Fastening device for a printed circuit board

A fastening device attaches a printed circuit board, such as a backplane, within a support framework of an electrical cabinet. The fastening device includes two adjacent members of the support framework. A threaded stud is attached to one of the members and extends toward the adjacent member. A captive fastener is attached to the other adjacent member. The captive fastener has a thread that cooperates with the thread of the stud. The fastener is aligned with the stud, the cooperative thread of the fastener is capable of engaging the thread of the stud. The fastening device secures the printed circuit board between the adjacent members of the support framework.

BACKGROUND OF THE INVENTION
 The invention relates generally to electrical cabinets adapted to store, or
 house, electrical components, and, more particularly to printed circuit
 boards used in data storage and transfer systems.
 As is known in the art, electrical cabinets are used to store, or house, a
 variety electrical components such as printed circuit boards. The
 electrical cabinets allow the components within the cabinet to be
 interconnected and also allow the internal components to be connected to
 components external to the cabinets. The cabinets typically have an access
 door and a number of compartments, such as a card cage, i.e., a housing to
 store the various interconnected printed circuit boards. In addition, the
 individual components within the cabinet may be replaced or removed to a
 different location for repair.
 Typically, some of the components are printed circuit boards arranged in a
 card cage, or housing, in an array of vertical or horizontal guide slots
 (i.e., a linear array of guide slots) provided between opposing sides of
 the cabinet. Each board is insertable into a corresponding pair of the
 opposing guide slots and is urged towards the rear of the cabinet to
 enable an electrical connector mounted to the rear edge of the board to
 engage, and thereby electrically connect to, a backplane. A backplane
 typically is a printed circuit board which contains a plurality of
 electrical connectors. The backplane commonly is referred to as a mother
 board. The other printed circuit boards discussed above, which connect to
 the mother board, commonly are referred to as daughter boards.
 When electrical cabinets are assembled, backplanes may be installed within
 housings using loose hardware such as pan-headed screws or flat-headed
 screws. However, such installation techniques are labor intensive. Also,
 the loose hardware increases the part counts required to assemble an
 electrical cabinet, which increases processing time prior to assembly of
 the electrical cabinet.
 Also, existing card cages may secure printed circuit boards, especially
 backplanes, using hardware that concentrates a load in a small area. For
 example, a bolt and washer used to secure a printed circuit board has a
 concentrated load bearing surface and can cause the printed circuit board
 to, e.g., delaminate.
 In addition, card cages of electrical cabinets may not be able to
 accommodate backplanes having different thicknesses. Typically, generic
 electrical cabinets are used in systems that are custom tailored. Thus,
 the structure of a single cabinet may be employed in a system in which
 different combinations of components and different types of components may
 be used. These various components may have varying dimensions. Also,
 several vendors may supply similar components for a system. For example,
 two different vendors may supply the backplanes for a single system. These
 different backplanes may have slightly different tolerances due to the
 differences in manufacturing standards of different vendors.
 SUMMARY OF THE INVENTION
 One aspect of the invention is a fastening device that attaches a printed
 circuit board, such as a backplane, within a support framework of an
 electrical cabinet. The fastening device includes two adjacent members of
 the support framework. A threaded stud is attached to one of the members
 and extends toward the adjacent member. A captive fastener is attached to
 the other adjacent member. The captive fastener has a thread that
 cooperates with the thread of the stud. The fastener is aligned with the
 stud, the cooperative thread of the fastener is capable of engaging the
 thread of the stud. The fastening device secures the printed circuit board
 between the adjacent members of the support framework.
 Preferred embodiments of this aspect of the invention include the
 following.
 The adjacent members are movable relative to one another along a plane in
 which the members are aligned. The fastener and the stud are aligned along
 an axis. The fastener includes a hollow cylindrical sleeve that attaches
 to one of the adjacent members. A shank extends through the sleeve. The
 shank having a cooperative thread and an internal captivating surface. A
 head attaches to the shank external to the sleeve with a width greater
 than an interior width of the sleeve to limit motion of the shank along
 the axis.
