Not Applicable
Not Applicable
The present invention relates to electrical cable attachments to circuit boards and other planar electrical devices (PCB), more particularly, to quickly, temporarily terminating an interconnect to a PCB with the mating pressure needed to make a good connection.
One purpose of a cable termination is to provide a separable electrical interconnection between a cable and a PCB or other planar electrical device. The characteristic of separability means that the cables are not interconnected by permanent mechanical means, such as soldering or bonding, but by temporary mechanical means.
Currently, cables are terminated using a conventional-type connector which is also controlled-impedance, like an SMA (SubMiniature Version A) connector, or the cables are soldered to the PCB which is then separably connected to the working environment. The SMA connectors, while being generally the same impedance environment as the cable, have impedance mismatches that cause high-frequency attenuation at the point of interface between the cable and the connector and between the connector and its working environment, like a PCB. Additionally, these cable terminations often require through holes in PCBs for mounting and consequently can make it difficult to design the best possible controlled-impedance environment. Solder-down versions exist, but they cannot be removed and reused after being installed.
These types of cable terminations are generally for a single cable. They often require turning a mating connector several times for proper seating, either manually or with a calibrated torque wrench. Allowances must be made for fingers or for the torque wrench when spacing multiple connectors on a board, thereby requiring a substantial amount of board real estate to terminate, and decreasing the density capability of connections.
The present invention is a connector assembly for terminating one or more cables to an electrical device, such as a printed circuit board (PCB), without screws or other latching hardware that cannot be removed without using tools. The connector assembly also does not require extra connectors to be soldered to the PCB. The connector assembly also provides a secure connection to the PCB for all typical thicknesses of PCB. The connector assembly imparts enough Z-axis force on the PCB to maintain a stable and repeatable interconnection.
The connector assembly uses compliant contact technology on a spring-loaded interface that does not require a mating half of a connector on the PCB. In one configuration, the interface is made of discrete, electrical, preferably compliant, contacts disposed within apertures in a cylindrical disk of dielectric material which holds the contacts in the correct orientation to make an electrical connection between a cable and the PCB. In another configuration, the interface is made of a sheet of isotropic conductive elastomer that conducts only in the Z axis extending perpendicularly between to its two parallel faces.
The cable is attached to a boss, an electrically-conductive, cylindrical ferrule. A through hole accepts the cable and the cable ground shield is electrically attached to the boss.
The interface and boss/cable assembly reciprocate freely within the bore of a cylindrical sleeve with the interface toward the PCB. An annular shoulder retains the interface within the sleeve. A boss spring and a sleeve spring bias the interface and boss/cable assembly, respectively, toward the PCB.
The sleeve has a pair of opposed knobs extending radially adjacent to the distal end and a pair of opposed alignment fingers extending paraxially from the proximal end. The alignment fingers make up the inner portion of alignment posts.
The sleeve, interface and boss/cable assembly, boss spring, and sleeve spring are slid into the bore of a barrel. The sleeve knobs fit into windows in the wall of the barrel. The barrel has a pair of opposed pawls extending paraxially from the proximal end. The pawls combine with the alignment fingers to form the alignment posts with circular cross-sections. Perpendicular fingers at the end of the pawls grab onto the underside of the PCB when the barrel is turned to the attached position.
An optional locking mechanism to prevents the connector assembly from inadvertently returning to the unattached position. The locking mechanism includes a hollow, cylindrical locking tube that slides into the upper portion of the barrel bore over the cable, boss spring, and sleeve spring and. Grips extending radially from the sides of the locking tube fit into slots at the distal end of the barrel. Rectangular tabs extend coaxially from the proximal end. Offset to one corner of the tab is a notch. The locking tube is biased toward the PCB by a locking tube spring.
All of the components are retained in the correct position in the barrel by a cap at the distal end of the barrel. The cap has a hole through which the cable enters the connector assembly.
To receive the connector assembly, the PCB has a pair of round holes for the alignment posts. Midway between the holes is the signal pad surrounded by a ground land.
The connector assembly is designed for a specific range of thicknesses of PCB. If necessary, the PCB thickness can be modified by building up or countersinking the underside of the PCB.
In the unattached position, the alignment posts are circular in cross-section so that they can fit into the PCB holes and the sleeve knob is resting on a proximal edge of the barrel window. A sloped edge of the window prevents the barrel from rotating relative to the sleeve. The end of the locking tube tab is resting against the sleeve knob so that the locking tube tab notch is not aligned with the knob.
The alignment posts are inserted in the PCB holes and pushed toward the PCB against the force of the boss and sleeve springs. The sleeve contacts the PCB and stops, but the barrel continues so that the knobs move from the window proximal edge. With the knobs no longer resting on the window proximal edges, the barrel is free to rotate relative to the sleeve. The barrel is rotated so that the pawl fingers slide under the PCB while the sleeve alignment fingers remain stationary in the holes.
