interface of claim 1, the object comprising a semiconductor
die.
15. An interface of claim 1, the object comprising a plurality of
dies, wherein a first set of the pins contact the plurality of
dies, and wherein a second set of pins do not contact the dies.
16. A method for transferring thermal energy from a body to a heat
sink, comprising the steps of: biasing a plurality of pins against
a surface of the object so that the plurality of pins contact with,
and substantially conform to, a macroscopic surface of the object,
and communicating thermal energy from the object through the pins
to a thermal spreader forming a plurality of gaps with the
plurality of pins.
17. A method of claim 16, the step of biasing comprising biasing a
plurality of pin heads against the object utilizing a plurality of
springs.
18. A method of claim 16, the step of biasing comprising utilizing
a spring element formed of thermally conductive material with a
substantially planar face, each of the pin heads being
substantially flush with the face.
19. A method of claim 16, the step of biasing comprising utilizing
a spring elemen formed of thermally conductive material with a
substantially planar face, each of the pin heads recessed within
the spring element.
20. A method of claim 16, the step of biasing comprising utilizing
a plurality of springs disposed between pin heads of the pins and
the spreader.
21. A method of claim 16, further comprising utilizing a thermal
spreader having at least one vent coupled with at least one
passageway through the thermal spreader, to vent pressure from the
passageway.
22. A method of claim 16, the step of biasing comprising utilizing
pins with non-cylindrical shape.
23. A method of claim 16, further comprising the step of disposing
thermal grease within the gap.
24. A method of claim 16, the object comprising a semiconductor
die.
Description
RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent Ser. No.
10/074,642; entitled THERMAL TRANSFER INTERFACE SYSTEM AND METHODS;
Attorney Docket No. 10018060-1, the aforementioned application is
incorporated herein by reference thereto.
BACKGROUND OF THE INVENTION
[0002] Electronic systems often incorporate a semiconductor package
(e.g., including a semiconductor die) that generates significant
thermal energy. System designers spend considerable effort to
provide sufficient heat dissipation capability in such systems by
providing a thermally conductive path from the package to a heat
sink. A heat sink may for example be a ventilated conductive plate
or an active device such as a thermoelectric cooler.
[0003] Certain difficulties arise when these electronic systems
utilize multiple dies and other heat-generating devices. More
particularly, each die and device must have its own heat
dissipation capability; this for example complicates system design
by requiring that there is adequate ventilation and/or thermally
conductive paths and heat sinks for the entire system. Such
ventilation, thermal paths and heat sinks increase cost and
complexity, among other negative factors.
[0004] Certain difficulties also arise in multiple die electrical
systems because of mechanical tolerance build-up. That is, the
physical mounting of multiple dies on a printed circuit board
(PCB), for example, results in some minute misalignment between
reference surfaces intended to be co-aligned. Accordingly, any
attempt to use a common heat sink must also accommodate the
tolerance build-up to ensure appropriate thermal transfer across
the physical interface. Tolerance build-up may for example occur
due to the soldering that couples the dies to the PCB, and/or due
to manufacturing inconsistencies in the rigid covers or "lids"
which sometimes cover individual dies. In any event, a thermal sink
coupled to multiple dies should account for tolerance issues at the
interface between the sink and the multiple dies in order to
properly dissipate generated thermal energy. Designers of the prior
art thus often over-compensate the thermal design to accommodate
worst-case interface tolerance issues. Once again, this increases
cost and complexity in the overall electrical system, among other
negative factors.
[0005] The invention provides certain features to advance the state
of the art by providing, among other features, a thermal transfer
interface system for dissipating heat from multiple dies in an
electrical system. Other features of the invention will be apparent
in the description which follows.
