Shielded electrical connector

Abstract: An electrical connector (10) is disclosed for interconnection to a printed circuit board (30) having signal traces and ground circuitry (31) thereon. The connector includes signal contacts (14) for termination to the signal traces on the printed circuit board. A conductive housing (12) has receptacles (16), including insulators (22), for mounting the signal contacts therein. A plurality of ground projections (32) are formed integral with the housing for interconnection to the ground circuitry on the printed circuit board.

Description: Field of the Invention This invention generally relates to the art of electrical connectors and, particularly, to a shielded electrical connector for interconnection to a printed circuit board having signal traces and ground traces thereon. Background of the Invention Electrical connectors are provided for termination of coaxial cables and for electrical connection of the cables to a printed circuit board or other device. With increasing signal requirements, connectors must terminate a large number of cables while controlling impedance between the cables and the printed circuit board. With the ever increasing densities of electrical contacts to accommodate an ever increasing number of signals within a given area of a printed circuit board, particularly in data processing and telecommunications applications, it has become increasingly difficult to design such electrical connector assemblies. The area allowed for such applications continues to decrease. This combination of requirements leading to such an increased density of the signal leads results in an ever increasing noise potential and greater problems in shielding the leads to prevent or reduce "crosstalk" between the signal contacts. Still further, it is necessary to simultaneously maintain a matched impedance from the site of cable termination into the printed circuit board through the region of interconnection. With such intertwined problems, the predominant design of electrical connector assemblies of the character described involves the utilization of both individual signal contacts and individual ground pin contacts within a connector receptacle, the signal contacts and ground pin contacts being terminated to signal traces and ground traces, respectively, on the printed circuit board. Some attempts at improving the density of such connector assemblies have involved the use of a honeycomb grounding block and the utilization of air as the dielectric between the contacts and pins and the block. Such an approach is shown in US-A-4,889,500 to Lazar, dated December 26, 1989 (= EP-A-0 343 567). However, such connector assemblies still use individual signal contacts and individual ground pin contacts mounted separately in holes in the honeycomb grounding block, as discloses, for ex., in WO-A-88/02560. This invention is directed to providing a unique electrical connector assembly of the character described which eliminates the need for separate ground pin contacts and which provides shielding and controlled impedance. Summary of the Invention An object, therefore, of the invention is to provide a new and improved shielded electrical connector for interconnection to a printed circuit board having signal traces and ground traces thereon. In the exemplary embodiment of the invention, generally, the connector includes separate signal contacts for termination to the signal traces on the printed circuit board. A conductive housing has receptacle means, including insulation means, for mounting the signal contacts therein. The grounding means are integral with the housing for interconnection to the ground circuitry on the printed circuit board, thereby eliminating the need of separate ground pin contacts. More particularly, the housing is provided in the form of a honeycomb grounding block which is die-cast, such as of zinc alloy material. The grounding means are provided in the form of projections protruding from an outside surface of the housing or block. Standoff means are provided integral with the housing, protruding from the outside surface, for engaging the printed circuit board to space the housing from the board and to provide post-process cleaning access. In the preferred embodiment, the projections are longer than the standoff means whereby the projections can be inserted into appropriate holes in the printed circuit board. However, the invention contemplates that the projections can be surface interconnected with the ground circuitry on the printed circuit board by means integral with the housing. The ground projections disclosed herein are generally conical in shape, with generally cylindrical tips for insertion into the holes in the printed circuit board. The receptacle means for receiving the signal contacts of the connector are provided by a plurality of receptacles arranged in a given pattern. The projections are located between the receptacles in a complementary pattern. In the exemplary embodiment, the receptacles are arranged in a pattern of rows and columns, and the projections are located at the interstices between the receptacles. In order to maximize the density, the receptacles and the projections in the rows are offset relative to the receptacles and projections in the columns. Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings, in which like reference numerals identify like elements in the figures and in which: FIGURE 1 is a sectioned perspective view of a portion of an electrical connector embodying the concepts of the invention; FIGURE 2 is a sectioned perspective view similar to Figure 1 with one of the contacts and insulation pairs prior to insertion into the housing; FIGURE 3 is a side elevational view of the electrical connector; FIGURE 4 is a bottom plan view of the electrical connector, illustrating the pattern of signal terminals and ground projections; FIGURE 5 is a perspective view of the housing of the present invention taken from the side opposite that of Figure 3; FIGURE 6 is a sectioned perspective view of a portion of the housing of Figure 5; FIGURE 7 is one half of the insulation sleeves of the present invention; and FIGURE 8 is a top plan view of one of the contact and insulation sleeve receiving holes in the housing. Detailed Description of the Preferred Embodiment Referring to the drawings in greater detail, and first to Figure 1, the invention is embodied in a shielded electrical connector, generally designated 10, which includes a housing, generally designated 12, for mounting a plurality of signal contacts, generally designated 14, within a plurality of through holes 16 which extend between a top surface 18 and a bottom surface 20 of the housing. The terms "top" and "bottom" are used for reference purposes only, the connector being omni-directional in use. Housing 12 is a unitary, die-cast component of conductive material, such as of a zinc alloy or the like. Housing 12 could alternatively be formed by other methods such as machining metal or molding plastic and plating it with conductive plating. Insulation means are provided between contacts 14 and housing 12 in the form of split insulating sleeves 22 surrounding contacts 14 within receptacles in the form of through holes 16 in the housing. The insulating sleeves 22 are hermaphroditic and include a contact receiving cavity 15 in which the contacts 14 are located. Through holes 16 are tapered with the diameter decreasing from the bottom surface 20 to ribs 40. Insulating sleeves 22 are similarly tapered. The pin receiving end 23 of sleeves 22 as well as the pin receiving end 17 of holes 16 are believed to act as a lead in to assist in guiding any misaligned male signal pins that are being mated with the connector assembly. Although the pair of insulating sleeves 22 without a contact 14 therein has a diameter less than the through hole 16, cavities 15 and contact 14 are dimensioned such that the contact and sleeve assembly has a greater diameter than the hole and must be press fit into the hole in an interference fit. During such press fit operation, the edges 27 of the contact 14 deform one of the cavities 15 of the plastic insulating sleeve 22 so that each contact is securely held between each pair of sleeves. As can be seen in Figure 1, the two sleeves 22 do not contact each other and are separated by gap 25. Circular ribs 40 project annularly from within holes 16 to create a shoulder 42 which acts as a stop during the insertion of the contact and sleeve assembly from the bottom 20 of housing 10. Each contact 14 includes a terminal portion or solder tail 24 and a receptacle portion, generally designated 26. The solder tails are provided for insertion into appropriate holes in a printed circuit board for termination to signal traces on the board or in the holes. Receptacle portion 26 of each contact is provided for receiving a male pin from an appropriate mating connector assembly (not shown), inserted into a respective through hole 16, generally in the direction of arrow "A". It is contemplated that such mating connector assembly includes a signal pin together with a ground sleeve that contacts the hole 16 of the housing 12. Each hole 16 has a pair of diametrically opposed flat surfaces 19 (Fig. 8) located between shoulder 40 and top 18. These flat surfaces are contacted by curved resilient arms on the ground sleeve of the mating connector because the resilient arms are curved, they only contact the flat surfaces over a small surfaces area. As a result, for a given contact force, the pressure of the contact is increased which increases the reliability of the contact. The signal pin being electrically and mechanically connected to the signal wire of a shielded, coaxial lead and the ground sleeve being electrically and mechanically connected to the shield of the lead. Referring to Figures 2 and 3 in conjunction with Figure 1, unitary housing 12 includes a plurality of standoffs 28 cast integral with the housing and protruding from bottom surface 20 for engaging a printed circuit board 30 to space the housing from the board. It can be seen that solder tails 24 of contacts 14 project into printed circuit board 30. As is conventional, the solder tails extend into pre-formed holes in the board, and the tails may be interconnected to signal traces connected to the holes. In addition, the signal contacts also may be surface interconnected to signal traces on the board, or even be provided with solder tails which extend slightly into recesses in the board, all of which are conventional methods of interconnecting signal contacts to signal traces on a printed circuit board. As is known, printed circuit board 30 is provided with ground circuitry in addition to the signal traces. Generally, the invention contemplates the provision of grounding means integral with housing 12 for interconnection to the ground circuitry on the board. Specifically, as best seen in Figure 1, the grounding means are provided in the form of a plurality of ground projections 32 formed integrally with and protruding from bottom surface 20 of housing 12. The projections are generally conical in shape, with cylindrical tips 32a for insertion into holes in printed circuit