Patent Publication Number: US-9837768-B2

Title: Direct backplane connector

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. Ser. No. 14/907,451, filed Jan. 25, 2016, now U.S. Pat. No. 9,548,570, which in turn is a national phase of PCT Application No. PCT/US2014/047856, filed Jul. 23, 2014, which in turn claims priority to U. S. Provisional Application No. 61/857,513, filed Jul. 23, 2013, all of which are incorporated herein by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to field of connectors that mount on a circuit board, more specifically to a connector suitable for use in a backplane application. 
     DESCRIPTION OF RELATED ART 
     Connectors suitable for backplanes are often specialized for their environment. Backplane connectors need to have reasonably high density (sometimes referred to as pins per inch) while supporting data channels that have high signaling frequencies. These conflicting requirements make backplane connectors challenging to design, particularly for applications where the channels need to support data rates of 20 Gbps or more (using NRZ encoding). 
     While a variety of connector configurations are possible, including right angle, mid-plane and mezzanine style connectors, one common application of such connector is known as an ortho mid-plane application. This application relates to the idea that a daughter card will be orthogonally orientated compared to a main board. In the past, such applications required the use of a mid-plane board to help bridge the connection between the daughter card and the main board. For example, the daughter card would have a right angle connector, the main board would have a right angle connector and the main board and the daughter card could be orientated so that two aspects of the main boards are rotated 90 degrees with respect to the daughter card. A mid-plane circuit board would be positioned at 90 degrees from both the main board and the daughter card and the mid-plane could include header connectors on both sides of the mid-plane. Thus, the corresponding header could engage the corresponding right-angle connector so as to help bridge the connection between the daughter card and the main board. The terminals in the headers could share the same vias on the mid-plane board, as is known in the art, so as to allow the electrical to pass through the mid-plane board appropriately. 
     It has been determined that for certain applications the mid-plane board is undesirable. One issue is that the existence of the mid-plane board makes it more complex to manage air flow in a resulting device. Another issue is that it is difficult to maintain consistent impedance through the first right angle connector, the header, the mid-plane board, the other header and the second right angle connector. Thus, resulting impedance discontinuities tended to introduce significant loss in the channel. One solution has been to use an adaptor to help bridge the needed orientation change while lessening impedance discontinuities and an example of such a design is disclosed in U.S. application Ser. No. 13/503,516, filed Apr. 23, 2012 and which is incorporated herein by reference in its entirety. For certain applications, however, further improvements would be appreciated. 
     BRIEF SUMMARY 
     A backplane connector system is disclosed that allows two right angle connectors to mate directly to each other without a secondary connector. One of the right angle connectors includes terminals with an edged-coupled alignment that has a 90 degree rotation at a mating side. A shroud is provided to help provide desirable electrical performance and to help maintain impedance and cross-talk levels in a mating side of the right angle connector with the contacts having the 90 degree rotation in alignment. 
     In an embodiment, a connector includes a plurality of wafers, each wafer including a first pair and a second pair of signal terminals with a ground terminal positioned between the first and second pairs, each of the terminals of the pair of signal terminals having a tail, a body and a contact, wherein the tails of the terminals are arranged in the wafer are arranged in a row and the bodies of the signal terminals edge-coupled and are aligned in a first alignment such that the body of the ground terminal is between the bodies of the two pairs of signal terminals and the contacts of each pair of signal terminals have a transition are so that the contacts are edge-coupled in a second alignment that is 90 degrees different than the first alignment. Each wafer can include a shield that is electrically connected to the ground terminal and a shroud that is positioned on a mating side of the wafers. The shroud is insulative and including apertures that support the contacts in the second alignment and further includes supports u-shields. The u-shields can be configured to partially shield a respective pair of contacts are electrically connected to the ground terminal. An insert can be positioned in the shroud and the insert can help electrically connect the u-shield to at least one of the ground terminal and shield. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention 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 an embodiment of a connector. 
         FIG. 2  illustrates a perspective view of a simplified version of the embodiment depicted in  FIG. 1 . 
         FIG. 3  illustrates a perspective partially exploded view of the embodiment depicted in  FIG. 3 . 
         FIG. 4  illustrates a perspective view of a cross section of the embodiment depicted in  FIG. 2 , taken along line  4 - 4 . 
         FIG. 5  illustrates a perspective view of a cross section of the embodiment depicted in  FIG. 2 , taken along line  5 - 5 . 
