Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2000-06-29
2001-10-16
Picard, Leo P. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S704000, C361S689000, C361S697000, C165S122000, C165S104320, C454S184000
Reexamination Certificate
active
06304442
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to cooling techniques for electronic circuitry. More particularly, the invention relates to techniques for cooling electronic components that are mounted on a daughterboard.
BACKGROUND
Computer-related electronic systems are commonly constructed using multiple interconnected circuit boards. The largest of these circuit boards is typically called the motherboard. Ancillary circuit boards such as CPU cards, memory cards and input/output cards are typically called daughterboards. Sockets are provided on the motherboard for receiving one or more daughterboards and making appropriate electrical connections between components mounted on the daughterboards and those mounted on the motherboard. Such sockets are usually designed so that the daughterboards may be easily removed and replaced.
Special thermal management problems are presented by motherboard/daughterboard systems wherein high heat dissipation components are mounted on the daughterboards. Specifically, it has been found that fan-driven heat sinks are necessary to prevent the high heat dissipation components such as CPU chips on the daughterboards from overheating.
One example of such a motherboard/daughterboard system is described in the single edge contact cartridge (“SECC”) packaging specifications promulgated by Intel Corporation. Referring now to
FIG. 1
, the packaging specification for boxed SECC
2
processors describes a daughterboard
100
on which a CPU is mounted. Daughterboard
100
is adapted to engage a socket
102
on a motherboard
104
so that daughterboard
100
is oriented substantially perpendicular to motherboard
104
. A heatsink
106
is disposed on one side of daughterboard
100
between the CPU and a fan
108
. On the opposite side of daughterboard
100
, an SECC
2
cover plate
110
is provided to help anchor heatsink
106
to daughterboard
100
. Heatsink
106
is generally rectangular and includes plural elongate fins
112
. Each of fins
112
lies on a plane that is substantially parallel to motherboard
104
. The axis of rotation of fan
108
is also substantially parallel to motherboard
104
. A fan shroud
114
is provided to direct air flow through heatsink
106
from the ends of fins
110
to the middle of fins
110
under fan
108
as shown in FIG.
2
.
Heatsink
106
also includes tabs
116
on either end. (Tabs
116
are best illustrated in
FIG. 3.
) Each of tabs
116
defines a notch
118
for engaging a retaining member of socket
102
. An example of such a retaining member is universal retention mechanism
400
(“URM”) shown in FIG.
4
. URM
400
includes a frame with top surfaces
406
and a resilient arm
402
. Resilient arm
402
includes retaining ledges
404
. Typically, one URM
400
is disposed on each end of socket
102
with its retaining ledges
404
facing inward toward the socket. When daughterboard
100
is pushed into socket
102
, notches
118
on either side of heatsink
106
engage the underside of ledges
404
, thereby helping to retain daughterboard
100
in socket
102
.
A number of disadvantages are associated with prior art motherboard/daughterboard systems such as those illustrated in
FIGS. 1-3
. For example, it is frequently necessary to place multiple daughterboards in parallel rows on the same motherboard. Because each prior art daughterboard has a heatsink
106
, a shroud
114
and a fan
108
stacked in a direction perpendicular to the plane of the daughterboard, multiple prior art daughterboards require a large amount of motherboard area. Moreover, systems that require multiple prior art daughterboards are expensive and noisy because each daughterboard in the system includes a noiseproducing and relatively expensive fan
108
.
It is therefore an object of the invention to provide a daughterboard system that conserves motherboard area when it is necessary to mount more than one daughterboard on the motherboard.
It is a further object to provide such a daughterboard system so that high heat dissipation components such as CPU chips can be mounted on the daughterboard.
It is a still further object to make the daughterboard system less expensive and less noisy than the daughterboard systems of the prior art.
SUMMARY OF THE INVENTION
These and other objects are realized by an actively cooled daughterboard system according to a preferred embodiment of the invention.
In one aspect, one more daughterboards are mounted in parallel rows on a motherboard. Each daughterboard is oriented substantially perpendicular to the motherboard, but may optionally be mounted at an oblique angle relative to the motherboard. Each daughterboard has a low-profile thermally-efficient heatsink mounted thereon. Each heatsink is thermally coupled to one or more heat dissipating electronic components mounted to the respective daughterboard. A fan shroud partially covers the daughterboards, but has openings in its sides for directing air flow through plural fins on the heatsinks and through a fan mounted to the top of the fan shroud. Preferably, the fan is oriented with its axis of rotation substantially parallel to the plural fins of the heatsinks. The inventive daughterboard system enables multiple high heat dissipating daughterboards to be placed closer together than the daughterboard systems of the prior art while still keeping the daughterboards adequately cooled. Moreover, because only a single fan is used to cool all of the daughterboards under the shroud, noise and expense are reduced relative to prior art systems that employed one or more fans per daughterboard.
In another aspect, the fan shroud may include one or more protrusions on each end for engaging retaining ledges housed in retaining members on opposite ends of the daughterboard sockets. In such an embodiment, the fan shroud may also include shoulder surfaces for engaging the tops of the retaining members. The shoulder portions act as insertion stops when the shroud is placed over the daughterboards. Insertion is stopped after the protrusions of the shroud have engaged the retaining ledges on the retaining members. This aspect enables easy removal and replacement of the shroud.
In another aspect, the fan shroud may include one or more guide slots on each end for engaging tabs on the heatsinks as the shroud is placed over the daughterboards. This aspect facilitates proper alignment of the shroud during installation.
In still another aspect, the daughterboard system may be housed in a host computer chassis so that the fan of the daughterboard system has its effluent air path proximate to the intake air path of a chassis ventilation fan. In this manner, heat removal from the daughterboards is further enhanced by the action of the ventilation fan for the host system.
REFERENCES:
patent: 5884692 (1999-03-01), Lee et al.
patent: 5936836 (1999-08-01), Scholder
patent: 6094346 (2000-07-01), Schweers et al.
patent: 6130819 (2000-10-01), Lofland et al.
patent: 6130820 (2000-10-01), Konstad et al.
Delano Andrew D
Roesner Arlen L
Smith Darren B
Trotter Donald
Tucker Sean W.
Datskovsky Michael
Hart Kevin M.
Hewlett--Packard Company
Picard Leo P.
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