Abstract:
An electrical connector assembly includes a receptacle connector and a mating plug connector. The receptacle connector has two rows of terminals, and a center internal wall with first ground buses disposed on opposite sides thereof. The plug connector has two rows of tongues with contacts and second ground buses respectively disposed on opposite outer and inner side surfaces thereof for engaging with the terminals and first ground buses. Each ground bus has two ribs for ensuring a reliable electrical connection. Adjacent tails of the first and second ground buses in a same row are spaced a distance larger than that between adjacent tails of the terminals and contacts in a same row, respectively.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of U.S. patent application Ser. No. 09/655,163, filed Sep. 5, 2000, now U.S. Pat. No. 6,290,515. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electrical connector assembly, and particularly to an electrical connector assembly having a plurality of grounding buses for enhancing the signal quality of high frequency signals transmitted therethrough. 
     2. Description of the Prior Art 
     U.S. Pat. No. 5,813,871 discloses an electrical connector assembly for interconnecting two circuit boards, which transmit relatively high frequency signals. The electrical connector assembly includes a receptacle connector and a mating plug connector. The plug connector includes a central elongated ground plate, which has a plurality of leads along its length for engaging with a circuit board. The leads extend from each side of the ground plate at equal intervals. The plug connector further includes an outer shield that substantially surrounds the plug connector and has a plurality of leads extending from a bottom edge thereof for contacting with corresponding leads of the ground plate. 
     The receptacle connector includes a base and a plurality of shield plates. The base has a cavity defined therein for receiving a mating portion of the plug connector and a central portion extending into the cavity with a slot defined therein running the entire length of the central portion. When the plug connector and the receptacle connector are fully mated, the elongated ground plate extends well into the slot and is in electrical engagement with each of the shield plates. This provides a relatively short ground path from a first circuit board positioning the receptacle connector to a second circuit board positioning the plug connector, thereby significantly reducing crosstalk between two adjacent signal contacts of the electrical connector assembly. 
     However, this design provides only one ground plate in the plug connector that only provides a grounding function. Further, once the planarity of the ground plate is lost, a reliable engagement between the ground plate of the plug connector and the shield plates of the receptacle connector cannot be achieved. Hence, an improved electrical connector assembly is required to overcome the disadvantages of the prior art. 
     BRIEF SUMMARY OF THE INVENTION 
     A first object of the present invention is to provide an electrical connector assembly having a plurality of grounding buses each having two engaging ribs for achieving reliable grounding performance; 
     A second object of the present invention is to provide an electrical connector assembly having a plurality of ground buses that can be used for either grounding or power transmission. 
     To achieve the above objects, an electrical connector assembly in accordance with the present invention comprises a receptacle connector and a mating plug connector. The receptacle connector comprises an insulative housing and a plurality of signal terminals. The insulative housing further has two elongated sidewalls defining a plurality of channels for receiving corresponding signal terminals, and an internal wall between the two elongated sidewalls defining a plurality of grooves for receiving a plurality of first ground buses therein. The plug connector comprises a dielectric housing and a plurality of signal contacts. The dielectric housing defines a base and two rows of tongues extending upward from the base. Each tongue has an outer side surface and an inner side surface. The outer side surface of the tongue defines a plurality of passageways for receiving a plurality of signal contacts which engage with the signal terminals of the receptacle connector, and the inner side surface of the tongue defines a plurality of grooves for receiving a plurality of second ground buses which engage with the first ground buses of the receptacle connector. Each first ground bus includes a mating portion consisting of two engaging ribs each having a free end section and an arcuate section, and each second ground bus includes a mating portion having two ribs for contacting corresponding two engaging ribs of the first ground bus. In assembly, the free end section of the first ground bus is released from being preloaded by the insulative housing, and the arcuate section of each engaging rib engages with a corresponding rib of the mating portion of the second ground bus thereby ensuring a reliable engagement between the first and second ground buses. 
     Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a mated electrical connector assembly in accordance with a first embodiment of the present invention; 
     FIG. 2 is a perspective view of the electrical connector assembly of FIG.  1  including a plug connector and a receptacle connector in an unmated state; 
     FIG. 3 is a fragmental view of the plug connector of FIG. 2; 
     FIG. 4 is a view similar to FIG. 3 but viewed from a different angle; 
     FIG. 5 is a fragmental view of the receptacle connector of FIG. 2; 
     FIG. 6 is a view similar to FIG. 5 but viewed from a different angle and with a portion cut out for illustrating the relationship between the signal terminals, the first ground buses and the housing; 
     FIG. 7 is a perspective view illustrating the engagement between the first ground buses and second ground buses in accordance with the present invention; 
     FIG. 8 is a cross-sectional view of the electrical connector assembly of FIG. 1 mated together and mounted to two different circuit boards; 
     FIG. 9 is a cross-sectional view of an electrical connector assembly in accordance with a second embodiment of the present invention mounted to two circuit boards; 
     FIG. 10 is a cross-sectional view of an electrical connector assembly in accordance with a third embodiment of the present invention; 
     FIG. 11 is a cross-sectional view of an electrical connector assembly in accordance with a fourth embodiment of the present invention; and 
     FIG. 12 is a cross-sectional view of an electrical connector assembly in accordance with a fifth embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     For facilitating understanding, like components are designated by like reference numerals throughout various embodiments of the present invention as shown in the various drawing figures. 
     Referring to FIGS. 1 and 2, an electrical connector assembly  1  in accordance with a first embodiment of the present invention comprises a plug connector  2  and a mating receptacle connector  4 . The plug connector  2  includes a dielectric housing  6  and a plurality of signal contacts  8  received in the dielectric housing  6 . The dielectric housing  6  includes a base  10 , four sidewalls  12 ,  14 ,  16 ,  18  extending upward from the base  10  to define a receiving cavity  20  therebetween, and four tongues  22  extending upward from the base  10  into the receiving cavity  20  to engage with the mating receptacle connector  4 . The receptacle connector  4  includes an insulative housing  24  and a plurality of signal terminals  26  received in the insulative housing  24 . A plurality of first ground buses  28  and second ground buses  30  is received in the receptacle connector  4  and in the plug connector  2 , respectively. 
     Referring to FIGS. 3 and 4, a plurality of passageways  44  is defined in an outer side surface  42  of each tongue  22  of the plug connector  2  to receive corresponding signal contacts  8  therein for signal transmission. Five grooves  34  having two different widths are defined in an inner side surface  46  of each tongue  22  for retaining five second ground buses  30 , also having two different widths, therein. A plurality of T-shaped ribs  32  is thus defined by the grooves  34 . Each second ground bus  30  can also be used to transmit power, and the width of each second ground bus  30  corresponds to several signal contacts  8 . In this embodiment, the two widths of second ground buses  30  are arranged in an alternating manner. Each broader second ground bus  30  can protect five signal contacts  8 , while each narrower second ground bus  30  can protect three signal contacts  8 . Each signal contact  8  includes an engaging section  38  positioned in the passageway  44 , a soldering section  36  for being soldered to a printed circuit board (PCB)  90  (FIG.  8 ), and a curved middle section  40  for connecting the soldering section  36  with the engaging section  38 . 
     Referring to FIG. 7, each second ground bus  30  includes a mating portion  48  for engaging with a corresponding first ground bus  28 , a soldering portion  50  retained in the PCB  90  (FIG.  8 ), and a joint portion  52  between the mating portion  48  and the soldering portion  50 . The joint portion  52  further includes two teeth  54  respectively formed on both side edges thereof. The teeth  54  engage with the T-shaped ribs  32  for retaining the second ground buses  30  in the grooves  34 . Each mating portion  48  has two ribs  78 . 
     Referring to FIGS. 5 and 6, the insulative housing  24  of the receptacle connector  4  comprises two elongate sidewalls  56  (only one shown) and two lateral end walls (not labeled), together defining a cavity (not labeled) therebetween, and an internal wall  58  upwardly extending into the cavity. A plurality of channels  60  is respectively defined in the two elongate sidewalls  56  with corresponding signal terminals  26  being received therein. An opening  70  is defined at one end of each channel  60 . Each signal terminal  26  includes a mating portion  62  and a soldering section  64 . The mating portion  62  defines a free end section  66  and an arcuate section  68 . The free end section  66  engages with an inner surface of the opening  70  of the channel  60  for preloading before the arcuate section  68  mates with the signal contact  8  of the plug connector  2 . The free end section  66  disengages from the inner surface of the opening  70  when the arcuate section  68  is mated with the signal contact  8 . By this design, breakage of the signal terminals  26  is prevented. 