         FIG. 6  illustrates a perspective enlarged view of the embodiment depicted in  FIG. 5 . 
         FIG. 7  illustrates a perspective simplified view of the embodiment depicted in  FIG. 6 . 
         FIG. 8  illustrates a partial perspective view of an embodiment of two adjacent wafers. 
         FIG. 9  illustrates an enlarged perspective view of one of the wafers depicted in  FIG. 8 . 
         FIG. 10  illustrates a perspective view of an embodiment of a wafer. 
         FIG. 11  illustrates a simplified 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 an enlarged perspective view of the embodiment depicted in  FIG. 11 . 
         FIG. 14  illustrates a perspective view of a transition area of an embodiment of two terminals configured to provide a differential pair. 
         FIG. 15  illustrates a top view of the terminals depicted in  FIG. 14 . 
         FIG. 16  illustrates an elevated front view of the embodiment depicted in  FIG. 15 . 
         FIG. 17  illustrates a perspective view of the embodiment depicted in  FIG. 15 . 
         FIG. 18  illustrates a perspective view of an embodiment of a wafer inserted in an insert that also shows u-shields. 
         FIG. 19  illustrates an enlarged perspective view of the embodiment depicted in  FIG. 18 . 
         FIG. 20  illustrates a perspective view of a cross section of the embodiment depicted in  FIG. 18 , taken along line  20 - 20 . 
         FIG. 21  illustrates another perspective view of the embodiment depicted in  FIG. 20 . 
         FIG. 22  illustrates a perspective view of an embodiment of an insert and a shroud in an exploded arrangement. 
         FIG. 23  illustrates another perspective view of the embodiment depicted in  FIG. 22 . 
         FIG. 24  illustrates a perspective view of a cross section of an embodiment of an insert partially assembled to a shroud. 
         FIG. 25  illustrates a simplified perspective view of a cross section of an embodiment of a wafer inserted into an insert and shroud. 
         FIG. 26  illustrates a further simplified perspective view of the embodiment depicted in  FIG. 25  but with the shroud omitted. 
     
    
    
     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 specification illustrates a number of features that can be used to provide a connector suitable to enable a direct connection between a daughter card and a main board. One feature that is useful is the 90 degree twist or rotation in alignment provided in mating interface. In the body of the connector, a wafer supports a differential pair in a vertical edge-coupled manner and the bodies of the differential pair are aligned in a first plane while the contacts are still edge coupled but are aligned in a second plane that is orthogonal to the first plane. This provides a beneficial continuation of the edge coupling from a first alignment  121  (e.g., a vertical alignment) that is in the first plane and extends along a first imaginary line to a second alignment  122  (e.g., a horizontal alignment) that is in the second plane and extends along a second imaginary line. Between the first and second alignments  121  and  122  is a transition area  123  that first folds the body over and then angles the terminals so that the contacts can be properly aligned. More will be said about this below. Typically such an orientation change is difficult to do in a mating interface that is as compact as would be suitable for backplane connector. Applicants have determined, however, that it is possible to use terminals with blanked and formed contacts and to ensure that features used to alter the orientation of the terminals are carefully controlled (and potentially somewhat of a mirror image of each other) so as to provide desirable electrical performance while shifting from a vertical alignment to a horizontal alignment (the vertical and horizontal alignments being relative to the supporting circuit board). 
     Because of the compact nature of the mating interface and the need to have signal terminals transition from a vertical arrangement to a horizontal arrangement (so as to provide the 90 degree rotation), there isn&#39;t space for convention ground terminal contacts. Thus ground terminals  80  do not have contacts that can engage a u-shield  105  so as to provide a direct electrical connection therebetween (it being understood that the u-shield  105  will engage ground terminals contacts of the mating connector). Normally in a system that is expected to function at high data rates, such an omission would prevent the connector system from working because the break in the ground terminals between the mating connectors would cause a substantial reflection. To prevent such a system breaking occurrence, an insert  30  is placed in a shroud  20 . The insert  30  includes conductive surfaces  36  that help electrically connect the ground terminals  80  to the u-shields  105 . The insert  30  can connect the ground terminals  80  directly to the u-shield or the insert can connect a shield to the u-shield, while the shield is electrically connected to the ground terminals. Thus, the insert provides for an electrical connection between the ground terminals and the u-shield even though the connection may not be direct (e.g., it passes through one or more intermediary components). 