 Embodiments within the scope of the claims may have one or more of the
 following advantages.
 The fastening device provides an efficient mechanism to secure a printed
 circuit board within a housing of an electrical cabinet. The fastening
 device eliminates the need for loose hardware to secure a printed circuit
 board within a housing of an electrical cabinet. The fastening mechanism
 accommodates printed circuit boards having varying thicknesses. The
 fastening mechanism provides a large load bearing surface to secure a
 printed circuit board.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 Referring to FIGS. 1-3, an electrical cabinet 100 is adapted for the
 storage and operation of electrical components, particularly, data storage
 and transfer technology. For example, electrical components include CPUs,
 printed circuit boards, batteries, cables, data servers, and laptop
 computers. Typically, the electrical components are housed within the
 interior of the cabinet (FIGS. 2 and 3). The electrical components can be
 interconnected with other components in other electrical cabinets, or are
 interconnected with other networks. The electrical components reside
 within various storage compartments 102, 104, 106 within cabinet 100.
 Electrical cabinet 100 has internal partitions 108 that define the storage
 compartments 102, 104, 106.
 The electrical cabinet 100, has four side-walls 110, 112, 114, 116. Two of
 the side-walls 110, 114 form access doors. Electrical cabinet 100 stands
 upright on four wheels 118 and is mobile. Among other elements, electrical
 cabinet 100 has an extendable platform 120, air vents 122, exhaust fans
 124, and a printed circuit board card cage 200.
 Referring to FIGS. 4 and 5, printed circuit board card cage 200 provides a
 housing to support a set of printed circuit boards. Card cage 200 includes
 two opposing sidewalls 202, 204, a ceiling 206, a movable ceiling member
 208, a floor 210, and a movable floor member 212. Sidewalls 202, 204
 extend from opposing sides of floor 210 to opposing sides of ceiling 206.
 Thus, card cage 200 includes an internal space for storing printed circuit
 boards and defines an opening 214 for receiving a printed circuit board,
 e.g., a daughter board 216. Card cage 200 is, e.g., 25.8" in length, 19.9"
 in height, and 17.7" in width.
 As shown, both ceiling 206 and floor 210 are permanently and securely fixed
 to sidewalls 202, 204 by corresponding sets of screws 232 (four screws
 being shown along each of floor 210 and ceiling 206). Sidewalls 202, 204
 are made of a sheet metal, and the edges of sidewalls 202, 204 are molded
 to form a corrugated-like section that provides additional structural
 support framework 220. Thus, floor 210, ceiling 206, and sidewalls 202,
 204 provide a predefined structure that resists deformation and is able to
 properly align printed circuit boards within card cage 200.
 As shown, sidewalls 202, 204 are substantially solid having only several
 holes punched to accommodate screws and provide certain other surfaces
 discussed below. Alternatively, sidewalls 202, 204 could be substantially
 open, e.g., providing only a structural support framework to accommodate
 daughter board 216, a backplane 226 (FIG. 5), ceiling 206, and movable
 ceiling member 208.
 Floor 210 and ceiling 206 each include a set of twenty slots 218. Floor 210
 and ceiling 206 are made of a metal casting to provide structural support.
 Slots 218 are defined by plastic members that attach to the interior
 surface of the metal castings. Slots 218 are aligned such that each slot
 218 on ceiling 206 is positioned directly above a corresponding slot 218
 on floor 210, i.e., card cage 200 includes 20 slot pairs that are aligned
 in the vertical direction.
 Daughter board 216 is sized to fit snugly between and within any two of the
 corresponding pairs of slots 218. As shown in FIG. 4, daughter board 216
 is partially inserted into card cage 200. However, the length of daughter
 board 216 is approximately the same as the length of both floor 210 and
 ceiling 206. Thus, when fully inserted, the end of daughter board 216,
 which is visible in FIG. 4, lies flush with the end of card cage 200 at
 opening 214.
