Abstract:
A communications connector with a flexible printed circuit board is provided. The flexible printed circuit board is electronically and mechanically connected to the plug interface contacts of the jack near the plug/jack interface, in order to provide effective crosstalk compensation. The flexible printed circuit board has fingers at one end allowing it to flex as individual plug interface contacts are depressed when a plug is installed into the jack. A second end of the flexible printed circuit board has through holes for accepting insulation displacement contacts. The second end of the flexible printed circuit board may be rigidly supported, to allow insertion of the insulation displacement contacts. Various designs for capacitive and/or inductive couplings are provided, resulting in improved crosstalk performance.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of U.S. application Ser. No. 11/180,216, filed Jul. 13, 2005 and claims the benefit of U.S. Provisional Application No. 60/587,416, filed Jul. 13, 2004, and U.S. Provisional Application No. 60/637,024, filed Dec. 17, 2004. The entireties of each of these applications are incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to electrical connectors, and more particularly, to a modular communication jack having a flexible printed circuit board.  
       BACKGROUND OF THE INVENTION  
       [0003]     In the communications industry, as data transmission rates have steadily increased, crosstalk due to capacitive and inductive couplings among the closely spaced parallel conductors within the jack and/or plug has become increasingly problematic. Modular connectors with improved crosstalk performance have been designed to meet the increasingly demanding standards. Many of these improved connectors have included concepts disclosed in U.S. Pat. No. 5,997,358, the entirety of which is incorporated by reference herein. In particular, recent connectors have introduced predetermined amounts of crosstalk compensation to cancel offending near end crosstalk (NEXT). Two or more stages of compensation are used to account for phase shifts from propagation delay resulting from the distance between the compensation zone and the plug/jack interface. As a result, the magnitude and phase of the offending crosstalk is offset by the compensation, which, in aggregate, has an equal magnitude, but opposite phase.  
         [0004]     Recent transmission rates, including those in excess of 500 MHz, have exceeded the capabilities of the techniques disclosed in the &#39;358 patent. Thus, improved compensation techniques are needed.  
     
    
     BRIEF DESCRIPTION OF FIGURES ILLUSTRATING PREFERRED EMBODIMENTS  
       [0005]      FIG. 1  is a front exploded perspective view of a communications jack  
         [0006]      FIG. 2  is a rear exploded perspective view of a communications jack;  
         [0007]      FIGS. 3A-3D  are different perspective views of an assembly composing an internal portion of the communications jack of  FIGS. 1 and 2 ;  
         [0008]      FIG. 4  is a perspective view of an assembly composing an internal portion of the communications jack of  FIG. 1 ;  
         [0009]      FIG. 5  is a side cross-sectional view of the communications jack of  FIG. 1 ;  
         [0010]      FIG. 6  is a side cross-sectional view of an embodiment of the communications jack of  FIG. 1 ;  
         [0011]      FIG. 7A  illustrates a design of a Flexible Printed Circuit for leads  3 ,  4 ,  5 , and  6  for a Printed Circuit Board in a communications jack;  
         [0012]      FIG. 7B  illustrates a design of a Flexible Printed Circuit for lead  3  for a Printed Circuit Board in a communications jack;  
         [0013]      FIG. 7C  illustrates a design of a Flexible Printed Circuit for lead  4  for a Printed Circuit Board in a communications jack;  
         [0014]      FIG. 7D  illustrates a design of a Flexible Printed Circuit for lead  5  for a Printed Circuit Board in a communications jack;  
         [0015]      FIG. 7E  illustrates a design of a Flexible Printed Circuit for lead  6  for a Printed Circuit Board in a communications jack;  
         [0016]      FIGS. 7F-7K  illustrate details and cross-sections of the leads  3 ,  4 ,  5 , and  6  at respective locations of the Flexible Printed Circuit shown in  FIG. 7A .  
