Abstract:
A method of making an electrical connector includes the steps of: providing a connector body ( 2 ) having an insert ( 5 ) defining a recessed area ( 54   a ) at one side and a number of channels ( 54   b ) at an opposite side; assembling a ground bus ( 4 ) to the recessed area of the insert, the ground bus including a carrier strip ( 46 ) with a number of fingers ( 460 ) extending therefrom; assembling a number of signal contacts ( 3 ) to the channels of the insert, each signal contact including a board mounting portion ( 32 ); and displacing the carrier strip such that each finger extends into space ( 320 ) between the mounting portions of two adjacent signal contacts.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This patent application is related to two other contemporaneously filed U.S. patent applications entitled “STRADDLE MOUNT CONNECTOR” and entitled “GROUND BUS FOR AN ELECTRICAL CONNECTOR”, invented by the same inventors as this patent application, and all assigned to the same assignee with this application. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a method, and more particularly to a method of making a straddle mount connector in which a lead-in is formed by displacing a carrier strip of a ground bus inserted into the connector. 
   2. Description of Related Art 
   There are commonly numerous electrical connectors available from the market and which are mounted to a printed circuit board (PCB) of an electronic device for implementing different functions. In order to meet the needs of the trend toward miniaturizaiton, the overall size of the electronic device becomes smaller and smaller. Consequently, a printed circuit board mounted within the device becomes small as well. Conversely, while the dimensions of the device decrease, the functions of the device are often increasing. As such, there is a need to install more and more connectors within a limited area of the printed circuit board. In order to mount more and more connectors on the printed circuit board without increasing the surface area, the dimension of the connector must be reduced. This means the terminal pitch within the connector has to be reduced as well. As such, a high-density connector is required. 
   In the early stages of the progression toward high density placement of the connectors, through-hole mounting technology was used. Mounting portions of the terminals were placed in through holes of the circuit board and held in place by soldering or some type of mechanical engagement of the pin with sidewalls of the through hole. As the need for high density of the connector increased, the number of through holes required also increased. However, since the diameter of the through holes is relatively large, only a limited number of through holes could be provided in a given area. Therefore, through-hole technology could not meet the requirement for high density applications. 
   In order to provide for a higher density of connectors on the board, surface mount technology has been utilized. Some surface mount connectors can be referred to U.S. Pat. No. 5,813,871 issued to Grabbe et al. on Sep. 29, 1998 and U.S. Pat. No. 5,860,814 issued to Akama et al. on Jan. 19, 1999. Because no through holes are required, conductive pads on the printed circuit board can be closely spaced, thereby allowing a connector with condensed terminals to be mounted in an area of the board which would be impossible for a through-hole version. 
   As the progression toward higher density continues, it has become imperative that every possible area of the printed circuit board be effectively utilized. A straddle mount connector located on an edge of the printed circuit board is then developed to occupy a minimal board area. Additionally, with the trend of high speed signal transmission, the straddle mount connector generally employs a ground bus to provide a ground reference to signal contacts from for improved signal integrity at higher speeds. Such a straddle mount connector can be referred to U.S. Pat. No. 5,320,541 issued to Korsunsky et al. on Jun. 14, 1994, U.S. Pat. No. 5,199,885 issued to Korsunsky et al. on Apr. 6, 1993 and U.S. Pat. No. 5,120,232 issued to Korsunsky on Jun. 9, 1992. 
   Referring to  FIG. 5  of U.S. Pat. No. 5,199,885, a straddle mount connector is disclosed therein and comprises an insulating housing having a mating surface and an opposite mounting surface. The housing defines a recess in the mating surface for receiving a mating connector therein, two rows of cavities extending from the mounting surface to the recess and a slot extending from the recess to proximate the mounting surface along a longitudinal direction thereof. A plurality of signal contacts is inserted into the cavities from the mounting surface of the housing with terminal portions extending out of the mounting surface so as to mount the connector to an edge of a printed circuit board in a straddle. A ground bus is inserted into the slot from the mating surface of the housing with solder tails penetrating through the mounting surface. When the terminal portions of the signal contacts slide over opposite side surfaces of the printed circuit board, the solder tails of the ground bus are inserted into plated openings in an edge surface of the printed circuit board, thereby establishing an electrical connection between the ground bus and the printed circuit board. 
   It is quite difficult to form the opening in the edge surface of the printed circuit board, thereby complicating the manufacturing process. 
   U.S. Pat. No. 6,231,355 issued to Trammel et al. discloses a straddle mount connector with the ground bus also straddle mounted on the printed circuit board for addressing to the problem encountered by the &#39;885 patent. However, in order to minimize the PCB used for signal contacts, the lead-in of the signal terminal portions for placement on the edge of the PCB is abbreviated. This leads to a potential stubbing condition upon placement, particularly because the leads are proportioned to be flexible. This flexibility also results in less accurate side-to-side placement of the leads on pre-soldered pads of the printed circuit board. In addition, the ground bus does not provide a robust lead-in for receiving the inserted printed circuit board. Trammel further discloses other solutions to the captioned connector, such as disclosed in U.S. Pat. Nos. 6,296,496 and 6,419,502 which are believed relevant to the present invention. 
   Further, the contact pitch of the high density connector is so small so as to create a possibility of “arcing” between the terminal portions of the signal contacts and adjacent solder tails of the ground bus. In order to avoid and prevent this shortcoming, the terminal portions of the signal contacts and the solder tails of the ground bus are kept at a safe distance. However, when the solder tail of the ground bus is cut short to keep this safe distance relative to the terminal portion of the signal contact, the end of the solder tail of the ground bus is almost in alignment with the inserted printed circuit board as the lead-in is cut-off. This will create great difficulty during the assembly because a front edge of the printed circuit board may easily abut against the solder tails unless the printed circuit board is kept completely and perfectly horizontally with respect to a plane defined by the solder tails. This no doubt increases the difficulty of assembly. 
   In addition, when the pitch of the contact of the connector becomes smaller and smaller, keeping the terminal portions of the contact in accurate spacing at all times, including handling and delivery, is a challenge to the manufacturer. If the pitch of the contacts is varied or displaced during handling and delivery, it will be impossible to achieve an accurate alignment between the terminal portions and the conductive pads of the PCB on which the connector is mounted. How to keep those terminal portions of the connector accurately aligned with the conductive pads of the printed circuit board even during the assembly is really a challenge to the manufacturer. 
   The present invention aims to provide a method of making an improved straddle mount connector which can overcome the disadvantages of the related art. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is an object of the present invention to provide a method of making a straddle mount connector which can be easier application to a printed circuit board and can keep signal contacts accurately aligning with corresponding conductive pads on the printed circuit board. 
   In order to achieve the object set forth, a method of making an electrical connector in accordance with the present invention comprises the steps of: providing a connector body having an insert defining a plurality of channels at one side and a recessed area at an opposite side; assembling a ground bus to the recessed area of the insert, the ground bus including a carrier strip with a plurality of fingers extending therefrom; assembling a plurality of signal contacts to the channels of the insert, each signal contact including a board mounting portion; and displacing the carrier strip such that each finger extends into space between the mounting portions of two adjacent signal contacts. 
   Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a straddle mount connector made by a method in accordance with the present invention and a printed circuit board on which the connector is to be straddle mounted; 
       FIG. 2  is a top, partially exploded view of the straddle mount connector of  FIG. 1 ; 
       FIG. 3  is a bottom, partially exploded view of the straddle mount connector of  FIG. 1 ; 
       FIG. 4  is an enlarged perspective view of a ground bus of the connector; 
       FIG. 5  is an enlarged perspective view showing the ground bus and signal contacts attached on an insulating insert of the connector; 
       FIG. 6  is a view similar to  FIG. 5  but taken from a different perspective; 
       FIGS. 7A and 7B  are cross-sectional views showing the insulating inserts installed into a dielectric housing of the straddle mount connector of  FIG. 1 ; 
       FIGS. 8A and 8B  are cross-sectional views showing the ground bus with carrier strips installed into the dielectric housing along an inner side of each insert; 
       FIGS. 9A and 9B  are cross-sectional views showing the signal contacts installed into the dielectric housing along an outer side of each insert; 
       FIG. 10  is a cross-sectional view showing the carrier strips of the ground bus in an angular fashion; 
       FIG. 11  is a perspective view showing the printed circuit board being inserted into the connector of  FIG. 1 ; 
       FIG. 12  is a perspective view showing the connector of  FIG. 1  mounted on the printed circuit board; and 
       FIG. 13  is a view similar to  FIG. 12  but showing the carrier strips removed from the ground bus. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference will now be made in detail to the preferred embodiment of the present invention. 
     FIG. 1  shows a straddle mount connector  1  in accordance with the present invention and a printed circuit board  8  on which the connector  1  is to be straddle mounted. For simplicity, only a half of the printed circuit board  8  is shown. It should be noted that this is not a limitation for the embodiment. The printed circuit board  8  defines a pair of channels  80  extending from a mounting edge  800  toward the opposite edge  802  and a plurality of signal pads  82  and ground pads  84  arranged in a staggered manner on opposite sides thereof. The ground pads  84  are closer to the mounting edge  800  of the printed circuit board  8  than the signal pads  82 . 
   Further referring to  FIGS. 2 and 3 , the connector  1  comprises an elongated dielectric housing  2  with two rows of signal contacts  3  and a pair of ground buses  4  provided therein for electrical connection with the printed circuit board  8 . The housing  2  defines a receiving space  20  in a top mating surface  200  along a longitudinal direction thereof for receiving a mating connector (not shown) therein and cavities  22  in a bottom mounting surface  202  communicating with the receiving space  20 . The cavities  22  of one pair are provided on opposite sides of the longitudinal axis of the housing  2 . The housing  2  further defines slits  220  ( FIG. 7A ) on an inner surface of the cavity  22  and ribs  222  on an outer surface of the cavity  22  to form channels  224  therebetween. 
   A pair of anchor clips  6  is employed to be positioned on opposite ends of the dielectric housing  2  to provide mechanical rigidity during the assembly and in use of the connector  1  onto the printed circuit board  8 . The pair of anchor clips  6  define a receiving space  60 . The anchor clip  6  is made of metal so as to perform additional ground or power function when needed. In doing so, the clip  6  is further formed with a footer  61  so as to electrically connected to a corresponding pad on the printed circuit board  8 . The metal clip  6  provides more rigidity as compared to plastic. However, if the clip  6  is made from plastic, it is preferably coated with a conductive material so as to provide additional ground to the whole system. 
   A pair of insulating inserts  5  is assembled into the housing  2  for assembling the signal contacts  3  and the ground bus  4  into the housing  2 . Even though a pair of inserts  5  is disclosed, however, it is noted that variation can be made according to different applications. In the preferred embodiment, each pair of the inserts  5  is substantially identical in structure, for simplicity, only a pair of the inserts  5  is shown in  FIG. 1  through  FIG. 13 . 
   Referring to  FIGS. 2 ,  3 ,  7 A and  7 B, each insert  5  is generally of a plate configuration defining a chamfer  50  at a top end for facilitating engagement with the mating connector and hooks  52  at a bottom end thereof. The insert  5  has a recessed area  54   a  for receiving the ground bus  4  on a first side and a mating tongue  51  defining a plurality of parallel channels  54   b  for receiving the signal contacts  3  on an opposite second side. The insert  5  has projections  56  formed adjacent to the top end thereof. Each insert  5  is dimensioned to be first ZIF (Zero Insertion Force) inserted into the corresponding cavity  22  from the top mating surface  200  of the housing  2  and then moved outwardly to allow the hooks  52  latching the ribs  222  of the housing  2 , whereby the insert  5  is pre-positioned in the housing  2 . The mating tongue  51  of the insert  5  extends into the receiving space  20  of the housing  2  for engagement with the mating connector. A slit  520  is thus formed between the housing  2  and the first side of the insert  5 . The slit  520  has a width slightly smaller than that of the ground bus  4 . At the same time, the channel  54   b  of the insert  5  and the channel  224  of the housing  2  together form passageways for receiving the signal contacts  3 . 