 Ceiling 206 has a length that is shorter than the length of sidewalls 202,
 204. The additional area created by the extra length of sidewalls 202, 204
 is occupied by movable ceiling member 208, which is aligned with ceiling
 206 in a horizontal plane. Movable ceiling member 208 also attaches to and
 extends between opposing sidewalls 202, 204. However, movable ceiling
 member 208 is not securely fixed.
 Rather, movable ceiling member 208 is slidable in the direction of slots
 218. Movable ceiling member 208 has two opposing edges that are directly
 adjacent to sidewalls 202, 204 and that each fit within a corresponding
 slide 222. Slides 222 are each formed by (1) an interior side of one of
 the sidewalls 202, 204 that provides lateral support, (2) an upper edge of
 structural support framework 220 that forms a lip along the edge of each
 sidewall 202, 204 to provide vertical support, and (3) a set of notches
 244 extending in a horizontal line that is a uniform distance from the lip
 of support framework 220. Each notch 244 is a portion of one of sidewalls
 202, 204 which is punched to form a notch. The line of notches 244 also
 provides vertical support.
 Similarly, movable floor member 212 is attached to and extends between
 sidewalls 202, 204. Movable floor member 208 also is slidable in the
 direction of slots 218. Movable floor member 212 attaches along two slides
 222 (only one slide being shown) that accommodate opposing side edges of
 movable floor member 212.
 Similar to ceiling member 208 and floor member 212, movable ceiling member
 208 and movable floor member 212 each include a set of twenty slots 218'.
 Slots 218' are defined by plastic members that are identical to the
 members that define slots 218. Card cage 200 includes twenty slot pairs
 that are aligned in the vertical direction.
 Card cage 200 is symmetrical about a plane that bisects card cage 200 into
 top and bottom portions. Card cage 200 also is symmetrical about a plane
 that bisects card cage 200 into left and right portions. Card cage 200 is
 assembled using parts having common structure. For example, sidewall 202,
 ceiling 206 and ceiling member 208 have the same structure as sidewall
 204, floor 210 and floor member 212 respectively. Each of the
 corresponding parts are assembled in a position that is rotated 180
 degrees from the position of the corresponding part, i.e., the
 corresponding parts face each other. Therefore, if card cage 200 were
 turned upside down, card cage 200 would have the same relative structure.
 Alternatively, card cage 200 could be manufactured without the
 above-described common parts, and card cage 200 could be asymmetrical
 either top to bottom or side to side. Thus, in essence, the corresponding
 parts of card cage 200 can be structurally the same and interchangeable or
 can be structurally distinct.
 Card cage 200 is not symmetrical front to back. For example, as shown,
 movable ceiling member 208 is approximately 2/3 the length of ceiling
 member 208, and movable floor member 212 is approximately 2/3 the length
 of floor member 212. Alternatively, card cage 200 could be symmetrical
 from front to back.
 As show in FIGS. 4 and 5, movable ceiling member 208 and movable floor
 member 212 are in unsecured positions. In the unsecured position, movable
 ceiling member 208 slides away from ceiling 206 and defines an opening 224
 for receiving a printed circuit board, e.g., backplane 226 (FIG. 5).
 Movable floor member 212 slides away from floor member 212 and defines
 another opening 228, e.g., also for receiving backplane 226. As shown,
 both movable ceiling member 208 and movable floor member 212 can be
 completely removed from card cage 200 to provide one large contiguous
 opening. Alternatively, rather than being removable, the range of motion
 of both movable ceiling member 208 and movable floor member 212 could be
 limited within corresponding slides 222.
