U.S. patent application number 10/268812 was filed with the patent office on 2004-04-15 for circuit card module including mezzanine card heat sink and related methods.
This patent application is currently assigned to Harris Corporation. Invention is credited to Beak, Todd David, Wells, Robert Grayson.
Application Number | 20040070944 10/268812 |
Document ID | / |
Family ID | 32042878 |
Filed Date | 2004-04-15 |
United States Patent
Application |
20040070944 |
Kind Code |
A1 |
Wells, Robert Grayson ; et
al. |
April 15, 2004 |
CIRCUIT CARD MODULE INCLUDING MEZZANINE CARD HEAT SINK AND RELATED
METHODS
Abstract
A circuit card module to be received in a card chassis includes
a host card assembly and a mezzanine card assembly carried in
spaced relation by the host card assembly. The host card assembly
includes a host card heat sink having an end to connect to the card
chassis to conduct heat thereto, and a host circuit card mounted on
the host card heat sink. The mezzanine card assembly includes a
mezzanine card heat sink, and a mezzanine circuit card mounted on
the mezzanine card heat sink. The mezzanine card heat sink has an
end to connect to the card chassis to conduct heat thereto in
parallel with heat conducted from the host card heat sink to the
card chassis. The mezzanine card heat sink may comprise a body
adjacent the mezzanine circuit card, and a flexible strap extending
outwardly therefrom to connect to the card chassis.
Inventors: |
Wells, Robert Grayson;
(Melbourne Beach, FL) ; Beak, Todd David; (West
Melbourne, FL) |
Correspondence
Address: |
ALLEN, DYER, DOPPELT, MILBRATH & GILCHRIST P.A.
1401 CITRUS CENTER 255 SOUTH ORANGE AVENUE
P.O. BOX 3791
ORLANDO
FL
32802-3791
US
|
Assignee: |
Harris Corporation
Melbourne
FL
|
Family ID: |
32042878 |
Appl. No.: |
10/268812 |
Filed: |
October 10, 2002 |
Current U.S.
Class: |
361/704 ;
361/715 |
Current CPC
Class: |
H05K 7/1461 20130101;
Y10T 403/76 20150115; H05K 1/141 20130101; H05K 7/1404 20130101;
H05K 7/20545 20130101 |
Class at
Publication: |
361/704 ;
361/715 |
International
Class: |
H05K 007/20 |
Claims
That which is claimed is:
1. A circuit card module to be received in a card chassis, the
circuit card module comprising: a host card assembly comprising a
host card heat sink having an end to connect to the card chassis to
conduct heat thereto, and a host circuit card mounted on said host
card heat sink; and a mezzanine card assembly carried by said host
card assembly in spaced relation therefrom and comprising a
mezzanine card heat sink having an end to connect to the card
chassis to conduct heat thereto and in parallel with heat conducted
from said host card heat sink to the card chassis, and a mezzanine
circuit card connected to said mezzanine card heat sink.
2. A circuit card module according to claim 1 wherein said
mezzanine card heat sink comprises a body adjacent said mezzanine
circuit card, and a flexible strap extending outwardly from said
body to connect to the card chassis.
3. A circuit card module according to claim 2 wherein said body and
said flexible strap are integrally formed as a monolithic unit.
4. A circuit card module according to claim 1 wherein said
mezzanine card heat sink comprises copper.
5. A circuit card module according to claim 1 wherein the ends of
said host card heat sink and mezzanine card heat sink are to be
connected together at the card chassis.
6. A circuit card module according to claim 1 wherein said host
card assembly further comprises a card retainer for connecting to
the card chassis.
7. A circuit card module according to claim 6 wherein said card
retainer overlies the ends of said mezzanine card heat sink and
said host card heat sink.
8. A circuit card module according to claim 1 wherein the ends of
said host card heat sink and mezzanine card heat sink are to be
connected in spaced relation at the card chassis.
9. A circuit card module according to claim 1 wherein said host
card assembly and said mezzanine card assembly each comprises
respective mating electrical connector portions.