SUMMARY OF THE INVENTION
[0006] In one aspect, the invention provides a thermal transfer
interface. A thermal spreader forms a plurality of passageways. A
spring element couples with the spreader. A plurality of thermally
conductive pins are included and arranged for movement along the
passageways. Each of the pins has a head and a shaft moving with
the spring element. At least part of the shaft is internal to the
passageway; and it forms a gap with an internal surface of the
passageway. The gap may be an air gap or filled with a thermally
conductive material such as thermal grease. In operation, the pin
heads collectively and macroscopically conform to an object to
transfer heat from the object to the thermal spreader through the
passageway gap formed between the heat sink and each of the
plurality of pins. In one aspect, the spreader is a heat sink; for
example the spreader is actively cooled by liquid or ventilated by
air to dissipate heat from the pins. In another aspect, a separate
heat sink couples with the spreader to dissipate the heat from the
spreader. In still another aspect, the pins extend through the
spreader so that they extend from the object through the spreader
and into a cooling medium (e.g., air); the pins extending into the
cooling medium act to dissipate heat and draw thermal energy from
the spreader and/or object to the medium.
[0007] The spring element of one aspect forms a layer with a
substantially planar face. One or more of the pin heads protrude
from the face in a direction away from the spreader. In another
aspect, one or more of the pin heads are substantially flush with
the face. In yet another aspect, one or more of the pin heads are
embedded within the spring element. Thermal grease or other
conductive medium may assist in thermal heat transfer from the
object to the pins and/or spring element.
[0008] In yet another aspect, the pin head is slightly smaller than
the remainder of the pin shaft so that a pin shoulder is formed. A
retaining element couples to the spreader to retain the pin shafts
between the spreader and the retaining element; the pins axially
move along the passageway to couple with the object, as above, but
the pin element will extend from the spreader only until the
shoulder abuts the retaining element.
[0009] In another aspect, the passageways are sealed to form a
cavity and the pin shafts seat in the passageways such that a
filler medium pressurizes the pins to form the spring element. The
filler medium may be air or a thermally conductive medium such as
thermal grease. A small gap in the spreader may be included with
one or more passageways to vent over-pressurization of the filler
medium.
[0010] In still another aspect, the spring element includes a
plurality of springs disposed between the spreader and the pin
heads. In another aspect, the spring element includes a plurality
of springs disposed within the passageways between the spreader and
the pin shafts.
[0011] The pin shafts may be rectangularly shaped. The passageways
have a similar though slightly larger shape to accommodate the pin
shaft dimensions. As an alternative, the pin shafts are cylindrical
in shape and the passageways are also cylindrical, through slightly
larger in size to accommodate pin movement of the shaft
therein.
[0012] The invention has particular advantages in dissipating heat
from objects in the form of one or more semiconductor dies. In one
aspect, a heat sink couples to the spreader. The heat sink may for
example be an active thermoelectric cooler, a cooled thermally
conductive element (e.g., a thermally conductive block cooled by
liquid), or a passive thermally dissipating metal block.
[0013] The invention has further advantages in that it may be
inverted depending upon desired application. That is, the invention
of one aspect is a thermal interface: it transfers heat from one
side to another irrespective of applied orientation.
[0014] In one aspect, the spring element is a thermally conductive
sponge-like material. The spring element may one or a combination
of various forms of spring elements disclosed herein.
[0015] The invention also provides a method for transferring
thermal energy from a body to a thermal spreader and/or heat sink,
including the steps of: biasing a plurality of pins against a
surface of the object so that the plurality of pins contact with,
and substantially conform to, a macroscopic surface of the object,
and communicating thermal energy from the object through the pins
to a thermal spreader forming a plurality of air gaps with the
plurality of pins. The step of biasing a plurality of pins against
a surface of an object may include the step of biasing the
plurality of pins against a plurality of dies or semiconductor
packages coupled with a printed circuit board or other electrical
apparatus. The thermal spreader may act as the heat sink with the
pins; or, in another aspect, a separate heat sink couples with the
spreader.
