Double-sided Circuit Having Terminal-receiving Portions

Abstract

A flexible, semirigid substrate, composed of a nonconducting material, supports a plurality of spaced, longitudinal conductors on one side thereof and a plurality of parallel, spaced, transverse conductors on the other side thereof. Through-hole connections are made through the substrate between selected longitudinal conductors and selected transverse conductors. The transverse conductors extend to a common edge of the substrate, which is formed with a longitudinal fold. The portion of each of the transverse conductors which extends over the longitudinal fold in the substrate is formed with an elongated opening which is disposed symmetrically about the axis of the transverse conductor. The longitudinal opening provides a saddle for receiving a portion of a terminal which rests in the saddle and can be subsequently soldered with the transverse conductor associated with the saddle.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to double-sided circuits having terminal-receiving portions and more particularly relates to double-sided circuits having terminal-receiving portions formed therein for easy assembly with associated terminals and subsequent securing of the circuit with the terminals.

2. Description of the Prior Art

In the manufacture of various types of electrical equipment, a multitude of terminals extend from a common surface of such devices and require interconnections between selected terminals to facilitate the subsequent operation of the device. In many instances the devices are relatively small and the spacing in any direction between adjacent terminals is extremely small. Due to the density of the terminals extending from the one surface of the device, it is a somewhat tedious and difficult operation for an operator or a machine to apply and secure interconnecting conductors between selected terminals of the device which must be interconnected to facilitate the subsequent operation of the device.

An example of an electrical device requiring interconnecting wiring is an electrical communications switch, such as a crossbar switch. In the past, the conventional crossbar switch has been of sufficient size to permit interconnecting conductors and wiring between selected terminals of the switch to be assembled and secured with the switch with little difficulty.

Recently a new and improved crossbar switch was developed which is considerably smaller than the conventional crossbar switch. The smaller crossbar switch is disclosed in U.S. Pat. No. 3,445,795, which was issued to R. P. Holtfreter and H. E. McCullough on May 20, 1969. The compactness of the newly designed crossbar switch permits a reduction in the amount of space required to accommodate a switch of this type in its ultimate environment, for example, in a telephone central office. With the smaller switch, more switches can be installed in available mounting equipment, thus reducing the expenses of switch users.

However, with the influx of smaller devices, such as the newly developed crossbar switch, it is necessary to confine the terminating areas of the switch to a smaller area compared to the conventional crossbar switch. Since the terminals which extend from one surface of the small crossbar switch are extremely close to adjacent terminals, it is extremely difficult for an operator to interconnect selected terminals using existing procedures and techniques. For example, the crowded display of terminals extending from the terminating area of the newly developed switch does not easily facilitate the maneuvering of individual conductors into the areas of the terminals and the subsequent positioning of securing means, such as solder and a soldering device, into the confined spaces between the terminals being secured to the conductor.

Consequently, it became obvious that new techniques and interconnecting facilities had to be developed in order to provide a small crossbar switch which would not be hampered by a high cost imposed upon the ultimate switch because of a tedious and time-consuming interconnecting of selected terminals of the switch.

SUMMARY OF THE INVENTION

It is, therefore, an object of this invention to provide a new and improved double-sided circuit which can be utilized to interconnect selected terminals in an area of high terminal density.

Another object of this invention is to provide a new and improved double-sided circuit having terminal-receiving portions which facilitate the easy assembly and securing of the circuit with closely spaced terminals in an area of high terminal density.

Still another object of this invention is the provision of a new and improved double-sided circuit which is relatively thin and semirigid to permit the circuit to be inserted between closely spaced rows of terminals and assembled with terminals of one row for interconnecting selected terminals within the row.

A further object of this invention is the provision of a new and improved double-sided circuit having terminating conductors formed with saddlelike openings for assembly and securing with closely spaced terminals of an electrical device to interconnect selected ones of the terminals.

