U.S. patent application number 10/663828 was filed with the patent office on 2004-08-26 for electronics assembly.
This patent application is currently assigned to Sun Microsystems, Inc.. Invention is credited to Schnabel, John David, Sparkes, Stephen David.
Application Number | 20040165366 10/663828 |
Document ID | / |
Family ID | 27612898 |
Filed Date | 2004-08-26 |
United States Patent
Application |
20040165366 |
Kind Code |
A1 |
Schnabel, John David ; et
al. |
August 26, 2004 |
Electronics assembly
Abstract
An electronics assembly comprises: (i) a frame (1); and (ii) a
motherboard (16) that is removable from the frame. One or more
daughterboards (20) extend in a plane generally perpendicular to
the plane of the motherboard; and a number of elongate guides (24)
are provided for the daughterboards to enable each daughterboard to
be moved toward the motherboard into engagement therewith and away
from the motherboard out of engagement therefrom. The motherboard
(16) has at least one location element (32) thereon, which can
engage one of the elongate guides (24) in order to locate the
guides and the motherboard with respect to one another. This
assembly enables accurate positioning of the daughterboards and the
motherboard for forming electrical connections between them even
where large tolerances are present in other parts of the
assembly.
Inventors: |
Schnabel, John David;
(Fareham, GB) ; Sparkes, Stephen David;
(Farnborough, GB) |
Correspondence
Address: |
B. Noel Kivlin
Meyertons, Hood, Kivlin, Kowert & Goetzel, P.C.
P.O. Box 398
Austin
TX
78767
US
|
Assignee: |
Sun Microsystems, Inc.
|
Family ID: |
27612898 |
Appl. No.: |
10/663828 |
Filed: |
September 16, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10663828 |
Sep 16, 2003 |
|
|
|
10166518 |
Jun 10, 2002 |
|
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6621709 |
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Current U.S.
Class: |
361/796 |
Current CPC
Class: |
G06F 1/185 20130101;
G06F 1/186 20130101; G06F 1/184 20130101; H05K 7/1488 20130101 |
Class at
Publication: |
361/796 |
International
Class: |
H05K 007/14; H05K
007/18 |
Claims
1. An electronics assembly which comprises: (i) a frame; (ii) a
motherboard that is removable from the frame; (iii) one or more
daughterboards that extend in a plane generally perpendicular to
the plane of the motherboard; and (iv) a plurality of elongate
guides for the daughterboards to enable each daughterboard to be
moved toward the motherboard into engagement therewith and away
from the motherboard out of engagement therefrom; wherein the
motherboard has at least one location element thereon, which can
engage one of the elongate guides in order to locate the guides and
the motherboard with respect to one another.
2. An assembly as claimed in claim 1, wherein the motherboard has
at least two location elements thereon, each of which can engage
one of the elongate guides in order to locate the guides and the
motherboard with respect to one another.
3. An assembly as claimed in claim 1, wherein the motherboard can
be removed from, or inserted in, the frame by movement in its own
plane.
4. An assembly as claimed in claim 3, wherein the motherboard is
located in a tray-shaped holder that can be slid into and out of
the frame.
5. An assembly as claimed in claim 2, wherein the or each location
element stands up from the printed circuit board forming the
motherboard so that it can engage its guide but the guides will
allow the motherboard to be removed from, or inserted in, the
frame.
6. An assembly as claimed in any claim 1, wherein at least one of
the guides, which is in a position corresponding to the position of
the or each location element on the motherboard, extends toward the
plane of the motherboard more than other guides.
7. An assembly as claimed in claim 1, wherein the or each location
element on the motherboard is in the form of a protuberance that
engages a recess in a respective one of the guides.
8. An assembly as claimed in claim 1, wherein the motherboard has
two location elements thereon, and engagement of one location
element on the motherboard with its corresponding guide limits the
relative movement of the motherboard and the guides in the
insertion direction of the motherboard, and engagement of the other
location element and its corresponding guide prevents rotation of
the motherboard relative to the guides about an axis normal to the
motherboard and passing through the said one location element.