10. A circuit card module according to claim 1 wherein said
mezzanine card assembly further comprises a plurality of support
posts extending outwardly to engage said host card assembly.
11. A circuit card module according to claim 1 wherein said host
circuit card comprises a host substrate and a plurality of
electronic components carried thereby; and wherein said mezzanine
circuit card comprises a mezzanine substrate and a plurality of
electronic components carried thereby and facing the electronic
components of said host circuit card.
12. A circuit card module according to claim 1 wherein said
mezzanine circuit card comprises a peripheral component interface
(PCI) card.
13. A circuit card module according to claim 1 wherein said
mezzanine card assembly is configured to conform to at least one of
the IEEE Standard for a Common Mezzanine Card (CMC) Family and the
Conduction Cooled PCI Mezzanine Card (CCPMC) Draft Standard, VITA
20-200x standards.
14. A circuit card module to be received in a card chassis, the
circuit card module comprising: a host card assembly comprising a
host card heat sink having an end to connect to the card chassis to
conduct heat thereto, and a host circuit card mounted on said host
card heat sink; and a mezzanine card assembly carried by said host
card assembly in spaced relation therefrom and comprising a
mezzanine card heat sink having an end to connect to the card
chassis to conduct heat thereto and in parallel with heat conducted
from said host card heat sink to the card chassis, and a mezzanine
circuit card connected to said mezzanine card heat sink, said
mezzanine card heat sink comprising a body adjacent said mezzanine
circuit card, and a flexible strap extending outwardly from said
body to connect to the card chassis; the ends of said host card
heat sink and mezzanine card heat sink to be connected together at
the card chassis.
15. A circuit card module according to claim 14 wherein said body
and said flexible strap are integrally formed as a monolithic
unit.
16. A circuit card module according to claim 14 wherein said
mezzanine card heat sink comprises copper.
17. A circuit card module according to claim 14 wherein said host
card assembly further comprises a card retainer for connecting to
the card chassis; and wherein said card retainer overlies the ends
of said mezzanine card heat sink and said host card heat sink.
18. A circuit card module according to claim 14 wherein said host
card assembly and said mezzanine card assembly each comprises
respective mating electrical connector portions.
19. A circuit card module according to claim 14 wherein said
mezzanine card assembly further comprises a plurality of support
posts extending outwardly to engage said host card assembly.
20. A circuit card module according to claim 14 wherein said host
circuit card comprises a host substrate and a plurality of
electronic components carried thereby; and wherein said mezzanine
circuit card comprises a mezzanine substrate and a plurality of
electronic components carried thereby and facing the electronic
components of said host circuit card.
21. A circuit card module according to claim 14 wherein said
mezzanine circuit card comprises a peripheral component interface
(PCI) card.
22. A circuit card module according to claim 14 wherein said
mezzanine card assembly is configured to conform to at least one
the IEEE Standard for a Common Mezzanine Card (CMC) Family and the
Conduction Cooled PCI Mezzanine Card (CCPMC) Draft Standard, VITA
20-200x standards.
23. A circuit card module to be received in a card chassis, the
circuit card module comprising: a host card assembly comprising a
host circuit card; and a mezzanine card assembly carried by said
host card assembly in spaced relation therefrom and comprising a
mezzanine card heat sink, and a mezzanine circuit card connected to
said mezzanine card heat sink, said mezzanine card heat sink
comprising a body adjacent said mezzanine circuit card, and a
flexible strap extending outwardly from said body and having an end
to connect to the card chassis to conduct heat thereto.
24. A circuit card module according to claim 23 wherein said body
and said flexible strap are integrally formed as a monolithic
unit.
25. A circuit card module according to claim 23 wherein said
mezzanine card heat sink comprises copper.
26. A circuit card module according to claim 23 wherein said host
card assembly and said mezzanine card assembly each comprises
respective mating electrical connector portions.
27. A circuit card module according to claim 23 wherein said
mezzanine card assembly further comprises a plurality of support
posts extending outwardly to engage said host card assembly.
