US 3317888 A
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Description (OCR text may contain errors)
May 2, 1967 L. MANCINI BI-METAL CIRCUIT BOARD CONNECTOR Filed Dec. 31, 1964 E R y m. Z M 2 Z M i d @w [B 45 United States Patent 3,317,888 BI-METAL CIRCUIT BOARD CONNECTOR Lloyd Mancini, Hershey, Pa., assignor to Berg Electronics, Inc., New Cumberland, Pa., a corporation of Pennsylvania Filed Dec. 31, 1964, Ser. No. 422,782 Claims. (Cl. 339-258) This invention relates to a bi-metal electrical connector used to make a positive electrical contact With a circuit board. The contact represents an improvement over conventional circuit board contacts in that it utilizes a gold-plated spring metal contact leaf carried by a malleable metal base. The leaf'is deformed by the circuit board when the circuit board is placed in contact with the connector so that a large contact area is provided between the circuit board and the connector. This area insures a positive electrical contact therebetween. The end of the base removed from the leaf contact forms a wire-wrap tail for making contact with an electrical conductor.
My construction not only assures an improved contact between the connector and the circuit board, but also is more cheaply produced than conventional circuit board connectors not utilizing bi-metal construction. Heretofore circuit board connectors have been made of one piece of spring metal. By reducing the amount of spring metal used in my connector to the contact portion thereof, I have reduced the cost of manufacture of the connector. Such reduction in cost is important since these connectors are manufactured at high volume where a small saving per connector represents an appreciable saving on a given quantity. A saving is also reflected due to the fact that in my connector only the spring blade need be gold plated, whereas in conventional spring metal circuit board connectors, it is usual to gold plate the entire connector.
Accordingly, a principal objective of my invention is to provide an improved bi-metal circuit board connector.
A further objective of the invention is to provide an improved circuit board connector having a deformable spring metal contact leaf and a base formed of cheaper, more readily malleable metal.
Another object is to provide a circuit board connector provided with a spring metal contact and a formable metal base, one end of which forms a wire wrap tail or terminal for a circuit wire.
Other and further objects of the invention will be apparent from the following description and claims and may be understood by reference to the accompanying drawing which, by way of illustration, shows a preferred embodiment of the invention and what I now consider to be the best mode of applying the principles thereof. Other embodiments of the invention may be used without departing from the scope of the present invention as set forth in the appended claims.
In the drawings:
FIGURE 1 is a side elevational view of my bi-metal connector;
FIGURE 2 is a front elevational view of my connector;
FIGURE 3 is a sectional view taken along section 3-3 of FIGURE 2 and showing the connection between the base and spring leaf;
FIGURE 4 is a sectional view taken through the wire wrap tail of the connector before the tail is coined;
FIGURE 5 is a sectional view taken through the coined wire wrap tail of the connector at section 55 of FIG- URE 2;
FIGURE 6 is a view of part of the mouth of an insulated circuit board connector assembly block carrying connectors according to my invention;
FIGURE 7 is a sectional view taken through the insulated block at section 77 of FIGURE 6; and
3,317,888 Patented May 2, 1967 FIGURE 8 is a section similar to that of FIGURE 7 except that a circuit board has been inserted into the mouth of the insulated :block so as to make contact with the connectors carried therein.
Referring to the drawings and particularly to FIG- URES l to 5, the connector 10 is provided with a base 12 and a spring metal contact leaf 14 secured thereto at the upper portion of the base 12. The base is normally formed from strip stock material, preferably being malleable or easily workable, such as brass, copper, Phosphor bronze, or other metal conventionally used in making electrical connectors. The leaf 14 is formed from resilient spring metal andis preferably provided with a gold plate coating to assure a positive electrical contact between the connector and the circuit board. As shown in FIGURE 1, the leaf 14 is bowed outwardly from the base 12. The lower portion 15 of the leaf 14 is secured to the base 12 by means of overlapping tabs 16 which are curled around the leaf so as to secure the leaf to the main portion of the base 12. As shown in FIGURE 3, the portion 15 of the leaf 14 preferably is also spot Welded to the base to assure a positive electrical contact therebetween. The upper portion 17 of the leaf 14 is secured between the body of the base 12 and the outer lip of a hook 20 which is punched out of the base 12. The spring leaf 14 is biased outwardly away from the base 12 so that the upper end 17 of the leaf is normally positioned against the lip of hook 20.
