LOW PROFILE PRESS FIT CONNECTOR

Abstract: An electrical connector (10) includes a conductive shell (21) and electrical contacts (25, 25, 25, 25) extending from an edge of a corresponding conductive strip (70, 70) the length of the strip (70, 70) from which the contacts (25, 25, 25, 25) extend is overlapped by and between the shell (21) and a ring (26), and the contacts (25, 25, 25, 25) extend parallel to the thickness of the strip (70, 70) and perpendicular to the length of the strip (70, 70).

Description: LO PROFILE PRESS FIT CONNECTOR The present invention relates to an electrical connector, and more particularly, to an electrical connector for mounting on a printed circuit board. A known connector is disclosed in French patent 552,939. The known connector includes a conductive strip member having a length that is formed to a U shaped section. The U shaped section encircles a conductive shell of the known connector. Electrical contacts extend lengthwise of the strip member and extend from opposite edges of the strip member. An integral tubular extension of the U shaped section extends transversely of the length of the U shaped section. The tubular section encircles the shell and in turn is encircled by a ferrule. The U shaped section is uncovered by the ferrule and in part extends away from the shell. The U shaped section is capable of collapse or bending, particularly when forces are applied to the U shaped section by the contacts during insertion of the contacts into corresponding apertures of a printed circuit board. According to the invention an electrical connector includes a conductive strip having a length extending transverse to an axis of a shell of the connector, the length is overlapped by and between the shell and a ring, and electrical contacts extend from an edge of the strip and extend perpendicular to a length of the corresponding strip. The advantage of the invention is that the length of the strip from which the contact extends is overlapped by the shell and by the ring. Accordingly, the strip is supported against collapse or bending, particularly during insertion of the contacts into apertures of a printed circuit board. Another advantage is that the length of the strip extends transverse to the axis of the shell, with the contacts extending parallel to a thickness of the strip and also perpendicular to the length of the strip. Accordingly, the strip and ring increase the size of the connector by only a small amount, thereby achieving a connector that covers a relatively small space on a printed circuit board. Further advantages and important features of the invention will become apparent hereinafter from a detailed description of the invention by way of example and in conjunction with accompanying drawings. FIG. 1 is an exploded perspective view of a coaxial connector for printed circuit boards; FIG. 2 is a cross-sectional view illustrating the connector of FIG. l assembled and mounted to a printed circuit board, and further illustrating a mating connector therefor; FIG. 3 is an enlarged perspective view of a grounding pin contact of FIGS. 1 and 2; FIG. 4 is an end view of the grounding pin contact of FIG. 3 looking in the direction of arrows 4-4 in FIG. 3; and FIG. 5 illustrates a stamping from which a grounding pin contact member of FIGS. 1 and 2 is made. FIGS. 1 and 2 illustrate exploded perspective and assembled, cross-sectional views, respectively, of an electrical connector by way of example. The connector is generally designated by reference numeral 10 and comprises a coaxial electrical connector for use with printed circuit boards. More particularly, connector 10 is adapted to be mounted to a printed circuit board schematically illustrated at 12, and to be mated with a complementary connector 14 (FIG. 2) connected to external circuitry or the like (not shown) , to complete electrical connection between the external circuitry and conductive paths on the printed circuit board. Connector 10 includes tubular-shaped outer shell 21 formed of a suitable, electrically conductive material such as zinc; a center contact assembly 22; and a dielectric plug body 23 for supporting the center contact assembly 22 axially within the outer shell and for electrically insulating the center contact assembly from the outer shell. An annular internal flange 21a of the shell 21 overlaps the dielectric plug 23. In addition, and as will be described more fully hereinafter, connector 10 includes grounding pin contact means 24 having a plurality of grounding pin contacts 25 thereon, and a retention ring 26 for securing the grounding pin contact means 24 to the outer shell 21. Center contact assembly 22 includes a center contact 27 of the socket type, and a center pin contact 28 attached thereto as by crimping as shown at 29. As best shown in FIG. 2, grounding pin contacts 25 and center pin contact 28 extend outwardly from the base 30 of the connector body which is generally designated by reference numeral 20. Connector 10 is matable with complementary coaxial connector 14 to complete electrical circuits through the connectors. Complementary connector 14 terminates a coaxial cable 54 having a center conductor 56 surrounded by a dielectric sheath 57. An outer braided conductor 58 surrounds sheath 57 and is, in turn, covered by an outer jacket 59. Braided outer conductor 58 functions to shield the center conductor 56 and the signals carried thereby from electromagnetic interference, and is electrically coupled to an outer contact 61 of the connector 14. Center conductor 56 of the cable 54 is electrically coupled to center pin contact 63 of connector 14. When connector 14 is mated with connector 10, center pin contact 63 mates with socket contact 27 of connector 10 to connect