Patent Publication Number: US-11652321-B2

Title: Backplane connector for providing angled connections and system thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to continuing U.S. application Ser. No. 16/866,158, filed May 4, 2020, now U.S. Pat. No. 11,018,454, which in turn claims priority to U.S. application Ser. No. 15/778,176, filed May 22, 2018, now U.S. Pat. No. 10,644,453, which is a national phase of PCT Application No. PCT/US2016/066522, filed Dec. 14, 2016, which in turn claims priority to U.S. Provisional Application No. 62/266,924, filed Dec. 14, 2015, and to U.S. Provisional Application No. 62/305,968, filed Mar. 9, 2016, all of which are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to field of connectors suitable for use in high data rate applications. 
     BACKGROUND 
     Backplane connectors, which are not limited to use in backplane applications, are generally designed to provide certain mechanical features. Common features include high numbers of pins per linear inch, mechanical robustness, and the ability to support high data rates. While there are a number of applications where older connectors are suitable, new connectors designed for backplane applications now are expected to support at least 25 Gbps data rates and certain applications are looking to extend to data rates as high as 56 Gbps. 
     A backplane connector, while possible to be provided in a variety of different configurations, often will be provided in either a mezzanine configuration (supporting two parallel circuit boards) or an orthogonal configuration (supporting two circuit boards that are orthogonal to each other). The orthogonal configuration is more common because it allows for a bottom main circuit board and a number of secondary circuit boards (often referred to as daughter cards) that are positioned parallel to each other but orthogonal to the main circuit board. Each daughter card can support one or more integrated circuits (IC) that provides the desired processing functionality. 
     One issue with orthogonal configurations is that there is a need to translate from a first right angle connector to a second right angle connector that is rotated 90 degrees from the first right angle connector. This has typically been accomplished by using an adaptor piece between two right angle connectors. One common configuration has been to have the adaptor piece consist of a circuit board with two header connectors mounted on both sides of the circuit board. The header connectors each provide a 45-degree rotation and collectively provide the desired 90-degree rotation. Due to the issues related to signal integrity (which becomes more problematic as data rates increase), the use of a circuit board in an adaptor is less desirable. Consequentially, improved adaptors have been developed that offer improved performance. However, it turns out that each mating interface provides the potential for signal reflections and further signal loss and therefore further improvements would be appreciated. 
     SUMMARY 
     A connector system can be configured so that it provides desirable signal integrity. The connector system includes a first connector that can provide a 90-degree right angle configuration and includes a second connector that includes a right-angle configuration with a 90-degrees twist at a mating interface. When mated together, the first and second connectors provide an orthogonal arrangement that offers performance and cost improvements while allowing signal pairs to communicate from one board to another with a single interface junction. As can be appreciated, a U-shaped ground shield can be provided for each signal terminal pair. A shield can further be provided on each wafer to improve electrical performance. The depicted configuration allows for high data rates in a dense package while minimizing the number of components and providing for desirable signal integrity. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements and in which: 
         FIG.  1    illustrates a perspective view of a connector system. 
         FIG.  2    illustrates a partially exploded perspective view of the embodiment depicted in  FIG.  1   . 
         FIG.  3    illustrates a perspective view of one of the connectors depicted in  FIG.  2   . 
         FIG.  4    illustrates a partially exploded perspective of the embodiment depicted in  FIG.  3   . 
         FIG.  5    illustrates a perspective view of another of the connectors depicted in  FIG.  2   . 
         FIG.  6    illustrates a partially exploded perspective of the embodiment depicted in  FIG.  5   . 
         FIG.  7    illustrates a simplified perspective view of an embodiment of the connector system of  FIG.  1    in an unmated condition. 
         FIG.  8    illustrates a perspective view of the embodiment depicted in  FIG.  7    with the connectors mated. 
         FIG.  9    illustrates a simplified perspective view of the embodiment depicted in  FIG.  8   . 
         FIG.  10    illustrates a simplified perspective view of the embodiment depicted in  FIG.  9   . 
         FIG.  11    illustrates an enlarged perspective view of the embodiment depicted in  FIG.  10   . 
