Printed circuit card frame assembly

Elongated, one-piece molded plastic supports are affixed in vertically spaced relation to the front of a printed circuit card frame assembly backplane equipped with a plurality of card connector receptacles. Each support is formed having a forwardly facing tongue and groove formation along the length thereof which mates with a complementing tongue and groove formation formed along the rear edge of a one-piece molded plastic shelf. A retainer rod, inserted through aligned openings in the support and shelf tongues, sustains the assembly. Guide tracks in the upper and lower surfaces of vertically adjacent shelves accept printed circuit cards for plug-in electrical connection with the backplane receptacles.

BACKGROUND OF THE INVENTION 
The invention related to printed circuit card frame assemblies and 
particularly to apparatus for supporting and aligning a plurality of 
printed circuit cards with the card connector receptacles in the backplane 
of a frame assembly. 
In complex computer systems a vast number of printed circuit cards are 
typically utilized, and the interconnections of these cards with each 
other and other components of the system requires a maze of wires. The 
cards are plugged into connector receptacles of a so-called backplane. The 
connector pins of these receptacles project outwardly from the rear of the 
backplane, and it is to these pins that individual wires must be 
electrically connected to give electrical signal paths both between 
individual plugged-in cards and the system. Due to the vast number of 
connector pins and wires involved in the backplane of a typical complex 
computer system, the only practical approach to making the multitudenous 
connections therebetween is to use automated wirewrapping equipment. In 
order that the equipment can accept a backplane for automated wiring, the 
physical depth of the assembly must be relatively small. Specifically, the 
equipment will not accept the dimensions of a backplane assembly to which 
the requisite card supporting and aligning structures have previously been 
installed. Consequently, these front structures had to be attached to the 
backplane after it had been auto-wire wrapped. 
This required access to the back of the backplane assembly amongst all of 
the wiring to manipulate suitable fasteners, such as screws or bolts, 
through mounting holes in the backplane assembly and front structures. Not 
only is this a tedious and time consuming procedure, but it involves 
disturbing the wires to the extent that their interconnection integrity is 
jeopardized. In addition, printed circuit and supporting structures of the 
prior art are often of many parts requiring considerable time and effort 
to assemble, before attachment to the backplane can be effected. 
It is accordingly an object of the present invention to provide an improved 
printed circuit card frame assembly. 
An additional object is to provide a printed circuit card frame assembly of 
the above-character having improved card supporting and aligning 
structure. 
An additional object is to provide a printed circuit card frame assembly of 
the above-character, wherein the improved card supporting and aligning 
structure comprise a minimal number of parts to thus promote ease of 
assembly. 
Yet another object is to provide a printed circuit card frame assembly of 
the above-character, wherein the improved structure is readily integrated 
into the frame assembly in a manner such as to render wiring of the frame 
assembly both convenient and reliable. 
Other objects of the invention will in part be obvious and in part appear 
hereinafter. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, there is provided a printed 
circuit card frame assembly having card supporting and aligning shelves of 
a unique one-piece construction which can be conveniently mounted to the 
front side of a backplane of the frame assembly after wiring of the 
backplane has been effected. This feature enables the backplane to be 
wired using automated wirewrapping equipment, since the shelves are not 
then present to prevent the equipment from accepting the backplane. 
Instead, mounted to the backplane prior to auto-wire wrapping are a 
plurality of elongated, unobtrusive shelf supports of minimal depth, such 
as not to inhibit acceptance by the automated equipment. 
The shelf support and the shelves are formed having complementary tongue 
and groove formations which interfit to accommodate assembly of the 
shelves to these supports. To sustain each shelf-shelf support assembly, a 
retainer rod is inserted through aligned openings in the tongue portion of 
both formations. Since the only attachment to the backplane itself are 
made prior to auto-wire wrapping and, since the subsequent assembly of the 
shelves to the backplane does not require disturbance of the wiring at the 
back side of the backplane, wiring integrity is not jeopardized. 
The invention accordingly comprises the features of construction, 
combination of elements, and arrangement of parts which will be 
exemplified in the construction hereinafter set forth, and the scope of 
the invention will be indicated in the claims.