9. An assembly as claimed in claim 1, wherein engagement of one
location element on the motherboard with the corresponding guide
will prevent relative movement of the motherboard and the guides in
two perpendicular directions.
10. An assembly as claimed in claim 1, wherein the motherboard is
located within the frame substantially horizontally.
11. An assembly as claimed in claim 10, wherein the motherboard is
located within the frame beneath the daughterboards.
12. An assembly as claimed in claim 1, which is located in a
cabinet and can be removed therefrom as a single unit.
13. A frame for an electronics assembly which comprises: (i) a
location in which a planar motherboard can be received; and (ii) a
plurality of guides that extend in a direction generally normal to
the plane of the motherboard when it is received in the frame in
order to enable a plurality of daughterboards to be located in the
frame in engagement with the motherboard, at least one of the
guides having a location element thereon that can engage a
corresponding location element on a motherboard in order to locate
the guides and the motherboard with respect to one another.
14. A frame as claimed in claim 13, wherein at least two of the
guides have a location element thereon.
15. A frame as claimed in claim 13, wherein the location for
receiving a motherboard allows the motherboard to be inserted
therein in a direction in a plane of the motherboard.
16. A frame as claimed in claim 13, wherein at least one of the
guides extends closer toward the location for receiving the
motherboard than the other guides.
17. A frame as claimed in claim 13, wherein the or each location
element in the guides comprises a recess that can accommodate a
protuberance on the motherboard.
18. A frame as claimed in claim 13, wherein the location for
receiving the motherboard will allow the motherboard to be received
substantially horizontally.
19. A frame as claimed in claim 16, wherein the location for
receiving the motherboard will allow the motherboard to be located
within the frame beneath the guides.
20. A method of installing a motherboard in a frame for an
electronics assembly comprising a plurality of guides for
daughterboards, the guides extending generally normal to the plane
of the motherboard, which method comprises: (i) sliding the
motherboard into the frame; and (ii) causing a location element on
the motherboard to engage a corresponding location element on at
least one of the guides in order to locate the guides and the
motherboard with respect to one another.
21. A method as claimed in claim 20, wherein the motherboard has at
least two location elements thereon, and each location element on
the motherboard engages a corresponding location element on a
different guide.
22. A method as claimed in claim 20, wherein the motherboard is
slid into the frame in its own plane.
23. A method as claimed in claim 20, wherein the motherboard is
slid into the frame in a horizontal plane.
24. A method as claimed in claim 20, which includes sliding one or
more daughterboards toward the motherboard and into engagement
therewith.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to electronics assemblies, and
is primarily concerned with racked assemblies. Many such assemblies
will be located in racks for housing in for example nineteen inch
cabinets, or other size cabinets such as twenty three inch or
metric cabinets. The assemblies may for instance be employed as
servers for a number of systems, for example in local area networks
(LANs), wide area networks (WANs), telecommunications systems or
other operations such as database management or as internet
servers.
[0002] Such an assembly will typically comprise a supporting frame
that houses a motherboard or backplane and a number of
daughterboards or module cards that extend in planes generally
perpendicular to the plane of the motherboard and which are
connected to the motherboard by connectors, e.g. high density
connectors, so that the daughterboards can simply be located on
guides and pushed toward the motherboard in order to connect them
to it.
[0003] In addition, the motherboard may need to be removed for
general maintenance purposes, upgrading or the like and so the
frame of the assembly will normally provide for removal of the
motherboard therefrom and re-insertion therein.
[0004] One problem that can be encountered is in alignment of the
daughterboards and the motherboard after the boards have been
removed and replaced. For example, it is quite possible for the
positional tolerance of the motherboard within the frame of the
assembly, and for the tolerance of the guides for the
daughterboards within the frame to be relatively large. In
addition, parts of the frame itself can flex due to the forces
applied to it during handling. All these tolerances add to one
another, with the result that it is possible for the variation in
the alignment between the connectors on the daughterboards and
those on the motherboard to exceed the maximum acceptable
positional deviation for the electrical connectors.