         FIG.  12    illustrates another perspective view of the embodiment depicted in  FIG.  11   . 
         FIG.  13    illustrates another perspective view of the embodiment depicted in  FIG.  12   . 
         FIG.  14    illustrates a perspective cross-sectional view taken alone line  14 - 14  in  FIG.  13   . 
         FIG.  15    illustrates an enlarged perspective view of the embodiment depicted in  FIG.  14   . 
         FIG.  16    illustrates another perspective view of the embodiment depicted in  FIG.  14   . 
         FIG.  17    illustrates a perspective view of features associated with an embodiment of a mating interface. 
         FIG.  18    illustrates a simplified perspective view of the embodiment depicted in  FIG.  17   . 
         FIG.  19    illustrates a perspective cross-sectional view taken alone line  19 - 19  in  FIG.  18   . 
         FIG.  20    illustrates a partially exploded perspective of the embodiment depicted in  18 . 
         FIG.  21    illustrates a simplified perspective view of the embodiment depicted in  FIG.  20   . 
         FIG.  22    illustrates a simplified perspective view of an assembly of connector system. 
         FIG.  23    illustrates an enlarged perspective view of the embodiment depicted in  FIG.  22   . 
         FIG.  24    illustrates a perspective view of a cross section taken along line  24 - 24  in  FIG.  23   . 
         FIG.  25    illustrates a perspective cross-sectional view taken along line  25 - 25  in  FIG.  13   . 
         FIG.  26    illustrates a perspective cross-sectional view taken along line  25 - 25  in  FIG.  25   . 
         FIG.  27    illustrates a partially exploded perspective view of an embodiment of a wafer. 
         FIG.  28    illustrates a perspective cross-sectional view of an embodiment of a connector formed from wafers similar to the wafer depicted in  FIG.  27   . 
         FIG.  29    illustrates a perspective view of an embodiment of a connector with a ground shield having angled tails. 
         FIG.  30    illustrates a partially exploded and simplified perspective view of an embodiment of a wafer. 
         FIG.  31    illustrates a perspective simplified view of a portion of a wafer, depicting contacts. 
         FIG.  32    illustrates a perspective cross-sectional view of a mating interface of an embodiment of a connector system that includes wafers with contacts as depicted in  FIG.  31   . 
         FIG.  33    illustrates a simplified elevated side view of an embodiment of a wafer. 
         FIG.  34    illustrates a simplified perspective view of low-speed wafer engaging low speed terminals. 
         FIG.  35    illustrates a perspective view of a mating interface of an embodiment of a connector. 
         FIG.  36    illustrates a perspective view of an embodiment of a ground shield engaging a U-shield. 
         FIG.  37    illustrates a perspective simplified view of the embodiment depicted in  FIG.  36   . 
         FIG.  38    illustrates a partially exploded perspective view of a connector system with separated transmit and receive signal terminals. 
         FIG.  39    illustrates another perspective view of the embodiment depicted in  FIG.  38   . 
         FIG.  40    illustrates another perspective view of the embodiment depicted in  FIG.  38   . 
         FIG.  41    illustrates a simplified perspective view of an embodiment of two wafers mated together. 
         FIG.  42    illustrates an enlarged perspective view of the embodiment depicted in  FIG.  41   . 
         FIG.  43    illustrates a perspective view of the embodiment depicted in  FIG.  41    with the wafers in an unmated configuration. 
         FIG.  44    illustrates a perspective view of an embodiment of two wafers positioned adjacent each other. 
         FIG.  45    illustrates a simplified perspective view of an embodiment of a wafer with the frame omitted for purposes of illustration. 
         FIG.  46    illustrates a perspective view of the embodiment depicted in  FIG.  45    with the signal terminals omitted for purposes of illustration. 
         FIG.  47    illustrates an enlarged perspective view of the embodiment depicted in  FIG.  45   . 
         FIG.  48    illustrates an enlarged perspective view of the embodiment depicted in  FIG.  46   . 
         FIG.  49    illustrates a schematic representation of insertion loss at 28 GHz for an embodiment of a connector. 
         FIG.  50    illustrates a schematic representation of return loss at 28 GHz for an embodiment of a connector. 