The locking tube rotates with the barrel relative to the sleeve to where the locking tube notch aligns with the knobs and the locking tube spring pushes the locking tube downwardly until the knobs are within the notches, thereby engaging the locking mechanism. When pressure toward the PCB is released, the boss and sleeve springs impart enough Z-axis force on the PCB to maintain a stable connection.
Objects of the present invention will become apparent in light of the following drawings and detailed description of the invention.
For a fuller understanding of the nature and object of the present invention, reference is made to the accompanying drawings, wherein:
The present application hereby incorporates by reference in their entireties U.S. Provisional Patent Application Nos. 62/396,448 and 62/436,160, on which this application is based.
The present invention, shown in
The connector assembly 10 of the present invention also does not require extra connectors to be soldered to the PCB 12 before connectors can be mated. The connector assembly 10 only requires one or more holes 122 in the PCB 12 to receive alignment posts 18.
The connector assembly 10 also provides a secure connection to the PCB 12 for all typical thicknesses of PCB 12. The connector assembly 10 imparts enough Z-axis force on the PCB 12 to maintain a stable and repeatable interconnection.
The connector assembly 10 is for use with controlled-impedance cables having one or more signal conductors. As shown in
The connector assembly 10 uses compliant contact technology on a spring-loaded interface 20 that does not require a mating half of a connector on the PCB 12. In one configuration, the interface 20 is made of discrete electrical contacts 30, 32 disposed within a cylindrical disk 22 of dielectric material which holds the contacts 30, 32 in the correct orientation to make an electrical connection between the cable 50 and the PCB 12. The contacts 30, 32 are made of a conductive material such as metal or conductive elastomer. A cross-sectional view of an example of an interface 20 is shown in
In another configuration, the interface 20 is made of a sheet of isotropic conductive elastomer, which is a resilient sheet of elastomer that conducts only in the Z axis extending perpendicularly between to its two parallel faces.
The term, “contact”, in the present specification and claims is intended to include all manners of signal transfer, including the discrete compliant contacts, the isotropic conductive elastomer, and any other compliant electrically-conductive structures that can be adapted to the present invention.
As shown in
A spring force is applied to the distal face 42, as described below. Optionally, the spring force is applied to an optional annular shoulder 44.
A cylindrical sleeve 58 with an axial bore 59 maintains the proper alignment of the interface 20, boss 38/cable 50 assembly, and the PCB 12, as shown in
The boss 38/cable 50 assembly also reciprocates freely within the sleeve bore 59. The boss proximal face 46 abuts the distal face 24 of the interface 20 such that the signal contact 30 is aligned with and in electrical contact with the signal conductor 56 of the cable 50 and the ground contacts 32 are aligned with and in electrical contact with the proximal face 46 of the boss 38.
The present invention also contemplates that the interface 20 is integral with the boss 38. In other words, the interface 20 and boss 38 are a single unit with the compliant contacts 30, 32 and to which the cable 50 is attached. For example, a sheet of isotropic conductive elastomer acting as the interface 20 is mechanically attached to the proximal face of an electrically-conductive, cylindrical ferrule that acts as the boss 38. The cable 50 is attached to the ferrule as it would be to the boss 38.
The interface 20 and boss 38/cable 50 assembly are biased toward the PCB 12 by a small-diameter coil spring, the boss spring 48. The boss spring 48 fits over the cable 50, as in
The sleeve 58 has a pair of opposed alignment fingers 62 extending paraxially from the proximal end 66. The alignment fingers 62 make up the inner portion of each alignment post 18, as described below.
The sleeve 58 has a pair of opposed knobs 112 extending radially adjacent to the distal end 26. The knobs 112 are described below.
The sleeve 58 is urged toward the PCB 12 by means of a middle-diameter coil spring, the sleeve spring 68. The sleeve spring 68 fits over the cable 50 and boss spring 48 and, when the connector assembly 10 is assembled, abuts the distal face 64 of the sleeve 58.
The sleeve 58 can be composed of a dielectric material or a conductive material. If a conductive material, the sleeve 58 can act as a radio frequency (RF) shield.
The sleeve 58 with the interface 20 and boss 38/cable 50 assembly installed in the bore 59, the boss spring 48, and the sleeve spring 68 are slid into the bore 71 of a barrel 70. The knobs 112 fit into windows 96 in the wall 95 of the barrel 70. Each window 96 has a flat proximal edge 97 that is the width of the knob 112. A sloped edge 98 slopes distally from one end of the proximal edge 97 to a longitudinal edge 99. The angle of the sloped edge 98 is preferably about 45°. The relationship between the knob 112 and window 96 is described below.
The barrel 70 has a pair of opposed pawls 74 extending paraxially from the proximal end 72. The pawls 74 form the proximal portion of each alignment post 18 by complementing the sleeve alignment fingers 62. Perpendicular fingers 75 at the end of the pawls 74 grab onto the underside 16 of the PCB 12 when the barrel 70 is turned to the attached position, as described below.