the center conductor 56 of the coaxial cable through the connectors to center pin contact 28 of connector 10. Similarly, outer contact 61 of connector 14 engages the conductive outer shell 21 of connector 10 to complete electrical connection of the braided outer conductor 58 of cable 54 to shell 21, and to the grounding pin contact means 24 and the grounding pin contacts 25 thereon. Connector 10 is adapted to be mounted to a printed circuit board 12 by extending grounding pin contacts 25 and center pin contact 28 into and through apertures in the printed circuit board. More particularly, printed circuit board 12 includes a plurality of four apertures 32 arranged in a generally circular pattern, and a single aperture 35 which is positioned substantially centrally within the circular pattern of apertures 32. Apertures 32 and 35 extend completely through the board from mounting side 33 to opposite side 34 thereof. The sidewalls of apertures 32 and 35 are plated with an electrically conductive coating 36, as shown in FIG. 2, which coatings are electrically connected to conductive paths 38 and 39 on the board. Coating 36 may comprise a thin layer of copper having a tin-lead coating plated thereon. When connector 10 is mounted to printed circuit board 12, the grounding pin contacts 25 extend through apertures 32 in the board; and the center pin contact 28 extends through aperture 35. The pin contacts will engage the conductive coatings 36 on the aperture sidewalls to complete electrical connection from the connector (and from cable 54) to the conductive paths 38 and 39 on the printed circuit board. Center pin contact 28 can be of any suitable construction, but preferably includes a compliant portion illustrated schematically at 40 which is adapted to be press-fit into aperture 35 to retain the pin contact 28 within aperture 35 by frictional engagement with the sidewall of the aperture, and to simultaneously electrically connect the center pin contact to conductive paths 39 on the board via the conductive coating 36 of the aperture. One known type of compliant pin contact is disclosed in U.S. Patent No. 4,191,440. Grounding pin contacts 25 are adapted to be press-fit into apertures 32 of the printed circuit board 12 to also be retained within the apertures by frictional engagement with the sidewalls of the apertures, and to electrically connect the grounding pin contacts to conductive paths 38 on the board to dissipate noise on the outer conductive sheath 58 of cable 54 to external ground. In addition, however, and for greater retention assurance, grounding pin contacts 25 are constructed to also mechanically lock the connector 10 to the board 12. As shown in FIG. 2, grounding pin contacts 25 have a length which is greater than the thickness of printed circuit board 12 such that when connector 10 is mounted to mounting side 33 of board 12, a first portion 41 of the grounding pin contacts will be positioned within apertures 32; and a second portion 42 will extend outwardly of the apertures beyond opposite side 34 of the board. In addition, the grounding pin contacts 25 are compliant over a substantial portion of their length from adjacent base ends 44 of the pin contacts to adjacent the tip ends 45 thereof (see FIG. 3) . The compliant portion of the grounding pin contacts is generally designated by reference numeral 43. As best shown in FIGS. 3 and 4, the compliant portions 43 of grounding pin contacts 25 are formed by partially shearing the pins transversely along a substantial portion of their length to define partially sheared grounding pin contact halves of sections 46 and 47. The partial shearing can be achieved in any suitable manner using appropriate shearing equipment to apply a shearing force to surfaces 48 and 49 of the grounding pin contacts as indicated in FIG. 4. Shearing of the grounding pin contacts is effected such that the grounding pin contacts are sheared to a maximum extent on the second grounding pin contact portions at approximately the location indicated by arrow 51 in FIG. 3 with the amount of shear decreasing gradually toward. base ends 44 and tip ends 45 of the contacts. In fact, although a light amount of shear is illustrated at the widened tip end 45 in FIGS. 3 and 4, it is preferable that the extent of widening at the tip end 45 be minimized to facilitate insertion of the pins into the apertures 32 in the printed circuit board. The shearing is effected to produce outer surfaces 52 and 53 on pin contact halves 46 and 47 which are tapered outwardly from the base ends 44 at an angle of about 5 degrees from the axis of the pins to vicinity 51 of maximum diameter, and then tapered inwardly toward the tip ends 45 of the pin contacts. As best shown in FIG. 4, the shearing produces a compliant pin contact portion 43 which has a maximum diameter which is greater than that of the aperture 32 (shown in dotted line in FIG. 4) , but which is compressible to permit the pin contact to be inserted into and through the aperture. In a typical embodiment, the apertures 32 in printed circuit board 12 have a maximum diameter 0.064 inch, grounding pin contacts 25 have a maximum diameter at location 51 of about 0.083 inch. Upon being inserted into the apertures 32, however, the compliant portions 43 are compressed inwardly by the sidewalls of the apertures to permit the pin contacts to be extended into and through the apertures. The first pin contact portions 41 are positioned within apertures 32 in press-fit relationship with the sidewalls thereof and exert a substantial force against the sidewalls to frictionally retain the pins within the apertures by frictional engagement with the sidewalls. After passing through the apertures 32 in the board, the second pin contact portions 