Method and Apparatus for Modifying Wire-Wrapped Back Planes

1. Field of the Invention

This invention relates to the assembling of electrical circuitry and more particularly to the installation of electrical connections between selected post terminals of a wire-wrapped back plane.

2. Prior Art

The back plane to which the present invention particularly applies is generally provided with a plurality of plug-in type modules mounted in a frame, one side of the back plane and modules being provided with symetrically arranged receptacles for receiving the flatted or planar terminals of printed circuit cards, and the other side of the back plane and modules being provided with a plurality of integrally formed post terminals which are variously interconnected by wires the ends of which have been wrapped therearound by means of automatic wire-wrapping equipment.

Whenever such a wire-wrapped back plane located at a remote point or on a users premises required modification, such as to accommodate a new or changed feature of the electronic circuitry of which the back plane formed a part, it was heretofore necessary either to ship the back plane to a production facility or to a well-equipped modification center for the incorporation of the required wiring changes, or to send a highly skilled technician to the users premises for the manual and laborious incorporation of such changes, the first named alternative normally entailing considerable expense, delays, and interruptions in service to the user, and the last named alternative being particularly susceptible to error by reason of the extreme difficulty of locating and identifying the precise post terminals to be interconnected.

It is accordingly an object of the present invention to provide an improved and simplified method for incorporating new features and changed characteristics in a wire-wrapped back plane, and for making the post terminal interconnections required thereby.

It is a further object of the present invention to eliminate from the wire changing process the time-consuming task of locating and identifying the precise post terminals in the back plane that require interconnection.

It is still another object of the present invention to greatly reduce the high incidence of error that has heretofore attended the manual incorporation of wiring changes in a wire-wrapped back plane.

It is yet another object of the present invention to so simplify the wire-changing process that a technician of ordinary skill might effect the required post terminal interconnections without first familiarizing himself with the detailed intricacies of the particular back plane.

Still another object of the present invention is to provide an improved wire-changing method that inherently affords segregation as between a particular back plane modification and the back plane wiring as it was originally produced, such that an outmoded modification might be readily removed from the back plane as a precedent to the incorporation of a subsequent change.

In carrying out the objects of the invention, a printed circuit board having apertures corresponding to the post terminals of the back plane has been provided, the printed circuit on the face of the board comprising at least a portion of the post terminal interconnections that are to be made in the back plane, and the apertures formed in the board permitting slip-on connection of the printed circuit board onto the post terminals of the back plane, the printed circuit board, upon said slip-on installation, providing either all of the post terminal interconnections that are required of the modification, or graphic instructions to the technician whereby jumper wires connected at one end to the printed circuit on the board may be connected to graphically identified post terminals of the back plane to complete the required post terminal interconnections.

Various other objects, advantages and meritorious features of the invention will become more fully apparent from the following specification, appended claims and accompanying drawing sheets.

The features of two specific embodiments of the invention are illustrated in the drawing, in which:

FIG. 1 shows a portion of a wire-wrapped back plane;

FIG. 2 shows one embodiment of the invention wherein a printed circuit board having apertures corresponding to the post terminals of the back plane of FIG. 1 is provided with a printed circuit that interconnects a pair of circuit terminals to which are connected a pair of jumper wires capable of being connected to a pair of post terminals requiring interconnections;

FIG. 3 shows the printed circuit board of FIG. 2 inserted over the post terminals of the back plane of FIG. 1; and

FIG. 4 shows another embodiment of the invention wherein a printed circuit board installed on a back plane is provided with circuit segments which are connected by plated through holes, the plated through holes serving to complete the interconnection of selected post terminals.