     Turning to the Figs, a connector  10  is depicted that includes the shroud  20  that extends around a wafer set  50  mounted to a circuit board  5 . The shroud includes a first recess  22  and a second recess  23 . The first recess  22  is configured to engage a mating connector. The second recess  23  is configured to engage the wafer set  50 . A shroud wall  26  divides the two recesses  22 ,  23 . To help control the alignment of the wafer set  50 , the shroud may optionally include a shoulder  21  that includes alignment grooves  21   a  that are configured to engage a portion of the wafers and ensure a proper alignment is made between the wafer set  50  and the shroud  20 . 
     As depicted the wafer set  50  includes two wafers  51  and  52  that are configured to be offset with respect to each other. As can be appreciated, a wafer set can be 2 or more wafers and often will be 4 or more wafers. While the offset configuration is not required, the offset nature of the adjacent wafers allows for a more compact terminal arrangement while providing good electrical isolation and thus is useful. As depicted, each wafer  51 ,  52  has an insulative frame  51   a ,  52   a  that supports a plurality of edge-coupled signal terminals  70  and a differential pair of signal terminals would include, for example, terminal  70   a  and terminal  70   b.  The frame can include impedance gaps  61  that help tune the individual terminals  70  in a desirable manner so that each differential pairs functions in a desirable manner. The terminals  70  can be formed of conventional materials and the size of the terminals (the thickness and width) can vary depending on the desired impedance of the system (for example, whether the system is tuned for 85 or 100 ohms). As can be appreciated, in a wafer the differential pairs would each be different lengths depending on where in the wafer they were positioned (the terminals at the top of the wafer would be longer then the terminals at the bottom of the wafer). The signal terminals  70  each include a contact  71 ,  72 , a body  73 ,  74  and a tail  75 . As can be appreciated, the bodies of the signal terminals  70  have an average width and a ground terminal  80  is positioned between the two vertically arranged signal terminals that form the differential pairs provided by the respective wafer, the ground terminal being wider than the signal terminal. 
     In an embodiment a shield  90  is provided on one side of the wafer  51 ,  52  and the shield  90  helps provides isolation between terminal pairs in adjacent wafers and because the shield  90  commons the ground terminals  80  with fingers  95  that engage ground terminal apertures  84 , the shield  90  also helps reduce cross-talk between terminals in the same wafer. To further improve performance, signal terminals in adjacent wafers can be offset (as noted above). As can be appreciated, the shield  90  includes shield cutouts  96  provided by rolled edges  93  and fingers  95  and the shield cutouts  96  are aligned with the body  83  of the ground terminals  80 . Thus the cutouts  96  can help manage the impedance of the ground terminals  80 . The shield  90  includes contacting portions  91 ,  91 ′ that configured to engage insert  30  (as will be discussed below). As depicted, the top ground terminal  80  extends above the shield  80  and this is beneficial from a construction standpoint but is not required. 
     Each of the signal terminals  70  that form a differential pair include the contact  71 ,  72  and the contacts  71  that make up the differential pair are configured to be edge coupled (just like the bodies  73 ,  74 ) but the contacts  71 ,  72  are spaced apart from each other a greater distance than the bodies  73 ,  74 . The contacts  71 , which are horizontally aligned, are positioned in the insulative shroud  20  (the contacts  71  extending through signal channels  28  in the shroud wall  26 ). As can be appreciated, merely having contacts arranged in such a compact configuration would be problematic from a cross-talk standpoint, particularly at higher data rates. To minimize cross-talk, a u-shield  105  can be inserted in u-channel  29  of the shroud wall  26  adjacent the contacts  71 . The u-shield  105  can be formed of a suitable alloy (such as a copper alloy) and is intended to connect to mating terminals of a mating connector (not shown). As can be appreciated, the u-shield  105  extends on both sides of the shroud wall  26 . 
     As noted above, because of the compact nature of the mating interface, the ground terminals  80  have an engaging portion  81  but do not have contacts that can engage the u-shield  105  so as to provide a direct electrical connection therebetween. To provide an electrical connection between the u-shield  105  and the ground terminals  80 , the insert  30  is provided. The insert  30  includes a base  31  that is insert molded but the base  31  has a conductive area  36  positioned in a and the conductive area is electrically conductive. The conductive area  36  can be provided by doing a two-shot mold with an insulative resin and a resin that is either conductive or can be made conductive through a suitable plating process. Naturally, if the plating can be selectively applied than a single resin could also be used and the plating could be positioned where desirable. Furthermore, if desired one could design a terminal that could be insert molded into the resin so as to provide the desired insulative and conduction portions. Thus, the method of forming the insert  30  is not intended to be limiting. Given the likely complicated geometry, it is expected that a two-shot molding process with the second resin either being conductive or plateable will be the most effective construction. 