   Referring to  FIGS. 4 ,  5 ,  8 A and  8 B, the ground buses  4  are loaded into the housing  2  from the bottom mounting surface  202  along the first sides of the inserts  5 . Since the width of the ground bus  4  is larger than that of the slit  520 , the insert  5  is further pushed toward the ribs  222  of the housing  2  during the assembly of the ground bus  4  into the housing  2 , thereby securely retaining the insert  5  in the housing  2 . 
   The ground bus  4  is directly stamped from a conductive sheet material. In order to facilitate assembly of the connector  1  to the printed circuit board  8  by forming a lead-in  424  on the ground bus  4 , the ground bus  4  is accompanied with a carrier strip  46  so as to ensure certain functions. As will be described hereinafter, the lead-in  424  of the ground bus  4  is ideally formed by displacement of the carrier strip  46  after the signal contacts  3  are assembled to the housing  2 . The lead-in  424  is used for eliminating stubbing during the assembly of the connector  1  onto the printed circuit board  8 . The carrier strip  46  defines a row of round holes  464  therein for engaging with a driving wheel whereby the carrier strip  46  can be moved by the driving wheel in the continuous stamping process. 
   The ground bus  4  includes a plurality of solder tails  42  extending from an edge of the carrier strip  46 , a ground plane body  40  extending from the solder tails  42  and a plurality of finger  460  extending from the edge of the carrier strip  46  to define a plurality of slits  462  therebetween. The ground plane body  40  is positioned in the corresponding recessed area  54   a  of the insert  5  for electrically engaging with a corresponding ground contact of the mating connector. The solder tails  42  extend beyond the mounting surface  202  for soldering to the printed circuit board  8 . The plane body  40  has a pair of openings  400  at a top end to receive the projections  56  of the insert  5  for guiding the insertion of the ground bus  4  and adding stability in use. The ground bus  4  further includes spring tabs  402  stamped from the plane body  40  to be received in the slits  220  of the housing  2  and tangs  404  extending perpendicularly from the plane body  40  to abut against the mounting surface  202  of the housing  2  for securely retaining the ground bus  4  in the housing  2 . 
   Each solder tail  42  has a solder joint  420  for electrical connection to the printed circuit board  8 . According to the application, the solder tails  42  are formed in pair and each is a thin section. As such, in order to increase rigidity of the solder tails  42 , the solder tails  42  of each pair are bridged with a cross bar  422  at the solder joints  420  which is further soldered to the ground pad  84  of the printed circuit board  8 . The provision of the cross bar  422  may further increase the size of the solder joint between the solder tails  42  and the ground pad  84 . This increased solder joint will serve as a solid anchor when the carrier is removed after the connector  1  is soldered to the printed circuit board  8 . This will be further discussed hereinafter. 
   The ground bus  4  has V-cuts  466  formed adjacent to the cross bar  422  of the solder tails  42  for removing the carrier strip  46  after the connector  1  is soldered to the printed circuit board  8 . 
   Referring to  FIGS. 9A and 9B , after the carrier strips  46  are slightly bent inwardly, each row of the signal contacts  3  are then simultaneously inserted into the housing  2  via a signal carrier strip  300  from the bottom mounting surface  202  along the second sides of the inserts  5 . Each signal contact  3  includes a mating portion  30  received in the channel  54   b  on the mating tongue  51  of the insert  5  for electrically engaging with a corresponding signal contact of the mating connector, a terminal portion  32  extending beyond the mounting surface  202  for soldering to the printed circuit board  8  and an intermediate portion  34  received in the channel  224  of the housing  2 . The terminal portion  32  of the signal contacts  3  are substantially in alignment with the slits  462  of the carrier strips  46 . 
   Referring to  FIG. 10 , after the signal contacts  3  are assembled in the housing  2  and with the signal carrier strip  300  removed therefrom, the carrier strips  46  of the ground buses  4  are then bent outwardly to allow the terminal portions  32  of the signal contacts  3  extending through the slits  462  between the fingers  460  of the carrier strips  46 , whereby the fingers  460  of the carrier strips  46  are accordingly extended into space  320  ( FIG. 5 ) between every two adjacent terminal portions  32  and are positioned between the terminal portions  32  to keep the signal contacts  3  organized. It is noted that the lead-in  424  of the ground bus  4  is thus formed when the carrier strip  46  is bent outwardly to keep the signal contacts  3  organized. 
   Referring to  FIGS. 11–13 , when the electrical connector  1  is assembled to the printed circuit board  8  from the mounting edge  800 , the anchor clip  6  is received in the channel  80  for providing a vertical alignment for the inserted printed circuit board  8 . By this arrangement, the terminal portions  32  of the signal contacts  3  and the solder tails  42  of the ground bus  4  are respectively accurately aligned with the signal pads  82  and the ground pads  84  on the printed circuit board  8 . During the assembly of the printed circuit board  8  to the electrical connector  1 , the carrier strips  46  of the ground buses  4  provide lead-in capability for easier reception to the printed circuit board  8  by bending outwardly. Once the mounting edge  800  of the printed circuit board  8  abuts against the mounting surface  202  of the dielectric housing  2 , the terminal protions  32  of the signal contacts  3  and the solder tails  42  of the ground bus  4  are respectively positioned on the signal pads  82  and the gound pads  84  onthe opposite sides of the printed cuircuit board  8  benefited by the footer  61  of the anchor clip  6  received within a corresponding slot  81  of the printed circuit board  8 . After the terminal portions  32  and the solder tails  34  are respectively soldered on the signal pads  82  and the ground pads  84 , the carrier strips  46  of the ground buses  4  are removed at the V-cuts  466 . Since the signal pads  82  and the ground pads  84  on the printed circuit board  8  are arranged in a staggered manner, the terminal portions  32  of the signal contacts  3  do not interfere with the ground pads  84  during the assembly of the connector  1  onto the printed circuit board  8 . 
   The solder tails  42  of the ground buses  4  are located between the two rows of the terminal portions  32  of the signal contacts  3  and have a low profile after the carrier strip  46  is removed therefrom. Thus, the board real estate is still saved although the solder tails  42  of the ground buses  4  are soldered on the opposite sides of the printed circuit board  8 . 
   It is noted that the carrier strip  46  of each ground bus  4  can provide lead-in to eliminate stubbing during the placement of the electrical connector  1  onto the printed circuit board  8 . Thus, the carrier strip  46  of the ground bus  4  is removed after the connector  1  is soldered on the printed circuit board  8 . 
   It is appreciated that during the assembly of the connector  1  to the printed circuit board  8 , the anchor clips  6  of the connector  1  are first received in the channels  80  of the printed circuit board  8 , the terminal portions  32  of the signal contacts  3  then contact with the signal pads  82  on the printed circuit board  8 , and the solder tails  42  of the ground buses  4  finally and easily contact with the ground pads  84  on the printed circuit board  8  via the lead-in  424  of the ground bus  4 . At the same time, the signal contacts  3  are kept between the fingers  460  of the ground buses  4  at all times. Thus, the terminal portions  32  of the signal contacts  3  are accurately aligned with the signal pads  82  on the printed circuit board  8 . 
   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 full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.