28. A circuit card module according to claim 23 wherein said host
circuit card comprises a host substrate and a plurality of
electronic components carried thereby; and wherein said mezzanine
circuit card comprises a mezzanine substrate and a plurality of
electronic components carried thereby and facing the electronic
components of said host circuit card.
29. A circuit card module according to claim 23 wherein said
mezzanine circuit card comprises a peripheral component interface
(PCI) card.
30. A circuit card module according to claim 23 wherein said
mezzanine card assembly is configured to conform to at least one of
the IEEE Standard for a Common Mezzanine Card (CMC) Family and the
Conduction Cooled PCI Mezzanine Card (CCPMC) Draft Standard, VITA
20-200x standards.
31. A mezzanine card assembly to be carried by a host card assembly
in spaced relation therefrom and to conduct heat to a card chassis
receiving the host card assembly, the mezzanine card assembly
comprising: a mezzanine card heat sink; and a mezzanine circuit
card connected to said mezzanine card heat sink; said mezzanine
card heat sink comprising a body adjacent said mezzanine circuit
card, and a flexible strap extending outwardly from said body and
having an end to connect to the card chassis to conduct heat
thereto.
32. A mezzanine card assembly according to claim 31 wherein said
body and said flexible strap are integrally formed as a monolithic
unit.
33. A mezzanine card assembly according to claim 31 wherein said
mezzanine card heat sink comprises copper.
34. A mezzanine card assembly according to claim 31 further
comprising an electrical connector portion carried by said
mezzanine circuit card for mating with the host circuit card
assembly.
35. A mezzanine card assembly according to claim 31 further
comprising a plurality of support posts extending outwardly from
said mezzanine circuit card to engage the host card assembly.
36. A mezzanine card assembly according to claim 31 wherein said
mezzanine circuit card comprises a peripheral component interface
(PCI) card.
37. A mezzanine card assembly according to claim 31 wherein said
mezzanine card is configured to conform to at least one of the IEEE
Standard for a Common Mezzanine Card (CMC) Family and the
Conduction Cooled PCI Mezzanine Card (CCPMC) Draft Standard, VITA
20-200x standards.
38. A method for conduction cooling of a mezzanine circuit card
assembly comprising: mounting the mezzanine circuit card assembly
to a host circuit card assembly in spaced relation therefrom, the
mezzanine card assembly comprising a mezzanine card heat sink and a
mezzanine circuit card connected to the mezzanine card heat sink,
the mezzanine card heat sink comprising a body adjacent the
mezzanine circuit card, and a strap extending outwardly from the
body; and connecting the strap of the mezzanine card heat sink to a
card chassis receiving the host circuit card assembly.
39. A method according to claim 38 wherein the strap is
flexible.
40. A method according to claim 38 wherein the body and the
flexible strap are integrally formed as a monolithic unit.
41. A method according to claim 38 wherein the host card assembly
comprises a host card heat sink having an end, and a host circuit
card mounted on the host card heat sink; and further comprising
connecting the end of the host card heat sink to the card chassis
together with the end of the strap of the mezzanine card heat
sink.
42. A method according to claim 38 wherein the host card assembly
comprises a host card heat sink having an end, and a host circuit
card mounted on the host card heat sink; and further comprising
connecting the end of the host card heat sink to the card chassis
in spaced relation from the end of the strap of the mezzanine card
heat sink.
43. A method according to claim 38 wherein the mezzanine circuit
card comprises a peripheral component interface (PCI) card.
44. A method according to claim 38 wherein the mezzanine card
assembly is configured to conform to at least one of the IEEE
Standard for a Common Mezzanine Card (CMC) Family and the
Conduction Cooled PCI Mezzanine Card (CCPMC) Draft Standard, VITA
20-200x standards.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of electronic
circuits, and, more particularly, to circuit cards.
