Patent Publication Number: US-10777936-B2

Title: Electrical device having a ground termination component with strain relief

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of and claims benefit to U.S. application Ser. No. 15/915,282, filed Mar. 8, 2018, titled “ELECTRICAL DEVICE HAVING A GROUND TERMINATION COMPONENT WITH STRAIN RELIEF”, the subject matter of which is herein incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The subject matter herein relates generally to an electrical device having a ground termination component with a strain relief element. 
     Communication cables electrically couple to various types of electrical devices to transmit differential signals, such as connectors and circuit boards. In some applications, such as high-speed data transmission applications, electromagnetic interference (EMI) and/or radio frequency interference (RFI) are concerns. So, the electrical cables are shielded to protect against interference from environmental sources of EMI/RFI. For example, some known communication cables include a differential pair of signal conductors surrounded by a shield layer that, in turn, is surrounded by a cable jacket. The shield layer includes a conductive foil, which functions to shield the signal conductor(s) from electromagnetic interference (EMI) and generally improve performance. In addition, the shield layer may function as a grounding element. At an end of the communication cable, the cable jacket, the shield layer, and insulation that covers the signal conductor(s) may be removed or stripped to expose the signal conductor(s) and/or the shield layer. The exposed portions of the conductor(s) and shield layer may then be mechanically and/or electrically coupled, such as soldering, to corresponding elements of an electrical device, such as signal contacts, ground contacts, ground busbars, and or substrates. 
     Coupling the communication cables to the various components of the electrical connector may be a time consuming and expensive process. For example, electrical connectors may have a substrate, such as a circuit board, with signal contacts for coupling with signal conductors of the communication cable, and a ground busbar with ground contacts for electrically coupling with grounding elements of the communication cable, such as the conductive foil shield layer or a drain wire, held by a housing. Furthermore, each component used in a connector requires additional tooling and assembly. Thus, communication cables and connectors that use less components and require less mechanical and electrical coupling reduce cost, tooling, and assembly time. 
     During assembly, the communication cables are subject to significant forces which may cause disconnection or damage at the connection points between the communication cables and the substrate. For example, the cables may be pulled on during routing of the cables within the system. Therefore, the connection points between the communication cables and the circuit board must be protected. 
     Accordingly, there is a need for an electrical device that includes a ground termination component with a strain relief element. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one embodiment, an electrical device is provided that includes a substrate having a plurality of signal contacts and a ground contact along a surface of the substrate. A communication cable includes a differential pair of signal conductors, a grounding element that surrounds the signal conductors, and a cable jacket surrounding the signal conductors and the grounding element. Each of the signal conductors has a wire-terminating end that is terminated to a corresponding signal contact of the substrate, the wire-terminating end projecting beyond a jacket edge of the cable jacket. A ground termination component has a main panel electrically coupled with the ground contact, and a strain relief element engaged with at least a portion of the communication cable. The strain relief element includes a connective terminal electrically coupled to the grounding element. 
     In another embodiment, an electrical device is provided having a substrate having a plurality of signal contacts and a ground contact along a surface of the substrate. A communication cable includes a differential pair of signal conductors, a grounding element that surrounds the signal conductors, and a cable jacket surrounding the signal conductors and grounding element. Each of the signal conductors has a wire-terminating end that is terminated to a corresponding signal contact of the substrate, the wire-terminating end projecting beyond a jacket edge of the cable jacket. The cable jacket has an access opening located a longitudinal distance from the jacket edge of the cable jacket. The electrical device also includes a ground termination component having a main panel electrically coupled with the ground contact, and a strain relief element engaged with at least a portion of the communication cable. The strain relief element includes a connective terminal electrically coupled to the grounding element through the access opening. 
     In yet another embodiment, an electrical device is provided having a substrate having a plurality of signal contacts and a ground contact along a surface of the substrate. A first communication cable includes a differential pair of signal conductors, a grounding element that surrounds the signal conductors, and a cable jacket surrounding the signal conductors and the grounding element. Each of the signal conductors has a wire-terminating end that is terminated to a corresponding signal contact of the substrate, the wire-terminating end projecting beyond a jacket edge of the cable jacket. A second communication cable includes a differential pair of signal conductors, a grounding element that surrounds the signal conductors, and a cable jacket surrounding the signal conductors and the grounding element. Each of the signal conductors has a wire-terminating end that is terminated to a corresponding signal contact of the substrate, the wire-terminating end projecting beyond a jacket edge of the cable jacket. The electrical device also includes a ground termination component electrically coupled with the ground contact and having a first strain relief element configured to engage with at least a portion of the first communication cable, and a second strain relief element configured to engage with at least a portion of the second communication cable. The first strain relief element includes a first connective terminal electrically coupled to the grounding element of the first communication cable, and the second strain relief element includes a second connective terminal electrically coupled to the grounding element of the second communication cable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an electrical device formed in accordance with an embodiment. 