As will be described in more detail below, the connector assembly 10 attaches to the PCB 12 by the barrel rotating about the sleeve 58 from an unattached position to an attached position. The connector assembly 10 optionally includes a locking mechanism to prevent the connector assembly 10 from inadvertently returning to the unattached position.
In the present configuration, the locking mechanism includes a hollow, cylindrical locking tube 80 that fits over the cable 50, boss spring 48, and sleeve spring 68 and slides into the upper portion of the barrel bore 71. Grips 116 extending radially from the sides of the locking tube 80 fit into slots 73 at the distal end 78 of the barrel 70. Generally rectangular tabs 86 extend coaxially from the proximal end 84. Offset to one corner of the tab 86 is a notch 110.
The locking tube 80 is biased toward the PCB 12 by a large-diameter coil spring, the locking tube spring 88. The locking tube spring 88 fits over the cable 50, sleeve spring 68, and boss spring 48, and abuts the distal end 82 of the locking tube 80. The locking tube spring 88 biases the locking tube 80 towards the PCB 12 so that when the barrel 70 and the sleeve 58 are at a particular angle to one another, the locking tube 80 is pushed into place. The operation of the locking mechanism is described in detail below.
All of the components are retained in the correct position in the barrel 70 by a cap 90 that is mechanically attached to the distal end 78 of the barrel 70. Any method of mechanical attachment is contemplated. In the present configuration, the cap 90 is turned onto a thread 92 at the distal end 78 of the barrel 70. The cap 90 has a hole 94 through which the cable 50 enters the connector assembly 10.
As mentioned above, when the connector assembly 10 is assembled, the sleeve alignment fingers 62 and the pawls 74 join together longitudinally to form the alignment posts 18, as shown in
The present invention contemplates that the connector assembly 10 can be designed for use with one cable 50, as described herein, or with two or more cables. The invention is not limited to coaxial cables, as the invention can be designed to accommodate twinaxial and multiaxial cables. Two cables can be used to connect to a differential pair on the PCB 12.
Midway between the holes 122 is the signal pad 150. The signal pad 150 is nearly completely surrounded by a ground land 152. The ground land 152 will typically surround the holes 122, as in
Vias 158 connect the ground land 152 to inner ground layers on the PCB 12.
The connector assembly 10 is designed for a specific range of thicknesses of PCB 12. Parameters that determine the range of PCB thicknesses include the length of the alignment posts 18, the spring displacement of the interface 20, the compliance of the contacts 30, 32, and the distance of the upper surface 76 of the pawl fingers 75 from the interface 20.
If the PCB 12 is thinner than the minimum design thickness, the underside 16 of the PCB 12 can be built up, as at 136 in
Alternatively, if the PCB 12 is thicker than the maximum design thickness, the holes 122 can have countersinks 126 on the underside 16 of the PCB 12, as shown in
Typically, the diameter of the holes 122 is 0.001 inch larger than the diameter of the alignment post 18. For example, the hole diameter to receive a 0.1-inch-diameter alignment post 18 is 0.101 inch.
In
In
In
The interface 20 is compliant due to the boss spring 48 and the compliant contacts 30, 32, thereby providing the connector assembly 10 with great signal integrity by keeping the interface 20 flat on the PCB 12.
In
As seen in
In
When pressure toward the PCB 12 is released from the connector assembly 10, the boss spring 48 and sleeve spring 68 impart enough Z-axis force on the PCB 12 to maintain a stable connection.
To remove the connector assembly 10, the locking tube grips 116 are pulled away from the PCB 12 and against the locking tube spring 88. The result is that the locking tube 80 is pulled away so that the knobs 112 are no longer within the notches 110. The barrel 70 is rotated counterclockwise by the knobs 112 sliding down the sloped edge 98 of the window 96 to the proximal edge 97. At the same time, the boss spring 48 and the sleeve spring 68 push the connector assembly 10 off the PCB 12 and the connector assembly 10 returns to the unattached position.
Thus it has been shown and described a connector assembly for attaching a cable to an electrical device. Since certain changes may be made in the present disclosure without departing from the scope of the present invention, it is intended that all matter described in the foregoing specification and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.
Number | Name | Date | Kind |
---|---|---|---|
3275970 | Johanson | Sep 1966 | A |
6261130 | Huynh | Jul 2001 | B1 |
6350155 | Mullinger-Bausch | Feb 2002 | B1 |
6861862 | Tate | Mar 2005 | B1 |
7972173 | Hyzin | Jul 2011 | B1 |
8562380 | Li | Oct 2013 | B2 |
8926342 | Vinther | Jan 2015 | B2 |
9130328 | Huang | Sep 2015 | B1 |
9748688 | Hagmann | Aug 2017 | B2 |
Number | Date | Country | |
---|---|---|---|
62396448 | Sep 2016 | US | |
62436160 | Dec 2016 | US |