US 3518612 A
Description (OCR text may contain errors)
June 1970 J. P. e. DUNMAN ET AL 3,
INVENTORS JOHN P. G. DUNMAN JOHN G. AXFORD AGENT June 30, 1970 J, P, DUNMAN ET AL 3,518,612
CONNECTOR ASSEMBLY 4 Sheets-Sheet 2 Filed June 22, 1967 FBG. 8
Jume 30, 1970 J. P. G. DUNMAN ET AL 3,
CONNECTOR ASSEMBLY Filed June 22, 1967 4 Sheets-$heet 5 Fee. 10 A i" 8 FIG. 11 65 FIG.12
J1me 30, 1970 J. P. G. DUNMAN ET AL 3,513,612
CONNECTOR ASSEMBLY Filed June 22, 1967 4 Sheets-Sheet 4 FIG. 14
United States Patent 3,518,612 CONNECTOR ASSEMBLY John P. G. Dunman, Ramsey, and John G. Axford, Winchester, England, assignors to International Business Machines Corporation, Armonk, N.Y., a corporation of New York Filed June 22, 1967, Ser. No. 648,133 Claims priority, application Great Britain, Aug. 6, 1966, 35,309/ 66 Int. Cl. H01p 3/08; Hk 1/04 US. Cl. 339--19 2 Claims ABSTRACT OF THE DISCLOSURE A connector assembly comprising a plurality of conducting elements interleaved with insulating elements, each conducting element being adapted to be connected to a respective pair of conductors, and all the elements being designed and relatively positioned to maintain the desired impedance between selected adjacent conductors.
BACKGROUND OF THE INVENTION The present invention relates to connectors for coupling together printed circuit conductors which are located on opposite surfaces of a printed circuit board. Such a connector may be formed with a tag for connection to another conductor not on the printed circuit board.
By way of example the two conductors on opposite surfaces of the printed circuit board may be parts of two transmission lines to be coupled together. Each transmission line may comprise a line conductor and a ground conductor. For coupling together the two transmission lines, two connectors must be provided, one to couple together the two line conductors and another to couple together the two ground conductors. It is essential that the coupling of the two transmission lines should maintain the correct impedance between the line conductor and the ground conductor. A plurality of such connectors may be mounted together in a connector assembly.
SUMMARY The object of the present invention is to provide an improved connector assembly for connecting together in pairs a plurality of conductors so as to maintain the desired impedance between adjacent conductors.
According to one embodiment of the invention, each conducting element is adapted to make direct contact with its respective pair of conductors. Each conducting element in this embodiment may be resiliently biased so as to make good contact with its respective conductors, and means may be provided for overcoming the bias so as to interrupt the coupling between the pairs of conductors and enable the connector assembly to be removed from the conductors, which may, for example, be on a printed circuit board.
According to another embodiment, each conducting element is adapted to be connected to its respective pairs of conductors by means of two adapter elements. In this embodiment the adapter elements for adjacent conducting elements may be mounted together in a subassembly and suitably insulated from each other.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic isometric view of a con- 3 518,612 Patented June 30, 1970 ice nector assembly coupling together conductors on opposite surfaces of a substrate;
FIG. 2 is a plan view of a substrate including printed circuit boards on the surfaces of which are conductors coupled together in pairs by a connector assembly embodying the invention;
FIG. 3 is an isometric view of a connector assembly embodying the invention;
FIG. 4 is a side view of the substrate illustrated in FIG. 2 sectioned along the lines 44;
FIG. 5 is a side view of the substrate illustrated in FIG. 2 sectioned along the lines 55;
FIG. 6 is an isometric view of another connector assembly embodying the invention attached to a substrate;
FIG. 7 is a side view of the connector assembly illustrated in FIG. 6 sectioned along the axis 77 of the shaft therein;
FIGS. 8 and 9 are end views of the connector assembly illustrated in FIG. 6 sectioned along the lines 88 illustrating the connectors in the closed and open positioris respectively;
FIG. 10 is a plan view of a substrate including printed circuit boards on the surfaces of which are conductors coupled together in pairs by a further connector assembly embodying the invention, showing the connector assembly partly cut away;
FIG. 11 is a side view of the substrate illustrated in FIG. 10 sectioned on the lines 11-11;
FIG. 12 is a side view of the substrate illustrated in FIG. 10 sectioned on the lines 12-12;
FIG. 13 is an isometric view of one adapter element used with the connector assembly illustrated in FIG. 10;
FIG. 14 is an isometric view of the connector assembly illustrated in FIG. 10; and
FIG. 15 is a view of the adjacent ends of two connector assemblies of the type illustrated in FIG. 14, coupled together.
DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates diagrammatically the way in which a connector assembly embodying the invention couples together in pairs conductors on opposite surfaces of a composite substrate. With reference to FIG. 1, the substrate 1 comprises two base layers 2, 3, two ground planes 4, 5 of electrically conducting material, two outer layers 6, 7 of insulating material, and strip conductors 8, 9 on the free surfaces of the layers 6, 7. The conductors 8, 9 are spaced apart on the surfaces of the layers 6, 7 and may be connected into circuitry not illustrated. For eX- ample, each conductor 8 may form a transmission line in combination with the ground plane 4.
Connectors 11 are provided for coupling together each conductor 8 and a corresponding conductor 9. Connectors 12 are also provided for coupling together the ground planes 4, 5. The constructions of the connectors 11, 12 are similar. Each connector is C-shaped with each of the arms arranged to contact a conductor (or a ground plane) and the central portion extending from one surface of the substrate 1 to the other, spaced from the edge of the board. Each connector is provided with a tag 13 from which a connection may be made to another circuit (not illustrated). The connectors are spaced apart from each other and are so designed as to maintain the desired impedance between each conductor and the ground plane and to provide the desired impedance between adjacent tags 13.
FIGS. 2, 3, 4 and 5 illustrate in greater detail a connector assembly embodying the present invention. FIG. 2 is a plan view of the substrate 1 illustrating the connectors 11, 12 grouped together in groups of three, two conductor connectors 11 with one ground plane connector 12. The
tags 13 of the connectors 11 of each group of connectors are attached to two flexible conductors 14, 15 of a screened cable 16, the connector 12 of each group being connected to the screen 17 of the cable.
FIG. 3 is an isometric view of one group of connectors 11, 12. Each connector is C-shaped and is formed from a fiat strip of suitable material, for example, beryllium copper. At the free end of each arm of each connector is formed a contact portion 18 which has a rounded edge 19 at the inside. The rounded edge 19 of each connector is the portion which actually makes contact with the corresponding conductor or ground plane.
The group of connectors is assembled with interleaved elements 20 of insulating material so as to form a connector assembly. The insulating elements 20 are attached to the connectors 11, 12 by any suitable means. The connector assembly is constructed so that the arms of the connectors can the forced apart by opposing forces acting on the inside edges of the arms of each connector. The
dimensions of the components of the connector assembly, their spacing and the dielectric constant of the insulating element are important and are selected to ensure that the impedance between each conductor and the ground plane has a desired value and to provide the correct spring rate of the assembly.
The construction of the substrate 1 and the way in which a connector assembly couples together the conductors 8, 9 in pairs is illustrated in FIGS. 4 and 5. At the edge of the substrate 1 the base layers 2, 3 projectand extend laterally to form two halves 24, of a projection which extends level with the surfaces of the ground planes 4, 5. The end of each conductor 8, 9 is fiush with the edge of the corresponding layer 6, 7, which edge is recessed back from the edge of the corresponding ground plane 4, 5 so that part of each ground plane is exposed. The connector assembly is adapted to be mounted around the edge of the substrate 1 so that the edges 19 of the connectors 11 make contact with corresponding conductors 8, 9 and the edges 19 of the connector 12 make contact with the exposed portions of the corresponding ground planes 4, 5.
FIG. 4 illustrates more clearly the way in which a connector 11 makes contact with the corresponding conductors, and FIG. 5 illustrates more clearly the -way in which a connector 12 makes contact with the ground planes. It will be noted that the inside edges of adjacent arms of the connectors of the assembly extend in the same plane. In order to mount the assembly as illustrated, the arms of the connectors have to be forced outward against the natural resilient bias provided by the material of the connectors. The assembly is placed around the edge of the board and then the arms are allowed to spring back towards their natural positions and in doing so the ends 18 of the connectors are brought firmly into contact with the conductors and ground planes. A certain amount of wiping action will be inherent in the operation so as to improve the contact. The contact pressure will depend on the natural shape of each arm and the Spring rate of the material used for the connectors.