         [0017]      FIG. 8A  illustrates a design of a Flexible Printed Circuit for leads  1 - 8  for a Printed Circuit Board in a communications jack;  
         [0018]      FIG. 8B  illustrates a design of a Flexible Printed Circuit for lead  1  for a Printed Circuit Board in a communications jack;  
         [0019]      FIG. 8C  illustrates a design of a Flexible Printed Circuit for lead  2  for a Printed Circuit Board in a communications jack;  
         [0020]      FIG. 8D  illustrates a design of a Flexible Printed Circuit for lead  3  for a Printed Circuit Board in a communications jack;  
         [0021]      FIG. 8E  illustrates a design of a Flexible Printed Circuit for lead  4  for a Printed Circuit Board in a communications jack;  
         [0022]      FIG. 8F  illustrates a design of a Flexible Printed Circuit for lead  5  for a Printed Circuit Board in a communications jack;  
         [0023]      FIG. 8G  illustrates a design of a Flexible Printed Circuit for lead  6  for a Printed Circuit Board in a communications jack;  
         [0024]      FIG. 8H  illustrates a design of a Flexible Printed Circuit for lead  7  for a Printed Circuit Board in a communications jack;  
         [0025]      FIG. 8I  illustrates a design of a Flexible Printed Circuit for lead  8  for a Printed Circuit Board in a communications jack;  
         [0026]      FIG. 9A  illustrates an alternative design of a Flexible Printed Circuit for leads  1 - 8  for a Printed Circuit Board in a communications jack;  
         [0027]      FIG. 9B  illustrates a design of a capacitive coupling portion of a Flexible Printed Circuit for leads  3 ,  4 ,  5 , and  6  for a Printed Circuit Board in a communications jack;  
         [0028]      FIG. 9C  is an upper perspective view of a portion of the design for traces  3 ,  4 ,  5 , and  6  for the Flexible Printed Circuit of  FIGS. 9A and 9B ;  
         [0029]      FIG. 10  is a rear exploded perspective view of an alternative communications jack;  
         [0030]      FIG. 11  is a side cross-sectional view of the communications jack of  FIG. 10 ;  
         [0031]      FIGS. 12 and 13  are perspective views of an internal portion of the communications jack of  FIG. 10 ;  
         [0032]      FIG. 14A  illustrates a design of a Flexible Printed Circuit for leads  1 - 8  for a Printed Circuit Board in the communications jack of  FIG. 10 ;  
         [0033]      FIGS. 14B and 14C  illustrate cross-sections of the leads  1 - 8  at various locations of the Flexible Printed Circuit shown in  FIG. 14A ;  
         [0034]      FIG. 15A  is a perspective view of a portion of a communications jack;  
         [0035]      FIG. 15B  is a perspective view of a portion of a housing of a communications jack;  
         [0036]      FIG. 15C  is a side cross-sectional view of a communications jack;  
         [0037]      FIG. 15D  is a perspective view of a front sled assembly;  
         [0038]      FIG. 15E  is an exploded perspective view of a front sled assembly, viewed from below;  
         [0039]      FIG. 15F  is perspective view of a top front sled and flexible printed circuit board as it might appear during assembly, viewed from below; and  
         [0040]      FIG. 15G  is a perspective view of a top front sled and flexible printed circuit board as it might appear during a later stage of assembly, viewed from above. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0041]      FIGS. 1 and 2  are exploded perspective views of a communications jack  100  having a Flexible Printed Circuit (FPC)  102  in accordance with an embodiment of the present invention. The jack  100  includes a main housing  106  and a bottom front sled  104  and top front sled  108  arranged to support eight plug interface contacts  112 . The FPC  102  attaches to the plug interface contacts  112  adjacent to where the plug interface contacts  112  interface with contacts from a plug (not shown). The FPC  102  is attached by conductors  110  (preferably flexible) to a PCB (Printed Circuit Board)  114 . The FPC  102 , conductors  110 , and PCB  114  may all be part of the FPC  102 , with the PCB  114  portion of the FPC being a rigid extension of the FPC  102 . As illustrated, eight IDCs (Insulation Displacement Contacts)  116  engage the PCB  114  from the rear via through-holes in the PCB  114 . A rear housing  118 , having passageways for the IDCs  116 , and a wire cap  120  serve to provide an interface to a twisted pair communication cable or punch-down block.  
         [0042]     In this and other embodiments described herein, the FPC  102  is or includes a substrate with a conductive layer laminated to each side. Unwanted conductive material is etched away from each side during manufacture. To reduce the variation in coupling changes due to registration variation between the conductors on each of the two sides of the FPC  102 , a minimum registration tolerance is maintained between the patterns on each side of the FPC  102 . In addition, variations in couplings due to trace width tolerances are also minimized in the disclosed design. Because the length of the Near-End Crosstalk (NEXT) compensation zone is approximately equal to the length of the NEXT crosstalk zone, variations in FPC  102  trace width, which tend to be consistent on an individual FPC  102 , change the capacitive coupling of the NEXT compensation zone and the NEXT crosstalk zone by approximately the same magnitude. This minimizes the compensation variation due to trace width variation.  