         FIG.  51    illustrates a schematic representation of near end crosstalk (NEXT) at 28 GHz for an embodiment of a connector. 
         FIG.  52    illustrates a schematic representation of far end crosstalk at 28 GHz for an embodiment of a connector. 
     
    
    
     DETAILED DESCRIPTION 
     The detailed description that follows describes exemplary embodiments and is not intended to be limited to the expressly disclosed combination(s). Therefore, unless otherwise noted, features disclosed herein may be combined together to form additional combinations that were not otherwise shown for purposes of brevity. 
     The depicted configurations illustrate features that can be used to provide a connector system that can be used in a backplane configuration with a first connector and a second connector. The first connector can be a right-angle connector. The second connector can be a right-angle connector with a 90-degree twist. As can be appreciated, the twist is possible due to the fact that the second connector includes signal terminals that have a contact that is blanked and formed. As can be further appreciated, the ground shield is provided in a U-shaped shielding arrangement that at least partially encloses a pair of signal terminals to help provide shielding. In the depicted embodiment the U-shaped shielding configuration is provided substantially along an entire length of the terminals path from the first circuit board to a mating interface and from the mating interface to a second circuit board and there is also shielding in the mating interface between the signal terminals of the first connector and signal terminals of the second connector, thus allowing for shielding on three sides of a particular terminal pair. Thus, the depicted configuration provides a potentially high performing and suitably dense configuration. 
     Turning to the Figs., an embodiment of a connector system  10  includes a connection between a first circuit board  6  and a second circuit board  8  that are positioned orthogonally to each other. Specifically, a connector  100  is mounted on the circuit board  8  and is configured to mate with a connector  200  mounted on the circuit board  6 . The connector  100  includes a shroud  110  that helps support a wafer set  140  that includes a plurality of wafers  150 , which each include a frame  155 , formed of an insulative material, that supports terminals as will be discussed below. To help provide additional stability and performance, the connector  100  includes an insert  120  that supports a plurality of U-shields  125 . The insert  120  includes a first face  121   a  and a second face  121   b . A tail aligner  130 , which can be plated plastic and have electrical commoning features between ground shields, can be provided to help support the tails while a plurality of combs  112  can be used to help hold the wafer set  140  in a desired alignment and orientation. 
     As can be appreciated, the shroud  110  can be configured to be connected to the supporting circuit board and may be fastened to the circuit board if desired. The structure of the shroud  110 , in combination with the use of the combs  112 , allows for the elimination of an additional housing to support the wafer set  140 . 
     In should be noted that the insert  120  is depicted as a separate component mounted in the shroud  110 . The insert  120  can be formed of an insulative material and includes a conductive path (which can be formed in a desired manner via separate terminals or plating) that allows the insert  120  to electrically connect the U-shields  125  to a ground shield  160 , as discussed below. Due to manufacturing limitations associated with preferred high-volume construction methods, it is expected that the insert  120  will be a separate piece from the shroud  110 , but such a construction is not required and thus the insert  120  can also be formed integrally with the shroud  110  if desired. Thus, the shroud  110  can include a conductive path that electrically connects the U-shield to the ground shield. 
     The U-shield  125  includes a top wall  125   a , two opposing side walls  125   b , and a mating end  127 , with the side walls  125   b  having edges  125   c . As depicted, the mating end  127  is configured to engage the insert  120  through aperture  124 , which is on the second face  121   b , and can be configured differently than the aperture  122  on the first face  121   a . Specifically, the aperture  124  can include pockets  126  that receive the mating ends  127 . 
     The connector  200  can be constructed in a manner similar to connector  100  and includes a shroud  210  that helps support a wafer set  240 . The connector  200  further includes a tail aligner  230 , which can be plated plastic and have commoning features, that helps hold the plurality of wafers  250  in the wafer set  240  together while a plurality of combs  212  can be used to hold the wafer set  240  in a desired alignment and configuration. Each wafer  250  includes an insulative frame  255  for supporting terminals, as will be discussed below. 