     The engaging portion  81  of the ground terminals  80  can directly engage the conductive area  36  on the insert  30 . Alternatively, the ground terminals  80 , which are electrically connected to the shield  90  via the fingers  95 , can omit any direct connection to the conductive area  36 . Instead the shield  90  can engage the conductive area  36  with contacting portions  91 . As the conductive area  36  is electrically connected to the u-shield  105 , the ground terminals  80  can be electrically connected to the u-shield  105  via one or two intermediate structures. 
     The depicted insert  30  is positioned in the second recess  23  of the shroud  20  and includes insert channels  34  that provide a path for the signal terminals to extend through the insert. As noted above, portions of the insert channels  34  have conductive area  36  that operative to couple the shield  90  (and the ground terminal  80  if so configured) to the u-shield  105 . The conductive area  36  does not contact the signal terminals. The depicted insert  30  includes notch  39  (which can be u-shaped) to engage the u-shield  105  and engagement surface  37  to engage the contacting portion  91  of the shield  90 . The conductive area  36  can extend into the notch  39  and on the engagement surface  37 , thus in an embodiment at least a portion of the notch  39  and the engagement surface  37  are part of the conductive area  36 . 
     As depicted, the contacts  71  (which are in a horizontal alignment) extend through insert channels  34  in the insert  30  and are supported by the signal channels  28  in the shroud wall  26  without contacting the insert  30 . The shroud  20  thus helps control the position of the contacts  71  so that they can engage a mating connector in a reliable manner. The u-shield  105  is positioned in the u-channel  29  so that the u-shield  105  at least partially surrounds the contacts  71  on three sides. As can be appreciated and discussed elsewhere, adjacent rows of horizontally aligned contacts are offset so as to provide the desired electrical performance while maintaining pin field density. 
     As can be appreciated, transitioning from a vertical alignment to a horizontal alignment while preserving signal integrity is not easy to do. The depicted embodiment uses a mirror image forming operation that folds the top of the body  73  of terminal  70   a  (which was in the first plane) in a first direction while folding the bottom of the body  74  of terminal  70   b  in a second direction (the first and second directions being opposite). The forming operation provides a first horizontal ledge  76   a  and a second horizontal ledge  76   b  that are parallel but offset both vertically and horizontally. An angled ledge  77   a  brings the terminal  70   a  down to the second plane and the contact  71   a  extends along the second plane in the second alignment  122  (e.g., the horizontal alignment). Angled ledge  77   b  brings terminal  70   b  up to the second plane and the contact  71   b  extends along the second plane in the second alignment  122 . Thus, the terminals that form a differential pair have a transition area  123  where the top terminal is folded left and down and the bottom terminal is folded right and up (e.g., the terminals that form the differential pair are formed oppositely through the transition area  123 ). Naturally, the first form of the top and bottom terminal could be folded in the opposite direction of what is depicted (e.g., the top terminal could be folded right instead of left and the bottom terminal could be folded left instead of right). 
     As can be appreciated from the above disclosure, in an embodiment the most direct electrical path from the ground terminal to the u-shield is from the ground terminal to the shield and then to the conductive area and then to the u-shield. It is expected that do to the limited number of mating cycles such a configuration should provide a reliable low resistance electrical connection between each of the conductive mediums while avoiding issues with large changes in impedance. Thus, the depicted embodiment can provide 90 degrees of rotation about two different axes when comparing the mating side to the mounting side. 
     As can be further appreciated, therefore, in an embodiment a plurality of pairs of signal terminals are supported by the connector and each of the pairs is arranged in an edge-coupled first alignment (which can be a vertical alignment). Each of the signal terminals includes a contact and a ground terminal is positioned between each pair of signal terminals, the ground terminal and the signal terminals arranged in the first alignment (e.g., in a first plane). A shroud is provided with a first recess and the shroud supports the contacts. The contacts of each pair of signal terminals can be arranged in an edge-coupled second alignment in the first recess. As can be appreciated, the first alignment can be 90 degrees different than the second alignment. A u-shield is supported by the shroud and is electrically connected to the ground terminal, however the u-shield and the ground terminal are not in direct physical contact. In an embodiment, the shroud supports an insert that helps provide an electrical connection between the ground terminal and the u-shield. 
     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.