Abstract:
A high speed, low impedance shielded connector is disclosed. The shield is formed of sheet material and includes multiple integral shield-to-plug contacts in a limited longitudinal space. Such contacts are forwardly facing, to reduce ground path lengths or are arranged substantially parallel to a plug insertion axis, to below development of high normal forces. Shielding of an array of connectors is enhanced by the use of transverse flanges having interfitting sections that provide effective shielding are allow close spacing or adjacent connectors in the array.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to electrical connectors and particularly to shielded, high speed connectors. 
     2. Brief Description of Prior Developments 
     As signal speeds, in particularly data transfer speeds, have increased, interconnection systems, such as those used for input output terminals for data processing equipment have had to be designed to pass these higher speed signals within acceptable limits of signal degradation. These efforts have involved shielding and impedance control. Such efforts are typified with connectors, such a modular jacks, that have separate metal shields applied over the connector housing. In many instances, these shields are in two parts, one to cover the body of the connector and the other to be applied over the front face of the connector. Similar approaches have been taken for other connectors, such as the HSSDC connector marketed by AMP, Inc., which is designed to meet the ANSI X3T11 Fiber Channel committee standards. However, as signal speeds have increased, the difficulty of meeting impedance control and shielding requirements by the use of such wraparound shields has increased. An additional complication is that these interconnection systems require reliable contact with shielding structures on the mating plug connectors so that overall performance of the interconnection system is maintained. 
     Another approach that has been taken is illustrated in recent designs of Universal Serial Bus connectors. Recent designs utilize a central insulative molded member to retain the contacts. The outer shell of this connector comprises a formed sheet metal shield that is wrapped about the molded member and forms the walls of the connector housing. One such connector has been marketed by Berg Electronics under the part number designation 87520. 
     While the above described connectors have been able to achieve adequate performance in terms of minimizing signal degradation at high frequencies, the drive for ever higher signal frequency has necessitated the development of connectors with higher performance capabilities. 
     SUMMARY OF THE INVENTION 
     High speed interconnection performance is assured according to the present invention by incorporating latching features directly into a metal shield of the board mounted receptacle connector. In a preferred embodiment, metal latch engagement surfaces are formed directly from bent portions of the metal shield. 
     Shielding performance is enhanced by providing opposed laterally extending flanges on the shields. The flanges have interfitting structures arranged along an outer edge or distal so that the flanges of adjacent connectors can be interfit, thereby enhancing shielding integrity and minimizing space requirements. 
     Contacts for establishing electrical connection between the shield of the receptacle conductor and the mating plug connector have a flexural axis extending generally in alignment with the insertion axis of the mating connector. These contacts are canted inwardly from the shield and can be additionally compliant toward and away from the flexural axis. In a preferred embodiment, these contacts are formed integrally with the sheet metal shield. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric view of the connector embodying features of the invention; 
     FIG. 2 is a rear isometric view of the connector shown in FIG. 1; 
     FIG. 3 is a front elevation of the connector shown in FIG. 1; 
     FIG. 4 is a side elevation of the connector of FIG. 1; 
     FIG. 5 is a bottom view of the connector shown in FIG. 1; 
     FIG. 6 is an isometric view of four connectors mounted in side by side relationship on a printed circuit board; 
     FIG. 7 is a depiction of a stamped shield blank before it is folded to shape; 
     FIG. 8 is a isometric view of a plug connector for mating with the receptacle connector of FIG. 1; 
     FIG. 9 is a fragmentary cross-sectional top view showing the plug connector of FIG. 8 inserted into the receptacle connector of FIG. 1; 
     FIG. 10 is a side view of the receptacle connector of FIG. 1 with the plug connector of FIG. 8 mated in the receptacle; and 
     FIG. 11 is a front elevational view of the connector shown in FIG. 1 with the plug of FIG. 8 shown (in cross-section) in mated condition. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates a receptacle connector 20. This receptacle comprises a molded plastic contact retaining body 22 having an integral rear wall 23. A plurality of conductive contact terminals 24 are retained on the retainer body 22. The body 22 is molded of a polymeric insulator material. A pair of upper guide members 23a (FIGS. 1, 3 and 10) extend forwardly from the wall 23. The tails 24a of the terminals 24 extend rearwardly from the body 22 and, as shown, can comprise surface mount tails (FIG. 2). One or more pegs 26 may be integrally molded with insulator 22. The pegs 26 provide location and hold down functions when the connector is mounted on a printed circuit board. 
