CA1169163A

CA1169163A - Pin arrangement for a backplane

Info

Publication number: CA1169163A
Application number: CA000396263A
Authority: CA
Inventors: John W. Perry
Original assignee: Northern Telecom Ltd
Current assignee: Nortel Networks Ltd
Priority date: 1982-02-15
Filing date: 1982-02-15
Publication date: 1984-06-12

Abstract

PIN ARRANGEMENT FOR A BACKPLANE
Abstract of the Disclosure A backplane, in the form of a printed circuit board (PCB), is provided with an arrangement of electrically conductive pins for increasing the ease and versatility of providing electrical interconnections. The back surface of the "backplane" carries four parallel columns of pins for each "circuit board" location. At each circuit board location, on the backplane, the pins of two of these four parallel columns protrude from the back surface, extend through the backplane, and protrude from the front surface where they are available to accept the circuit board. The remaining two columns of pins, at each circuit board location, are carried by the backplane and protrude only from the back surface. The pins of one of these columns (i.e. protruding only from the back surface) are electrically connected, pin for pin in a one-to-one relationship, to the pins of one of the columns of pins that protrude from both the back and front surfaces of the backplane. The pins of the other column of pins (i.e protruding only from the back surface) are electrically connected, pin for pin, to respective pins in corresponding columns at each circuit board location.

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Description

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Field of the Invention The present invention relates generally to backplane interconnections and more particularly to the arrangement of electrically conductive pins on the backplane to facilitate interconnections~
Background of the Invention It is common practice, when packaging electronic equipment such as electronic telephone switching equipment, to provide a printed circuit board (PCB) to function as a "backplane". The backplane contains pins, protruding from its front surface, into which circuit boards (e.g.
PCBs) are fitted so as to make electrical interconnections between the "backplane" and the "circuit boards".
The back surface of the backplane (and sometimes the front surface) commonly carries printed circuitry for providing predetermined electrical interconnections between the pins on the front surface, and consequently between the circuit boards themselves. Pins may also be provided, protruding from the back surface of the backplane, for providing the opportunity to make additional interconnections on the back surface of the backplane. The pins on the back surface are commonly an extension of the pins from the front surface; in other words, the pins protrude through the backplane and the same pin appears at both the front surface and the back surface of the backplane.
The additional interconnections made to the back plane, via the pins, are commonly made either by wire-wrapping or by overlaying additional PCBs and soldering the pins to points on the additional PCBs (or by a combination of these two methods). One prior art method of wire-wrapping back planes is depicted in U.S. patent 3,935,372 dated January 27, 1976 by G.H. Triplett et al. Another prior art use of 1 ~ 69 1 63 wire-wrap terminals is depicted in U.S. patent 4,031,371 dated June 21, 1977 by H.G. DeVries. U.S. patent 3,509,268 dated April 28, 1970 by L.
Schwartz et al depicts a scheme of interconnecting pins by the use of a plurality of PCBs. U.S. patent 4,195,896 dated April 1, 1980 by G.G.
Wagner et al depicts a "plug-in" PCB that provides an interconnection between "binding posts" on electrical equipment. U.S. patent 3,296,362 dated January 3, 1967 by F.C. Parry depicts yet another scheme for interconnecting electrical terminals.
Summary of the Invention The present invention is directed to the arrangement of the electrically conductive pins on the back plane so as to increase the ease and versatility of providing interconnections therebetween. The term "backplane" is defined by the Electronics Dictionary, fourth edition, copyrighted 1978 by the McGraw-Hill Book Company as: "A wiring board, usually constructed as a printed circuit, that is used in microcomputers and minicomputers to provide the required connections between logic, memory, and input/output modules.". By common useage in the telephone art, the term "backplane" is not quite as restricted as that given above frorn the Electronics Dictionary. Rather, the term "backplane" is used to refer to a wiring board (usually a printed circuit board) that is used in electronic equipment to provide the required connections between other circuit boards (usually plug-in printed circuit boards). It is this latter broader definition that will be employed in this specification and the claims appènded hereto.
In simplistic terms, the pin arrangement of the present invention is as follows. The back surface of the backplane carries four parallel columns of pins for each circuit board location. At each circuit l 1 B9163 board location, on the backplane, the pins of two of these four parallel columns protrude from the back surface, extend through the backplane, and protrude from the front surface where they are available to accept the circuit board. The remaining two columns of pins, at each circuit board location, are carried b~y the backplane and protrude only from the back surface. The pins, of one column of pins at each circuit board location that protrudes only from the back surface, are electrically connected, pin for pin in a one to one relationship, to the pins of one of the colwnns of pins that protrude through both the front and back surfaces; i.e. one pin from one column is connected to one pin on the other column, so as to form a number of etectrically paired pins at each circuit board location. The pins, of the remaining column of pins at each circuit board location that protrude only from the back surface, are electrically connected, pin for ; pin, to pins of a corresponding column of pins at each circuit board location on the backplane i.e. one pin from one column is connected to one pin on each corresponding column at each circuit board location, so as to form a number of electrically grouped pins.
Expressed in other terms, the present invention is a planar sheet of electrically insulating material supporting a first pluality and a second plurality of electrically conductive pins, the sheet characterized by: the first plurality of pins being arranged in a predetermined fashion on a front surface of the sheet so as to be able to establish electrical connections with electrical connectors, and extending through the sheet and protruding from the back surface of the sheet so as to be available for electrical interconnections; the second plurality of pins being arranged in a predetermined fashion protruding only from a back surface of the sheet so as to be available to establish electrical connections.

