Patent Publication Number: US-7722399-B2

Title: Connector apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a divisional of U.S. Ser. No. 10/788,684, filed Feb. 27, 2004, now U.S. Pat. No. 7,513,797, the disclosure of which is incorporated by reference in its entirety herein. 

   BACKGROUND 
   This invention relates to electrical connectors, and particularly to high-speed electrical connectors for attachment to printed circuit boards. 
   Conductors carrying high frequency signals and currents are subject to interference and cross talk when placed in close proximity to other conductors carrying high frequency signals and currents. This interference and cross talk can result in signal degradation and errors in signal reception. Coaxial and shielded cables are available to carry signals from a transmission point to a reception point, and reduce the likelihood that the signal carried in one shielded or coaxial cable will interfere with the signal carried by another shielded or coaxial cable in close proximity. However, at points of connection, the shielding is often lost, thereby allowing interference and crosstalk between signals. The use of individual shielded wires and cables is not desirable at points of connections due to the need for making a large number of connections in a very small space. In these circumstances, two-part high-speed backplane electrical connectors containing multiple shielded conductive paths are used. Specification IEC 1076-4-101 from the International Electrotechnical Commission sets out parameters for 2 mm, two-part connectors for use with printed circuit boards. 
   As users modify and upgrade systems to achieve improved performance, problems related to backward compatibility arise between, for example, CompactPCI® or FutureBus® connectors and modern high-speed shielded connectors. This means that users wishing to upgrade their system performance by changing to a shielded connector system must upgrade both connector elements (header and socket components) and perhaps additionally change the overall packaging of their system. A connector system that provides an increase in performance, while still permitting backwards compatibility with, for example, CompactPCI® or FutureBus® connectors is desirable. 
   SUMMARY 
   One aspect of the invention described herein provides an electrical header connector. In one embodiment according to the invention, the header connector includes a header body having an internal surface and an external surface. The header body includes a plurality of first openings and a plurality of second openings extending from the internal surface to the external surface. A plurality of signal pins are configured for insertion into the plurality of first openings to form an array of pin contacts extending from the internal surface of the header body. A plurality of shield blades are configured for insertion into the plurality of second openings. Each of the plurality of shield blades has at a first end thereof a generally right angle shielding portion configured to be disposed adjacent to a corresponding one of the plurality of signal pins. The first ends of the plurality of shield blades are substantially coplanar with the internal surface of the header body. 
   Another aspect of the invention described herein provides a system for connection to a printed circuit board. In one embodiment according to the invention, the connector system includes a first header body and a second header body. The first and second header bodies have a front wall formed to include a plurality of first openings and a plurality of second openings therethrough. The first and second header bodies are positioned on opposite sides of a printed circuit board. A plurality of signal pins are configured for insertion in the plurality of first openings in the first and second header bodies. Each of the plurality of signal pins extends continuously through the first openings of the first and second header bodies and the printed circuit board. A first plurality of shield blades is configured for insertion in the plurality of second openings in the first header body, and a second plurality of shield blades configured for insertion in the plurality of second openings in the second header body. Each shield blade of the first plurality of shield blades has a first end that is substantially coplanar with an internal surface of the first front wall. 
   Another aspect of the invention described herein provides a connector system. In one embodiment according to the invention, the connector system includes a header connector and a socket connector configured to mate with the header connector. The header connector has a front wall with an internal surface. The front wall includes a plurality of first openings and a plurality of second openings extending therethrough. A plurality of signal pins are inserted in the plurality of first openings to form an array of pin contacts extending above the internal surface of the header body. A plurality of shield blades are inserted in the plurality of second openings. Each of the plurality of shield blades has a first end that is substantially coplanar with the internal surface of the header body. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of a header connector in accordance with the invention having an array of male pin contacts and shield blades. 
       FIG. 2  is a perspective view of the continuous strip of shield blades of  FIG. 1 . 
       FIG. 3  is a cross-sectional view of the front wall of the header connector showing signal pins surrounded by right angle portions of the shield blades forming coaxial shields around each signal pin. 