BACKGROUND OF THE INVENTION
[0002] The electronic components of computers and other modern
electronic devices are frequently mounted on a printed wiring board
(PWB). The PWB and electronic components mounted thereon define a
circuit card that can be inserted into a chassis and electronically
coupled to a backplane of the electronic device. One circuit card
may serve as a host card to another circuit card electrically and
physically connected thereto. The circuit card connected to the
host circuit card is typically carried in piggyback fashion above
and parallel to the host circuit card and is conventionally
referred to as a mezzanine circuit card.
[0003] Commercial off-the-shelf mezzanine circuit cards are
increasingly used for a variety of functions. A peripheral
component interconnect (PCI) mezzanine card, for example, provides
an efficient network interface allowing multiple computers and/or
other electronic devices to electronically communicate and exchange
data with one another. A particular example of such a mezzanine
card is a fiber channel (FC) network interface card (NIC) that is
mounted to a host card that can be used, for example, in the
avionics field.
[0004] As with electronic devices generally, operation of a circuit
card can generate heat that, if not adequately controlled through
some cooling mechanism, may cause damage to the electronic
components carried on the circuit cards. One approach has been to
use convection cooling techniques and devices. With convection
cooling, the circuit cards may be mounted to a chassis in a way
that permits cooling air to flow over the circuit cards.
[0005] For proper convection cooling, an adequate flow of cooling
air should be generated. This may be done, for example, using a fan
encased in the electronic device. The circuit cards, moreover,
should be arranged so that a sufficient amount of the circuit
card's surface area is exposed to the cooling air, and so that the
cooling air flows relatively freely within the electronic device.
Such arrangements may be incompatible, however, with some uses of
circuit cards where electronic devices typically need to be quite
small in size. Accordingly, there may not be space in such devices
for a fan or to arrange the circuit cards so that air flows freely
over them.
[0006] Accordingly, there is increasing demand for mezzanine and
other circuit cards that can be conduction cooled. This increased
demand is evinced, for example, by the Conduction Cooled PCI
Mezzanine Card (CCPMC) Draft Standard VITA 20-200x (Draft 1.16)
released in July of 2001 by the VITA Standards Organization. There
is also a need to make conduction cooling more effective so that
circuit cards can be used in environments subject to extreme
temperature ranges, such as for military applications and in
avionics.
[0007] U.S. Pat. No. 6,212,075 to Habing et al. discloses a kit for
adapting circuit cards to increase their cooling efficiency while
allowing them to remain compliant with IEEE 1101.2 specifications.
The kit includes an extended width wedgelock that connects a frame
to the cold wall of a card chassis. The frame, in turn, connects to
a base card and a mezzanine card carried thereon. Heat is
transferred via the frame from the cards and from a
component-mounted thermal heat sink to the cold wall. The wedgelock
has an extended width so as to increase the surface area contact
between the frame and the cold wall.
[0008] With conventional conduction cooling techniques and devices
for host and mezzanine circuit cards, heat is conducted from both
the host circuit card and the mezzanine circuit card carried
thereon to a single heat sink. Thus heat is conducted additively
from both circuit cards to the single heat sink, which, in turn,
may connect to the cold wall of the chassis to conduct the combined
heat in serial fashion to the cold wall.
[0009] Attempts to provide better cooling of circuit card devices
have not been wholly satisfactory. For example, thermoelectric
cooling may require a relatively large amount of power, while
another technique--that of conducting heat via heatpipes--does do
not appear suited for robust environments such as those associated
with military avionics. Moreover, standards such as the Conduction
Cooled PCI Mezzanine Card (CCPMC) Draft Standard may be difficult
to conform to using such conventional approaches.
BRIEF SUMMARY OF THE FIGURES
[0010] FIG. 1 is a perspective view of a circuit card module and
chassis portion according to the present invention.
[0011] FIG. 2 is another perspective view of the circuit card
module in FIG. 1.
[0012] FIG. 3 is a greatly enlarged side elevation view of the
circuit card module and chassis in FIG. 1.
[0013] FIG. 4 is a greatly enlarged side elevation view of another
embodiment of the circuit card module and chassis in FIG. 1.