     As both the connectors  100 ,  200  are both right angled connectors, the connectors allow for a connection between circuit boards  6  and  8  via the wafers  150 ,  250 . It can be appreciated that circuit boards  6  and  8  are aligned in an orthogonal manner. Typically, two right angle connectors that are configured to join two orthogonally orientated circuit boards would require some sort of intermediary connector that would map the alignment of the contacts in one right angle connector to the contacts of the other right angle connector. The depicted system works without such an intermediary connector. 
     As can be appreciated, the signal terminals  172   a ,  172   b  form a terminal pair  170  that is supported by the insulative frame  155 . The signal terminals each include a contact  174   a , a tail  174   b , and a body  174   c  that extends therebetween. The bodies  174   c  of the signal terminals  172   a ,  172   b  are coupled together to form a differential pair and as depicted, are arranged to provide a vertical edge-coupled configuration. Each signal terminal  172   a ,  172   b  includes a folded section  175  that provides the transition from vertical to horizontal orientation that is still edge-coupled. Each insulative frame  155  will typically be configured to support a plurality of terminal pairs  170  (typically four or more such pairs, it being understood that an upper limit will be reached as manufacturing tolerances and issues with warpage are expected to prevent excessively high numbers of pairs such as 15 or 20 terminal pairs). As noted above, each terminal pair  170  has the body  174   c  of the two terminals aligned in an edge-to-edge configuration so that spacing of the terminals can be carefully controlled when the terminals are insert-molded into the wafer  150 . Naturally, in a right-angle connector, the top terminal pair will tend to be longer than a bottom terminal pair but such arrangements are well known in the art. 
     The terminals pairs  170  are configured to mate with terminals pairs  270  that are provided by signal terminals  272   a  and  272   b . Specifically, the terminal pairs  170  extend through apertures  122  in the insert  120  so that they can connect with the terminal pairs  270 . Each of the signal terminals  272   a ,  272   b  include a contact  274   a , a tail  274   b , and a body  274   c  extended therebetween. The terminal pairs  270  thus provide a differential pair of the signal terminals  272   a ,  272   b  where the bodies  274   a  of these signal terminals are edge coupled. 
     In a typical edge-to-edge coupled terminal configuration suitable for higher performance (above 15 Gbps and more preferably above 20 Gbps using non-return to zero (NRZ) encoding), each adjacent terminal pair in a wafer will be separated by a ground terminal. The ground terminal acts as a shield between adjacent pairs of terminals in a wafer and can also provide a return path, thus the use of a ground terminal is generally accepted as being highly desirable at higher date rates (rates above 15 Gbps) as it helps prevent crosstalk between those adjacent pairs. While such a configuration is effective, it takes up additional space as both the ground terminals and the signal terminals need to be connected to the mating connector (otherwise unmated terminals would provide highly undesirable electrical performance). This turns out to be limiting when attempting to increase the density of the mating interface. 
     The depicted embodiment avoids the use of ground terminals between adjacent terminals pairs in a wafer while still supporting high data rates of at least 20 Gbps using NRZ encoding. Instead, a ground shield  160 ,  260  is mounted to the frame  155 ,  255  and the ground shield  160 ,  260  provides a U-channel  162 ,  262  around the terminal pairs  170 ,  270  (respectively). As can be appreciated, the ground shields  160 ,  260  provide broad-side coupling to the terminal pairs  170 ,  270  and provide a return path while also helping to shield the terminal pairs  170 ,  270  from adjacent terminal pairs in the same wafer and in an adjacent wafer. 
     The ground shield  160  includes an end  163  that is inserted into the insert  120  and a connection frame  161  that provides an electrical connection between adjacent U-channels  162 . The ground shield  260  also includes connection frames  261  to provide similar electrical connections between adjacent U-channels  262 . Thus, the U-channels  162 ,  262  can be commoned together at one or more locations to reduce the electrical length between points of commoning. Such a feature tends to reduce shift any resonances that can form between commoned locations to a high frequency, which in turn causes resonances to shift out of the frequency range of interest. Depending on the intended frequency of signaling, additional connector frame locations can be provided. 
     As can be appreciated, therefore, the U-channel  162  and U-shield provide a three-sided shield for a terminal pair  170  from the tail to the contact in a substantially continuous manner. 