[0016] The invention is next described further in connection with
preferred embodiments, and it will become apparent that various
additions, subtractions, and modifications can be made by those
skilled in the art without departing from the scope of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] A more complete understanding of the invention may be
obtained by reference to the drawings, in which:
[0018] FIG. 1 shows a cross-sectional side view of one thermal
interface system constructed according to the invention;
[0019] FIG. 2 shows a top view of the system of FIG. 1;
[0020] FIG. 3 shows the system of FIG. 1 used to dissipate heat
from a plurality of dies, in accord with one embodiment of the
invention;
[0021] FIG. 4 shows a side view of another thermal interface system
of the invention;
[0022] FIG. 5 shows a top view of one other thermal interface
system of the invention;
[0023] FIG. 6 shows a cross-sectional view of the thermal interface
system of FIG. 5;
[0024] FIG. 7 shows a perspective view of the thermal interface
system of FIG. 5;
[0025] FIG. 8 shows a perspective view of several of the thermal
interface systems of FIG. 5 operationally connected to dissipate
heat from semiconductor packages of a printed circuit board;
[0026] FIG. 9 shows a cross-sectional view of the system of FIG. 8
coupled with two of the packages;
[0027] FIG. 10 shows another spring element configuration for
biasing pins according to one thermal interface system of the
invention; and
[0028] FIG. 11 shows another spring-element configuration for
biasing pins according to one thermal interface system of the
invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 shows a cross-sectional side view of one thermal
interface system 10 of the invention. System 10 includes a
plurality of thermally conductive pins 12 that interface with an
object 14 to transfer heat from object 14 to a thermal spreader 16.
A spring element 18 facilitates coupling between pins 12 and object
14 such that pins 12 collectively conform with a surface 14A of
object 14, even if surface 14A is non-planar, such as shown. As
used herein, each of pins 12 may for example be described with a
head 12A and a shaft 12B, such as shown in FIG. 1. By way of
operation, for those pins 12 that are in range of object 14, pin
heads 12A are adjacent to, or in contact with object 14, while
shafts 12B of pins 12 have at least some portion adjacent to, or in
contact with thermal spreader 16. In one embodiment, pins 12 pass
within a like plurality of passageways 16A of spreader 16. For
purposes of illustration, only one passageway 16A is shown and
identified in FIG. 1; pins 12 slide within passageways 16A to
accommodate movement of pins 12, and/or element 18, in conformal
contact with object 14.
[0030] FIG. 2 shows a top view of object 14 and system 10. For
purposes of illustration, spring element 18 is transparently shown
so as to clearly show the plurality of passageways 16A with pins
12. In operation, system 10 serves to dissipate heat from object 14
to spreader 16. Pins 12 are in thermal communication with object 14
when pins 12 (a) directly contact object 14, (b) couple to object
14 through a thermally conductive medium (e.g., thermal grease or a
thermally conductive spring element 18), and/or (c) are close to
object 14 such that the air gap between pin heads 12A and object 14
does not substantially prohibit heat transfer. It is not necessary
that every pin 12 thermally communicate with object 14. System 10
utilizes a plurality of pins that number in the tens, hundreds,
thousands or millions; collectively these pins macroscopically
conform to surface 14A of object 14 to transfer heat from object
14, through a plurality of pins 12 and to spreader 16.
[0031] Thermal spreader 16 may also form a heat sink to draw heat
from object 14. Pins 12 may also form a heat sink; for example, by
communicating air 19 across pins 12 extending through spreader 16,
as shown, pins 12 are cooled to collectively function as a heat
sink. Optionally, a separate heat sink 21 may couple to thermal
spreader 16, as shown, to dissipate or assist in drawing heat from
object 14.
[0032] Object 14 may for example be a semiconductor die or package,
such as described in connection with FIG. 3. Spring element 18 may
be replaced or augmented with different spring-like elements as
described in more detail below.