42 extend beyond the opposite face 34 of the board; and upon clearing the board, the compliant portions expand somewhat. At the location 51 of largest diameter, for example, which is preferably positioned on the grounding pin contacts to just clear the apertures, the grounding pin contacts expand.to a diameter of approximately 0.068 inch, which is slightly greater than that of the apertures. The compliant second pin contact portions of the grounding pin contacts thus function as locking means for mechanically locking the connector to the board. The grounding pin contacts 25 oppose withdrawal of the connector 10 from the printed circuit board 12, both frictionally by engagement of the compliant first pin contact portions with the sidewalls of the apertures and mechanically by expansion of the compliant second pin contact portions to lock the connector to the board. Greater retention of the connector to the printed circuit board is thus achieved without using solder or separate retention structure. In accordance with a further important aspect of the invention, the grounding pin contacts 25 are formed on a pair of grounding pin contact members 24 which are formed separate from the outer shell 21 of the connector 10, and are attached to the outer shell after the grounding pin contacts have been fully formed and shaped thereon. The grounding pin contact members are each stamped and formed from a flat sheet to provide a relatively thin and flat stamping 24a as illustrated in FIG. 5.- Stamping 24a is formed of a copper-iron alloy or another electrically conductive material having spring-like properties suitable for forming the compliant portions 43 on the grounding pin contacts 25. Stamping 24a is cut and shaped, and the compliant portions on the grounding pin contacts formed thereon using conventional stamping and forming equipment as is well known to those skilled in the art. As shown in FIG. 5, stamping 24a comprises a relatively thin and flat, elongated strip of plate 70 having a plurality of integral grounding pin contacts 25 extending from one edge thereof. A pair of elongated slots 71 is formed in the plate 70 as shown. Slots 71 are sized and positioned to receive elongated ribs 73 formed on the. outer surface of outer shell 21 as shown in FIG.l. Slots 71 and ribs 73 function as alignment means to automatically position the grounding pin contact members on the outer shell. After the stampings 24a have been formed, they are curved for mounting to the outer shell 21, and are attached to the outer shell by fitting the ribs along the slots 71. After the grounding pin contact members 24 are mounted to the outer shell, a crimp ring 26 is positioned around the members and crimped to secure the members to the outer shell. Two grounding pin contact members 24 are provided, each having two grounding pin contacts thereon and each extending around approximately one-half the circumference of the outer shell 21. If desired, a single grounding pin contact member completely surrounding the outer shell can be provided. By providing the grounding pin contacts on one or more separate members which are secured to the outer shell of the connector, rather than formed integral with the outer shell as in known connectors, several advantages are achieved. Shearing of the grounding pin contacts to provide the compliant portions thereon can be accomplished more easily with less complex conventional equipment when the pin contacts extend from a flat stamping 24a rather than a curved cylindrical shell. The stamping 24a is thin and increases the size of the connector 10 only a small amount, thereby achieving a connector 10 that covers a relatively small space on the board 12. Furthermore, the stamping can be made of a suitable, flexible, conductive metal such as copper-iron alloy; and the shell can be made of less expensive zinc. Zinc has relatively poor spring properties and is not suitable for the formation of the compliant portions on the pin contacts; and if the pin contacts are formed integral with the outer shell, it is necessary to form the entire outer shell of the more expensive copper-iron alloy to achieve the necessary compliant properties. It should also be noted that the plane of thickness of each of the grounding pin contact members 24 has an upper edge 76 surrounding the connector body 20. Edge 76 conveniently functions as a bearing surface engagable by a suitable tool to push the plurality of pin contacts 25 and 28 into and through the apertures 32 and 35. Alternatively, flange 21a may be engaged by a suitable tool entering the shell 21 to push the pin contacts 25,28. The ribs 73,73 provide bearing surfaces against corresponding edges 71a,71a of the plane of thickness of each of the corresponding members 24,24 to effect insertion of the pin contacts 25,28 and to resist separation of the members 24,24 from the shell. The plane of thickness of each corresponding stamping 24a extends along the longitudinal axis of each corresponding contact 25,25 and along the common direction of insertion of the contacts 25,25,28, and resists buckling of the stamping 24a during insertion of the contacts 25,25,28 or when the stamping 24a resists separation from the shell 21, for example, during coupling or uncoupling of the connectors 10 and 14. It should be understood that the invention could take other forms. For example, although pin contacts 25 comprise grounding pin contacts for grounding the outer braided conductor of a coaxial cable, the invention can be incorporated into signal-carrying and power-carrying pin contacts as well. Because the invention can take other forms, it should be recognized that the invention should be limited only insofar as is required by the scope of the following claims.