SUMMARY OF THE INVENTION
[0005] According to one aspect the present invention provides an
electronics assembly which comprises:
[0006] (i) a frame;
[0007] (ii) a motherboard that is removable from the frame;
[0008] (iii) one or more daughterboards that extend in a plane
generally perpendicular to the plane of the motherboard; and
[0009] (iv) a plurality of elongate guides for the daughterboards
to enable each daughterboard to be moved toward the motherboard
into engagement therewith and away from the motherboard out of
engagement therefrom;
[0010] wherein the motherboard has at least one location element
thereon, which can engage one of the elongate guides in order to
locate the guides and the motherboard with respect to one
another.
[0011] By locating the motherboard directly with the card guides
for the daughterboards it is possible to decrease misalignment of
the connectors on the motherboard and on the daughterboards
significantly since any misalignment of the motherboard within the
assembly frame and any slight flexing of the frame that might cause
those parts thereof that support the card guides to become
displaced can be ignored insofar as alignment of the motherboard
and daughterboard connectors is concerned.
[0012] The problems of misalignment are particularly severe in
assemblies where the motherboard can be removed from, or inserted
in, the frame by movement in its own plane. For example the
motherboard may be located in, and fixed to, a substantially
tray-shaped holder that can be slid into and out of the frame via
an elongate slot. For ease of assembly and disassembly it is often
desirable to dispense with screw-fixing in such circumstances and
instead to rely on a stop that abuts the tray-shaped holder to
locate the motherboard correctly within the frame and some form of
manually engageable fixing arrangement to fix the motherboard and
holder in place. Such an arrangement has the disadvantage that the
potential degree of misalignment between the motherboard and the
daughterboards is substantially greater than when employing screw
fixings and alignment of the daughterboards with the motherboard
can be impossible to achieve to the tolerance required by the
connectors for correct mating. According to the invention, however,
the relevant card guides themselves effectively provide a stop for
limiting insertion of the motherboard.
[0013] In such an arrangement the location elements on the
motherboard may stand up from the printed circuit board forming the
motherboard so that they can engage their corresponding card guides
but the guides will allow the motherboard to be removed from, or
inserted in, the frame without inadvertently hitting any other
components on the motherboard.
[0014] The assembly will normally contain an array of
daughterboards each located between a pair of card guides. It is
not necessary for all the card guides to extend sufficiently close
to the motherboard to engage a location element, but only for a
minimum of one and preferably of two card guides which are in
positions corresponding to the positions of the location elements
to extend that closely to the motherboard while the other card
guides may terminate a greater distance away. Clearly it is
desirable if the positions of the location elements on the
motherboard are separated by a significant fraction of the overall
dimensions of the motherboard, for example by at least 1/3 or at
least 1/2 the overall dimensions in order to provide improved
resistance to relative rotation of the motherboard and the card
guides about an axis normal to the plane of the motherboard.
Normally, the daughterboards will all be located in the same region
of the frame, for example in a single sub-enclosure, so that if the
frame as a whole is subjected to any strain by insertion of the
motherboard into engagement with the card guides, all the card
guides will move together as the frame flexes slightly and so will
stay in alignment with the motherboard. If, however, daughterboards
are provided in different sub-enclosures in the frame, it may be
necessary for additional location elements for the daughterboards
in each sub-enclosure to be provided.
[0015] The location elements on the motherboard may, for example,
be in the form of protuberances, for instance pins, that become
located in recesses in the corresponding card guides when the
motherboard is in position. It is not necessary for each location
element to prevent relative movement of the motherboard and the
card guides in all directions in the plane of the motherboard, but
instead, engagement of one location element on the motherboard with
the corresponding card guide may prevent relative movement of the
motherboard and the guides in a direction perpendicular to the
direction in which movement is prevented by engagement of the other
location element and its corresponding guide. In one example,
engagement of one location element on the motherboard with its
corresponding card guide may prevent relative movement of the
motherboard and the corresponding card guide in two orthogonal
directions (in the plane of the motherboard) while engagement of
the other location element with its guide need only prevent
movement of the motherboard in one direction, that is to say,
engagement of the other location element with its card guide simply
needs to prevent any rotation of the motherboard about the first
location element.