[0014] FIG. 5 is a greatly enlarged side elevation view of yet
another embodiment of the circuit card module and chassis in FIG.
1.
SUMMARY OF THE INVENTION
[0015] In view of the foregoing background, it is therefore an
object of the present invention to provide a more efficiently
cooled circuit card module.
[0016] This and other objects, features, and advantages in
accordance with the present invention are provided by a circuit
card module that includes both a host card assembly and a mezzanine
card assembly carried thereon, both the assemblies having
respective heat sinks that may conduct heat in parallel to a card
chassis. The parallel heat conduction contrasts sharply with
conventional cooling techniques and devices in which heat is
transferred to a common heat sink and then conducted to the card
chassis. Instead, the heat paths from the respective assemblies in
accordance with the invention are decoupled so that the conduction
of each of the respective heat sinks is more thermally efficient.
The enhanced thermal efficiency is achieved easily and without
having to reduce the number or power of heat dissipating electrical
components that may be carried on the respective card
assemblies.
[0017] The host card assembly of the circuit card module may
include a host card heat sink, which has an end that connects to
the card chassis to conduct heat thereto. The host card assembly
also may include a host circuit card mounted on the host card heat
sink.
[0018] The mezzanine card assembly may be carried on the host card
assembly in a spaced relation therefrom. The mezzanine card
assembly may include a mezzanine card heat sink, which has an end
that connects to the card chassis to conduct heat thereto in
parallel with heat conducted from the host card heat sink to the
card chassis. The mezzanine card assembly also may include a
mezzanine circuit card connected to the mezzanine card heat
sink.
[0019] The mezzanine card heat sink may comprise a body adjacent
the mezzanine circuit card, and a flexible strap extending
outwardly from the body and connecting to the card chassis. The
body and flexible strap may be integrally formed as a monolithic
unit. The body, moreover, can be formed or reinforced to provide
added rigidity to the mezzanine card assembly for use in harsh
dynamic environments. The mezzanine card heat sink may comprise a
material having a relatively high thermal conductivity, such as
copper or aluminum. An end of the mezzanine card heat sink may
connect to an end of the host card heat sink at the card chassis.
The flexibility of the strap aids in installation.
[0020] The host card assembly may comprise a card retainer for
connecting to the card chassis. The card retainer may overlie the
ends of the mezzanine card heat sink and the host card heat sink
where they connect at the card chassis. Alternately, the card
retainer may overlie the end of the mezzanine card heat sink and an
end of a heat sink of a host card assembly different than the one
on which the mezzanine card assembly is mounted, the card retainer
overlying the respective ends where they connect at the card
chassis.
[0021] In other embodiments, the ends of the host card heat sink
and mezzanine card heat sink may connect to the card chassis in a
spaced relation from one another. The host card assembly and the
mezzanine card assembly, accordingly, may each comprise a card
retainer for connecting to the card chassis.
[0022] The host card heat sink and mezzanine card heat sink also
may each include respective mating electrical connector portions.
The mezzanine card assembly further may include a plurality of
support posts that extend outwardly to engage the host card
assembly.
[0023] The host circuit card may have a host substrate on which a
plurality of electronic components may be carried, and the
mezzanine circuit card may have a mezzanine substrate on which a
plurality of electronic components may be carried. The plurality of
electronic components may be carried on the mezzanine substrate so
that they face the electronic components of said host circuit
card.
[0024] The mezzanine circuit card may comprise a peripheral
component interface (PCI) card. Additionally, the mezzanine card
assembly may be configured to conform to at least one of the IEEE
Standard for a Common Mezzanine Card (CMC) Family and the
Conduction Cooled PCI Mezzanine Card (CCPMC) Draft Standard, VITA
20-200x.