         [0043]      FIGS. 3A-3D  are perspective views of an assembly  300  comprising an internal portion of the communications jack  100  of  FIGS. 1 and 2 . This assembly includes the bottom front sled  104 , top front sled  108 , plug interface contacts  112 , FPC  102 , conductors  110 , PCB  114 , and IDCs  116 . In one embodiment, the FPC  102  extends back into the jack  100  and includes an integrally formed vertically oriented rigid extension of the FPC  100 , through which IDCs  116  make contact with the FPC  102 . The rigid extension serves as a support and mounting mechanism, and contains no electrical components itself. Alternative embodiments, however, might utilize portions of the rigid extension for remote capacitive compensation, and are intended to be within the scope of the present invention. Similarly, a rigid compensation PCB may serve to sandwich the FPC  102  between the rigid compensation PCB and the rigid extension. In  FIG. 3 , the rigid extension is shown as part of the PCB  114 .  
         [0044]     While the jack  100  and jack components of  FIGS. 1-3D  are of the type that is terminated to a four-pair communications cable, the same concepts would apply to a punch-down version, with appropriate modifications being made to the rear housing  118 , wire cap  120 , and possibly the IDCs  116 , of the jack  100 .  
         [0045]      FIG. 4  is an exploded view of the assembly  300  showing the FPC  102  detached from the plug interface contacts  112  of  FIGS. 1-3D . One portion of the FPC  102  might normally be disposed in the bottom front sled  104 , with an opposite portion of the FPC  102  situated in a rigid extension of the FPC  102 . The rigid extension contains eight through-holes (e.g. through-hole  402 ) to allow eight IDCs  116  to make mechanical and electrical contact with the FPC  102 .  
         [0046]      FIG. 5  is a side cross-sectional view of the communications jack  100  and  FIG. 6  is a side cross-sectional view of the communications jack  100 , with a slightly different interface between the plug interface contacts  112  and FPC  102 . The two different contact/FPC interfaces  402   a  and  402   b  shown both have the FPC  102  electrically and mechanically attached to the plug interface contacts  112 . Interface  402   a  utilizes a rearward attachment, while Interface  402   b  utilizes a forward attachment. An advantage of the designs shown in  FIGS. 5 and 6  is that the plug interface contacts  112  are short and substantially no signal current flows in the plug interface contacts  112 , since the contact/FPC interface is located adjacent the plug/jack interface  112   a , where the plug interface contacts  112  interface with the plug contacts  3  of the plug  1 . This removes a possible source of crosstalk and other noise. The flexibility of the FPC  102  allows it to be connected to all the plug interface contacts  112 , which do not move exactly in unison when a plug is installed.  
         [0047]      FIGS. 7A-7E  illustrate a design of an FPC  102  for leads  3 ,  4 ,  5 , and  6  for a PCB in a communications jack  100 . Solid lines indicate a trace located on the top surface of the FPC substrate, while dashed lines indicate placement on the underside of the FPC substrate. Only leads  3 ,  4 ,  5 , and  6  are shown because these leads are most susceptible to crosstalk and other noise; thus, compensation is typically targeted toward optimizing at these leads.  
         [0048]     In the top elevational views of  FIGS. 7A-7E , the FPC  102  is in a flat (unbent) configuration. In the jacks shown in  FIGS. 1-6 , however, the FPC is shown bending vertically down from the contacts to a horizontal position at the sled, and then vertically up along the rigid extension and/or PCB  114 .  FIGS. 10-14C  illustrate an alternative embodiment, in which the FPC  102  extends back horizontally from the sled, rather than vertically, with vertically oriented IDCs  116  making electrical contact with the horizontally disposed FPC  102 .  
         [0049]      FIGS. 7F-7K  illustrate cross-sections of the leads  3 ,  4 ,  5 , and  6  at respective locations of the FPC  102  shown in  FIG. 7A . Each of these figures includes an elevational view of a portion of the design shown in  FIG. 7A , with a corresponding cross-sectional view taken across a sectional line. While the substrate of the FPC  102  itself is not shown in these views, the vertical displacement between trace cross-sections indicates on which side of the FPC  102  substrate the traces are located.  
         [0050]     The configurations and specifications illustrated in  FIGS. 7A-7K  are directed to a preferred embodiment, and many other designs are possible and are intended to be within the scope of the present invention. Variations in design may be made to compensate for crosstalk and other effects. Similarly, jacks designed for communications cables having more or fewer than four pairs will obviously have different configurations and tolerances; however, the design concepts disclosed herein will apply similarly.  