FIGS. 6, 7, 8 and 9 illustrate a larger connector assembly in accordance with the invention which includes means for forcing apart the arms of each connector to enable the assembly to be mounted on the edge of a composite substrate and then allowing the arm to spring back and provide the required coupling between pairs of conductors and the ground planes, as described above.
With reference to FIG. 6, the connector assembly comprises a plurality of groups 31 of connectors 11, 12 of the type illustrated in FIG. 3, mounted in a body 32 of insulating material. A shaft 33 extends longitudinally through the body 32 and is formed with portions 34 which engage in bearing surfaces 35 formed in the body and are interspersed with cams 36, as illustrated more clearly in FIG. 7. The groups 31 of connectors are assembled in the body 32 so that the arms of the connectors of each group extend symmetrically on either side of a corresponding cam 36 (see FIG. 7) and the tags 13 of the group extend in staggered array through the wall of body 32, as illustrated most clearly in FIG. 6.
Each end of the shaft 33 is formed with a cylindrical boss 37, which may be eccentric with respect to the shaft, and at least one of the bosses is formed with a square socket 40 adapted to receive a square key for use to rotate the shaft 33.
To the edge 1a of the substrate 1 are attached two spring lugs 38 (only one illustrated) and in each lug is formed a hole 39. The spring lugs are spaced apart by a distance slightly less than the length of the body 32 and if the body is placed around the edge of the board, the lugs 38 will deflect and the bosses 37 will engage in the holes 39, allowing the spring lugs 38 to move towards each other, thereby retaining the body 32 around the edge of the board.
In order to mount the connector assembly in position, it is first necessary to open the arms of the connectors. This is performed by rotating the shaft 33. As will be seen from FIG. 8, the cams 36 on the shaft each include two fiat surfaces 41 and two curved surfaces 42. The curved surfaces 42 are spaced further from the axis than the flat surfaces 41. All the flat surfaces 41 on the cam extend in parallel planes and are spaced from the axis by equal amounts.
If the shaft-33 is angularly located so that the flat surfaces 41 are nearest to the arms of the connectors, the flat surfaces will be spaced from the arms and will allow the arms to move inwardly towards their natural positions. If the shaft is then rotated, the curved surfaces 42 will come into contact with the arms and will force them apart. With the arms of the connectors forced apart, the body 32 can be placed around the edge of the substrate 1, as illustrated in FIG. 9. If the shaft 33 is then rotated so that the fiat surfaces 41 of the cams move adjacent to the arms, the connectors will then make contact with the conductors and the ground planes in the manner already described, as illustrated in FIG. 8. If the bosses 37 are slightly eccentric, a contact wiping action will be achieved.
In order to interrupt the coupling between the pairs of conductors and the ground planes as provided by the assembly within the body 32, the shaft 33 is rotated until the curved surfaces of the cams 36 force the arms of the connectors apart and there is no longer contact between the connectors and the conductors and ground planes. The coupling can subsequently be restored, or the body 32 can be removed while the arms of the con nectors are still forced apart.
The earns 36 are only necessary if a large number of contacts and a high contact pressure and the danger of damaging the conduction prevents the body 32, together with the connectors, from being pushed onto the substrate 1.
An alternative embodiment of the invention is illustrated in FIGS. 10, 11 and 12. A composite substrate, constructed as described above, has conductors and ground planes on each surface which are to be coupled together in pairs. This is provided for by a connector assembly molded ito a housing 51 of insulating material. The connectors comprise flat plates 52 of conducting material which are spaced apart by distances equal to the distances between adjacent conductors 8 (and 9), and flat plates 53 located between each pair of plates 52. The plates 52, 53 extend to the surface of the housing at selected points and are adapted to be connected to the conductors and the ground planes on substrate 1 by two adapter elements 54, one of which is illustrated in FIG. 13.
The housing 51 extends adjacent to and along one edge of the substrate 1 and is shaped as illustrated in FIG. 14. The housing has a rear surface 55 through which extend tags 56 from the connector plates 52, 53 for connection to a further circuit, not illustrated, a top surface in two parts 57, 58 and a bottom surface in two parts 59, 60. The parts 58, 60 are recessed back from parts 57, 59 respectively. The connector plates 52 extend to the surface parts 57, 59 and the connector plates 53 extend to the surface parts 58, 60 to enable connections to be made to these plates.
