Female electrical contact

Abstract: A female electrical contact (10) is disclosed to include an elongate body (12) having a terminal portion (14) at one end and a receptacle portion (16) at the other end for receiving a complementary male pin (30). A pair of cantilevered arms (20a, 20b) are provided of substantially equal length and in opposed relationship to each other with contact portions (22) at their distal ends. The cantilevered arms are axially offset from each other in the longitudinal direction (B) of insertion of the complementary male pin, whereby the male pin engages the contact portions sequentially. The cantilevered arms are bowed inwardly so that the contacted portion of one of the arms engages the other arm under a preload.

Description: Field of the Invention This invention generally relates to the art of electrical connectors and, particularly, to a female electrical contact for receiving a complementary male terminal in an electrical connector system. Background of the Invention In the ever increasing miniaturization of electronic circuitry , it has become increasingly difficult to fabricate separable electrical contacts that are as reliable and as durable as the larger components which they replace. In high density or miniaturized systems, as many as 96 pairs of contacts may be disposed in less than 3,2 mm 2 (0.5 inch square) of area. Yet, the electrical contacts must have sufficient contact force to ensure reliable electrical connections with the complimentary male terminals. In turn, the terminals themselves are very small and, consequently, the electrical contacts must allow easy insertion and withdrawal of the terminals. A common type of female or receptacle electrical contact for connecting to the terminals of electrical connectors in such environments as described above, includes at least a pair of contact blades or spring arms extending in cantilevered fashion longitudinally within the contact. The cantilevered spring arms have distal ends providing contact portions for engagement by the terminals of the electrical connectors, with the proximal ends of the cantilevered arms being rigid with a body portion of the contacts. US document 3,955,869, on which the preamble of claim 1 is based, relates to an electrical socket and to a socket contact, wherein the contact includes two pairs of arms at which each of the arms is bent transverse to a base. One portion of each of the arms is attached to the base and the other portion of each of the arms is a longitudinally extending free candilever portion which is bent first toward the center of the base and at a defined point the free end of each of the arms is bent back. Also patent EP-A-0 191 539 discloses an electrical connecting terminal with a female contact portion which has a pair of opposing support segments extending from two side edges in the lateral direction. Further segments extends slightly inward from the corresponding side edges of the support segments. At a defined point, the segments are bent slightly outward at the central portion, so that their free distal ends are substantially parallel to each other. Further examples of such cantilevered arm contacts are shown in U.S. Patents Nos. 4,076,369 to Ostapovitch, dated February 28, 1978; 4,607,907 to Bogursky, dated August 26, 1986; and 4,784,622 to Senor, dated November 15, 1988. This invention is directed to improvements in cantilevered arm type female contacts of the character described above. Summary of the Invention An object, therefore, of the invention is to provide a new and improved female electrical contact for receiving a complementary male pin. In the exemplary embodiment of the invention which is disclosed in claim 1, generally, the female contact or receptacle includes an elongate body having a terminal portion at one end and a receptacle portion at the other end. The receptacle portion provides means for receiving a complementary male pin and includes a pair of cantilevered arms. The arms are of substantially equal length and in opposed relationship to each other with contact portions at their distal ends. The cantilevered arms are axially offset from each other in the longitudinal direction of insertion of the complementary male pin whereby the male pin engages the contact portions sequentially. The female contact is fabricated as a unitary stamped and formed metal component. The cantilevered arms project at their proximal ends from base portions rigid with the elongated body, the base portions being spaced transversely of the body wider than the contact portions. The cantilevered arms are uniformly bowed, with the contact portion of the arms preloaded against each other so that they contact each other. Other features of this invention are set forth with particularity in the appended claims 2-4. Brief Description of the Drawings The invention, together with its objects and the advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the figures and in which: FIGURE 1 is a perspective view of a female electrical contact embodying the concepts of the invention; FIGURE 2 is a plan view of a blank from which the terminal is fabricated; FIGURE 3 is an edge elevational view illustrating how the cantilevered arms are formed from the blank in a bowed configuration prior to forming the terminal as shown in Figure 1; and FIGURE 4 is a perspective view of a plurality of the terminals mounted in a representative connector 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 female electrical contact or receptacle, generally designated 10, which includes an elongate body 12 having a terminal portion or solder pin 14 at one end and a female or receptacle portion, generally designated 16, at the other end. The terminal is unitarily fabricated of extremely thin stamped and formed metal material, such as from 0,102 mm (0.004 inch) metal stock. Solder tail 14 has a generally U-shaped cross-section for rigidifying purposes. Body 12, itself, is provided with supporting walls 18 intermediate its ends to form a larger U-shaped cross-section. Although the exemplary embodiment shows terminal portion 14 as a solder tail for insertion through a hole in a printed circuit board, it should be understood that the terminal portion of female electrical contact 10 can be of a variety of configurations, including terminal means for surface mounting or interconnection to other electrical circuit means. Receptacle portion 16, generally, provides means for receiving a complementary male pin, as described in greater detail hereinafter, which would comprise the lead of an appropriate mating electrical component. Specifically, receptacle portion 16 includes a pair of cantilevered arms 20a and 20b of substantially equal length and in opposed relationship to each other, as shown. Each cantilevered arm has a contact portion 22 at its distal end, with the proximal ends of the arms king integral with base portions 24 formed integral with body 12 to be rigid therewith. With cantilevered arms 20a and 20b being of substantially equal length, the invention contemplates that the arms are axially offset from each other in the longitudinal direction of insertion of the complementary male pin, as indicated by arrow "B", whereby the male pin engages the contact portions 22 sequentially. To this end, it can be seen that base portion 24a of cantilevered arm 20a is shorter, in the longitudinal direction of the terminal, than base portion 24b of cantilevered arm 20b. Therefore, as the complementary male pin is inserted between base portions 24a and 24b into receptacle portion 16, the male pin will engage contact portion 22 of cantilevered arm 20a before the male pin engages contact portion 22 of cantilevered arm 20b. Base portions 24a and 24b are spaced transversely of the terminal substantially the same as the spacing of supporting walls 18, although such an alignment is not required, with cantilevered arms 20a and 20b being bent inwardly. The cantilevered arms are bent in a uniform bow, as shown, with generally equal radii. It can be seen in Figure 1 that contact portion 22 of cantilevered arm 20a engages the inside of cantilevered arm 20b, at a point 26, spaced from contact portion 22 of cantilevered arm 20b in the direction of the insertion end of the terminal. The invention contemplates that this engagement be under a preload. To that end, Figure 2 shows a blank from which female electrical contact 10 is formed. As stated above, the blank would be formed from thin metal stock, such as of 0,102 mm (0.004 inch) thickness. Before the terminal is formed into the ultimate shape shown in Figure 1, cantilevered arms 20a and 20b are formed into their bow as shown in Figure 3. Then, when the cantilevered arms and base portions 24 are formed at generally right-angles to body portion 12, as at fold lines 28 (Fig. 2), contact portion 22 of cantilevered arm 20a will engage cantilevered arm 20b, at point 26, under a preload which is determined by the amount of bow formed into the arms as indicated in Figure 3. Such preload improves manufacturability and ensures adequate contact between both arms 20a and 20b and a male pin inserted therein even if the pin is off-center. Figure 4 simply shows a plurality of female electrical contacts 10 disposed in insulators 30 which, in turn, are mounted in bores 32, of a connector housing, generally designated 34. The housing is designed for mounting to a printed circuit board, with standoffs 36 spacing the housing from the printed circuit board. It can be seen that terminal portions or solder tails 14 of the terminals project beyond standoffs 36 for insertion into holes in an appropriate printed circuit board for connection to appropriate circuit traces around or within the holes in the board. The tail portions could, however, alternatively be surface mounted to the circuit board. Figure 4 also shows a complementary male pin 38 having a diameter of approximately 0,25 mm (.01 inches) inserted into the top female terminal 10, spreading cantilevered arms 20a and 20b, with the contact portions 22 of the arms engaging the complementary male pin. As stated above, during insertion, the male pin first will engage contact portion 22 at the distal end of cantilevered arm 20a and then, sequentially, engage contact portion 22 at the distal end of cantilevered arm 20b. The arms are under a predetermined preload, as described above, and, with the cantilevered arms being of substantially equal length, equal engagement pressure will be applied by the arms in opposing directions on opposite sides of the complementary male pin. It will be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.