 Backplane 226 is inserted transversely to slots 218 and slots 218' and
 subsequently aligned. To align backplane 226 within card cage 200, four
 notches 410 (shown in, and discussed in greater detail in relation to,
 FIG. 11) of backplane 226 accommodate four corresponding registration pins
 230 (only one registration pin being shown due to the perspective of FIG.
 4). Each sidewall 202, 204 has two registration pins 230 that are
 symmetrically arranged as described above and that extend from the
 interior surface of sidewalls 202, 204. As backplane 226 is placed within
 card cage 200, registration pins 230 are disposed within corresponding
 notches 410 of backplane 226.
 After backplane 226 is inserted and aligned, backplane 226 is attached
 within card cage 200. Sidewalls 202, 204 each include a corresponding
 support member 234 to attach the printed circuit board in position within
 card cage 200. Each support member 234 extends inward along the interior
 surface of corresponding sidewalls 202, 204. Support members 234 are
 punched from a section of corresponding sidewalls 202, 204 and are
 disposed at a 90 degree angle to corresponding sidewalls 202, 204. Each
 support member 234 has a support portion 236 that includes two holes 240.
 The holes accommodate screws that attach backplane 226 to card cage 200.
 Each support member 234 also has an attachment portion 238 that connects
 support members 234 to corresponding internal sides of sidewalls 202, 204.
 Alternatively, support members 234 could be, e.g., an L-shaped bracket
 riveted to the internal surface of corresponding sidewalls 202, 204.
 After backplane 226 is inserted, aligned, and attached within card cage
 200, movable ceiling member 208 and movable floor member 212 are placed in
 a secured position (FIG. 6) to firmly secure backplane 226 to card cage
 200. Movable ceiling member 208 and movable floor member 212 each slide
 toward ceiling 206 and floor 210 respectively. Backplane 226 is sandwiched
 between ceiling 206 and movable ceiling member 208 as well as between
 floor 210 and movable floor member 212.
 In the present embodiment, a variety of fastening mechanisms can be used to
 firmly secure backplane 226 between ceiling 206 and movable ceiling member
 208 (or floor 210 and movable floor member 212). As shown most clearly in
 FIG. 4, movable ceiling member 208 and movable floor member 212 each
 include a set of fasteners 300 while ceiling 206 and floor 210 each
 include a set of studs 302. Studs 302 are aligned with corresponding
 fasteners 300 along an axis extending in the direction of slots 218, 218'.
 Both fasteners 300 and studs 302 include cooperative threads that allow
 card cage 200 to securely fasten backplane 226. An upper edge of backplane
 226 fastens between ceiling 206 and movable ceiling member 208. A lower
 edge of backplane 226 fastens between floor 210 and movable floor member
 212.
 Card cage 200 also includes an additional securing mechanism to secure
 movable members 208, 212 in the secured position. The securing mechanism
 presses one of four corresponding corner portions of sidewalls 202, 204
 between movable members 208, 212 and the head of one of four corresponding
 rotatable screws 246. A shank of each of the screws 246 extend into a
 corresponding corner of the movable members 208, 212. Each of the movable
 members 208, 212 have two screws 246 located on opposite side edges and
 nearest an exterior edge of movable members 208, 212.
 The corresponding corners of sidewalls 202, 204 have a relieved portion
 that forms a slot 242. Each of the four slots 242 accommodates the shank
 of corresponding screws 246. When movable members 208, 212 are in the
 secured positions, the heads of the screws 246 can be rotated to secure
 movable members 208, 212. The securing mechanism additionally secures
 backplane 226. In addition, the securing mechanism provides a means to
 quickly secure movable members 208, 212 in the secured positions without
 engaging fasteners 300, e.g., when moving or installing card cage 200
 within cabinet 100, e.g., prior to installing backplane 226.