[0025] An additional aspect of the invention relates to a method
for conduction cooling of a mezzanine circuit card assembly. The
method may include mounting the mezzanine circuit card assembly to
a host circuit card assembly in spaced relation therefrom, wherein
the mezzanine card assembly includes a mezzanine card heat sink and
a mezzanine circuit card connected to the mezzanine card heat sink,
and wherein the mezzanine card heat sink, in turn, includes a body
adjacent a strap extending outwardly from the body. The method also
may include connecting the strap of the mezzanine card heat sink to
a card chassis receiving the host circuit card assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] The present invention will now be described more fully
hereinafter with reference to the accompanying drawings, in which
preferred embodiments of the invention are shown. This invention
may, however, be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein. Rather,
these embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
invention to those skilled in the art. Like numbers refer to like
elements throughout, and prime and multiple prime notation are used
to indicate similar elements in alternate embodiments.
[0027] Referring initially to FIGS. 1 and 2, a circuit card module
20 according to the present invention is described. The circuit
card module 20 illustratively includes a host card assembly 22 and
a mezzanine card assembly 24, the mezzanine card assembly being
carried by the host card assembly in a spaced relation therefrom.
The circuit card module 20 is received in a circuit card chassis 26
that illustratively includes a plurality of slots 28, at least one
of which may receive the circuit card module 20 as shown.
[0028] The host card assembly 22 illustratively includes a host
card heat sink 30, which has an end that connects to the card
chassis 26 to conduct heat thereto. The host card assembly 22 also
illustratively includes a host circuit card 32 mounted on the host
card heat sink 30. The host circuit card 32 illustratively
comprises a host substrate 31 that carries a plurality of
electronic components 33. The host circuit card 32 is
illustratively mounted on the host card heat sink 30.
[0029] The mezzanine card assembly 24 illustratively includes a
mezzanine card heat sink 34 that has an end that connects to the
card chassis 26 to conduct heat thereto. The heat is conducted by
the mezzanine card heat sink 34 in parallel with heat conducted
from the host card heat sink 30 to the card chassis. The mezzanine
card assembly 24 also illustratively includes a mezzanine circuit
card 36 connected to the mezzanine card heat sink 34. The mezzanine
circuit card 36 illustratively includes a mezzanine substrate 29 on
which a plurality of electronic components 35 is carried. Support
posts 21 illustratively extend outwardly from the mezzanine card
assembly 24 to engage the host card assembly 22 with the mezzanine
card assembly in a spaced relation thereto.
[0030] The host card assembly 22 and the mezzanine card assembly 24
illustratively include respective mating electrical connector
portions 37, 39. The electrical connector portions 37, 39 serve to
electrically link the electrical components 33, 35 carried
respectively by the host substrate 31 and mezzanine substrate 29.
Additionally, an electrical connector 41 illustratively connects to
the host circuit card 32 to electrically connect the circuit card
module 20 to a backplane (not shown) of a computer or electronic
device as will also be readily understood by those skilled in the
art.
[0031] As will be readily understood by those skilled in the art,
the mezzanine card heat sink 34 conducts heat generated by the
electrical components 35 carried on the mezzanine substrate 29.
Because the mezzanine card heat sink 34 conducts the heat to the
card chassis 26 rather than directly to the host card heat sink 30,
the heat is conducted in parallel rather than being added to the
host card heat sink 30, which conducts heat generated by the
electrical components 33 carried by the host substrate 31. Parallel
conduction lessens the amount of heat that must be conducted by the
host card heat sink 30 and accordingly enhances the thermal
conduction of both the host card heat sink 30 and the mezzanine
card heat sink 34.
[0032] Referring additionally now to FIG. 3, the mezzanine card
heat sink 34 illustratively comprises a body 38 adjacent the
mezzanine circuit card 36, and a strap 40 that extends outwardly
from the body to connect to the card chassis 26. The body 38 and
the strap 40 may be integrally formed as a monolithic unit. One
skilled in the art will readily appreciate, however, that the body
38 and the strap 40 may alternately comprise discrete,
non-integrally formed elements that are in thermal communication
with one another.