[0033] FIG. 3 shows system 10 in another configuration, where the
object is a plurality of objects 30A-30C. In one embodiment of the
invention, objects 30A-30C are semiconductor packages and/or dies
(collectively "dies" 30). As shown, objects 30 are beneath system
10, illustrating that system 10 may be configured in multiple
orientations without departing from the scope of the invention; by
way of example, system 10 may mount on top of dies 30 using its
weight or other force to couple pins 12 to dies 30. Each of dies 30
is shown with a different physical size and with a different
physical separation 32 from system 10, as compared with other dies
30, so as to illustrate that system 10 may accommodate physical
non-uniformities and uneven surfaces of objects 30. Dies 30 may for
example couple with a PCB 34 via solder or socket connections 36,
as shown; solder or socket connections 36, and the manufacturing
build-up tolerances of PCB 34 and dies 30, may cause the variations
in separation differences 32 between the multiple dies and system
10, such as shown. Pins 12 axially move along direction 31, within
passageways 16A and relative to thermal spreader 16 to accommodate
conformal contact with object 30. As above, spreader 16 and/or pins
12 may function as a heat sink, or a separate heat sink (e.g., sink
21, FIG. 1) may couple with spreader 16.
[0034] Spring element 18 serves to bias pins 12 in accommodating
physical separation differences 32 to relevant pins 12 so as to
ensure macroscopic conformity (i.e., where multiple pins conform to
an object surface larger than any one pin) between pins 12 and
outer surfaces of dies 30. By way of example, spring element 18
biases pins 38 with die 30C, spring element 18 biases pins 40 with
die 30B, and spring element 18 biases pins 42 with die 30A. Pins 44
are not engaged with object 30 and are in this example maximally
extended from system 10. Other pins 12--not shown in FIG. 3--may or
may not connect with object 30.
[0035] FIG. 4 shows a cross-sectional view of one thermal interface
system 50 of the invention. System 50 is shown with three different
pin configurations, one for each of pins 52, 54, 56. Though not
required, typically each pin is in a same configuration (e.g., each
of pins is in the configuration of pin 52, pin 54 or 56); in
addition, only three pins 52, 54, 56 are shown when system 50
generally has many more pins that enable coupling to micro-features
of an object 59 (e.g., object 14, FIG. 1). Pins 52, 54, 56 couple
with a thermal spreader 58 via a spring pad 60, as shown (other
spring elements may augment or replace pad 60, such as described
below). In the configuration of pin 52, a head 52A of pin 52
extends from spring pad 60 while a shaft 52B of pin 52 extends at
least partially within a passageway 58A of spreader 58. In the
configuration of pin 54, a head 54A of pin 54 is coplanar with
spring pad 60 while a shaft 54B of pin 54 extends at least
partially within a passageway 58B of heat sink 58. In the
configuration of pin 56, a head 56A of pin 56 is embedded within
spring pad 60 while a shaft 56B of pin 56 extends at least
partially within a passageway 58C of heat sink 58. In each pin
configuration, the shaft length of the pin 52 is sufficiently long
to ensure thermal transfer between the shaft and spreader 58.
[0036] Passageways 58A, 58B, 58C are shown with a closed end 62,
though the passageways(s) may extend entirely through spreader 58
as a matter of design choice (e.g., as in FIG. 1). In the
configuration of FIG. 4, passageways 58A-58C thus form a cavity 65
within spreader 58. Cavity 65 may itself function as a spring
element. By way of example, air or other thermally conductive
medium may fill cavity 65 and compress/expand with pin movement
within passageways 58A-58C. A small vent 67 may be included within
end 62 as a matter of design choice to vent over-pressurization of
material in cavity 65; vent 67 is shown with only one passageway
58A for ease of illustration even though system 50 may include
multiple vents 67 as a matter of design choice.
[0037] Each of pins 52, 54, 56 form a gap 64 with an internal
surface 66 of respective passageways 58A, 58B, 58C; gap 64 is
formed between the smaller diameter of shaft 52B, 54B, 56B within
the larger diameter of respective passageways 58A, 58B, 58C. By way
of example, each of pin shafts 52B, 54B, 56B may have a cylindrical
shape with a diameter of about 0.06 inch, and each passageway 58A,
58B, 58C then has a diameter of between about 0.0605 to 0.065 inch.
Gaps 64 (and/or cavities 65) may be filled with thermally
conductive grease, gas, air or other thermally conductive medium.
Pin shafts 52B, 54B, 56B may also be rectangular in shape;
passageways 58A, 58B, 58C accordingly would-also be rectangular,
though larger in size to accommodate pin movement therein.
[0038] Pins 52, 54, 56 may move with spring element 60. Spring
element 60 is for example a thermally conductive sponge-like
material, though a non-conductive pad may also be used so long as
an aperture cut into the pad permits thermal energy transfer from
object 59 to the relevant pin 52. A layer 70 of thermally
conductive grease may cover over element 60 and pins 52, 54, 56 to
encourage transfer of thermal energy from object 59 to spreader 58;
grease 70 is particularly useful in the configurations of pin 52,
54 as spring element 60 can provide thermal microscopic contact
between object 59 and pin 56.
[0039] Though not required, system 50 may include a heat sink 71 to
draw thermal energy from pins 52 and spreader 58. Thermal grease 73
can improve thermal conductivity between spreader 58 and heat sink
71, as shown. Illustratively, thermal energy 75 from object 59
travels through layer 70, into pins 52, 54, 56, out of pin shafts
52B, 54B, 56B and into spreader 58 through the gap 64 between
shafts 52B, 54B, 56B, and into heat sink 71, such as shown.
[0040] The interfaces of FIG. 1-FIG. 4 take advantage of the
physics of thermal resistance, which equals L/KA (where L is the
path length of heat flow, K is the conductivity, and A is the area
though which the heat flows). A way to decrease thermal resistance
of interfaces 10, 50 is therefore to decrease path length L or to
increase area A. Since interface 10, 50 is already very close to
object 59 from which it dissipates heat, L is already small; the
invention thus has particular advantages in increasing area A. Area
A is approximately equal to the number of pins forming the
interface times the barrel area of the pin shafts forming gap 64.
By ensuring gap 64 is small, there is negligible heat resistance
across the gap, and spreader 58 maximally dissipates heat from
object 59. Increasing the number of pins in interface 50 increases
heat transfer efficiency by increasing the cumulative area of gaps
64 between object 59 and spreader 58; this efficiency improves
further when gaps 64 are filled with thermally conductive grease or
paste. Accordingly, the interfaces of the invention may utilize
hundreds, thousands or millions of pins, as a matter of design
choice. Pins may also be arranged in any pattern with the spreader,
such as shown by the configuration of pins 12, FIG. 2, or pins 82,
FIG. 7. The pins are thermally conductive; accordingly, copper,
aluminum or other thermally conductive material provides acceptable
materials for construction of the pins.
[0041] A thermal pad of the prior art may exhibit a thermal
resistance of between about 2-5 inches-squared per Watt per degree
C. while accommodating surface irregularities of only about 0.06
inch. A prior art thermal pad with a thickness exceeding about
0.002 inch exhibits thermally insulating properties or behaviors
compounding the undesirable issues discussed above relative to the
prior art. The interfaces 10, 50 of the invention, on the other
hand, can for example improve such thermal resistances to at least
about 0.2-0.5 inches-squared per Watt per degree C., and further
accommodate macroscopic surface variations and differences (e.g.,
differences 32, FIG. 3) exceeding 0.06 inch.
[0042] FIG. 5 shows a top view of one thermal interface system 80
of the invention; FIG. 6 shows a cross-sectional view of system 80;
and FIG. 7 shows a perspective view of system 80. A plurality of
pins 82 conform to a surface of an object 83 (e.g., object 14, FIG.
1) so as to dissipate heat from object 83 to a thermal spreader 84.