       FIG. 4  is a perspective view showing two header bodies positioned end to end, and a strip of shield blades extending across the two header bodies, the strip of the header blades being configured to be inserted into the two header bodies to connect them together to form a monoblock. 
       FIG. 5  shows a socket connector partially inserted into a header connector so that the array of pin-insertion windows in the socket connector are aligned with the array of pin contacts in the header connector prior to the reception of the pin contacts in the header connector in the receptacle contacts in the socket connector. 
       FIGS. 6A and 6B  are graphs illustrating the reduction in crosstalk achieved by a header connector in accordance with the invention. 
       FIG. 7A  is a partial cross-sectional view of two header connectors according to the invention positioned on opposite sides of a printed circuit board. 
       FIG. 7B  is a cross-sectional view taken along line  7 B- 7 B in  FIG. 7A  showing the staggered tails of the shield blades. 
   

   DETAILED DESCRIPTION 
   In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. 
     FIGS. 1 ,  2 , and  3  show a header connector  100  in accordance with the present invention. The header connector  100  is configured for attachment to a printed circuit board  30  and connection to a mating socket connector  200  (shown in  FIG. 5 ). The header connector  100  includes a header body  102 , a plurality of signal pins  104 , a continuous strip of material having a plurality of shield blades  106  formed therein, and a plurality of ground pins  108 . Except for their length, the ground pins  108  are substantially identical to the signal pins  104 . The header body  102  is formed to include a vertical front wall  110 , and top and bottom laterally-extending, horizontal walls  112  and  114  projecting perpendicularly therefrom. The front wall  110  is formed to include a plurality of first signal-pin-receiving openings  116 , a plurality of second shield-blade-receiving openings  118 , and a plurality of third ground-pin-receiving openings  120 , all of which extend between an internal surface  122  and an external surface  124  of front wall  110 . The plurality of second shield-blade-receiving openings  118  are formed to have a generally right angle cross-section. The openings  116 ,  118 ,  120  may include chamfered entrances at one or both of internal surface  122  and external surface  124  to assist in the insertion of pins  104 ,  108  and shield blades  106 . 
   The plurality of signal pins  104  are configured for insertion into the plurality of first signal-pin-receiving openings  116  in the header connector  100  to form an array of signal pins  104  which are configured for reception in an array of pin-insertion windows  230  in mating socket connector  200  (shown in  FIG. 5 ), when the socket connector  200  is inserted into the header connector  100 . Each signal pin  104  includes a first end  152  extending above the front wall  110  of the header connector  100 , and a second end  154  spaced apart from the first end  152  and configured for insertion into an opening  32  in printed circuit board  30 . 
   The plurality of shield blades  106  are formed to include a generally right angle shielding portion  128  configured to be inserted into the plurality of second, generally right angle shield-blade-receiving openings  118 . The generally right angle shielding portion  128  of each of the plurality of shield blades  106  includes substantially perpendicular first leg portion  130  and second leg portion  132 . Each shield blade  106  includes a first end  162  and a second end  164 . The generally right angle shielding portion  128  preferably extends to first end  162 . When inserted into header body  102 , the first end  162  of shield blade  106  extends to the plane of internal surface  122  of the front wall  110  of the header connector  100 , adjacent to a signal pin  104 , such that first end  162  is substantially coplanar with internal surface  122 . First end  162  may be positioned slightly above or below the plane of internal surface  122 . The second end  164  of each shield blade  106  is spaced apart from the first end  162  and configured for insertion into a hole  34  in the printed circuit board  30  adjacent to the second end  154  of the signal pin  104 . In one embodiment, second ends  164  of shield blades  106  are electrically connected to a ground plane  40  within printed circuit board  30 . In a preferred embodiment shield blades  106  are commonly grounded. In an alternate embodiment, shield blades are not commonly grounded. In another alternate embodiment, at least one signal pin  104  is electrically connected with ground plane  40  and commonly grounded with at least shield blade  106  via the ground plane. 