Corresponding reference numerals refer to like parts throughout the several 
views of the drawings. 
DETACHED DESCRIPTION 
The printed circuit card frame assembly of the present invention, indicated 
generally at 10, in FIG. 1, includes a backplane, generally indicated at 
12, equipped with a plurality of female card connector receptacles 
represented by slots 14. It will be appreciated that these receptacles 
include a vertical array of connector strips which are brought out 
rearwardly of the backplane to individual pin terminations. Since such 
connector receptacles are well known in the art and since their 
construction is not material to the present invention, their structural 
details have been omitted from the drawings for the sake of simplicity. 
Mounted in the frame assembly 10 are vertically spaced shelves, generally 
indicated at 16, of unique, one-piece construction, which serve to 
removably support a plurality of printed circuit cards 18 in alignment 
with the backplane connector receptacles 14. Electrical installation of a 
card simply involves plugging a configured leading edge portion 18a 
thereof into a receptacle to make electrical connection between the 
receptacle connector strips and contactor strips 18b imprinted on the card 
configured edge portion. 
Each shelf 16 is mounted by a separate shelf support generally indicated at 
20, which is formed in one-piece from a suitable, structurally rigid 
molded plastic material, such as a glass-filled polyetherimide, nylon and 
the like. These supports are attached to backplane 12 in vertically, 
spaced parallel relation by self-tapping screws 22 (FIG. 3) which are 
driven into an array of blind holes 24 performed in the back surface 26 of 
each support as seen in FIG. 5. Ideally, this support attachment is made 
prior to auto-wirewrapping of the backplane connector receptacle pins (not 
shown). As best seen in FIGS. 1 and 2, the supports are formed having a 
back wall 28 which is interrupted at regularly spaced intervals by 
forwardly projecting tongues 30 arrayed along the entire support length. 
Also spanning the entire support length are upper and lower flanges 32 
disposed in overlying and underlying relations with the distributed series 
of tongues 30. There is thus created between the tongues a distributed 
series of recesses or grooves 34 and thus the shelf supports, as attached 
to the backplane, present a forwardly facing tongue and groove formation. 
As best seen in FIGS. 2 and 3, each tongue 30 of this formation is created 
having a transverse opening therein in the form of a rearwardly opened 
slot 30a. These slots are in alignment along the entire length of the 
tongue and groove formation. 
Like their supports 20, the shelves 16 are structurally rigid, one-piece 
plastic moldings created from a suitable material such as a glass-filled 
polyetherimide, etc. As seen in FIGS. 1 and 2, each shelf is formed having 
a longitudinal array of uniformly spaced parallel rails 38 joined together 
at their rearward ends by a wall 40 and at their forward ends by a wall 
42. The gaps between these rails promote movement of cooling air 
throughout the card frame assembly. Formed in the upper and lower edge 
surfaces of each rail 38 are guide tracks 44 with flared forward entry 
sections for acceptance and guiding of the cards 18 into their plugged-in 
portions, as best seen in FIG. 1. Projecting rearwardly from shelf back 
wall 40 is a series of tongues 46 uniformly distributed along the entire 
shelf length. The gaps or recesses between these tongues constitute a 
distributed array of grooves 48, and thus the shelves present along their 
entire lengths rearwardly facing tongue and groove formations 
complementing the forwardly facing tongue and groove formations presented 
by their supports 20. As seen in FIGS. 2 through 4, each shelf tongue is 
created with a transverse opening in the form of a downwardly opened slot 
46a which is aligned with all of the other tongue slots along the entire 
shelf tongue and groove formation. 
To assemble the shelves 16 to their supports 20, which in accordance with a 
primary objective of the present invention is accomplished after the 
backplane has been auto-wired, the tongue and groove formations of the 
shelves and supports are simply inter-meshed or mated. By virtue of the 
support flanges 32 intimately overlying and underlying the shelf tongues 
46, as seen in FIG. 4, the shelves are mounted by their supports in 
cantilever fashion. To sustain each shelf-shelf support assembly, a 
retainer rod 50 is inserted through the longitudinally aligned slots 30a 
and 46a in the support and shelf tongues, as seen in FIGS. 2 and 4. 
As seen in FIG. 1, card frame assembly 10 is also provided with side panels 
52 which cooperate with backplane 12 in providing a form of enclosure for 
housing the cards 18. To lend further support to shelves 16, these side 
panels are provided with clearance holes 52a which accept self-tapping 
screws 54 driven into preformed blind holes 56 created in block formations 
58 created at the front corners of the shelves. In addition, the side 
panels are provided with clearance holes 52b along their rear vertical 
edge to accept screws 60 (FIG. 2) threaded into tapped holes 50a in each 
end of retainer rods 50 to maintain their positions in the shelf 
support-shelf assemblies despite mechanical disturbances, such as 
vibration and shock. 
In practice, the most expeditious assembling procedure has been found to be 
that the shelves are first attached to the side panels with screws 54, and 
then this sub-assembly is united with the pre-wired backplane by mating 
the shelf support and shelf tongue and groove formations. The side panel 
holes 52b are made sufficiently large so as to accept the retainer rods 50 
incident to their insertion through the tongue slots 30a and 46a. 
It will be appreciated that tongue slots 30a and 46a are created in the 
manner shown due to injection molding considerations. Obviously, these 
slots may be oriented in other angular relationships and still serve to 
provide effectively fully bounded tongue openings enabling the retainer 
rods to sustain the shelf support-shelf assemblies. It will also be 
appreciated that the retainer rods may have other cross-sectional 
configurations than the illustrated round configuration. 
It will thus be seen that the objects of the invention made apparent from 
the foregoing description are efficiently attained and, since certain 
changes may be made in the above constructions without departing from the 
scope of the invention, it is intended that all matter contained in the 
above description or shown in the accompanying drawings shall be 
interpreted as illustrative and not in a limiting sense.