[0033] The strap 40 is illustratively flexible. One skilled in the
art will appreciate from the ensuing description, however, that a
relatively rigid strap may be adequate in some arrangements for
conducting heat from the mezzanine circuit card 36 to the card
chassis 26 in parallel with heat connected thereto by the host card
heat sink 30. Flexibility of the strap 40, though, provides a
number of distinct advantages. For example, the connection of the
strip 40 to the card chassis 26 is more easily made if the strap 40
is flexible. Flexibility can also accommodate tolerance buildup
through the mezzanine and host circuit card assemblies 24, 22 as
will be readily understood by those skilled in the art.
[0034] To efficiently conduct heat, the mezzanine card heat sink 34
may comprise a material that has a high thermal conductivity as
will be readily understood by those skilled in the art. For
example, the mezzanine card heat sink 34 may comprise copper.
Accordingly, as illustrated, the body 38 and strap 40 comprise a
thin strip of 30 mil copper thermal flex that extends outwardly
from the mezzanine circuit card 36. As will be readily understood
by those skilled in the art, other thermally conductive materials
of different thickness may alternately be used in accordance with
the particular application and environment.
[0035] Further by way of illustration, a first 15 mil thermally
conductive adhesive layer 42 connects the body 38 of the mezzanine
card heat sink 34 to a surface of the mezzanine circuit card
opposite the surface on which electrical components may be carried,
and a second 15 mil thermally conductive adhesive layer 44
illustratively connects a rigid layer 46 (e.g., aluminum) to the
body 38 of the heat sink. The illustrated construction provides
particular advantages in, for example, a robust environment such as
ones associated with military avionics, but, again, as will be
readily appreciated by those skilled in the art, layers of
different thickness may alternately be used. Those skilled in the
art will further appreciate that the mezzanine heat sink 34 and the
mezzanine circuit card 36 may be thermally connected using other
techniques and/or devices as well.
[0036] Similarly, while the rigid layer 46 provides added
structural integrity, the rigid layer 46 need not be included
depending on the particular application and use environment.
Moreover, although the mezzanine card heat sink 34 is
illustratively mounted above the mezzanine circuit card 36, it will
be readily appreciated by those skilled in the art that alternately
the mezzanine card heat sink 34 may instead be laminated within the
mezzanine circuit card. This can be accomplished, for example, with
a mezzanine circuit card 36 that comprises a standard wiring board
and by using rigid flex construction techniques known to those
skilled in the art.
[0037] The strap 40 and the host card heat sink 30 illustratively
connect together at a point where they also connect to the card
chassis 26, within a slot 28 of the card chassis. As illustrated, a
card retainer 48 overlies the ends of the mezzanine card heat sink
34 and the host card heat sink 30. The card retainer 48 as further
illustrated is expandable, so that that it can be expanded
vertically by a desired amount AL within the slot 28 of the card
chassis 26. The card retainer 48 accordingly serves to more
securely connect the mezzanine card heat sink 34 and the host card
heat sink 30 to the card chassis 26. The card retainer 48 also
conducts heat flow (indicated by the direction of the flow arrows
in FIG. 3) from the mezzanine card heat sink 34 to the card chassis
26, which further enhances the thermal efficiency of the circuit
card module 20.
[0038] In an alternate embodiment of the circuit card module 20'
illustrated in FIG. 4, the strap 40' of the mezzanine card heat
sink 34' connects to the card chassis 26' in a spaced relation from
the host card heat sink 30'. The mezzanine card heat sink 34' and
the host card heat sink 30' accordingly connect to the card chassis
26' in respective slots 28A', 28B' of the card chassis.
[0039] Respective card retainers 48A', 48B' illustratively overlie
respective ends of each of the mezzanine card heat sink 34' and the
host card heat sink 30'. Illustratively, the respective card
retainers 48A', 48B' adjustably expand vertically by a desired
amounts .DELTA.D, .DELTA.D' to force the respective ends more
tightly against the card chassis 26'. Again, this improves the
thermal connection of the host card and mezzanine card heat sinks
30', 34' to the card chassis 26', thereby further enhancing their
thermal conduction.