[0016] The invention is applicable to any assembly comprising a
motherboard and a number of daughterboards or module cards
irrespective of their orientation, for example in a conventional
orientation in which the motherboard is arranged in a vertical
plane at the back of a cabinet and the daughterboards are arranged,
either in a vertical or horizontal plane, so that they can be
removed or inserted in a horizontal direction from the front of the
cabinet. The invention is also applicable to a new design of
assembly in which the motherboard is located within the assembly
frame substantially horizontally, especially beneath the
daughterboards, and the daughterboards are arranged in an array in
vertical planes. In such a case the assembly may need to be removed
from the cabinet in one piece in order to remove the
daughterboards, in which case it can be supported on telescopic
sliders.
[0017] According to another aspect, the present invention provides
a frame for an electronics assembly which comprises:
[0018] (i) a location in which a planar motherboard can be
received; and
[0019] (ii) a plurality of guides that extend in a direction
generally normal to the plane of the motherboard when it is
received in the frame in order to enable a plurality of
daughterboards to be located in the frame in engagement with the
motherboard, at least one of the guides having a location element
thereon that can engage a corresponding location element on a
motherboard in order to locate the guides and the motherboard with
respect to one another.
[0020] According to yet another aspect, the invention provides a
method of installing a motherboard in a frame for an electronics
assembly comprising a plurality of guides for daughterboards, the
guides extending generally normal to the plane of the motherboard,
which method comprises:
[0021] (i) sliding the motherboard into the frame; and
[0022] (ii) causing a location element on the motherboard to engage
a corresponding location element on at least one of the guides in
order to locate the guides and the motherboard with respect to one
another.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Embodiments of the present invention will now be described
in detail with reference to the accompanying drawings, in which
corresponding parts are given like reference numbers. In the
drawings:
[0024] FIG. 1 is a schematic isometric view of an assembly
according to the present invention;
[0025] FIG. 2 is a schematic view corresponding to FIG. 1 but with
the daughterboards removed and the motherboard partly removed;
[0026] FIG. 3 is a top plan view of the motherboard shown in FIG.
2;
[0027] FIG. 4 is a side elevation of the assembly shown in FIGS. 1
and 2;
[0028] FIG. 5 is a view of the motherboard and a card guide in
greater detail; and
[0029] FIG. 6 and FIG. 7 show schematically two alternative modes
of operation
DESCRIPTION OF PARTICULAR EMBODIMENTS
[0030] Referring now to the drawings, in which like reference
numerals are used to designate corresponding elements, FIG. 1 shows
an assembly according to one embodiment of the invention that forms
part of a server that may be employed for a number of services, for
example as part of a local area network (LAN) and is designed as a
nineteen inch rack to be located in an electronics cabinet. Other
sizes of rack, e.g. twenty three inch or metric racks may be also
employed.
[0031] The assembly comprises a frame 1 in which the various
components are located. The frame 1 contains a number of power
modules 2 for converting mains a.c. power to an appropriate d.c.
voltage, a part 4 that contains hard disk drives 6, a tape drive 8
and a CD-ROM or digital video disc drive 10, and a part 12 that
contains a number of I/O cards 14. A motherboard 16 is located
within the frame in a horizontal plane at the bottom of the frame
in a tray-shaped holder 18, and a number of daughterboards 20 are
arranged next to each other in a vertical plane above the
motherboard 16 and to the side of the power modules 2. The
daughterboards may serve any of a number of purposes, for example
having CPUs or may be repeater boards etc. Finally, a number of
fans 22 are provided in an array at the front of the frame in order
to blow air through the assembly between the daughterboards 20 for
cooling.