The connections are made by means of the adapter elements 54, one of which is illustrated in FIG. 13. The adapter element comprises a backing sheet 61 of electrically insulating material, for example Mylar (trademark of E. I. du Pont de Nemours Co.), on one surface of which are formed printed circuit conductors 62 spaced apart by distances equal to the distances between the conductors 8 (and 9) and the plates 52. Over part of the conductors 62 is formed an insulating layer 63, also of Mylar for example, and on the surface of layer 63 extends a conducting sheet 64, for example of copper. The adapter 54 is so shaped that when the housing 51 is placed in position adjacent to one edge of the substrate 1, the adapter element will extend between the substrate and the housing with the sheet 64 making contact with the ground plane on the substrate 1 and the exposed edges of plates 53 in the housing, while the conductors 62 make contact with conductors 8 or 9 on the substrate 1 and the exposed edges of the plates 52 in the housing 51.
Only one adapter element is illustrated in FIGS. 11 and 12, but it will be appreciated that there is one on each side of substrate 1 providing connections between the plates 52, 53 and the conductors 8 on one surface of substrate 1, the conductors 9 on the other surface of substrate 1, and the two ground planes 4, of substrate 1.
The adapter elements are retained in position by clamps 65 with resilient pads 66.
FlG. 11 illustrates how a coupling is made from a conductor 8 through one of the conductors 62 to one of the plates 52, while FIG. 12 illustrates how a coupling is made from the ground plane 4 to a plate 53.
The plates 52, 53 are designed and positioned so that the required impedance is maintained between each conductor and the ground plane. The impedance between adjacent plates is determined by the material and dimensions and spacing of the plates and by the dielectric constant of the insulating material.
FIG. 15 illustrates how the housings 51 can be attached along the edge of a composite substrate. Each housing 51 is formed with a recess 71 in each end (FIG. 14) and the associated substrate is formed with a projection 72 which engages in the recesses 71 of the two adjacent housings 51. A rod 73 at the end of each housing extends through one clamp 65, the first portion of the housing, the projection 72, the second portion of the housing and out through the other clamp 65. Nuts 74 on the ends of the rod secure the clamps 65 in position and attach the housing to the substrate. The adjacent housing 51 is attached in a similar way.
The above description covers two kinds of connector assembly for connecting together in pairs conductors on opposite surfaces of a printed circuit board or substrate. In the first example, each connector makes direct contact with its associated conductor (or ground plane). Contact can be interrupted by forcing apart the arms of the connectors. This also enables the whole connector assembly to be removed. In the second example each connector is adapted to be connected to its associated conductor (or ground plane) through conductors provided by adapter elements. When the adapter elements are removed, the connector assembly can also be removed.
By using closely spaced interleaved conducting and insulating elements, it is possible to provide connections to closely spaced conductors and ground planes while still maintaining the desired impedance between each conductor and the ground plane, and enabling connections to be made between the ground planes and an external circuit adjacent to connections from the conductors, thus maintaining ground continuity.
While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.
What is claimed is:
1. A connector for establishing a matched impedance contact to a strip transmission line circuit on opposite sides of a circuit board, comprising:
(a) first conductive elements for establishing contact with the signal conductors positioned on opposite sides of a circuit board,
(b) a second conductive element for establishing contact with the ground conductors positioned on opposite sides of the circuit board, and
(c) insulating elements positioned intermediate to said first conductive elements and said second conductive element and secured to which said conductive elements, and which function to hold the connector conductive elements predetermined distances apart whereby the connector characteristic impedance substantially matches the strip transmission line characteristics impedance.
2. A connector assembly as defined in claim 1 in which the connector conductive elements are C-shaped with the ends of the arms adapted to make contact with the respective strip transmission line conductors.
References Cited UNITED STATES PATENTS 2,654,872 10/1953 Saul et a1. 339- 2,765,450 10/1956 Richardson 339--l7 XR 2,937,357 5/ 1960 Kennedy 33917 3,129,990 4/1964 Rice et a1. 339-47 3,366,916 1/1968 Oktay 339-74 3,218,584 11/1965 Ayer 333-84 3,221,286 11/1965 Fedde 339-17 FOREIGN PATENTS 1,073,056 8/ 1958 Germany.
RICHARD E. MOORE, Primary Examiner P. A. CLIFFORD, Assistant Examiner US. Cl. X.R.