 As shown in FIG. 6, movable ceiling member 208 firmly secures backplane 226
 when movable ceiling member 208 is in the secured position. Studs 302 of
 ceiling 206 extend through holes along the upper edge of backplane 226
 while the lower edge of backplane 226 has notches that rest on studs 302
 of floor 210. When each fastener 300 engages a corresponding stud 302 and
 is tightened, movable ceiling member 208 acts as a vice to firmly secure
 backplane 226 against ceiling member 208. Similarly, floor 210 and movable
 floor member 212 engage the lower edge of backplane 226. Thus, when
 movable members 208, 212 are in secured positions, backplane 226 is fixed
 in position.
 Referring to FIGS. 7 and 8, fasteners 300 are captive metal fasteners that
 are permanently anchored in the casting of the corresponding movable floor
 member 212 (FIG. 4) or movable ceiling member 208 (FIG. 4). Fasteners 300
 (as well as studs 302) are made of, e.g., 316 stainless steel. Each
 captive fastener 300 is arranged about a longitudinal axis 318. Each
 fastener 300 has a head 304, a shank 306 and a sleeve 308. Head 304 is
 attached to shank 306 and both rotate freely within sleeve 308.
 Shank 306 includes a hollow interior portion 310 containing an internal
 thread 312. Hollow interior portion 310 faces, and is aligned with, stud
 302 when fastener 300 is attached to movable members 208, 212. Thus, when
 movable members 208, 212 are in the secured positions, shank 306 fits over
 stud 302 and internal thread 312 cooperates with and engages an external
 thread 314 (FIG. 9) of stud 302.
 Head 304 has, e.g., a hexagonal recess to accommodate an allen-type wrench.
 Thus, head 304 can be used to secure fastener 300 over stud 302. Head 304
 interacts with sleeve 308 to partially captivate shank 306 within sleeve
 308. Because head 304 is external to sleeve 308 and has an outer diameter
 that is wider than the internal diameter of sleeve 308, head 304 limits
 the movement of shank 306 in the direction of stud 302 along longitudinal
 axis 318.
 A pair of internal ridges 320 and 322 complete the captivation of shank 306
 within sleeve 308. Ridge 320 extends about the inner surface of sleeve 308
 to form a circular ring. Ridge 322 extends about the outer surface of an
 end of shank 306 to form an opposing circular ring. Thus, as ridge 322
 moves towards ridge 320, e.g., when fastener 300 is loosened, ridge 322
 will ultimately engage ridge 320 and prevent further motion along
 longitudinal axis 318 in the direction away from stud 302.
 Sleeve 308 further includes a ribbed portion 316 having a set of parallel
 ribs that extend completely about the circumference of the end portion.
 Ribbed portion 316 has ribs that extend longitudinally along fastener 300
 and in the direction of slots 218 when fastener 300 is attached to one of
 movable members 208, 212.
 To attach fastener 300 to one of movable members 208, 212, shank 306 is
 inserted into sleeve 308 prior to the complete formation of ridge 320.
 Ribbed portion 316 of sleeve 308 is clenched into a prefabricated hole in
 the metal casting of movable members 208, 212. Ribbed portion 316 provides
 both longitudinal resistance that tends to secure fastener 300 within the
 hole as well as rotational resistance that tends to prevent sleeve 308
 from turning within the hole. Ribbed portion 316 reforms the metal casting
 around the ribs and may prevent cracking or other deformation of the
 casting, which may occur when a fastener having a serrated/toothed tip is
 clenched into a metal casting.
 When fastener 300 is clenched into the metal casting, e.g., of movable
 ceiling member 208, an additional force is applied to head 304 which
 compresses sleeve 308 against the casting. Thus, ridge 320 is forced
 further inward and into a fully formed position that captivates shank 306.
 Referring to FIGS. 9-10, each stud 302 has arms 324, 326 located on
 opposite ends of a support shank 328. Opposing arms 324, 326 extend in
 opposite directions from support shank 328 along longitudinal axis 318.
 Both of arms 324, 326 have external threads 314 sized to engage internal
 thread 312 of (FIG. 8) fastener 300.