         FIG. 2  is a perspective view of an electrical assembly according to one embodiment that may be used with the electrical device of  FIG. 1 . 
         FIG. 3  is an enlarged perspective view of the electrical assembly according to one embodiment that may be used with the electrical device of  FIG. 1 . 
         FIG. 4  is a perspective view of a substrate and a ground termination component of the electrical assembly in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments described herein include electrical devices that have electrical connectors, communication cables, and/or a ground termination component. For example, the communication cables may have one or more differential pairs of signal conductors electrically connected to the connectors and grounding elements, such as a conductive foil shield layer coupled with the ground termination component. The ground termination component may have a variety of configurations as set forth herein. For example, embodiments may include the ground termination component having a main panel and a strain relief element configured to engaged with at least a portion of the communication cables. The strain relief element may include a connective terminal that is electrically coupled to the grounding elements. Optionally, a solder material, such as a metal alloy material, may be deposited within the connective terminal and melted to mechanically and electrically couple the grounding element and the ground termination component. The ground termination component may have a variety of configurations as set forth herein. 
       FIG. 1  is a perspective view of an electrical device  100  formed in accordance with one embodiment that includes a substrate  122 , such as a circuit board, and a communication cable  110  having one or more differential pairs of signal conductors and a grounding element (not shown). In the illustrated embodiment, the electrical device  100  is an electrical connector, such as a small form-factor pluggable (SFP) transceiver. However, the electrical device  100  may be another type of electrical connector in an alternative embodiment. For example, the electrical device  100  may be any device that includes a circuit board having differential pairs of signal conductors and a grounding element terminated thereto. 
     As shown in  FIG. 1 , the electrical device  100  has a mating end  102 , a loading end  104 , and a central axis  150  extending therebetween. The electrical device  100  may include a plug portion  106  at the mating end  102  and a cable portion  108  at the loading end  104 . The plug portion  106  is configured to be inserted into a receptacle (not shown) of a communication system (not shown). The cable portion  108  is configured to couple to the communication cable  110  which has an insulative jacket  112 . The insulative jacket  112  may surround the one or more differential pairs of signal conductors and the drain wire. The insulative jacket  112  may comprise a number of layers that surround the differential pairs for shielding the differential pairs and providing strain resistance for the communication cables. The layers may include, for example, polyvinyl chloride (PVC), copper braid, aluminized mylar, and/or tape. 
     The electrical device  100  includes a device housing  114  that has a housing cavity (not shown) configured to hold a portion of a connector assembly  120 . The connector assembly  120  includes the substrate  122 , which has electrical contacts  124  located at a mating edge  128  of the substrate  122 , which is proximate to the mating end  102  of the electrical device  100 . In an exemplary embodiment, the mating edge  128  is configured to mate with an electrical connector (not shown) of the receptacle and establish a communicative connection through the electrical contacts  124 . The electrical contacts  124  may be communicatively coupled to the differential pairs of the signal conductors and a grounding element. 
       FIG. 2  is a perspective view of an electrical assembly  200  according to one embodiment that may be used with the electrical device  100  of  FIG. 1 . The electrical assembly  200  may be used as the connector assembly  120  ( FIG. 1 ) and may be disposed at least partially within the device housing  114  ( FIG. 1 ). The electrical assembly  200  includes the substrate  202  having a terminating edge  204 , a mating edge  206 , and side edges  208 ,  210  that extend from the terminating edge  204  toward the mating edge  206  along a central axis  212 . In the exemplary embodiment, the substrate  202  may be a printed circuit board, including a number of dielectric layers, traces, vias, defining ground and signal contacts. 
     The substrate  202  includes upper and lower board surfaces  220  that face in opposite directions although only the upper surface  220  is fully shown in  FIG. 2 . As shown, the upper board surface  220  includes electrical contacts  222  that are proximate to the terminating edge  204  and electrical contacts  224  that are proximate to the mating edge  206 . In the illustrated embodiment, the electrical contacts  222 ,  224  are contact pads and may include signal contacts  226  and ground contacts  228 . The electrical contacts  222 ,  224  may be communicatively coupled to one another through the substrate  202 . For example, the traces (not shown) of the substrate  202  may communicatively couple the electrical contacts  222 ,  224  of the terminating edge  204  with the electrical contacts  222 ,  224  of the mating edge  206 . Optionally, the lower board surface  220  may include electrical contacts similarly configured to the electrical contacts  222  of the upper board surface. For example, the lower board surface  220  may include signal and ground contacts communicatively coupled through traces of the substrate  202 . 
     The electrical assembly  200  also includes a plurality of communication cables  230  that are electrically coupled to the substrate  202  along the upper board surface  220 . Eight communication cables  230  are shown terminated to the upper board surface  220 , however, alternate embodiments may include any number of communication cables  230 . A ground termination component  300  electrically couples a grounding element  236  of the communication cables  230  and the electrical contacts  224  to create an electrical ground connection. The ground termination component  300  includes a plurality of strain relief elements  310  configured to engage with a portion of the corresponding communication cables  230  along an interface  302 . 
       FIG. 3  is an enlarged perspective view of the electrical assembly  200  according to one embodiment that may be used with the electrical device  100  of  FIG. 1 . In the exemplary embodiment, the communication cables  230  may be characterized as twin-axial or parallel-pair cables that include a differential pair of signal conductors  232  in which the two signal conductors  232  of a single differential pair extend parallel to each other through a length of the communication cable  230 . The communication cables also include one or more insulators  234  surrounding the signal conductors  232 , a grounding element  236 , such as a shield layer, that peripherally surrounds the insulators  234  and the signal conductors  232  to provide electrical shielding, and an insulative jacket  238  that surrounds the grounding element  236 . The grounding element  236  may include, for example, a conductive foil or tape composed of copper, aluminized mylar or other suitable material. The insulative jacket  238  may comprise a number of layers that surround the differential pairs for providing environmental protection for the communication cable  230 . The layers may include, for example, polyvinyl chloride (PVC), copper braid, aluminized mylar, and/or tape. Optionally, a drain wire (not shown) also extends parallel with the signal conductors through the length of the communication cable  230 . 
     As shown in  FIG. 3 , the communication cables  230  have had a portion of the jacket  238 , grounding element  236 , and insulators  234  stripped or removed therefrom to expose the signal conductors  232  and the grounding element  236 . Exposed portions of the signal conductors  232  project beyond a jacket edge of the jacket  238 , to define as wire-terminating ends  240  configured to be terminated to the signal contacts  226  of the electrical contacts  224 . For example, the wire-terminating ends  240  may electrically connect to the electrical contacts  224  by laser termination, soldering, crimping, welding, using conductive adhesive, using insulation displacement contacts, and the like. 
     Although not shown, the communication cables  230  of  FIGS. 2 and 3  may be part of a larger cable and may be surrounded by an external jacket or sleeve. The external jacket may be stripped to permit manipulation of the communication cables  230  as set forth herein. In alternative embodiments, the signal conductors within the communication cable  230  may form a twisted pair of signal conductors. In other various embodiments, the communication cable  230  may be a single-ended cable having a single central conductor rather than the pair of signal conductors. 
     For parallel-pair configurations, the communication cable  230  has opposite contoured sides  241 ,  242  and opposite planar sides  244  that extend between and join the contoured sides  241 ,  242 . Only one planar side  244  is shown in  FIG. 3 , but it is understood that the communication cable  230  has another planar side  244  that is opposite the planar side  244 . The contoured sides  241 ,  242  may have cross-sections taken transverse to a length of the communication cable  230  that have a semi-circle shape. The communication cable  230  has a width W C . 
     As shown, the grounding element  236  is exposed through an access opening  250  of the cable jacket  238 . The access opening  250  may be spaced from an end of the cable jacket  238 . For example, the cable jacket  238  includes a jacket edge  252 . The access opening  250  may be located a longitudinal distance X 1  away from the jacket edge  252  along a length of the communication cable  230 . The access opening  250  extends a depth into the communication cable  230  from an exterior surface of the cable jacket  238  to the grounding element  236 . The access opening  250  may be formed by, for example, using a laser (e.g., CO 2  laser) to etch the cable jacket  238  to remove the material of the cable jacket  238  and expose the grounding element  236 . Accordingly, the access opening  250  may be a void along the grounding element  236 . The access opening  250  may be partially defined by the material of the cable jacket  238  and the grounding element  236  (e.g., conductive foil). The access opening  250  may open to an exterior of the communication cable  230 . 
     The access opening  250  may have a width W A  and a length L A . In the illustrated embodiment, the width W A  is less than the width W C  of the communication cable  230 . The width W A  may be sized such that the access opening  250  extends only along the planar side  244  and does not extend into the contoured sides  241 ,  242 . However, the width W A  may be larger in other embodiments such that portions of the contoured sides  241 ,  242  also have material from the cable jacket  238  removed. For example, the width W A  may be substantially equal to the width W C . 