   As shown in  FIG. 3 , the first signal-pin-receiving openings  116  and the second shield-blade-receiving openings  118  are arranged symmetrically in the front wall  110  of the header body  102  such that the generally right angle shielding portions  128  of shield blades  106  substantially surround the signal pins  104  to form a coaxial shield around each of the plurality of signal pins  104 . Each of the plurality of second, generally right angle shield-blade-receiving openings  118  includes a central portion  134  coupled to first and second end portions  136  and  138  by first and second narrowed throat portions  140  and  142 . The first and second narrowed throat portions  140  and  142  are dimensioned to frictionally engage the first and second leg portions  130  and  132  of the shield blades  106  to hold the shield blades  106  in place. The central portion  134  and the first and second end portions  136  and  138  of each of the plurality of second generally right angle openings  118  are formed to provide air gaps  144  surrounding the generally right angle shield portion  128  of a shield blade  106 . The geometry and dimensions of the air gaps  144 , the geometry, dimensions and material of the right angle shielding portions  128 , and the geometry, dimensions and material of the header body  102  surrounding the air gaps  144  are configured to tune the header connector  100  to match a specified impedance (for example, 50 ohms). The configuration of the right angle shield blades  106  lends itself to mass production in a continuous strip in a manner that economizes material usage. 
   In one embodiment of header  100 , a plurality of ground pins  108  are configured for insertion into the plurality of third ground-pin-receiving openings  120  in the front wall  110  of the header connector  100 . The plurality of ground pins  108  are configured to engage contact arms  296  of corresponding grounding structures of socket connector  200  when the socket connector  200  is inserted into the header connector  100  as shown in  FIG. 5 . Each ground pin  108  includes a first end  172  extending above the front wall  110  of the header connector  100 , and a second end  174  spaced apart from the first end  172  and configured for insertion into a hole  38  in printed circuit board  30 , where electrical contact with ground plane  30  is provided. If socket connector  200  does not include or require a grounding contact, ground pins  108  may be omitted from header  100 . 
   Each of the plurality of signal pins  104  and ground pins  108  includes a pin tail  146 , and each strip of shield blades  106  includes at least one shield tail  148 . The number of shield tails  148  may be the same as the number of shield blades  106 , or may be different than the number of shield blades  106 . In a preferred embodiment, each strip of shield blades  106  has a plurality of shield tails  148 , with one shield tail  148  for every two shield blades  106 , wherein the shield tails  148  are staggered and aligned with alternate shield blades  106  along the strip of shield blades  106 . In alternate embodiments, other ratios of shield tails  148  to shield blades  106  may be provided, with the shield tails  148  either uniformly or non-uniformly spaced along the length of the strip of shield blades  106 . Embodiments having staggered shield tails  148  on shield blades  106  are particularly useful in back-to-back mounting of header connectors  100  on a printed circuit board, as described with respect to  FIG. 7 , as the staggered shield tails  148  permit back-to-back mounting of header connectors  100  without interference between shield tails  148  of the opposing header connectors  100 . In preferred embodiments, pin tails  146  and shield tails  148  are positioned in an evenly spaced matrix, such that back-to-back mounted header connectors may be mounted orthogonally to each other. When the signal pins  104  and shield blades  106  are inserted into the front wall  110  of the header body  102 , the pin tails  146  and the shield tails  148  extend outwardly from the external surface  124  of the front wall  110 . The pin tails  146  and shield tails  148  of header  100  can be either press fitted into the holes  32 ,  34  in the printed circuit board  30  or soldered thereto. Alternatively, the pin tails  146  and shield tails  148  could instead be surface mounted to the printed circuit board  30 . 
     FIG. 4  is a perspective view showing first and second header bodies  102 ,  102 ′ positioned end to end, and one of a plurality of continuous strips of shield blades  106  configured for insertion into a row of shield-blade-receiving openings  118  in the first and second header bodies  102 ,  102 ′. The continuous strips of shield blades  106  extend between the first and second header bodies  102 ,  102 ′ to tie them together to form a monoblock. The continuous strips of shield blades  106  can be used to connect any number of header connectors  100  to create header connectors of variable length. As shown in  FIG. 2 , the strip of shield blades  106  may be formed to include a right angle tab  106 ′ at opposite ends thereof to provide a secure connection between the header bodies  102 . 