Claims: CLAIMS : 1. In an electrical connector 10 for mounting on a printed circuit board 12 and for connection to conductive coatings of the printed circuit board 12 in apertures 32,32,32,32 extending through the printed circuit board 12, the connector 10 comprising, a conductive shell 21 and conductive electrical contacts 25,25,25,25 integral with a conductive corresponding strip 70,70 and projecting from an edge of the corresponding strip 70,70 parallel to a thickness of the corresponding strip 70,70 for insertion into corresponding apertures 32,32,32,32, characterized in that; the electrical contacts 25,25,25,25 extend from an edge of the corresponding strip 70,70 and extend perpendicular to a length of the corresponding strip 70,70, the length of the corresponding strip 70,70 is transverse to the axis of the shell 21, a conductive ring 26 overlaps the length of the corresponding strip 70,70, and the length of the corresponding strip 70,70 is overlapped by and between the shell 21 and the ring 26. 2. In an electrical connector 10 as recited in claim 1, further characterized in that; the corresponding strip 70,70 and the contacts 25,25,25,25 are fabricated from a material with spring properties, and the shell 21 is fabricated from a material with spring properties lesser than that of the corresponding strip 70,70. 3. In an electrical connector as recited in claim 2, a rib 73,73 projecting from the shell 21 and a slot 71,71 in the corresponding strip 70,70 for locked engagement with the rib 73,73, and the rib 73,73 overlaps the thickness of the corresponding strip 70,70 and provides a bearing surface against the thickness of the corresponding strip 70,70. 4. In an electrical connector 10 as recited in claim 1, 2, or 3; -li¬ the external surface of the shell 21 is concentrically encircled by the corresponding strip 70,70 and by the ring 26. 5. In an electrical connector 10 as recited in claim 1, 2, 3, or 4; each said electrical contact 25,25,25,25 having a free end and a portion of its length divided by a shear into a pair of separate contact portions 43,43 elongated lengthwise of said contact 25,25,25,25 and having separate tip ends 45,45 at the free end, and each said contact portion 43,43 being bowed in a direction transverse to a corresponding other of said contact portion 43,43. 6. In an electrical connector 10 as recited in claim 1, 2, 3, 4, or 5; an edge of the corresponding strip 70,70 extends lengthwise of the corresponding strip 70,70 along the thickness of the strip 70,70, and extends transverse to the lengths of the electrical contacts 25,25,25,25, and provides a tool bearing surface projecting outwardly from the shell 21.

Inventors: CAPP RANDOLPH ERIC, JOHNESCU DOUG MICHAEL, LAUDIG RONALD CLAIR, MICHAEL GEORGE WILSON III, PEARL CHARLES DANFORD, CAPP, RANDOLPH, ERIC, JOHNESCU, DOUG, MICHAEL, LAUDIG, RONALD, CLAIR, MICHAEL, GEORGE, WILSON, III, PEARL, CHARLES, DANFORD
Applicants: AMP INC, AMP INCORPORATED
Application year: 1987
Main classification: H01R9
IPC codes: H01R12, H01R13, H01R24