A double-sided circuit illustrating certain features of the invention may include a nonconductive substrate having at least one bus conductor on one side thereof and a plurality of terminating conductors on the other side thereof which are interconnected through connection to the bus conductor. Each of the terminating conductors is formed with means for receiving and engaging a portion of an associated terminal so that all terminals in engagement with the terminating conductors are interconnected through the terminating conductors and the bus conductor.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and features of the present invention will be more readily understood from the following detailed description thereof when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a partial perspective view of an electrical device such as a small crossbar switch showing an area of high terminal density on one side of the switch;

FIG. 2 is a plan view of a double-sided circuit embodying certain principles of the invention;

FIG. 3 is a sectional view, taken along line 3--3 of FIG. 2, showing a cross section of the circuit with a terminal of an electrical device, shown in phantom view, being assembled with the circuit;

FIG. 4 is a perspective view showing a plurality of double-sided circuits assembled with terminals extending from the electrical device of FIG. 1, and

FIG. 5 is a partial perspective view showing a terminal assembled and secured within a saddle portion of a conductor of a double-sided circuit.

DETAILED DESCRIPTION

Referring to FIG. 1, there is illustrated in partial view an electrical device, such as a small crossbar switch, designated generally by the reference numeral 11. The switch 11 is of the type described and claimed in the aforementioned U.S. Pat. No. 3,445,795. A plurality of terminals 12--12 extend from a rather confined area of one side of the switch and are connected to circuit portions of the switch, such as switching contacts, to provide interconnections between the circuit portions and external circuits. As an example of one type of crossbar switch 11 having such a high terminal density, the terminals are arranged in spaced rows with each terminal in each row being spaced 0.209 inch from adjacent terminals in the same row. Each row of terminals is 0.220 inch from adjacent rows of terminals. In one type of the crossbar switch 11 which has a high terminal density, there are 20 groups of six terminals 12--12 each for a total of 120 terminals in each row, and there are 12 rows of terminals. Generally, 1,440 terminals extend from an area which measures approximately 25 inches by 21/2 inches.

In the ultimate operation of the switch 11, it is necessary to connect each terminal 12 of each group within a given row of the terminals with its corresponding terminals in the remaining groups in the same row. Thus it is readily seen that, in view of the high density of the terminals 12--12, it would be a tedious and time-consuming operation to assemble conventional wiring with the terminals to be interconnected and further to secure the conductors with the terminals. For example, if conventional wiring was utilized, the wiring would have to be placed at varying depths within the maze of terminals 12--12 in order to avoid crossover connections. Further, sufficient space would have to be provided at the free ends of the terminals 12--12 to facilitate connection, such as wire-wrapped connections, from the terminals to external circuits. It became obvious during the development of the small crossbar switch 11 that some means had to be developed which would facilitate an easy and relatively quick interconnecting of the selected terminals 12--12 in order to maintain the ultimate switch at a reasonable cost.

Referring now to FIG. 2, there is illustrated a double-sided, flexible, substantially flat, semirigid, printed circuit, designated generally by the numeral 13. The printed circuit 13 includes a substrate 14, which is flexible and which is composed of a nonconductive material, such as a polyimide film. In the particular embodiment of the double-sided printed circuit 13 illustrated in FIG. 2, six longitudinal, spaced, parallel, bus conductors 16--16 are supported on one side of the substrate 14 and extend the entire length of the substrate.

A plurality of groups 17A through 17L of terminating conductors 18--18 are secured to the opposite side of the substrate 14 and extend generally in a transverse direction between opposite longitudinal edges 19 and 21 of the substrate. In examining the arrangement of the terminating conductors 18--18 of the group 17A, it is observed that the leftmost conductor extends substantially across the entire width of the substrate 14 and the rightmost conductor extends from the longitudinal edge 19 toward the longitudinal edge 21 but only for a short distance. The remaining terminating conductors 18--18 extend varying distances from the edge 19 of the substrate 14 toward the edge 21 thereof. The remaining groups 17B through 17L of the terminating conductors 18--18 are arranged in a similar fashion.

Each leftmost terminating conductor 18 of the groups 17A through 17L are connected to the uppermost bus conductor 16 by through-hole connections, indicated by the circles 22--22. By utilization of the through-hole connections 22--22, each leftmost terminating conductor 18 of the groups 17A through 17L are thereby interconnected with the leftmost terminating conductors of the other groups of terminating conductors. The remaining terminating conductors 18--18 of each of the groups 17A through 17L are connected in a similar fashion so that each terminal 12 of each group of six terminals in a given row is connected to its corresponding terminal in the remaining groups of terminals.

It is noted that the bus conductors 16--16 and the terminating conductors 18--18 can be secured with the substrate 14 in any manner, such as, for example, by depositing positively the conductive material onto the substrate in a defined pattern. In addition, in one embodiment of the invention, the substrate 14 can be composed of any suitable nonconductive material, such as a polyimide film, which is sufficient to provide a flexible but semirigid support for the conductors 16--16 and 18--18. In another embodiment of the invention, the substrate 14 could be rigid. For example, the substrate 14 could include a metal sheet having an insulating-material coating. While the illustrated example of the switch 11 is shown with six terminals 12--12 in each of the groups 17A through 17L, it is to be understood that each group could contain any number of terminals other than six and not depart from the spirit and scope of the invention.

Subsequent to the securing of the conductors 16--16 and 18--18 with the substrate 14, an elongated opening 23 is punched and formed in each of the terminating conductors 18--18 at a location which is adjacent to the end of the conductor which terminates adjacent to the edge 19 of the substrate 14, as illustrated in FIG. 2, which edge is common to all of the terminating conductors. The opening 23 could also continue through the substrate 14. As viewed in FIGS. 2 and 3, a longitudinal portion of the substrate 14, which is adjacent to the edge 19, and which includes the elongated openings 23--23, is formed with a longitudinal fold 24. The fold 24 in the substrate 14 provides a humplike configuration near the edge 19 of the substrate so that each of the elongated openings 23 are formed to provide a saddle, designated generally by the numeral 26, to receive a corresponding one of the terminals 12--12 of the crossbar switch 11. The saddle 26 provides a nest which is thereby positioned in planar displacement from the remaining portions of the terminating conductors 18--18.

Thereafter a nonconducting film 27, which could be flexible, is placed over the longitudinal bus conductors 16--16, and is adhesively bonded to the conductors and the adjacent portion of the substrate 14 to insulate the bus conductors from external elements. In addition, a longitudinal nonconductive film 28, which could be flexible, is positioned over portions of the terminating conductors 18--18, leaving the saddles 26--26 exposed to insulate the portions of the terminating conductors from external elements.

Referring now to FIG. 3, there is illustrated a cross section of the double-sided circuit 13, taken along line 3--3 of FIG. 2. Also illustrated in phantom view is one terminal 12 extending from the switch 11 with an intermediate portion of the terminal being positioned within the saddle 26. It is noted that the saddle 26 does not provide an opening wherein the terminal 12 passes through the circuit, but rather provides a nesting facility onto which the intermediate portion of the associated terminal is positioned. This permits an easy and fast assembly of the double-sided circuit 13 with a selected row of the terminals 12--12.

In an assembly procedure, the circuit 13 is inserted into a position beneath the selected row of terminals 12--12. Thereafter any one of the saddles 26--26 of the circuit 13 is visibly aligned with the associated terminal 12 and the circuit moved upwardly so that all of the saddles of the circuit move into engagement with adjacent portions of the associated terminals.

If an apertured configuration in a printed circuit had been utilized, the alignment and insertion procedure of the circuit with the terminals would be a difficult procedure in view of the position of the apertures of the circuit relative to the free ends of the terminals and the high terminal density of the terminals.

Referring now to FIG. 4, a first one of the double-sided circuits 13--13 is positioned beneath the lowermost row of terminals 12--12 with longitudinal edge 21 of the circuit being positioned substantially adjacent to the portion of the switch 11 from which the terminals extend. After the double-sided circuit 13 has been positioned beneath the lowermost row of terminals 12--12, the circuit is manipulated to align the leftmost terminating conductor 18 of the circuit with the leftmost terminal 12 of the switch 11 in the lowermost row. The terminating conductors 18--18 of the double-sided circuit 13 have been placed on the substrate 14 in a parallel and spaced fashion with the centerline spacing between the terminating conductors being equal to the centerline spacing between the terminals in any row. Thus, the terminating conductors 18--18 are now aligned with associated terminals 12--12 with which they are to be assembled and secured. The circuit 13 is then raised so that portions of each of the terminals 12--12 are engaged by the saddle 26 of the associated terminating conductors 18--18.

As illustrated in FIG. 5, after the portions of the terminals 12--12 have been positioned in the associated saddles 26--26 of the associated terminating conductors 18--18, an operator applies molten solder 29 into the area of each saddle so that, when the solder solidifies, each terminal is not only electrically connected but is also firmly secured with the associated terminating conductor. Since the circuit 13 is lightweight, the soldered areas of each saddle 26 and terminal 12 are sufficient to provide the only means by which the circuit is firmly secured with the switch 11.

Since the saddles 26--26 of the terminating conductors 18--18 of a given circuit 13 are aligned longitudinally, the soldering operation of soldering the terminating conductors to the associated terminals 12--12 of a given row can be accomplished in a relatively short period of time and with relative ease. This permits an operator who is performing the soldering operation to move a soldering device and solder supply in a relatively straight line along the longitudinal path of the saddles 26--26 adjacent to the free ends of the terminals 12--12.

Referring again to FIG. 4, the operator then places a second circuit 13 between the lowermost row of terminals 12--12 and the next-to-lowermost row of terminals. The aligning and assembling procedure then follows the same pattern as that outlined in assembling the circuit 13 with the lowermost row of terminals 12--12. This pattern is followed until each row of terminals 12--12 is assembled and electrically secured with an associated one of the double-sided printed circuits 13--13.

When the assembly is complete, it is apparent that selected terminals 12--12 in each row of terminals are interconnected through the associated terminating conductors 18--18 and the bus conductors 16--16. For example, in the illustrated switch 11, the terminals 12--12 are also separated into groups of six terminals each. With the double-sided circuit 13 being arranged as previously described in groups 17A through 17L, each terminal 12 of one group of terminals is interconnected with the corresponding terminal in each of the other groups of terminals within a given row. This provides an interconnecting arrangement which is necessary for the switch 11 to function as intended.

The width of the double-sided printed circuit 13 is sufficient to permit a substantial free-end portion of the terminal 12 to extend from the saddles 26--26 after the circuit has been assembled and secured with the terminals. This substantial free-end portion of the terminals 12--12 permits subsequent wire-wrap connections to be made between the terminals and external circuits which utilize the switching capabilities of the switch 11.

The semirigid nature of the printed circuit 13 permits the operator to easily manipulate and position the circuits between the closely spaced rows of terminals 12--12 and to easily align the circuit with the associated terminals. Additionally, due to the semirigid feature of the circuit 13, the circuit is easily held during the soldering of the terminating conductors 18--18 with the associated terminals 12--12. Further, the semirigid nature of the printed circuit 13 permits the circuit to maintain a position which is relatively close to the underside of the row of terminals 12--12 to which it is assembled and secured, thereby precluding the drooping of the circuit onto the row of terminals immediately therebelow.

In view of the semirigid nature of the printed circuit 13, the outer films 27 and 28 are not necessary to accomplish the intended purpose of the inventive design of the circuit 13. However, to prevent the bus and terminating conductors 16 and 18, respectively, from being connected undesirably to unassociated terminals 12--12 or other elements external of the desired connections, the films 27 and 28 are placed over the conductors in the manner previously described and as shown in FIGS. 2 and 3.

Claims

We claim:

1. A double-sided circuit which comprises:

a substrate composed of a nonconductive material;

at least a pair of conductive paths supported on one side of a substrate;

at least one conductive path supported on a side of the substrate opposite from the one side;

the one conductive path being connected to each of the pair of conductive paths to connect the pair of conductive paths together; and

at least portions of each of the pair of conductive paths supported on the substrate being formed with a saddle having a depression contoured to receive at least portions of terminations of external circuits to facilitate interconnecting of the terminations, the contoured depression of the saddle being spaced from the connection of the one conductive path and the pair of conductive paths.

2. The double-sided circuit as set forth in claim 1, wherein the pair of conductive paths are supported in their entirety upon the one side of the substrate.

3. The double-sided circuit as set forth in claim 1, wherein the substrate is formed from polyimide material.

4. The double-sided circuit as set forth in claim 1, wherein portions of the substrate which include at least portions of the pair of conductive paths are formed with a fold whereat the saddles of the pair of conductive paths are located so that the saddles are prominently positioned for assembly with external terminations.

5. The double-sided circuit as set forth in claim 1, which further comprises an insulating material placed over the portions of the pair of conducting paths exclusive of the saddles and over the one conducting path.