   One embodiment of socket connector  200  is illustrated in  FIG. 5 , as socket connector  200  is mated with header  100 . Socket connector  200  may be any of a variety of connector types, such as a connector configured for connection to a printed circuit board or a cable connector. In one embodiment according to the invention, socket connector  200  is a hard metric connector according to industry standard IEC 61076-4-101. In another embodiment, socket connector  200  is a hard metric connector according to the CompactPCI® or FutureBus® industry standards. In each embodiment, socket connector  200  includes a plurality of signal contacts  210  for making electrical contact with the array of signal pins  104  of the header connector  100 , and at least one shielding element  212  associated with the plurality of signal contacts  210 . In one embodiment, the at least one shielding element  212  of the socket connector  200  comprises a plurality of strip line shielding elements associated with the plurality of signal contacts  210 . When socket connector  200  is configured to mate with a printed circuit board, socket connector  200  may be provided with signal tails  206  and shield tails  276  that can be either press fitted into the holes in the printed circuit boards or soldered thereto. Alternatively, the pin tails  206  and shield tails  276  could instead be surface mounted to the printed circuit boards. 
     FIG. 5  shows assembly of the header connector  100  with socket connector  200 . External guide means such as guide slots  150  or guide pins (not shown) may be provided on the opposite sides of the header connector  100  to guide the insertion of the socket connector  200  into the header connector  100  so that the array of pin-insertion windows  230  in the socket connector  200  are aligned with the array of signal pins  104  in the header connector  100  prior to insertion of the signal pins  104  into mating receptacle contacts  204  of the socket connector  200 . As the socket connector  200  is inserted into the header connector  100 , signal pins  104  of header  100  make electrical contact with signal contacts  210  of socket connector  200 . However, the shield blades  106  of the header connector  100  are too short to contact any shielding elements  212  of the socket connector  200 . In one embodiment, the plurality of shield blades  106  of the header connector  100  and the at least one shielding element  212  of the socket connector  200  are unable to make electrical contact when the header connector  100  and the socket connector  200  are in a mated condition. In other embodiments, inadvertent or intermittent contact between shield blades  106  of the header connector  100  and the at least one shielding element  212  of the socket connector  200  is possible, although unnecessary. If provided, the ground pins  108  of the header connector  100  may contact corresponding contact arms  296  or similar structure of socket connector  200 . 
   Because shield blades  106  of header connector  100  do not make grounding electrical contact with shielding elements  212  of socket connector  200 , one skilled in the art would not expect the provision of shield blades  106  to improve the electrical performance of the interconnect over a header lacking shield blades, and specifically would not expect a decrease in crosstalk. However, as seen in the graphs of  FIGS. 6A and 6B , the crosstalk experienced in the interconnection decreases unexpectedly. The graph of  FIG. 6A  illustrates a signal having a 35 ps rise time, while the graph of  FIG. 6   b  illustrates a signal having a 100 ps rise time. In the example of  FIG. 6A , the crosstalk decreased from approximately 3.5% for a header lacking shield blades  106  (line  300 ) to approximately 2.5% for a header provided with shield blades  106  (line  302 ), providing an improvement of over 28%. In the example of  FIG. 6B , the crosstalk decreased from approximately 3.1% for a header lacking shield blades  106  (line  300 ′) to approximately 2.3% for a header provided with shield blades  106  (line  302 ′), providing an improvement of over 25%. 
   Another embodiment of a connector system according to the invention is illustrated in  FIGS. 7A and 7B . First and second header connectors  100 ,  100 ′ are positioned back-to-back on opposite sides of printed circuit board  30 . The first and second header connectors  100 ,  100 ′ are each generally constructed as described above, and each includes header body  102 , signal pins  104 , shield blades  106 , and optional ground pins  108 . In an alternate embodiment, shield blades  106  of one header connector  100 ,  100 ′ may alternately extend above the plane of interior surface  122  for connection to a shielded socket connector, as illustrated by dashed lines  107 . In the latter embodiment, the mating socket connector  200  may have relief areas to receive the extended shield blades  107 . 