[0040] In another embodiment illustrated in FIG. 5, the strap 40"
of the mezzanine card heat sink 34" connects to the card chassis
26" in a spaced relation from the host card heat sink 30A" of the
host card assembly 22" on which the mezzanine card assembly 24" is
mounted. As shown, an end of the strap 40" connects to the end of a
host card heat sink 30B" of a second host card assembly 22B", the
ends connecting to the card chassis 26" in a slot 28B" of the card
chassis.
[0041] Aside from the cooling efficiency provided by conducting
heat via the mezzanine card heat sink 34 in parallel with heat
conducted from the host card heat sink 30 to the card chassis 26,
the circuit card module 20 provides other advantages. Among these
is the fact that the parallel heat conduction can be achieved
without having to reduce the number or power of heat dissipating
electrical components that may be carried upon the substrates of
either the host circuit card 32 or the mezzanine circuit card 36.
Yet a further advantage is that, because the mezzanine card heat
sink 34 may comprise a flexible strap 40 for connecting to the card
chassis 26, the circuit card module 20 may be more easily connected
along with the host card assembly 22 at the card chassis 26.
[0042] Another distinct advantage is that the circuit card module
20, 20', 20" may be made to conform to various standards as well as
made for custom applications in different environments. For
example, the mezzanine card assembly 24, 24', 24" may be made to
mount to different types of host cards, including those conforming
to the IEEE-1101 family of standards. The mezzanine card assembly
24, 24', 24" also may be made to mount to non-standard host cards
that include a mezzanine card interface conforming to the Common
Mezzanine Card (CMC) IEEE 1386 standards and extensions such as the
1386.1 and P1386.2 extensions. Likewise, the mezzanine card
assembly 24, 24', 24" may be made to mount to non-standard host
cards that include a mezzanine card interface conforming to the
Conduction Cooled PCI Mezzanine Card (CCPMC) VITA 20-200X standard.
Accordingly, the mezzanine circuit card 24, 24', 24" may comprise,
for example, a peripheral component interface (PCI) that conforms
to at least one these standards.
[0043] More generally, the mezzanine card assembly 24 may be made
to fit other host applications. Accordingly, the mezzanine card
assembly 24 may advantageously have different sizes. Likewise, the
mezzanine card heat sink 34 connected to the mezzanine circuit card
36 may have different constructions. For example, the mezzanine
card heat sink 34 may comprise more than one flexible strap. Each
of the flexible straps, moreover, may extend outwardly in a
different direction. The mezzanine heat sink 34, moreover, may
mount differently to a thermal interface (e.g., card chassis 26 or
cold rail). For example, the mezzanine heat sink 34 may be bolted
to the thermal interface. Alternately the mezzanine heat sink 34
may be bonded to the thermal interface.
[0044] An additional aspect of the present invention relates to a
method for conduction cooling of a mezzanine circuit card assembly
24. The method includes mounting the mezzanine circuit card
assembly 24 to a host circuit card assembly 22 in spaced relation
therefrom, the mezzanine card assembly comprising a mezzanine card
heat sink 34 and a mezzanine circuit card 36 connected to the
mezzanine card heat sink, and the mezzanine card heat sink
comprising a body 38 adjacent the mezzanine circuit card and a
strap 40 extending outwardly from the body. The method also
includes connecting the strap 40 of the mezzanine card heat sink 34
to a card chassis 26 that receives the host circuit card assembly
22, which includes a host card heat sink 30.
[0045] The method illustratively further includes connecting the
end of the host card heat sink 30 to the card chassis 26 together
with the end of the strap 40 of the mezzanine card heat sink 34.
Alternately, the method entails connecting the end of the host card
heat sink 30' to the card chassis 26' in spaced relation from the
end of the strap 40' of the mezzanine card heat sink 34'.
[0046] Many modifications and other embodiments of the invention
will come to the mind of one skilled in the art having the benefit
of the teachings presented in the foregoing descriptions and the
associated drawings. Therefore, it is to be understood that the
invention is not to be limited to the specific embodiments
disclosed, and that other modifications and embodiments are
intended to be included within the scope of the appended
claims.
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