     The internal wall  58  comprises two rows of grooves  72  (only one row is shown in FIGS. 5 and 6) each defining a recess  74  at one end thereof. As is clearly shown in FIG. 7, each first ground bus  28  includes a mating portion  76  including two engaging ribs  80  each having a free end section  82  and an arcuate section  84 , a soldering portion  86  for mating with a PCB  92  (FIG.  8 ), and a retention portion  85  between the mating portion  76  and the soldering portion  86 . Two teeth  88  are formed on both side edges of the retention portion  85 . The two teeth  88  interferentially engage with the groove  72  to retain the first ground bus  28  therein. In assembly, the free end section  82  is preloaded by the recess  74 , and the two arcuate sections  84  of the engaging ribs  80  of the mating portion  76  engage with the two ribs  78  of the corresponding second ground bus  30  of the plug connector  2 . 
     The signal contacts  8  of the plug connector  2 , the signal terminals  26  of the receptacle connector  4 , and the first ground buses  28  and second ground buses  30  are formed, so the reliability thereof is better than if they were stamped. The first ground buses  28  and second ground buses  30  can serve as a grounding plane and an electrical connector ground, or for electrical power transmission. First ground buses  28  and second ground buses  30  are arranged back-to-back in pairs, pairs of their soldering portions  86  and  50  engaging with signal holes  96 ,  94  in the PCBs  92 ,  90 . Therefore, the footprint of the electrical connector assembly on the PCBs is compatible with the prior art assembly. 
     Referring to FIG. 8, in use, the plug connector  2  soldered to the PCB  90  mates with the receptacle connector  4  soldered to the PCB  92 , whereby the signal contacts  8  engage with the signal terminals  26 . Thus, an electrical circuit is established between the PCBs  90  and  92  via the contacts  8  and the terminals  26 . In addition, the first ground buses  28  and second ground buses  30  contact each other. The two rows of soldering portions  86  and  50  of the respective ground buses  28  and  30  together extend through corresponding holes  96  and  94  defined in the respective PCBs  92  and  90 . 
     FIG. 9 is a second embodiment of the present invention, which is similar to the first embodiment. When the plug connector  2 ′ mates with the receptacle connector  4 ′, the first ground buses  28 ′ and second ground buses  30 ′ engage with each other. However, the two rows of the soldering portions  86 ′ and  50 ′ are respectively separated from each other and extend through the corresponding holes  96 ′ and  94 ′ defined in the PCBs  92 ′ and  90 ′. The first and second embodiments are for use in situations where the PCBs  90  and  92  are parallel to each other. 
     FIG. 10 is a third embodiment of the present invention, wherein the PCB  92 ″ engaging with the receptacle connector  4 ″ is perpendicular to two PCBs  90 ″ which each form part of a cable assembly (not labeled) terminated to the plug connector  2 ″. In this embodiment, each row of the signal contacts  8 ″ and the soldering portions  50 ″ of the second ground buses  30 ″ are soldered to one PCB  90 ″, and the two rows of the soldering portions  86 ″ of the first ground buses  28 ″ together extend through one row of corresponding holes  96 ″ in the PCB  92 ″. 
     FIG. 11 is a fourth embodiment of the present invention, wherein the plug connector  2 ′″ is configured as a right angle connector. When the plug connector  2 ′″ mates with the receptacle connector  4 ′″, the two rows of signal contacts  8 ′″ and the soldering portions  50 ′″ of the second ground buses  30 ′″ are soldered to both sides of the PCB  90 ′″ which connects perpendicular to the PCB  92 ′″. 
     FIG. 12 is a fifth embodiment of the present invention. When the plug connector  2 ″″ mates with the receptacle connector  4 ″″ the two rows of signal contacts  8 ″″ and signal terminals  26 ″″ engage with each other, and the soldering portions  50 ″″ and  86 ″″ of the second and first ground buses  30 ″″ and  28 ″″ are soldered to both sides of the respective PCBs  90 ″″ and  92 ″″. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the fall extent indicated by the broad general meaning of the terms in which the appended claims are expressed.