[0032] The daughterboards 20 are each located between a pair of
elongate card guides 24 (FIG. 2) that extend normal to the plane of
the motherboard 16 between the motherboard and openings 26 at the
top surface of the frame 1 for insertion of the daughterboards. The
card guides 24 terminate at their lower end some distance short of
the motherboard in order to allow sufficient clearance for any
components that are located on the motherboard to pass beneath the
guides as the motherboard is removed from the frame. The card
guides may be formed from metal, or from a suitable, relatively
rigid, plastics material such as a polyamide, and have generally
"U"-shaped cross-sections into which the edges of the
daughterboards 20 can be slotted.
[0033] Any of the electronics components of the assembly may need
to be removed and replaced from time to time, for example for
repair or for upgrading, and in order to do this the daughterboards
20 can simply be lifted out of the frame through the openings 26.
If the motherboard 16 needs attention, the daughterboards must
first be removed, and then the motherboard may be removed by
sliding it horizontally out of the frame 1 in its own plane after
first removing screws 28. A new motherboard may then be inserted
into the frame 1 and the daughterboards 20 re-inserted into frame
along the card guides 24 into engagement with the motherboard via
connectors 30 on the motherboard 16 and corresponding connectors
(not shown) on the daughterboards.
[0034] In order for the connectors on the daughterboards 26 to mate
correctly with the connectors 30 on the motherboard 16, the
connectors should not be misaligned with one another or otherwise a
poor electrical connection can result, or even damage to the
connectors. This tolerance required between the connectors can
often be tighter than can be achieved if the tolerance between the
connectors is determined by the total tolerance of the connectors
30 on the motherboard 16, the motherboard 16 within the frame 1,
the position of the daughterboard card guides 24 within the frame
1, the location of the daughterboards 20 within the guides 24, the
position of the electrical connectors on the daughterboards, and
any slight torsion or other strain in the frame 1.
[0035] Instead of relying on the position of the motherboard and
the daughterboard card guides with respect to the frame in order to
set the alignment of the motherboard and daughterboard connectors,
two of the card guides 24' are longer than the remaining card
guides by a few centimetres as shown in FIG. 4 so that they end at
their lowermost ends only a few millimetres above the plane of the
motherboard, and these card guides 24' together with the
motherboard are provided with location elements that engage each
other directly so that the alignment of the connectors 30 on the
motherboard 16 and those on the daughterboards is determined by the
tolerance of the location of the connectors on their respective
boards and of the location elements on the motherboard and on the
card guides respectively.
[0036] The location elements on the motherboard are each in the
form of a protuberance or pin 32 that stands up from the surface of
the motherboard 16 by a distance greater than the clearance of the
two card guides 24' and the motherboard surface, and the lower end
region of each of the two card guides 24' is provided with a
generally cup-shaped recess 34 that can receive one of the pins 32,
when the motherboard 16 is inserted into the frame 1 as shown in
FIG. 5.
[0037] If desired, the protuberance 32 and recess 34 can taper in
the direction of insertion of the motherboard into the frame in
order to provide some degree of lateral guidance for location of
the motherboard and the daughterboard card guides.
[0038] Where lateral guidance is provided for insertion of the
motherboard, and a degree of relative movement between the
motherboards and the daughterboard card guides is expected, either
the motherboard or the card guides may move with respect to the
frame. For example, as shown in FIGS. 6a and 6b the daughterboard
card guides 24 are fixed with respect to the frame 1 and the
motherboard 16 is allowed to move laterally with respect to the
frame in order to align itself with the card guides. In this case
elongated screw holes 29 will be provided in the motherboard holder
or in the frame for receiving screws 28 when the motherboard is
finally located in the frame.
[0039] Alternatively, as shown in FIGS. 7a and 7b, the card guides
may move laterally within the frame in order to become aligned with
the motherboard if the motherboard is constrained not to move
laterally within the frame 1. In practice, it may not be clear
which of these alternatives is used: For example both the
motherboard 16 and the card guides 24 may be allowed to move
slightly with respect to the frame, or alternatively both the
motherboard 16 and the card guides 24 may have relatively tight
tolerances with respect to the frame 1, and the required relative
lateral movement between the motherboard and the card guides may be
provided by torsion of various parts of the frame.