 Support shank 328 has two recesses 330 located on opposite sides of shank
 328. Together, recesses 330 form a grip to accommodate a tool used to
 install stud 302 to either ceiling 206 or floor 210 (FIG. 4). Stud 302 is
 screwed into a prefabricated hole of one of the metal castings. Stud 302
 can be screwed rather than clenched into the hole because a hollow passage
 is not required to pass shank 306 from one side of the hole to another.
 Stud 302 is symmetrical and either arm 324, 326 can be inserted into the
 prefabricated hole of the casting.
 When installed, the entire external thread 314 can extend into and engage
 internal thread 312. However, the entire external thread 314 does not need
 to engage internal thread 312 to secure one of the movable members 208,
 212 in the secured position. Thus, in combination, fastener 300 and stud
 302 provide a range of positions in which movable members 208, 212 can be
 secured. In the present embodiment, movable member 208, 212 can be tight
 against backplane 226 within the range of positions provided by fastener
 300 and stud 302. For example, each arm 324, 326 containing an external
 thread 314 is 0.375" and can be entirely accommodated within fastener 300.
 In addition, fastener 300 can accommodate a portion of support shank 328.
 For example, stud 302 can extend into fastener 300 approximately 0.6".
 Thus, in the secured position, card cage 200 can accommodate backplanes
 having various widths as long as the widths of the backplanes fall within
 the range of positions defined by stud 302 and fastener 300, e.g., between
 zero and less than 0.6" (to provide sufficient engagement between threads
 312, 314 to secure the backplane.)
 The range of positions is limited by the threaded length of arms 324, 326
 of stud 302 as well as by the internal length of internal thread 312 of
 fastener 300. Alternatively, therefore, a longer internal thread capable
 of accommodating a longer stud 302 would allow movable members 208, 212 to
 be secured through a wider range of positions.
 Referring to FIGS. 11-12, backplane 226 includes a support device 400 to
 reinforce backplane 226 when daughter board 216 is inserted or extracted.
 Support device 400 is a stiffener to provide additional structural
 support. Support device 400 is metal finished with an electrodeposited
 zinc coating.
 Support device 400 includes a cross member 402 which is a cross beam
 mounted horizontally and approximately bisecting backplane 226. Cross
 member 402 provides an opposing force in a direction of motion of the
 daughter boards along slots 218 to resist the force of daughter boards 216
 against backplane 226. Cross member 402 is, e.g., 16.14" in length, 0.375'
 in width, and 0.438" in depth. Cross member 402 includes three
 equidistantly spaced holes 412 through which cross member 402 can be
 attached to backplane 226 by screws. Cross member 402 also includes twenty
 equidistantly spaced guide holes 414 to provide a further mechanism to
 ensure backplane 226 is properly positioned.
 Two end support members 404, 406 are attached to corresponding ends of the
 cross member, e.g., to form an H-shaped structure. End support members
 404, 406 extend vertically along two side edges of backplane 226. Each end
 support member 404, 406 is, e.g., 6.75" in length, 0.375", in width and
 0.438" in depth. End support members 404, 406 provide a mechanism to
 secure cross member 402 and attach backplane 226 to sidewalls 202, 204 of
 card cage 200 (FIG. 4). For example, each end support member 404, 406
 includes four holes 412' to accommodate screws. The outer two holes 412'
 of each end support member 404, 406 are used to attach each corresponding
 end support member 404, 406 to backplane 226. The inner two holes 412' are
 used to attach the corresponding end support member 404, 406 to support
 member 234 of card cage 200 (FIG. 4). When backplane 226 is properly
 aligned, the two inner holes 412' align with holes 240 of support member
 234. When backplane 226 is not properly aligned, the two inner holes 412'
 will be misaligned and the screws will not engage card cage 200 to secure
 backplane 226.