During the manufacture of the connector the lower portion 18 of the base 12 is bent over in -U-shaped fashion as shown in FIGURE 4. The outer curved surface of the bent-over portion of the base is then coined inwardly as shown at 22 of FIGURE 5 so that lower portion 18 of the connector forms a generally square wire wrap tail around which a wire 24 may be wrapped, as shown in FIGURES 5 and 7, so as to make an electrical contact therebetween. The upper portion of the base 12 is generally flat and is provided with a transverse bead 26 which projects outwardly therefrom.
As shown in FIGURES 6, 7 and 8, opposed pairs of my connectors are carried in an insulated connector base 28 so as to form an assembly into which a circuit board may be inserted so as to make contact with connectors 10. The insulated base 28 is provided with a circuit board groove 30 and a number of paired T-shaped slots 32 adjoining groove 30 into which my connectors 10 are inserted. When the connector 10 is inserted in slot 32, the wire wrap tail 18 of the connector projects through the square opening 38 in the bottom of insulated base 28. The fiat upper portion of the connector base 10 fits snugly within the slot 32 with the bead 26 acting as a spring to secure the connector within the slot. As shown in FIGURE 6, the spring leaves 14 of the individual connectors project into the circuit board groove 30 in the insulated base 28.
As the circuit board 34 is inserted into the circuit board groove 30, contact is made between the spring leaf 14 and the circuit board contact 36. Leaf 14 is then bent toward the base 12 until the upper portion 17 bottoms on the upper portion of the base 12 adjacent the book 20. With the continued insertion of the circuit board, the spring leaf 14 is forced against the base of hook 20 which serves as a stop and is deformed so as to provide a flat area of contact 40 between the circuit board contact 36 and the gold plated leaf 14. This area of contact is maintained until the circuit board is bottomed in groove 30. As the circuit board moves relative to the contact surface 40, the contact surface is wiped along the circuit board contact 36 so as to break up any oxides or contaminants on the contact 36 and the leaf 14, thereby assuring a minimum contact resistance between the connector and the circuit board.
While I have illustrated and described a prefrered embodiment of my invention, it is understood that this is capable of modification, and I therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes and alterations as fall within the purview of the following claims.
1. An electrical contact comprising an elongate base of malleable metal and a spring metal leaf contact, said base including an integral wire wrap tail portion formed at one end thereof for connection with an electrical conductor, a hook portion at the other end thereof extending away from said base and toward said one end thereof, said hook portion and base defining an opening facing said one end of said base, and a pair of tabs on said base adjacent said tail; said leaf contact lying along said base intermediate said tail and hook portions thereof and being uniformly bowed away from said base sufficiently to position the median portion thereof outwardly of said hook portion and expose the same for electrical contact to a circuit element, said tabs being folded over a flattened length of the end of said leaf contact adjacent said tail portion to hold said contact against said base and establish an electrical connection therewith, the other end of said leaf contact extending into said opening and being biased away from the base and against said hook portion.
2. An electrical contact as in claim 1 wherein the flattened length of said leaf contact from said tabs to said other end thereof is greater than the distance from said tabs to said hook portion whereby movement of said leaf contact toward said base extends such contact and 4 brings said other end thereof into abutment with said hook portion to form an essentially planar contact surface on said leaf contact.
3. An electrical contact as in claim 2 wherein said hook portion includes a leg extending away from said base and a lip at the outer end of said leg extending toward and being positioned closer to said one end of said base than said leg.
4. An electrical contact as in claim 2 wherein said base has a width greater than that of said leaf contact and wherein a transverse bead is formed in said base adjacent to and projecting toward said leaf contact, said bead extending laterally of said leaf contact to form a stop for securing said electrical contact relative to a carrier.
5. A connector according to claim 2 wherein said leaf contact is gold plated.
References Cited by the Examiner UNITED STATES PATENTS 1,531,816 3/1925 Russell.
1,965,270 7/1934 Werner 339--257 3,008,113 11/1961 Johnson 33917 3,040,291 6/ 1962 Schweitzer et al. 339-217 X 3,131,017 4/1964 Mittler 339259 3,142,891 8/1964 Travis.
3,172,718 3/1965 Lalon-de 339276 X EDWARD C. ALLEN, Primary Examiner.
P. TEITELBAUM, Assistant Examiner.