~ 7 ~ 3 Expressed in still other terms, the present invention is a printed circuit board (PCB) having both a front surface and a back surface and having a plurality of electrically conductive pins for facilitating electrical connections to the PCB, the PCB characterized by: a first plurality of pins carried by the PCB and protruding from both the front surface and the back surface of the PCB so as to be accessible for electrical connections; a second plurality of pins carried by the PCB and protruding only from one surface of the PCB so as to be accessible for electrical connections.
Stated in yet other terms, the present invention is a pin arrangement for a printed circuit board (PCB), the arrangement comprising: a plurality of pin groupings, each grouping comprising two first pins extending through the PCB to protrude both from a front surface of the PCB and from a back surface of the PCB, and two second pins mounted protruding only from the back surface of the PCB, such that one first pin is electrically ~solated from all the other pins, the other first pin is ; electrically connected to one of the second pins in its own grouping, and the other second pin is electrically connected to all the corresponding other second pins of all the pin groupings.
Brief Description of the Drawings The invention will now be described in more detail with reference to the accompanying drawings, wherein like parts in each of the several figures are identified by the same reference characters, and wherein:
Figure 1 is a simplified plan view of the back surface of an exemplary backplane configured according to the present invention;
Figure 2 is a simplified end view of the Figure 1 embodiment; and ~ 1 6~ 1 63 Figure 3 is a stylized representation of the same view as Figure 2, depicting the interconnections of one row of pins and additionally showing the connection of the circuit boards.
Detailed Description Figure 1 depicts, in simplified form, the back surface 10 of a backplane 12. Backplane 12 is constructed of an electrically insulating material such as glass-fibre reinforced resin (a material commonly used in the construction of printed circuit boards).
Electrically conductive pins 13 protrude from the back surface 10 as depicted in Figure 1. The pins 13 are arranged into three main groupings in the illustrative embodiment of Figure 1. These three groupings are indicated generally by the reference characters 16, 17, and 18; each one of the groupings 16, 17, and 18 corresponds to one circuit board location.
In Figure 1, locations for three circuit boards are provided; note that the circuit boards connect to the front surface 11 (see Figure 3).
First pin grouping 16 is depicted as having 15 rows and four columns so as to provide 60 pins. Column 16a consists of pins 13 that extend through backplane 12 and protrude from both back surface 10 and front surface 11 (this can be seen in Figure 2). Likewise, column 16b consists of pins 13 that extend through backplane 12 and protrude from both back surface 10 and front surface 11. The pins 13 of column 16c, on the other hand, are carried by backplane 12 and protrude only from back surface 10. Likewise, the pins 13 of column 16d are carried by backplane 12 and protrude only from back surface 10.
The pins 13 of columns 17a, 17b, 18a and 18b are carried by backplane 12 and protrude from both back surface 10 and front surface 11 of backplane 12. The pins 13 of columns 17c, 17d, 18c and 18d are carried by backplane 12 and protrude only from back surface 10.