6. The double-sided circuit as set forth in claim 1, wherein the substrate is flexible.

7. A double-sided circuit which comprises:

a substrate composed of a nonconductive material which is at least semirigid;

a first plurality of spaced, parallel conductors supported on one side of the substrate;

a second plurality of spaced, parallel conductors supported on the opposite side of the substrate;

selected conductors of the first plurality on the one side of the substrate being connected to selected conductors of the second plurality on the opposite side of the substrate;

the second plurality of conductors being arranged on the substrate in a connecting relationship with the first plurality of conductors to interconnect selected conductors of the first plurality;

at least portions of the substrate which support the first plurality of conductors thereon being formed with a fold which positions portions of the first plurality of conductors in a planar displacement from remaining portions of the conductors, and

a nest formed in each of the first plurality of conductors in the displaced portion thereof to receive and engage a termination of an external circuit.

8. The double-sided circuit as set forth in claim 7, wherein the nonconductive material of the substrate is polyimide.

9. The double-sided circuit as set forth in claim 7, wherein the first plurality of conductors are of the type which are deposited on, supported by and conform to the shape of the underlying portions of the substrate.

10. The double-sided circuit as set forth in claim 7, wherein the nest of each of the first plurality of the conductors includes an opening formed in the displaced portion of each of the conductors on the fold of the substrate.

11. The double-sided circuit as set forth in claim 7, wherein the first plurality of conductors is divided into groups of conductors extending transversely of the substrate and the second plurality of conductors extend longitudinally of the substrate with each of the conductors of the second plurality being connected selectively to at least one conductor in each of the group of conductors to interconnect selected conductors of different groups.

12. The double-sided circuit as set forth in claim 7, wherein an insulating material is placed over the first and second plurality of conductors exclusive of the portions of the conductors which include the nests.

13. An electrical device having circuit portions which comprises:

a plurality of terminals extending from the device and connected to the circuit portions of the device;

a double-sided circuit including:

a substrate composed of a nonconductive material which is at least semirigid,

a first plurality of spaced, parallel conductors supported on one side of the substrate,

a second plurality of spaced, parallel conductors supported on the opposite side of the substrate,

selected conductors of the first plurality on the one side of the substrate being connected to selected conductors of the second plurality on the opposite side of the substrate,

the second plurality of conductors being arranged on the substrate in a connecting relationship with the first plurality of conductors to interconnect selected conductors of the first plurality,

at least portions of the substrate which support the first plurality of conductors thereon being formed with a fold which positions portions of the first plurality of conductors in a planar displacement from remaining portions of the conductors, and

a nest formed in each of the first plurality of conductors in the displaced portion thereof; and

each of the terminals having at least portions thereof positioned in the nest of one of the first plurality of conductors and secured thereto to interconnect selected terminals thereby.

14. The electrical device as set forth in claim 13, wherein the device is a crossbar switch.

15. The electrical device as set forth in claim 13 which further comprises:

the terminals which extend from the device being arranged in at least one row containing a plurality of groups of terminals;

the first plurality of conductors being divided into groups of conductors extending transversely of the substrate and the second plurality of conductors extending longitudinally of the substrate with each of the conductors of the second plurality being connected selectively to at least one conductor in each of the groups of conductors, and

selected terminals of each group in the row being connected to selected conductors of the first plurality of conductors to interconnect each selected terminal of one group with at least one other selected terminal in another group through the interconnecting relationship of the first and second plurality of conductors.

16. The electrical device as set forth in claim 13, wherein an insulating material is placed over the first and second plurality of conductors exclusive of the portions of the conductors which include the nests.

17. A double-sided circuit which comprises:

a substrate composed of a nonconductive material;

at least a pair of conductive paths supported on one side of the substrate;

at least one conductive path supported on a side of the substrate opposite from the one side;

the one conductive path being connected to each of the pair of conductive paths to connect the pair of conductive paths together;

at least portions of each of the pair of conductive paths supported on the substrate being formed with a saddle upon which at least portions of terminations of external circuits can rest to facilitate interconnecting of the terminations;

at least portions of the substrate which include at least portions of the pair of conductive paths formed with a fold whereat the saddles of the pair of conductive paths are located so that the saddles are prominently positioned for assembly with external terminations; and

at least a portion of each of the pair of conductive paths which form the saddle formed with an opening to provide the saddle on the fold of the substrate.