     As depicted, the mating interface includes a double deflecting contact so that the signal terminals of the first connector  100  and second connector  200  both have a stub  173 ,  273  (as can be appreciated from  FIG.  20   ). While such a configuration is beneficial for electrical performance, alternative configurations that have configurations with a single deflecting contact (and corresponding stub) are also contemplated. When using a double contact configuration, such as is depicted, for a portion of the mating interface there is a dual signal path region  199  and the dual signal path region  199  is protected by the U-shield  125 . The U-shield  125  can include one or more notches  129  to help provide clearance for terminal stubs  173 . 
     As noted above, the U-channel  162  uses the end  163  to connect the U-shield  125  via a conductive element  123  provided in the insert  120  (or shroud  110 ). The conductive element  123  can be a separate terminal supported by the insert  120  (in an embodiment it can be insert molded into the insert  120 ) or it can be a conductive plating formed on the insert  120  using additive manufacturing techniques. Thus, any desirable method of forming the conductive element  123  is suitable. The conductive element  123  can directly contact the U-shield  125  and thus electrical continuity between the ground shield  160  and the U-shield  125  is ensured. 
     The ground shield  260  is configured to make electrical contact with the U-shield  125 . Fingers  266  are provided to engage the U-shield  125 , for instance, on opposing sides walls  125   b  of the U-shield  125  so that a reliable electrical connection can be formed. If desired, multiple contact points on each side wall  125   b  can be provided. The ground shield  260  can also include a cutout  264  to provide space for the stubs  273 . To provide improved electrical performance, the U-channel  262  can have an end  269  that extends past a front edge  125   a  of the ground shield  125  so that there is a partial overlap between the U-shield  125  and the U-channel  262 . 
     As can be appreciated from  FIGS.  27 - 48   , alternative and optional features can be used to provide variations on the connector and connector system depicted in  FIGS.  1 - 26   . 
     Specifically, a wafer  350  (which can replace wafer  250 ) can include a frame  355  that supports terminal pairs  370  formed of signal terminal  372   a  and signal terminal  372   b . The signal terminals will each include a contact  374   a , a tail  374   b , and a body  374   a  extending therebetween. The wafer  350  includes a ground shield  360  that has U-channels  362  that are commoned with the use of connection frames  361 . 
     It turns out that a secondary shield  390  can be added to the wafer  350  to provide an improvement in crosstalk and can be press directly against the ground shield  360 . While the use of the secondary shield  390  does not provide significant improvements in shielding as the ground shield  160  already provides excellent shielding, it has been determined that the secondary shield  390  can reduce resonances that might otherwise exist. In addition, the secondary shield  390  can be readily fastened to the frame  355  of the wafer with a projection  359  that can be formed by a staking operation in securing apertures  391 , thus providing desirable stiffening to the wafer. The secondary shield  390  can be connected to the ground shield  360  with conventional techniques such as, but not limited to, soldering, welding and conductive adhesives, and can cover a majority of the ground shield  360 . 
     The ground shield  360  can extend from tails  367  on the mounting face of the connector to contacts on the mating face of the connector. The tails  367  of the ground shield  360  can be arranged in a substantially linear manner with the tails  274   b  that for a corresponding terminal pair  270  and can positioned on two sides of a terminal pair  270  but with the ground tails  367  can be arranged at about a 45-degree angle compared to the signal tails to help provide improved electrical performance in the footprint while allowing for desirable routing of signal traces in the corresponding circuit board. A plated plastic frame  330  can help common the various ground shields  360  (which also act as reference grounds for the edge-coupled differential pairs of signal terminals). 
     As can be appreciated, the ground shield  360  has a plurality of fingers  366   a ,  366   b ,  366   c  that preferably extend in directions so that the fingers  366  are configured to mate with surfaces that that are opposite and/or in orthogonal directions to each other. Naturally, the angles may not be perfectly opposite or orthogonal depending on the corresponding U-shield configuration. In an embodiment as depicted in  FIG.  31   , the contacts  366   c  are configured to engage side walls  125   b  of a first U-shield while contacts  366   a  are configured to engage edges  125   c  of the first U-shield and contacts  366   b  are configured to engage the top wall(s)  125   a  of one or more different U-shields  125 . While not required, having the fingers  366  of the ground shield  360  connect to multiple U-shields helps common the U-shields in the mating interface and provides improved electrical performance. 