 End support members 404, 406 can include additional structures. For
 example, the notch 410 provides a registration point as discussed above in
 conjunction with FIG. 4. Each support member 404, 406 includes two notches
 410. Each notch 410 is a recess along an edge of one of end support
 members 404, 406. Notches 410 accommodate registration pin 430, which
 extends from and interior surface of sidewalls 202, 204. Each notch 410 is
 disposed on a corner of corresponding end support members 404, 406. Each
 notch 410 has an opening with a forward facing portion 410a and a side
 facing portion 410b (FIG. 12). Thus, as backplane 226 is positioned,
 backplane is moved forward and registration pin 230 enters notch 410
 through the forward facing portion 410a and, once in place, is disposed
 through side facing portion 410b.
 Each end support member 404, 406 also includes two guide holes 414'. Guide
 holes 414' provide a further mechanism to ensure that backplane 226 is
 properly positioned.
 End support members 404, 406 can be attached to cross member 402 using
 several different embodiments. For example, as shown in FIG. 13, end
 support members 404, 406 can be directly attached to the ends of cross
 member 402, e.g., by a weld, a rivet or a screw. In another embodiment,
 end support members 404, 406 can extend over the corresponding ends of
 cross member 402 but not be directly attached to the ends. In these
 embodiments, end support members 404, 406 can provide both a means to fix
 backplane 226 to card cage 200 as well as additional structural support
 for cross member 402. Alternatively, end support members 404, 406 can abut
 the corresponding ends of cross member 402 without overlapping the ends in
 the direction of motion of daughter board 216. In the later embodiment,
 end support members 404, 406 provide a means to attach backplane 226 to
 card cage 200 without further reinforcing cross member 402 in the
 direction of motion of daughter board 216. Also, support device 400 can be
 manufactured as a single integrated member.
 Support device 400 is installed as part of backplane 226 prior to
 installing backplane 226 within card cage 200. Thus installed, backplane
 226 has additional structural support, a mechanism to register the
 position of backplane 226 within card cage 200, a mechanism to quickly
 attach backplane 226 to card cage 200, and cabinet 10 has a reduced part
 count at the time of installing components such as backplane 226.
 Support device 400 is symmetrical about a horizontal axis, i.e., an axis
 extending longitudinally along cross member 402. Support device is also
 symmetrical about a vertical axis, i.e., an axis parallel to end support
 members 404, 406. The structure of both end support members 404, 406 is
 identical. Therefore, end support members 404, 406 are interchangeable.
 Also, cross member 402 can be installed as shown or rotated 180 degrees
 with each end of cross member 402 adjacent to the opposite end support
 member 404, 406.
 In addition, support device 400 can be installed on either side of
 backplane 226. Thus, as shown in FIG. 12, an identical supplemental
 support member 400' can be installed upon the opposite side of backplane
 226. As shown, supplemental support member 400' entirely overlays support
 member 400 in the direction of motion of daughter board 216. Thus,
 supplemental support member 400' is expected to provide improved
 reinforcement and support of backplane 226.
 Referring to FIGS. 15-16, daughter board 216 includes a different type of
 stiffener 500 for inserting and removing daughter board 216, e.g., from
 slot 218 (FIG. 4) without buckling or breaking daughter board 216.
 Stiffener 500 is a rigid elongated member that has an elongated channel
 502 that extends along the elongated member. Stiffener 500 includes an
 engagement portion 510, a driver portion 512 and a force translator
 portion 520 extending between engagement portion 510 and driver portion
 512. Stiffener 500 is, e.g., metal finished with an electrodeposited zinc
 coating.
 Channel 502 is defined by three distinct portions of stiffener 500: two
 lateral portions 504, 506 extend in parallel from a cap portion 508. The
 three portions 504, 506, 508 are connected at right angles to form a
 U-shaped member. Stiffener 500 attaches to daughter board 216 along an
 edge of daughter board 216 that moves through slot 218. The edge of
 daughter board 216 fits within channel 502, and stiffener 500 extends
 substantially along the entire edge of daughter board 216, e.g., from a
 front portion of daughter board 216 where force is applied to a back
 portion of daughter board 216 where force is distributed.
 When attached to daughter board 216, stiffener 500 is oriented so that
 engagement portion 510 receives a force applied either to electrically
 connect daughter board 216 with backplane 226 (FIG. 5) or to electrically
 disconnect daughter board 216 from backplane 226.
 Engagement portion 510 flares downward away from cap portion 508 to provide
 additional area in which to place a hole 514 to accommodate a pivot pin
 516. Pivot pin 516 provides both an attachment mechanism as well as a
 fulcrum to apply insertion and extraction forces. As shown most clearly by
 comparing FIGS. 15 and 16, when stiffener 500 is attached to daughter
 board 216, pivot pin 516 extends through both engagement portion 510 and a
 card injector/ejector lever 518. Thus, due to the force of pivot pin 516
 against engagement portion 510, force applied from lever 518 is translated
 through stiffener 500.
 Alternatively, engagement portion 510 can be oriented in other position.
 For example, the end of engagement portion 510 could abut pivot pin 516 to
 translate an insertion force without directly contacting pivot pin 516
 when an extraction force is applied to daughter board 216. Similarly,
 stiffener 500 could be attached to daughter board 216 without abutting
 pivot pin 516 when either an extraction or insertion force is applied to
 daughter board 216.
 When attached to daughter board 216, stiffener 500 is oriented so that
 driver portion 512 is directly adjacent to a surface of electrical
 connector mechanism 522. Electrical connector mechanism includes the
 electrical connectors that engage backplane 226. Driver portion 512 forms
 a right angled notch that abuts a corner surface of electrical connector
 mechanism 522 to force electrical connector mechanism 522 into electrical
 connectors of backplane 226 and electrically connect daughter board 216 to
 backplane 226.
 As configured, driver portion 512 does not exert a force on electrical
 connector mechanism 522 during extraction of daughter board 216 because
 driver portion 512 abuts electrical connector mechanism 522 and is not
 otherwise attached to connector mechanism 522 in the opposite direction.
 Rather, during extraction of daughter board 216, the extraction force is
 translated through stiffener 500 and applied to daughter board 216 via
 attachment points 514', 514".
 Attachment points 514', 514" are parallel pairs of tabs arranged along
 stiffener 500 on opposite sides of channel 502. Each tab of attachment
 points 514', 514" includes a hole to accommodate a screw or a pin. The
 pairs of holes of each attachment point 514', 514" are aligned across
 channel 502 so that, e.g., the screw or pin extends through the holes and
 through the daughter board 216.
 During insertion of daughter board 216, attachment points 514', 514" are
 thought to distribute the applied force through daughter board 216 in
 conjunction with driver portion 512. During extraction, attachment points
 514', 514" are thought to bear the entire force applied force through
 engagement portion 510 (discounting frictional forces between stiffener
 500 and daughter board 216). However, alternatively, driver portion 512
 could include, e.g., an additional lip or ridge capable of engaging
 connector mechanism 522 during extraction of daughter board 216. In such a
 configuration, driver portion 512 would distribute some or all of the
 force applied to engagement portion 510.
 One skilled in the art may now make numerous modifications and uses of and
 departures from the specific apparatus and techniques disclosed herein
 without departing from the inventive concepts. The invention has been
 described with reference to vertical and horizontal directions. However,
 other orientations are possible (e.g., card cage 200 could be rotated 90
 degrees to lie on one side). All materials, dimensions, configurations,
 orientations, and combinations are provided as illustrative examples only
 and are not intended to be the only possible embodiments within the scope
 of the claims. Consequently, the invention is to be construed as embracing
 each and every novel feature and novel combination of features present in
 or possessed by the apparatus and techniques disclosed herein and limited
 only by the spirit and scope of the appended claims.