Referring to FIGS. 1 through 4 by the characters of reference there is illustrated a method and apparatus for carrying out the objects of the invention. The apparatus of the invention consists of a printed circuit board 10 having apertures 20 corresponding to the post terminals 30 of a wire-wrapped back plane 40 which is to be modified in some predetermined manner, the board 10 being provided with the desired printed circuits 50, circuit terminals 60 fixed to the circuits 50, end anchored jumper wires 80 including SNAP-ON or slip-on terminal connectors 100, jumper wire anchorings 90, and graphically illustrated jumper wire pathways 70. The first step of the method of the invention, then, is the selection of a board 10 and the formation of a matrix of apertures 20 therein corresponding to the post terminals 30 of the back plane 40. A second step of the method of the invention is the application or formation of the desired printed circuit 50 on the printed circuit board 10, as by a subtractive process such as etching or other conventional method including additive or subtractive processes. Determination of the pattern of the printed circuit 50 would of course be based upon the character and configuration of the original wire-wrapping of the back plane 40, and upon the nature of the wiring changes that are required to be made therein. The printed circuit terminals 60 for any given segment of the printed circuit 50 may be disposed inwardly adjacent a pair of apertures 20 corresponding to a pair of post terminals to be connected, as is the case in the preferred embodiment, or may be disposed in coincidence with said pair of apertures as subsequently described in connection with another embodiment of the invention. In the event the circuit terminals 60 are to be disposed inwardly adjacent the apertures 20, the above described second step of the method would include the application of graphically illustrated jumper wire pathways 70 leading from the circuit terminals 60 to the apertures 20 corresponding to the post terminals to be connected, such pathways being in the nature of broken or dotted lines as illustrated in FIGS. 2 and 3. A provisional third step of the method would accordingly be the attachment of the circuit terminals 60 to the terminal ends of each segment of the printed circuit 50, as by soldering, and by establishing the jumper wire anchorings 90 by soldering one end of a jumper wire 80 to each of the circuit terminals 60, each of the jumper wires 80 being provided with a slip-on terminal connector 100 prior to its soldering to a circuit terminal 60.

A fourth step of the preferred method of the invention, then, includes the installation of the printed circuit board 10 onto the post terminals 30 of the back plane 40, as illustrated in FIGS. 3 and 4, and the forceable attachment of the slip-on terminal connectors 100 of the jumper wires 80 to the post terminals 30 disposed at the termination points of the graphically illustrated jumper wire pathways 70. Once the printed circuit board 10 is installed onto the post terminals 30 of the back plane 40, the frictional force between the post terminals 30 and the walls of apertures 20 will serve to hold the printed circuit board 10 in place, such holding force being augmented by the forceably attached slip-on terminal connectors 100 should said terminal connectors 100 be of greater outer diameter than the inner diameter of the apertures 20.

Another embodiment of the apparatus and method may be provided by modifying the second step application of the printed circuit 50 such that each segment of the printed circuit 50 extends to a rim-abutting relationship with the pair of apertures 20 corresponding to the pair of post terminals to be connected, and by adding thereafter the subordinate step of plating-through each such pair of apertures 20, the circuit terminals 60 for each circuit segment in such case being coincidably disposed relative to the pair of apertures 20 interconnected by the segment, and consisting of the plated-through apertures which are mechanically and electrically connected to the terminal ends of the circuit segment. This modified method would eliminate the need of the jumper wires 80 and of the jumper wire pathways 70, the desired interconnection of the post terminals 30 of the back plane 40 being accordingly accomplished by the various segments of the printed circuit 50 and of the plated-through apertures 20 that are received by the post terminals 30 requiring interconnection, such post terminals being receivably and contractably disposed within the plated through apertures 20 after installation of printed circuit board 10 onto the post terminals of the back plane.

Included among the many advantages of the present apparatus and method are: (1) a particular modification of a wire-wrapped back plane may conveniently be removed upon the occurrence of its obsolescence, by simply reversing the steps of the method enumerated above; (2) individual wiring modifications that have been made on a back plane will be readily reorganizable by a technician, in that they will be physically segregated from the original back plane wiring; and (3) the development of the printed circuit boards required for future back plane modifications will be facilitated in that each future modification may emanate from the original and uncontaminated state of the back planes wiring configuration, with complete disregard to the intricacies of intervening modifications, it being recognized that all or any part of a preceding modification may be incorporated in the printed circuit board that is developed at the production facility for any particular new modification.

While the above referenced embodiments of the invention have been described in considerable detail, both with respect to the apparatus and method thereof, it will be appreciated that other modifications and variations therein may be made by those skilled in the art without departing from the true spirit and scope of the invention.