     Because of the offset stagger in the terminal pairs  370 , every other signal wafer has some extra space at a top side of the connector (such as connector  100 ). In an embodiment the space may be filled with a single-ended terminal  410 . The single-ended terminal  410  has a contact  415  and can use the ground shield  360  of an adjacent wafer as a reference ground and thus the depicted connector system provides a way to offer desirable electrical performance with the terminal pairs (which are intended to support up to 56 Gbps using NRZ encoding) and still provide single-ended terminals useful for low-speed signaling. One interesting feature of the depicted design, as can be appreciated by  FIG.  34   , is that a low-speed wafer  395  can be provided in the mating connector and the single-ended terminals  410  can use an edge-coupled terminal as the reference ground shield in the low-speed wafer. Thus, the system allows a single-ended communication link that goes from broad-side coupled to edge-coupled. 
     As can be appreciated from  FIGS.  38 - 40   , a connector configuration can be provided with connector  500  positioned on circuit board  8  mating with connector  600  positioned on circuit board  6 . While connectors  500  and  600  can include the other features discussed herein, the corresponding connector system separates transmit and receive channels. In the interface a mating wall  612  is provided on the connector  600  while a corresponding gap  512  is provided in connector  500 . The wafers can include a void  514  where no signal terminals are provided in the wafers that for the connector  500  while the connector  600  can provide a blank  614  (which can be a wafer without signal terminals or the omission of the wafer entirely). A shroud  510  can include a shoulder  518  that helps hold the connectors together while the connector  600  can include a T-shaped comb that supports terminals and also can be terminated to the circuit board  6 . By spacing the transmit channels and the receive channels apart as depicted it has been determined that near end crosstalk (NEXT) can improved a significant amount, potentially about 5 dB. 
       FIGS.  41 - 48    illustrate an alternative configuration of the wafers that would be suitable for use in one of the connectors referenced above. Specifically, wafers  750  are configured to mate with wafers  850 . Both wafers are similar to wafer  350  in that they can include a frame  755 ,  855  and may include a secondary shield, such as secondary shield  790  that is secured to the frame  755  via projections  759  (which can be staked as discussed above). 
     The wafers  850  supports terminals pairs  870  that mate with terminal pairs  770 . As discussed above, U-shields  125  are provided to shield the mating interface and provide a return path. The primary difference is that the ground shield  760 , which includes tails  767 , U-channels  762  and connection frames  761  as discussed above, includes fingers  766   a  and  766   b . The fingers  766   a  are configured to engage the side walls  125   b  of the U-shield  125  surrounding terminal pair the while the fingers  766   b  are configured to engage top walls  125   a  of adjacent U-shields  125 . As noted above, this allows for commoning of the U-shields in the mating interface and helps improve the performance of the system. 
     As can be appreciated from  FIGS.  49 - 52   , the performance of the connector system, when looking only at two mated connectors from tail to tail, can be significant when using all the improvements and features depicted herein. Specifically, at 28 GHz signaling frequency the insertion loss (IL) can be less than −2 dB, return loss (RL) can be at least below −15 dB and both near end cross talk (NEXT) and far end cross talk (FEXT) can be at least below −47 dB. This provides at least a 45 dB insertion loss to crosstalk ratio (ICR) at 28 GHz. Naturally, if certain features are removed then the performance may be reduced and the 45 dB ICR might only exist at a lower frequency. For example, by removing the secondary shield one might get the above performance results only at up to 20 GHz. 
     It should be noted that the depicted embodiments illustrate an orthogonal configuration. If a simple right-angle to right-angle configuration is desired then the 90-degree rotation could be omitted. The same basic construction could also be used for vertical to vertical (e.g., mezzanine style) connectors. Thus, the depicted embodiments provide a technical solution that can be used for a wide range of connector configurations. 
     The disclosure provided herein describes features in terms of preferred and exemplary embodiments thereof. Numerous other embodiments, modifications and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure.