Abstract:
Methods and apparatus are disclosed for manufacturing and for providing electrical connectors having maximum shielding from electronic interference. Maximum shielding is inexpensively achieved by manufacturing a shield structure from a single piece of material in a manner yielding individual channels for shielding a contact terminal from the receptacle area to the tail area. Contact terminals are integrated into the shield structure via insertion molding to form a column connector module. A plurality of column connector modules are then inserted into an appropriately formed front housing. As described by the method of this invention, shielding from electronic interference occurs not only between adjacent terminals within a column structure, but also, between terminals contained in adjacent column connector modules.

Description:
RELATED APPLICATIONS 
     The present invention is related by subject matter to the inventions disclosed in commonly assigned application having Ser. No. 09/227,907, filed concurrently herewith on Jan. 8, 1999, entitled “Connector with Improved Shielding and Insulation”. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to electrical connectors and more particularly to shielded connectors and to a method of making connectors such that the connectors provide optimum shielding from electronic interference. 
     BACKGROUND OF THE INVENTION 
     The transition from analog electronics to digital electronics has caused sweeping technological changes within telecommunications and electronic instrumentation industries. For example, as clock-speeds in digital circuitry increase, so do the challenges in maintaining signal integrity with respect to adjacent signals interfering with one another. Other driving forces, that have also created technical challenges, are the demand for miniaturization of electronic devices and the demand for increasing the number of discrete functions associated with each electronic device. The latter two driving forces results in the packing of multiple electronic functions within a smaller cabinet volume, i.e., within a smaller surface space on a printed circuit board (PCB) within the cabinet dimensions. The limited PCB surface space requires closer component spacing that can result in components electrically interfering with or being influenced by neighboring components. For example, the phenomenon of antenna and receiver (crosstalk) is well known in the art. 
     More specifically, older connector designs were based on the use of low frequency signals using relatively high voltage and steady state current levels in which the flow of the energy was evenly distributed over the total cross-section of a conductor. A result of the effective impedance to the flow of such energy was electrical resistance. By contrast, contemporary digital signals operate at much higher frequencies with signal amplitudes in the micro-volt level. With such high frequency signals, transmission of energy migrates to the outer “skin” of the conductor and can be transmitted. Consequently, the impedance of the interconnect becomes an important design parameter. 
     In recent years, equipment designers and users have become more sensitive to the problems raised by increases in clock speed (frequency) and miniaturization. To alleviate these problems, there has been a gradual design shift towards coaxial or pseudo-coaxial shielded components. 
     New connector designs provide shielded interconnects with characteristics that allow propagation of high speed signals while reducing cross talk. In such interconnects, the electronic signal element, i.e., the connector terminal path, is preferably enclosed by an equi-spaced air annulus bounded by a metal shield, air being a preferred dielectric. 
     Optimum coaxial performance is achieved by a cylindrically shaped connector having a minimum of cross-section change over the length of the interconnect. In such a connector, the distance between the center conductor and the shield preferably will be uniform over the length of the connector. Unfortunately, round, coaxial connectors are typically machine-turned and expensive to manufacture. 
     Other types of shielded connectors, are substantially rectangular in shape, as a result of stamping. Connectors assembled with stamped components are easier and more cost-effective to manufacture. Generally such stamped structures typically include rectangular-shaped internal contact terminals. 
     Shielding such rectangular components requires an equi-spaced dielectric annulus. By the very fact that the shield structure is rectangular, rather than circular, there is a natural deviation with respect to ideal coaxial shielding. The performance of such shielding is less optimal than that of the ideal coaxial shielding and is, therefore, referred to as pseudo-coaxial. 
     Right angle or horizontal connectors are commonly used for many backplane applications. Not uncommonly, such right angle connectors, are designed to be press-fit to a printed circuit board and contain multiple rows and columns. In manufacturing such connectors, the contact terminals are stitched into a housing after which the back end of the terminal, known as the tail, is bent. Such bending is usually done row by row. The disparity in tail length between each row causes a difference in the impedance path for adjacent terminals. The resultant cross-talk from the tail section of such a connector is approximately 30 to 35% of the total crosstalk for the mated connector. A significant part of the cross-talk is attributed to the close spacing of the contact terminals. 
     Hence, there still exists a need to design a right-angle connecter having reduced size without sacrificing shielding performance for high frequency signals. 
     SUMMARY OF THE INVENTION 
     The above described problems are resolved and other advantages are achieved in a shielded electrical connector constructed by forming a shield from sheet material, fixing stamped terminals to the shield such that the terminals are positioned equal annular distances from the shield, whereby the terminals and the connector shield define a column connector module, and by inserting a plurality of the shielded connector modules into an appropriately formed housing. 
     According to one aspect of the invention, the step of forming a shield is performed by first forming the sheet material into a planar portion and a leg portion wherein the leg portion is defined by a plurality of legs having a first position lying in the same plane as the planar portion and that extend from the planar portion. Next the legs are bent so that they are perpendicular to the first position thereby defining a second position. Then, the legs are bent again from the second position over and onto the planar portion thereby defining a third position, forming a plurality of channels having a receptacle receiving portion and a tail receiving portion. 
     In preferred embodiments of the invention, the sheet material is metal and the plurality of legs are secured to the planar portion of the stamped piece of sheet material. 
     In yet another embodiment of the invention, the plurality of legs have a plurality of protrusions and the planar portion of the stamped piece of sheet material has a plurality of apertures designed to cooperate with and matingly receive the plurality of protrusions. In such an embodiment, the step of bending the legs includes bending the legs so that they are perpendicular to the first position of the leg portion defining a second position and bending the legs from the second position over and onto the planar portion defining a third position whereby the apertures in the planar portion of the stamped flat piece of sheet material matingly receive the protrusions thereby forming a plurality of channels. 
     According to another aspect of the invention a terminal is provided within each channel, wherein each terminal is formed to receive a mating pin and wherein each terminal defines a tail portion that protrudes beyond the angular tail section. In such an embodiment, the terminals and channels are fixed to one another by an insert-molding process. In such an embodiment it is preferred to insert-mold in only the tail receiving portion. It is especially preferred for the insert-molding material to be a dielectric material. 
     In yet another embodiment of the invention, a lobe is formed on the planar portion of the sheet material, preferably by pressing the sheet material. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The present invention will be better understood and its numerous objects and advantages will become apparent by reference to the following detailed description of the invention when taken in conjunction with the following drawings, in which: 
     FIG. 1 is a perspective, partial section view of an electrical connector according to the invention; 
     FIG. 1A is a flow chart of the processes by which the electrical connector of FIG. 1 is made; 
     FIG. 2 is a top planar view of a pattern formed in a flat piece of sheet metal; 
     FIGS.  3 A-C show a connector housing made according to the method of the invention; 
     FIG. 4A is a top planar view of a stamped and formed terminal for a five row module showing it&#39;s original pitch and still mounted on a carrier frame; 
     FIG. 4B is a cross sectional view of the terminal of FIG. 4A taken through line A—A of FIG. 4A; 
     FIG. 4C is a top planar view of the cut out terminal of FIG. 4A after the pitch has been translated; 
     FIG. 4D is a cross sectional view of the terminals of FIG. 4C taken through line B—B of FIG. 4C; 
     FIG. 4E is a side planar view of the terminals of FIG. 4C; 
     FIG. 5A is a top planar view of the conductor housing fitted with terminals, defining a connector column; 
     FIG. 5B is a vertical frontal view of the connector column of FIG. 5A; 
     FIG. 6 is a three-dimensional view of a connector column described in FIGS.  5 A-B; 
     FIG. 7 is a cross-sectional view of an electrical connector showing the connector column of FIG. 6A inserted into a front housing; and 
     FIG. 8 is a rear view of the electrical connector of FIG. 7 showing a plurality of connector columns inserted into the front housing that comprises the electrical connector. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     A right-angled shielded connector and method of making the same, according to the present invention, will now be described with reference to the Figures. It will be appreciated that the description given herein with respect to the Figures is for exemplary purposes only and is not intended in any way to limit the scope of the invention. For example, the Figures describe a right-angled shielded connector and a method for making the same. However, the concepts disclosed herein have a much broader application to a much wider variety of connectors. The concepts disclosed with reference to this connector could also be employed, for example, with a straight connector. 
     FIG. 1 shows a connector  10  constructed in accordance with the invention. Connector  10  comprises a front housing  12 , wherein front housing  12  includes a front face  13  having a plurality of receptacle openings  14 , and a plurality of connector columns  20  (only one is shown). Each connector column  20  includes a conductor shield  24  and terminals  26  for conducting electrical signals. Each conductor shield  24  includes a side spring  16  and an optional press-fit ground pin  18 . Each terminal  26  also includes a press fit tail  28  and a receptacle portion  30 . The plurality of the receptacle portions in the final assembled connector  10  are arranged in rows (horizontally) and in columns (vertically) to correspond to openings  14 . 
     FIG. 1A is a flow chart of the processes for making connector  10  of FIG.  1 . Processes A, B, and C are performed independently from each other, however, the products of processes B and C are required in process A as indicated by the dotted lines. In describing the processes for manufacturing connector  10 , reference will also be made to FIGS. 2 through 5, wherein there is shown a series of top, plan and perspective views of connector  10  during various stages of manufacture. 
     As shown in FIG. 1A, the process starts with a flat piece of sheet material  32  that is formed into a pattern  34  (Step  100 ). Preferably, the sheet material is metal. The pattern  34  is formed by cutting, stamping, or the like, into the shape as shown in FIG.  2 . At this stage, leg portion  37  lies in the same plane as planar portion  36 . 
     Pattern  34  is then pressed at  110  to form desired three-dimensional characteristics the function of which will become readily apparent from the description herein. FIG. 3A shows that, as a result of steps  100  and  110 , the pressed sheet material pattern now comprises planar portion  36 , a raised offset portion  40  (shown more clearly in FIG.  6 ), a leg portion  37  consisting of a plurality of legs  38 , and an extended portion shown as lobe  42 . 
     As indicated in FIG. 1A, legs  38  of conductor shield are bent at  120  first along axis y-y so that legs  38  are perpendicular to planar portion  36 . Referring now to FIGS.  3   a-c , two substantially 45 degree bends, B 1  (FIG. 3A) and B 2  (FIG.  3 B), are then made in legs  38 . In FIG. 3C, legs  38  are finally bent over axis x-x and into contact with the planar portion  36  thus creating a plurality of equidistant channels  44  whose bottom portion is defined by planar portion  36  and whose walls comprise legs  38 . The resulting angles of bends B 1  and B 2  are selected to create the desired equidistant channels. As a result of bends B 1  and B 2 , channels  44  also define tail receiving portion  46  and a receptacle receiving portion  48 . 
     Legs  38  are secured to planar portion  36  in order to more positively ensure that legs  38  are parallel to each other over their entire length, from tail receiving portion  46  to the receptacle receiving portion  48  thereby maintaining conformity in annular space within each channel. Such parallelism and conformity may be further assured in a particularly effective manner shown in FIG.  3 B. As shown in FIG. 3B, planar portion  36  includes apertures  50 , while legs  38  have protrusions  52  formed thereon. Apertures  50  and protrusions  52  are selectively located so that protrusions  52  will matingly cooperate with apertures  50  when legs  38  are bent around axis x-x onto planar portion  36 . Preferably, protrusions  52  are adapted to be press-fit into apertures  50 . 
     Lobe  42  can be used as a gripping or grasping section to hold a fully constructed connector column  20  (FIG. 5A) during the assembly process for either fitting column  20  into an appropriately formed front housing  12  or for press-fit mass insertion into a PCB. The use of the grasping section allows for easy manipulation of column  20  and permits the column to withstand relatively high assembly forces. 
     Lobe  42  may also have attached side springs  16  (shown in FIG.  1 ). If formed of electrically conductive material, side springs  16  operate to establish an electrical contact with an adjacent lobe thereby forming a continuous path across the plurality of lobes. This path, when utilized in conjunction with an optional press fit ground pin connector  18  (also shown in FIG. 1) at the base of lobe  16 , forms a ground through connector  10  to the PCB. 
     Referring to FIGS.  4 A- 4 E, terminals  26  are depicted. Terminals  26  are preferably formed in any manner from conductive material, such as metal, at step  210  in the manufacturing process in FIG.  1 A. FIG. 4B depicts preferred terminals  26  as stamped from sheet metal having a thickness “e” about 0.15 mm such that, when laying on a flat surface, the distance “f” from the flat surface to an upper most surface of the stamped terminal  26  is about 0.47 mm. The bend represented by distance f is incorporated into the terminal structure  26  specifically to center the receptacle  30  with respect to the other terminal components  56 ,  58 , and  28  to maximize the equidistant relationship of the terminal from the walls of conductor shield  24 , once terminals  26  are integrated into conductor shield  24 . 
     Other conductive material may be used to form terminals  26  such as metalized plastic. The number of stamped terminals  26  will preferably correspond to the number of rows in the final connector product. 
     As shown in FIGS. 4C and 4E, terminals  26  include a U-shaped receptacle  30  for receiving a plug pin, a straight portion  56 , a tail portion  58 , and a press-fit portion  28  for PCB insertion. The initial receptacle pitch “c” (FIG. 4A) of the stamped terminals  26  will be limited by the manufacturing process, for example, to approximately 2.54 mm. The initial pitch “g” (FIG. 4A) of press-fit tail portion  28  is less limited by the manufacturing process and will be about 2.0 mm. To reduce the initial receptacle pitch “c” to a desired pitch, bends  60  are made in the portion of the stamped terminals  26  between press-fit portions  28  and the carrier frame  62  at manufacturing step  230  (FIG.  1 A). Bends  60  are formed after portions of carrier frame  36  adjacent to receptacle portions  30  have been removed at step  220 . 
     For example, to reduce the receptacle pitch from about 2.54 mm to a new receptacle pitch “d” of about 2.0 mm, a series of stamps (bends  60 ) need to be made at different degrees as shown in FIG. 4D such that “h” is about 0.6 mm, “i” is about 0.87 mm, “j” is about 1.14 mm, “k” is about 1.41 mm, and “g,” which represents “f” from FIG. 4B, is adjusted to about 0.32 mm. 
     Referring to FIGS.  5 A-B and  6 , stamped terminals  26  are laid within the conductor shield  24  at equal annular distances from conductor shield  24  at step  130  (FIG.  1 A). At least part of the space between terminals  26  and the channels comprised of planar portion  36  and legs  38  is filled with an insulator. Preferably, an insert molding process is used to integrate terminals  26  and conductor shield  24  into one article. More preferably, molding material  64  is filled only in tail portion  46 . In such an embodiment, the bodies of insulative plastic material are inserted in the channels in surrounding relationship to the tail portions of the terminals. This integrated unit defines the shielded connector column  20 . 
     Once terminals  26  are integrated with conductor shield  24 , the remainder of carrier frame  62  is removed from press-fit portion  28  of terminals  26 . It is noted that removal of carrier frame  62  also involves removal of bends  60  previously formed therein. 
     Referring to FIGS.  7 - 8 , shielded connector column structure  20  is inserted into an appropriately formed front housing  12  to form connector  10  with the desired number of receptacle positions  14  at step  140  (FIG.  1 A). Preferably, the front part of the shielded connector column  20  is inserted into a short recess slot  66  at the rear of the front housing  12 . As can be seen in FIG. 7, a number of slots are formed in front housing  12  thereby forming a number of fingers  70 . Each finger  70  is sized to fit around receptacle portion  30  and within channel  44 . After insertion, a plurality of shielded connector column modules are positioned adjacent to each other and terminals  26  are shielded from electronic interferences for the entire length of contact area  48  through tail portion  46 . The terminals  26  will also be shielded from electronic interferences between all adjacent terminals—both vertically (between columns) and horizontally (between rows). 
     Front housing  12  can be made by molding plastic or plastic that is selectively metalized to establish and maintain a ground connection between a plug  68  and receptacle  30  (step  300 ). 
     While the present invention has been described in connection with the various figures, it is to be understood that other embodiments may be used or modifications and additions may be made to the described embodiment for performing the same function of the present invention without deviating therefrom. Therefore, the present invention should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the recitation of the appended claims.