   The plurality of signal pins  104  and optional ground pins  108  are configured for insertion into the plurality of first signal-pin-receiving openings  116  in the header connectors  100 ,  100 ′, as described above, except that pins  104 ,  108  extend continuously through first header connector  100 , printed circuit board  30  and second header connector  100 ′ to form an array of signal pins  104  on both sides of printed circuit board  30 . In at least one embodiment, at least one signal pin extending through the printed circuit board  30  does not make contact with the printed circuit board, as illustrated by signal pins  104 ′ in  FIG. 7A . 
   The plurality of shield blades  106  of first and second header connectors  100 ,  100 ′ are formed as described above, with generally right angle shielding portions  128  configured to be inserted into the plurality of second, generally right angle shield-blade-receiving openings  118 . The shield tails  148  of each shield blade  106  are configured for insertion into the printed circuit board  30  and are staggered as described above, such that the shield tails of the opposing header connectors  100 ,  100 ′ do not interfere with each other. In a preferred embodiment, shield tails  148  are positioned in a uniform matrix, such that the longitudinal axes of header connectors  100 ,  100 ′ may be positioned orthogonal to each other, if desired for a particular application. In one embodiment, shield tails  148  of shield blades  106  of first and second header connectors  100 ,  100 ′ are electrically connected to ground plane  40  within printed circuit board  30 . In a preferred embodiment shield blades  106  are commonly grounded. In an alternate embodiment, shield blades are not commonly grounded. In another alternate embodiment, at least one signal pin  104  is electrically connected with ground plane  40  and commonly grounded with at least shield blade  106  via the ground plane  40 . 
   In addition to the improved electrical performance described above, the header connector  100  described herein provides other advantages, particularly in assembly of the header connector  100  and attachment to a printed circuit board  30 . In one embodiment, shield blades  106  and pins  104 ,  108  may all be inserted into header body  102  prior to attachment to printed circuit board  30 . Alternately, shield blades  106  may be first inserted into header body  102 , and the header sans pins  104 ,  108  may be aligned with and secured to printed circuit board  30 , via shield tails  148 . Openings  116 ,  120  in header body  102  may then be used as insertion guides and straighteners for pins  104 ,  108 , thereby reducing the probability of stubbing or otherwise damaging pins  104 ,  108  during assembly. Chamfered entrances for openings  116 ,  120  may be provided at one or both of internal surface  122  and external surface  124  to assist in the insertion of pins  104 ,  108 . These assembly methods may be combined when mounting header connectors back-to-back on a printed circuit board, as illustrated in  FIG. 7 . In that instance, a first header connector  100  without pins  104 ,  108  may be mounted on one side of the printed circuit board  30 , and then a second header connector  100  with pins  104 ,  108  may be installed on the opposing side of the printed circuit board  30 . Chamfered entrances for openings  116 ,  120  at external surface  124  is useful in this assembly method, for capturing pins  104 ,  108  as they come through circuit board  30 . Finally, in each instance, securing header connector  100  to printed circuit board  30  using shield tails  148  provides additional resistance to pull-out forces is provided to header connector  100 . 
   All plastic parts of header connector  100  and socket connector  200  are molded from suitable thermoplastic material, such as liquid crystal polymer (“LCP”), having the desired mechanical and electrical properties for the intended application. The conductive metallic parts are made from, for example, plated copper alloy material, although other suitable materials will be recognized by those skilled in the art. The connector materials, geometry and dimensions are all designed to maintain a specified impedance throughout the part. 
   Although specific embodiments have been illustrated and described herein for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations calculated to achieve the same purposes may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. Those with skill in the mechanical, electro-mechanical, and electrical arts will readily appreciate that the present invention may be implemented in a very wide variety of embodiments. This application is intended to cover any adaptations or variations of the preferred embodiments discussed herein. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.