       FIG. 4  is a perspective view of the substrate  202  and the ground termination component  300  of the electrical assembly  200  in accordance with an embodiment. The communication cables  230  are not shown in  FIG. 4  to better illustrate the ground termination component  300 . In the exemplary embodiment, the ground termination component  300  includes a main panel  304  extending along the upper board surface  220  of the substrate  202 . The main panel  304  has a substantially rectangular shape with a plurality of fingers  306  extending therefrom to electrically couple with the ground contacts  228  of the substrate  202 . The ground termination component  300  has a length L 1 , the width W 1 , and a thickness T 1 . The fingers  306  are distributed along a width W 1  of the ground termination component  300  by a spacing S 1 . The spacing S 1  may be sized so that a differential pair of signal conductors may be positioned between the adjacent ground contacts  228 . The ground termination component  300  includes a top surface  312  and a bottom surface  314  that face in opposite directions. The thickness T 1  is measured between the top and bottom surfaces  312 ,  314 . In the illustrated embodiment, the thickness T 1  is substantially uniform, but may have varying sizes in other embodiments. As shown in  FIG. 4 , the main panel  304  may be positioned adjacent to the communication cables  230  such that the upper surface  312  along the main panel  304  interfaces with the lower planar side  244  of the communication cable  230 . 
     The main panel  304  includes a plurality of strain relief elements  310  integral with and extending from the main panel  304 , each being engaged with at least a portion of interface  302  ( FIG. 3 ) of corresponding communication cables  230  to confine the communication cables  230  in one or more directions and provide strain relief to the communication cables  230 , such as during assembly of the electrical assembly  200 . In the exemplary embodiment, each strain relief element  310  has a substantially hook shaped mating tab with a substantially vertical proximate end  320  connected to the main panel  304  and a substantially horizontal connective terminal  330  ( FIG. 3 ) configured to electrically couple with the grounding element  236  through the access opening  250 . 
     Each connective terminal  330  is mechanically and/or electrically coupled to the grounding elements  236  to provide electrical coupling between the ground termination component  300  and the communication cables  230 . In an exemplary embodiment, each connective terminal  330  is substantially rectangular tab aligned with corresponding access opening  250 . However, the connective terminals  330  can be configured in any shape and size to provide for electrical and mechanical coupling between the ground termination component  300  and the communication cables  230 . Each connective terminal  330  may be dimensioned to permit a conductive binding material to join the connective terminal to the grounding element  236  through the access opening  250 . In other embodiments, a different conductive binding material may be used. For example, the conductive binding material may be an adhesive, epoxy, foam, tape, or the like. 
     In other embodiments, the connective terminals  330  may have other configurations to mechanically and electrically couple the ground termination component  206  with the grounding elements  236 , including, but not limited to, a single tab, or an insulation displacement connector. In addition, the connective terminals  330  can be configured to couple with the grounding element  236  with an interference or pinch fit. 
     Each ground termination component  300  may be a single continuous piece of material. For example, the ground termination component  300  may be stamped and formed from sheet metal or may be molded or cast using a conductive material. Although one ground termination component  300  is shown in the illustrated embodiment, alternate embodiments of the electrical assembly  200  may include additional ground termination components  300 . For example, a second ground termination component (not shown) may electrically coupled between electrical contacts (not shown) and communication cable along the bottom board surface  220 . Optionally, the ground termination component  300  may be separated into multiple portions. For example, the ground termination component may include multiple discrete panels each having one or more strain relief elements to engage with corresponding communication cables. 
     As shown in  FIG. 4 , pairs of strain relief elements  310  are distributed along a width W 1  of the ground termination component  300  by a spacing S 2 . Each pair of strain relief elements  310  include a first strain relief element  331  having a first proximate end  334  attached to the main panel  304 , and a second strain relief element  332  having a second proximate end  336  attached to the main panel  304 . The first and second proximate ends  334 ,  336  are positioned adjacent to and substantially coplanar with each other. The connection terminals  330  of the first and second strain relief elements  332 ,  334  extend in substantially planar and opposite directions to align with corresponding access openings  250  and electrically couple with corresponding grounding elements  236  ( FIG. 3 ). 
     Although the strain relief elements  310  are shown to partially circumferentially surround at least two sides, such as one of the contoured sides  241 ,  242  and the planar side  244 , of the first communication cable, any portion and/or number of sides can be surrounded. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments, and are by no means limiting and are merely exemplary embodiments. Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. § 112(f), unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.