         [0051]      FIG. 8A-8I  illustrate a design of an FPC  102  for leads  1 - 8  for a PCB in a communications jack. The FPC of this design has a similar footprint to that of  FIG. 7A  and some of the trace configurations are similar (see, e.g., Zone F); however, the design of  FIGS. 8A-8I  uses slightly different couplings and compensation techniques. Note that the designs shown in  FIGS. 7A-7K  and  8 A- 8 I utilize an FPC  102  that has at least some compensation couplings that span a substantial portion of the entire length of the FPC  102 . Zones A-E in the figures correspond to the FPC  102  and conductors  110  in  FIGS. 1-5 , while Zone F corresponds to the PCB  114 , which is really just a rigid extension of the FPC  102  in this embodiment.  
         [0052]      FIGS. 9A-9C  illustrate an alternative design of an FPC  102  for leads  1 - 8  in a communications jack  100 , in which the FPC incorporates a capacitive coupling  900  in the compensation zone (Zone B in  FIG. 9B ). This design utilizes the teachings of U.S. patent application Ser. No. 11/099,110, which claims priority to U.S. Provisional Patent Application Ser. No. 60/559,846, filed Apr. 6, 2004, which utilizes an inductive coupling which effectively decreases a capacitive coupling as frequency increases. This application is incorporated herein by reference in its entirety. In addition, U.S. patent application Ser. No. 11/055,344, filed Feb. 20, 2005 and U.S. patent application Ser. No. 11/078,816, filed Mar. 11, 2005 are incorporated herein by reference in their entireties.  
         [0053]      FIG. 9B  shows the capacitive coupling portion of the FPC for leads  3 ,  4 ,  5 , and  6 .  FIG. 9C  is an upper perspective view of this portion showing the capacitive plates, with the substrate removed for ease of illustration. In general, the distributed capacitive coupling of the compensation zone would be reduced by the magnitude, at low frequency, of the remote capacitive coupling that was added.  
         [0054]     As was described above, the FPC  102  as installed in the jack  100  may be oriented vertically or horizontally. In  FIGS. 1-9C , a vertical orientation was described.  FIGS. 10-14C  illustrate an embodiment incorporating an FPC designed for horizontal orientation.  
         [0055]      FIG. 10  is a rear exploded perspective view of a communications jack  1000  having a horizontally oriented FPC  1002 . This design includes a sled mechanism  1004  configured to place the FPC  1002  in a horizontal position to receive the eight IDCs  1016  protruding downward from an intermediate IDC carrier  1018  that interfaces with the front and rear housings,  1006  and  1020 , respectively.  FIG. 11  is a side cross-sectional view of the communications jack  1000  of  FIG. 10 , in assembled form.  
         [0056]      FIGS. 12 and 13  are partially exploded perspective views showing plug interface contacts  1012 , the FPC  1002 , an FPC rigid support  1014 , the IDC carrier  1018 , and the IDCs  1016  that are included within the communications jack  1000  of  FIG. 10 .  
         [0057]      FIG. 14A  illustrates a design of an FPC  1002  for leads  1 - 8  in the communications jack  1000  of  FIG. 10 .  FIGS. 14B and 14C  illustrate cross-sections of the leads  1 - 8  at various locations of the FPC  1002 .  
         [0058]     In the embodiments described herein, the FPC  102 ,  1002  is mechanically and electrically connected to the bottom of each plug interface contact directly under the plug/jack interface. The other end of the FPC  102 ,  1002  electrically connects each plug interface contact to an IDC and provides compensation for the crosstalk couplings of a specification plug. The plastic guides between the plug interface contacts have been minimized to minimize the dielectric and the capacitive couplings between plug interface contacts.  
         [0059]     In  FIGS. 7A, 8A , and  14 A, Zones A-F are shown. These zones generally act as follows: Zone A is a transition zone from the connection to the plug interface contacts to the NEXT (Near-End CrossTalk) compensation zone; Zone B is the NEXT compensation zone; Zone C is a transition zone from the NEXT compensation zone to the NEXT crosstalk zone; Zone D is a compensation zone to compensate for the plug interface contacts; Zone E is the NEXT crosstalk zone; and Zone F is a neutral zone that connects the NEXT crosstalk zone to sockets for the IDCs.  