     Surrounding the insulator 22 is a shield 28 formed of suitable metallic sheet material. The shield 28 includes a top wall 30, opposed side walls 32a and 32b and a rear wall 34. Side walls 32a and 32b include through hole tails 33 adapted to be inserted and soldered or press fit into plated through holes of the circuit board on which the connector is mounted. Back wall 34 carriers similar through hole tails 34c. Alternatively the shield tails can be configured for surface mounting. Rear wall 34 also includes tabs 34a and 34b that are wrapped over the rear portions of the side walls 32a and 32b. A latch 35 formed on body 22 holds rear wall 34 in position. 
     The shield 28 also includes bottom wall portions 36a, 36b. The top wall 30, side walls 32a, 32b and bottom walls 36a, 36b define a generally rectangular opening or chamber 38 that is adapted to receive a mating plug connector (later described) adapted to be inserted into the receptacle 20 along the insertion axis A. 
     The shield also includes a plurality of flanges that extend generally transverse to the direction of the insertion axis A. These include the top flange 40, a bottom flange formed of flange portions 56a, 56b and a pair of opposed side flanges 50a, 50b. 
     As shown in FIGS. 1, 2 and 7, a latch receiving slot 42 is formed in the top wall 30 and flange 40. A pair of latching shoulders 44a, 44b are formed along opposed sides of the slot 42. The shoulders 44a, 44b are preferably formed by bending to form in-turned tangs that have flat latching surfaces or shoulders that are generally perpendicular to the insertion axis A. This structure is adapted to cooperate with a latch arm mounted on a mating connector, as will be subsequently described. It is also designed to emulate sensory perceptions of such plugs latching into molded plastic housings. 
     Each of the side flanges 50a, 50b is provided with interfitting sections along the distal edges of the flanges. In the embodiment shown in FIG. 1, these interfitting sections comprise a plurality of fingers 52a and 52b. The longitudinal axes of the fingers 52a are offset from the longitudinal axes of the fingers 52b so that, when similar receptacles 20a-20d (FIG. 6) are placed in side by side relationship, the fingers are interleaved. This improves shielding for the assembled row of connectors and allows closer side by side spacing of the connectors. As shown in FIG. 5, the side flanges 50a, 50b, are, prior to mounting, disposed at a slight angle α with respect to a transverse plane normal to the insertion axis A. These flanges are adapted to be flexed rearwardly to approximately a right angle position when the flanges are pushed against the back side of an equipment panel (not shown), against which the receptacles 20a-20b are mounted. 
     The shield 28 includes a plurality of contacts for assuring electrical connection between the receptacle 20 and a mating plug 60 (FIG. 8). These structures include the top contact members 46a and 46b, the side contact fingers 54a and 54b, and the bottom contact members 58a, 58b. The top contact members 46a, 46b are formed from the top wall 30 and are canted inwardly into the opening 38 along flexural axes D and E (FIG. 8). As shown in FIG. 7, the flexural axes D and E are preferably parallel to the insertion axis A, but could be disposed in angular relation thereto, up to about a 90° angle. As shown in FIG. 3, the upper contact members 46a, 46b are disposed at an angle β with respect to a plane normal to the top wall 30a. The contacts 46a, 46b include compliant contact members 48a, 48b, preferably in the form of cantilevered arms that can be flexed toward the flexural axes D and E respectively. 
     A plurality of forwardly extending contacts 54a, 54b are formed in the side walls 32a, 32b respectively. These contact fingers are positioned to engage side walls of the mating plug. Contact between the bottom walls 36a, 36b and the bottom surface of the plug is achieved through forwardly extending contact fingers 58a, 58b. Thus it can be seen that electrical contact is established between the top, bottom and side walls of the receptacle 20 and the plug 60. 