board 30 for interconnection with the ground traces on the printed circuit board. The tips 32a of the ground projections are soldered to the ground circuitry to complete a ground circuit with unitary diecast housing 12. As with the signal contacts, the ground projections 32 may extend through holes in the printed circuit board, into recesses that project part way into the printed circuit board or may be surface mounted to the surface of the printed circuit board. With the conductive housing surrounding the signal contacts 14, the signal contacts are effectively shielded to prevent or reduce crosstalk between the contacts, without providing any separate or independent ground contact pins . Figure 4 shows a bottom plan view of housing 12. It can be seen that receptacles or through holes 16 are arranged in a given pattern to form the housing in sort of a honeycomb grounding block. As illustrated, the receptacles or through holes 16 are arranged in a plurality of rows and columns. Ground projections 32 are shown located between the receptacles in a complementary pattern, namely between the rows and columns, and specifically at the interstices between the receptacles. With the pattern illustrated, the receptacles and projections in the rows are offset relative to the receptacles and projections in the columns. Consequently, an extremely dense array of signal contacts is provided. In addition, the large number of ground projections 32 provides a great deal of redundancy with respect to completing the ground circuit. As a result, poor contact between some of the projections and the ground circuitry or even elimination of up to 25% of the ground projections will not significantly affect the performance of the connector system, thereby providing high reliability. The ground projections also provide a shield "matrix" which encompasses individual signal pins in their transition from honeycombed grounding block to termination on the printed circuit board, thus further reducing the possibility of crosstalk and maintaining a controlled impedance through the transition. In actual practice, as many as 96 signal contacts and 96 ground projections have been provided in less than 3.226 sq.cm (0.5 square inches) of given space. This extremely high density configuration is afforded by the invention without any separate components for ground pin contacts. Not only is a very high density afforded, but it readily can be understood that the connector is very cost-effective because separate ground pin contacts need not be fabricated. It will be understood that the invention may be embodied in other specific forms without departing from the scope of the appended claims.

Claims: In an electrical connector (10) for interconnection to a printed circuit board (30) having signal traces and ground circuitry (31) thereon, the connector including an array of signal contacts (14) for termination to the signal traces on the printed circuit board, a conductive housing (12) having a plurality of generally cylindrical receptacles (16) for mounting the signal contacts therein, and insulation means including a plurality of insulation members (22) for insulating each said signal contact from said housing, characterised by : grounding means integrally formed with the housing and located among said signal contacts for interconnection to the ground circuitry on the printed circuit board, said grounding means including a plurality of projections (32) extending from an outside surface (20) of said housing configured to be positioned adjacent said printed circuit board, each projection being generally positioned between three adjacent receptacles. In an electrical connector as set forth in claim 1, wherein said housing comprises a unitary molded component. In an electrical connector as set forth in claim 2, wherein said housing is fabricated of a zinc die-cast alloy. In an electrical connector as set forth in claim 1, wherein said projections protrude from an outside surface of the housing. In an electrical connector as set forth in claim 4, including standoff means (28) integral with the housing protruding from said surface for engaging the printed circuit board to space the housing therefrom. In an electrical connector as set forth in claim 5, wherein said projections are longer than said standoff means whereby the projections can be inserted into appropriate recesses in the printed circuit board. In an electrical connector as set forth in claim 6, wherein said projections are generally conical in shape, with generally cylindrical tips (32a) for insertion into the recesses in the printed circuit board. In an electrical connector as set forth in claim 4, wherein the receptacles are arranged in a given pattern, and said projections are located between the receptacles in a complementary pattern. In an electrical connector as set forth in claim 8, wherein the receptacles are arranged in a pattern of rows and columns, and said projections are located at the interstices between the receptacles. In an electrical connector as set forth in claim 9, wherein the receptacles and projections in each row are offset relative to the receptacles and projections in adjacent rows.

Inventors: BRINKMAN DONALD J, BRUNKER DAVID L, HARWATH FRANK A, JOHNSON RICHARD ALFRED, LANDGRAF GLENN A, SCHWARTZ HOWELL BARRY, WASHO BASIL DANIEL, BRINKMAN, DONALD J., BRUNKER, DAVID L., HARWATH, FRANK A., JOHNSON, RICHARD ALFRED, LANDGRAF, GLENN A., SCHWARTZ, HOWELL BARRY, WASHO, BASIL DANIEL
Applicants: MOLEX INC, MOLEX INCORPORATED
Application year: 1992
Main classification: H01R13
IPC codes: H01R13, H01R12