Claims: A female electrical contact (10) for mating with a complementary male pin (38) from only one direction (B), said contact comprising a generally planar elongate body (12) having a terminal portion (14) at one end for electrical and mechanical termination to a circuit board and a receptacle portion (16) adjacent the other end; the receptacle portion (16) providing means for receiving said complementary male pin (38) and including a pair of cantilevered arms (20a, 20b) of substantially equal length and in opposed relationship to each other with contact portions (22) at their distal ends and each extending from one of a pair of base portions (24) towards said terminal portion (14), said cantilevered arms (20a, 20b) being bowed with their distal ends disposed inwardly of their proximal ends, the receptacle portion (16) further includes said pair of base portions (24) rigid with and spaced transversely of the body (12), said base portions (24) extending generally perpendicularly from said body (12) at an end of said body opposite said terminal portion (14) and including generally abrupt end surfaces at the top thereof and a second pair of upstanding walls (18) rigid with and spaced transversely of the body (12), said second pair of walls (18) extending generally perpendicular from said body (12) and including generally abrupt end surfaces at the top thereof, said second pair of walls (18) being positioned between said receptacle (16) and said terminal portion (14), such that said cantilevered arms (20a, 20b) are longitudinally positioned between a pair of generally U-shaped portions (12, 18; 12, 24) formed by said pair of base portions (24) and said body (12) on the one hand and said pair of second walls (18) and said body (12) on the other hand in order to rigidify said contact (10) within an insulator (30), characterized in that said cantilevered arms (20a, 20b) are axially offset from each other in the longitudinal direction (B) of insertion of the complementary male pin (38) whereby the male pin engages the contact portions sequentially and the end of one arm being preloaded against the other arm, each said cantilevered arms (20a, 20b) having a generally uniform bow between its base portion (24) and its contact portion (22). The female electrical contact (10) of claim 1 wherein one of said U-shaped portions includes said base portions (24) and the other of said U-shaped portions includes said upstanding walls (18). The female electrical contact (10) of claim 2 wherein said contact is stamped and formed from sheet metal material approximately 0,102 mm (0,004 inches) thick. The female electrical contact (10) of claim 2 wherein said terminal portion (14) is an elongated solder tail having a generally U-shaped cross-section.

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