Each of pins 82 has a shaft 85 within respective passageways 87 of
spreader 84; sizing of pins 82 within passageways 87 forms a small
gap 86 between each pin 82 and spreader 84. Gap 86 may be filled
with thermally conductive material such as grease. In one
acceptable configuration of system 80, a dimension 88 is 6 mm, a
dimension 90 is 6.5 mm, a dimension 92 is 0.86 mm, a dimension 94
is 2.1 mm, a dimension 96 is 25.4 mm, a dimension 98 is 1.35 mm, a
diameter 100 of each of pins 82 is 0.084 mm, a dimension 102 is
1.70 mm, and a pin length dimension 104 is 1.52 mm. For purposes of
clarity, a spring element is not shown in FIG. 5 and FIG. 6;
however a spring element such as spring element 60, FIG. 4, may for
example be included with system 80 within the space provided by
dimension 92. Helical springs such as shown in FIG. 9 or FIG. 10
may also be used.
[0043] FIG. 8 illustrates how two or more systems 80 may for
example dissipate heat from multiple semiconductor packages 81 of a
printed circuit board 110. As shown, three thermal interface
systems 80 couple to packages 81 to dissipate heat generated
thereby. Each package 81 may include a die (85, FIG. 9) that is
typically smaller in surface area than each of systems 80. That is,
each package 81 may be larger than system 80 as a matter of design
choice; generally, however, each system 80 at least covers the
surface area of die 85 within package 81. As described in more
detail below, a common heat sink 83 may couple with multiple
systems 80, as shown, to dissipate heat from spreaders 84.
[0044] FIG. 9 shows a cross-sectional side view of two thermal
interface systems 80 coupled with two packages 81; a semiconductor
die 85 is within each package 81, as shown. Pins 82 move within
spreaders 84 to accommodate the height differences 93 of packages
81; accordingly, common heat sink 83 may couple to a substantially
flat plane 101 along the top of spreaders 84. Thermal grease at
plane 101 between spreaders 84 and heat sink 83 facilitate thermal
communication therebetween.
[0045] Those skilled in the art should appreciate that changes may
be made to the above description without departing from the scope
of the invention. By way of example, spring elements 18, 60 may be
replaced, or augmented by tiny springs disposed within passageways
16A, 58A, 58B, 58C so as to outwardly push pins outward from heat
sink 16, 58, 84 in conforming to a heat generating object 14, 30,
59, 83. A configuration such as this is shown in FIG. 10. FIG. 10
specifically illustrates one thermal interface system 150 of the
invention that incorporates a plurality of spring elements 152
disposed with passageways 154 of a thermal spreader 156 to bias
pins 158 outwardly (along direction 159) from spreader 156 to
conform to an object 160. Elements 152 couple with spreader 156 and
pins 158 via connectors 162 so that pins 158 appropriately bias
against object 160 to collectively conform to surface 160A by
appropriate compression against spreader 156.
[0046] Spring elements may also be utilized underneath the heads of
the pins, and between the heads and the spreader, as shown in the
thermal interface system 161 of FIG. 11. Three pins 162A-162C are
shown in FIG. 11. A plurality of springs 164 generate compressive
forces to bias pins 162 along direction 166, as shown, for thermal
communication with an uneven object 168; springs 164 compress
between spreader 172 (or against element 176 described below) and
pin head 163 to accommodate the uneven surface of object 168. Like
above, pins 162 move along direction 166 and within a like
plurality of passageways 170 of a thermal spreader 172. A heat sink
174 may optionally couple to spreader 172 to facilitate cooling of
object 168.
[0047] FIG. 11 also illustrates one pin embodiment of a thermal
interface system to retain pins 162 relative to spreader 172. In
this embodiment, a retaining element 176 couples with spreader 172.
Pins 162 are shown with a shoulder 178 that abuts element 176 when
extended as in pin 162A; element 176 forms apertures to accommodate
passage of the above-shoulder extensions 180 of pins 162.
Accordingly, the retaining embodiment of FIG. 11 ensures that pins
162 do not completely separate from spreader 172.
[0048] Since certain changes may be made in the above methods and
systems without departing from the scope of the invention, it is
intended that all matter contained in the above description or
shown in the accompanying drawing be interpreted as illustrative
and not in a limiting sense. It is also to be understood that the
following claims are to cover all generic and specific features of
the invention described herein, and all statements of the scope of
the invention which, as a matter of language, might be said to fall
there between.
* * * * *