l J 6~163 It should be noted that, while the pins of columns 16c, 16d, 17c, 17d, 18c, and 18d are referred to as protruding only from back surface 10, they may in actual practice protrude slightly from front surface 11. This may be necessary in order to provide adequate support from the pins; however, the protrusion of the pins from front surface 11 is insufficient to allow convenient connection therewith, and of necessity must be short enough so as not to interfere with the circuit boards that connect to the other pins on front surface 11. Consequently, when pins 13 are referred to as protruding only from one surface (i.e. back surface 10) of backplane 12, in the specification and claims, it is to be understood that a small protrusion from the other surface (i.e. front surface 11) is to be permitted and is encompassed by the expression "protruding only from one surface" or any equivalent expression.
Figure 3 is a stylized representation of the same view as Figure 2, but additionally depicts both circuit boards 21, 22 and 23 connected to backplane 12 via pins 13 and the interconnection of the pins 13. Note that each circuit board 21, 22 and 23 has associated therewith a female connector referenced as 24, 25, and 26 respectively, to establish a connection with pins 13 of backplane 12. Note that only pins 13 of columns 16a, 16b, 17a, 17b, 18a, and 18b connect with connectors 24, 25, and 26 as depicted.
Only one row of pins 13 is visible in Figure 3; it should be noted that as far as the present invention is concerned there are no interconnections between rows, just interconnections between various pins 13 within a given row. Each row of pins is interconnected in the same manner as is the exemplary row depicted in Figure 3.
From Figure 3 it will be noted that pins 13 of columns 16a, ~ 1~9163 :

17a, and 18a are not connected to any other pins. It will also be noted that, within a given row, the pins 13 from columns 16b and 16c are - connected, the pins 13 from columns 17b and 17c are connected, and the pins 13 from columns 18b and 18c are connected. It will also be noted that the pins 13 from columns 16d, 17d, and 18d are all connected together. It should be noted that the interconnections between pins 13 are depicted in a representative fashion in Figure 3 in order to be more readily visible, and in actual practice those interconnections would form printed circuitry upon either back surface 10 or front surface 11 of backplane 12.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A planar sheet of electrically insulating material supporting a first plurality and a second plurality of electrically conductive pins, said sheet characterized by:
said first plurality of pins being arranged in a predetermined fashion on a front surface of said sheet so as to be able to establish electrical connections with electrical connectors, and extending through said sheet and protruding from the back surface of said sheet so as to be available for electrical interconnections;
said second plurality of pins being arranged in a predetermined fashion protruding only from a back surface of said sheet so as to be available to establish electrical connections.

2. The sheet of claim 1 further characterized by said first plurality of pins being arranged in a plurality of separate groups, each said group separated from the others so as to be able to accept a connector to establish electrical interconnections and said second plurality of pins arranged in a plurality of separate groups adjacent to and corresponding to respective groups of said first plurality of pins.

3. A printed circuit board (PCB) having both a front surface and a back surface and having a plurality of electrically conductive pins for facilitating electrical connections to said PCB, said PCB characterized by:
a first plurality of pins carried by said PCB and protruding from both the front surface and the back surface of said PCB so as to be accessible for electrical connections;

a second plurality of pins carried by said PCB and protruding only from one surface of said PCB so as to be accessible for electrical connections.

4. The PCB of claim 3 wherein said first plurality of pins defines a location, on the front surface of said PCB, for receiving an electrical connector, and said second plurality of pins protruding from said back surface of said PCB are associated physically therewith and at least some of said pins in said first plurality of pins are electrically connected to at least some of said pins in said second plurality of pins.

5. A printed circuit board (PCB), having both a front surface and a back surface, and having a plurality of electrically conductive pins for facilitating electrical connections to said PCB, said PCB characterized by:
a plurality of connector receiving locations;
each said connector receiving location characterized both by a first plurality of electrically conductive pins carried by said PCB, protruding from both the front surface and the back surface of said PCB so as to be accessible for electrical connections and by a second plurality of electrically conductive pins carried by said PCB, protruding only from the back surface of said PCB so as to be accessible for electrical connections.

6. The PCB of claim 5 wherein the number of pins in said first and second plurality of pins is equal and wherein a) a first half of the pins in said first plurality are electrically connected to a first half of the pins in said second plurality, in a one-to-one relationship, and b) the remaining second half of the pins in said second plurality of pins are connected to respective ones of said pins in respective second halves of said second pluralities of pins at each connector receiving position.

7. The PCB of claim 6 wherein the pins of both halves of said first plurality of pins are arranged in straight columns, parallel to each other, and both halves of said second plurality of pins are arranged in straight columns parallel to, and spaced apart from, the columns of said first plurality of pins, so as to result in four parallel columns of pins.

8. A pin arrangement for a printed circuit board (PCB), said arrangement comprising:
a plurality of pin groupings, each said grouping comprising two first pins extending through said PCB to protrude both from a front surface of said PCB and from a back surface of said PCB, and two second pins mounted protruding only from the back surface of said PCB, such that one said first pin is electrically isolated from all said other pins, the other said first pin is electrically connected to one of said second pins in its own grouping, and the other said second pin is electrically connected to all the corresponding other second pins of all said pin groupings.