         [0060]     The design objectives of Zone C are to make its inductive and capacitive couplings and the length of the circuit paths equal to those of Zone A. The magnitude of the total crosstalk coupling of the NEXT crosstalk zone is approximately equal to that of a specification plug. The magnitude of the total compensation coupling of the NEXT compensation zone is slightly less than twice the crosstalk coupling of a specification plug plus twice the total coupling of Zone A.  
         [0061]     In a preferred embodiment shown in  FIG. 7A , which includes only leads  3 ,  4 ,  5  and  6 , all the zones except Zone D have distributed couplings and no remote couplings. The design of the FPC for leads  3 ,  4 ,  5  and  6  reduces the variation in coupling changes due to registration variation between the conductors on each of the two sides of the FPC  102  and reduces couplings due to trace width variations. Zone D provides remote capacitive coupling, and is connected close to the plug/jack interface. The phase angle change between the effective center of couplings of a specification plug and the center of the NEXT compensation zone is approximately equal to the phase angle change between the center of the NEXT crosstalk zone and the NEXT compensation zone. The combination of the jack and a specification plug is therefore symmetrical about the center of the NEXT compensation zone. As a result, Forward NEXT is equal to Reverse NEXT.  
         [0062]     Since the NEXT compensation zone is connected to the plug/jack interface by short circuit paths in the FPC, the phase angle change between them is minimized, as is the change in compensation versus frequency.  
         [0063]     The total inductive coupling of the NEXT compensation zone is approximately equal to the total inductive couplings of the balance of the circuit path of the jack and a specification plug. This results in a very low FEXT.  
         [0064]     The flexibility of the FPC  102 ,  1002  allows it to be connected to all the plug interface contacts, which do not move exactly in unison when a plug is installed. It also facilitates connection to various orientations of IDCs or to a PCB. The relatively thin dielectric layer of the FPC  102 ,  1002  as compared to that of a PCB facilitates a relatively short NEXT compensation zone. As shown in the various figures herein, the FPC  102 ,  1002  may include a plurality of fingers for attachment to the plug interface contacts.  
         [0065]     The length of the NEXT compensation zone is approximately equal to the length of the NEXT crosstalk zone. The result is that variations in FPC trace width, which tend to be consistent on an individual FPC  102 ,  1002 , change the capacitive coupling of the NEXT compensation zone and the NEXT crosstalk zone by approximately the same magnitude. This minimizes the compensation variation due to trace width variation.  
         [0066]     The circuit paths for pairs  1 , 2  and  7 , 8  in the embodiments described herein illustrate how compensation between other pair combinations can be attained. The required compensation for other pair combinations is typically much more easily attained than for pairs  3 , 6  and  4 , 5 , due to the orientation of these pairs in a specification plug.  
         [0067]      FIGS. 15A-15G  illustrate an alternative embodiment of a flexible PCB for a front assembly in a communications jack  1500 . Disposed in a housing  1502  of the communications jack  1500  is a front sled assembly comprising a top front sled  1510 , a bottom front sled  1512 , plug interface contacts  1504 , an FPC  1508 , staking posts  1514 , and a front sled mandrel  1506 .  
         [0068]     The FPC  1508  is placed in the comb slot on the underside of the top front sled  1510  (see  FIGS. 15E and 15F ). While being held in place, the FPC  1508  is attached with multiple staking posts  1514 . The plug interface contacts  1504  are placed, staked, and bent around the front sled mandrel  1506  of the top front sled  1510 , along with the FPC  1508 . To allow for the presence of the FPC  1508  without changing the profile of the plug interface contacts  1504 , the diameter of the front sled mandrel  1506  has a smaller diameter than that of some previous communication jack designs.  
         [0069]     Unlike some top front sleds in previous communication jack designs, the upper half of the combs have been moved from the top front sled and are instead located on the housing  1502  (see  FIG. 15B ). The housing  1502  has fingers that slide over the FPC  1508  and move the FPC  1508  away from the back of the contacts (see  FIG. 15A ). Separation of the FPC  1508  from the plug interface contacts  1504  helps to prevent crosstalk between the FPC  1508  and the plug interface contacts  1504 .  
         [0070]     Because the FPC  1508  is attached directly to the plug interface contacts  1504 , crosstalk compensation circuitry (located on the FPC  1508 ) is provided at the closest point to the plug/jack interface. As a result, performance is significantly improved, and transmission rates at 10 Gigabits/sec. or more are attainable in some embodiments.