     As shown in FIG. 4, the shield 28 includes a front zone B, wherein the mating plug is surrounded on all four sides by the metal shield, and a rear zone C, wherein the insulator 22 is surrounded at the top and on the sides by the shield 28. The arrangement of the shield sections and surrounding relationship of the contacts 46a, 46b, 54a,54b, and 58a,58b ensures a low impedance connection between the shield 28 (and ultimately the printed circuit board) and the plug 60. 
     FIG. 7 illustrates the flat blank from which the shield 28 is formed. As can be seen from FIGS. 1 and 2, the back wall 34 is formed by bending downwardly along the junction between wall 34 and top section 30. The tabs 34a, 34b are formed by bending the tabs forwardly at approximately a 90° angle to the back wall 34. Side walls 32a, 32b are formed by bending along the top wall edges generally parallel with insertion axis A. Similarly, bottom walls 36a, 36b are formed by bending the shield along the junctions between the sections 36a, 36b and the side walls 32a, 32b. The flanges 40, 50a, 50b, and 56a, 56b, are similarly formed by bending from the blank shown in FIG. 1. As well, the contact elements 46a, 46b, 54a, 54b and 58a, 58b are formed by stamping and bending from the blank shown in FIGS. 1 and 2. 
     Referring to FIG. 8, a typical mating plug connector 60 is illustrated. This plug includes an insulative nose section 62 that serves as an insulator for contacts (not shown) that are carried on the bottom side of the nose and engage the receptacle contacts 24. The nose is preferably formed of an insulative polymeric material. A latch arm 63, having latching surfaces 64, is preferably integrally molded with the nose 62. The plug includes a metallic shield section 66 that surrounds the conductors within the plug from the nose 62 rearwardly toward the cable 70. The plug includes an overmold section 68 utilized primarily for gripping the plug. 
     As shown in FIG. 9, when the plug 60 is inserted into the receptacle 20 in its fully mated position, the side contacts 54a, 54b engage the side walls of the shield 66 to establish an electrical connection therewith. In this position, the front wall of the nose section 62 is positioned against the wall 23 of insulator 22. The nose section is held in vertical location by the body 22 and the guide sections 23a. 
     As shown in FIG. 10, when the plug 60 is in fully mated position within the receptacle 20, the top contact 46a, 46b engage the top wall of shield 66 via the cantilever arms 48a and 48b. Similarly, the forwardly extending bottom contact members 58a, 58b engage the bottom surface of the shield 66. As shown in FIG. 11, in the mated position, the top contact members 46a and 46b touch the top surface of the shield 66 of the plug. The upper contacts 46a, 46b are capable of being deflected by rotation about the flexural axes D and E respectively and by compliance of the cantilevered arms 48a, 48b. This structure allows the generation of substantial normal forces by the upper contacts 46a and 46b within the relatively limited axial length of the zone B of shield 28. 
     As can be realized particularly from FIGS. 4 and 8, the plug 60 and receptacle 20 are held in mated condition by the engagement of the latch surfaces 64 with the bent latch tangs 44a, 44b. Release of the plug is permitted by pressing the latch arm 63 downwardly toward the shield 66 to release the surfaces 64 from the tangs 44a, 44b. 
     The described features above result in an interconnection system that has improved shielding and overall lower impedance. As a result, higher signal frequencies can be passed through this interconnection system within acceptable levels of signal degradation. The improved performance is believed to result, at least in part, by minimization of the length of ground paths from the plug to the printed circuit board as a result of the location and/or orientation of the various grounding contacts formed in the shield. 
     The latching structure described provides essentially the same tactile feel and aural sensation as achieved with latch structures formed in molded plastic housings. Thus the user has the same sensory perceptions that occur when the plug latch assumes the latched position or is unlatched with the disclosed structure as with previous molded receptacle housings. 
     While the present invention has been described in connection with the preferred embodiments of the various Figs., it is to be understood that other similar 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.