[0040] It is possible for the location elements on both the card
guides 24', and both the location elements on the motherboard 18 to
prevent relative movement between the motherboard and the card
guides in two orthogonal directions (e.g. in the direction of
insertion of the motherboard 18 into the frame 1 and in a direction
perpendicular thereto), but this is not absolutely necessary.
Recess 34 on one of the card guides 24' nearest the front of the
frame 1 is arranged so that the corresponding pin 34 on the
motherboard 16 will abut the internal apex thereof so that relative
movement between the motherboard and the card guide is prevented in
two orthogonal directions, while the recess 34 on the other card
guide 24' is arranged so that the corresponding pin 32 on the
motherboard is received in the recess but does not abut the
internal apex of the recess. In this arrangement the card guide 24'
and pin 32 nearest the front of the frame 1 prevents relative
movement between the motherboard and the card guides both in the
direction of insertion of the mother board and also laterally,
while the other end guide 24' and pin 32 only prevent relative
movement in a lateral direction (shown by the arrow in FIG. 3). In
other words, the card guide 24' and pin 32 farthest from the front
of the frame simply resists relative rotation of the motherboard
and the frame about the card guide 24' and pin 32 nearest to the
front of the frame 1.
[0041] Normally, where location elements are provided on one of the
front and one of the rear card guides 24, the two card guides on
which the location elements are provided must be laterally offset
in order to allow any location protuberance 32 on the motherboard
corresponding to a rear card guide to pass the location element on
the front card guide. If, however, the location element on the
front end guide is required only to prevent relative movement in
the lateral direction, it may be designed to allow any protuberance
at the rear of the motherboard to pass through it when the
motherboard is inserted, in which case location elements could be
provided on both card guides 24 that are used for location of a
single daughterboard. Indeed, it would be possible to employ card
guides having different forms of location element at each end, so
that only one design of card guide is required but the particular
form of location element that is employed on the card guide will be
determined by its orientation.
[0042] After the motherboard has been inserted into engagement with
the card guides 24', it can be secured by screwing it into the
front plate 36 of the housing for the daughterboards by means of
screws 28. Any slight movement of the card guides 24 with respect
to the front plate 36 by virtue of this operation will not affect
alignment with the motherboard since all the card guides 24 will
move together with the motherboard.
[0043] It is not necessary for the pins 32 to be mounted on the
motherboard and the recesses 34 to be located in the card guides.
The pins 32 may instead be located on the card guides and the
motherboard may be provided with upstanding posts or other
protuberances that have recesses in their front surfaces (i.e. in
the direction of insertion) in order to locate the motherboard with
respect to the card guides. The particular form of the location
elements is not critical to the invention, but they should be
arranged so that they can be brought into engagement by sliding the
motherboard in the direction of insertion thereof into the frame
and can be disengaged by sliding the motherboard in the direction
of removal from the frame. In addition, it is not essential for the
location elements to be mounted directly on the motherboard 16.
They could, for example, be mounted on the tray-shaped holder 18
for the motherboard, but it will be appreciated that this will add
the tolerance of the motherboard in the holder to the alignment of
the motherboard and the card guides.
[0044] The scope of the present disclosure includes any novel
feature or combination of features disclosed therein either
explicitly or implicitly or any generalisation thereof irrespective
of whether or not it relates to the claimed invention or mitigates
any or all of the problems addressed by the present invention. The
applicant hereby gives notice that new claims can be formulated to
such features during the prosecution of this application or of any
such further application derived therefrom. In particular, with
reference to the appended claims, features from dependent claims
can be combined with those of the independent claims and features
from respective independent claims can be combined in any
appropriate manner and not merely in the specific combinations
enumerated in the claims.
* * * * *