EP0251556A2

EP0251556A2 - Dual slot electrical contact

Info

Publication number: EP0251556A2
Application number: EP87305329A
Authority: EP
Inventors: Wilbur Arthur Hamsher, Jr; William Brian Long; William Charles Arbogast, Jr.; John Raymond Shuey
Original assignee: AMP Inc
Current assignee: TE Connectivity Corp
Priority date: 1986-07-03
Filing date: 1987-06-16
Publication date: 1988-01-07
Also published as: JP2782437B2; EP0251556A3; JPS6417381A

Abstract

A contact terminal (16,50,80,100) has a termination section (26,60,82,104) including a spaced pair of axially extending slots (42A,42B; 68A,68B; 90A,90B; 110,110) within each of which a respective one of a pair of conductor wires (24A,24B; 72A,72B; 114,114) is held In interference fit for weld termination (74A,118) such as by laser welding. The terminal (16,50,80,100) is stamped from a metal blank and its termination section is preferably formed by forming a raised central portion (56,84,112) therein of a height about equal to a wire diameter with a planar top surface (87) and with parallel vertical side surfaces defining the inner slot walls, and bending parallel vertical side walls (64A,64B; 8BA,88B; 108,108) upward from side portions of the termination section spaced from the side surfaces of the raised central portion (56,84,112) and defining the outer slot walls, where the slot width at least at one location is just less than the wire diameter. The raised central portion may be formed by striking an axially extending boss (84) upwardly in the center of the termination section (82), or by bending a rearwardly extending tab portion (56) back along the top of the termination section (60).

Description

This relates to the field of electrical connectors and more particularly to contact terminals for conductor termination.
Electrical contact terminals are known which are used to terminate a pair of conductors in a single slot by welding, particularly by laser welding. Such contact terminals are known from U.S. Patent No. 4,57₉,₄04 for use in a single-row electrical connector for terminating the pairs _'of ground conductors in tri-lead high speed signal transmission cables. A similar but double-row connector is known from European Patent Application Publication No. ₀211496. Such terminals require the pairs of ground conductors to be brought together side-by-side near the top of the slot and in interference fit therein for termination remote from the respective signal conductors of the cables. The signal conductors are separately but similarly terminated to respective signal terminals insulated from the ground terminals by the dielectric carrier to which the terminals are secured, and the entire conductor-terminated subassembly is then overmolded forming the connector. Contact sections of the terminals are disposed at the forward end of the connector, ready for electrical engagement with corresponding terminal means of a mating electrical connection means.
When the side-by-side conductors are laser welded, the area of the weld joint, of course, is wider than if a single conductor were being welded in a correspondingly narrower slot. In both cases, the weld joint must join to the side walls of the slot whose top surfaces are preferably approximately coplanar with the top portions of the conductor or conductors for optimizing the laser weld termination. However, a typical conductor diameter is about 0.010 inches and the corresponding weld joint for the side-by-side conductors is about 0.040 to 0.045 inches in diameter. A smaller weld joint for only one such conductor requires less energy of the laser beam during welding, and a lower energy level incurs less risk of damaging the very small conductor wire.
From U.S. Patent No. 4,602,831 (for a single-row connector) and No. 4,655,515 (for a double-row connector), it is known to place individual signal terminals along one side of a dielectric contact carrier, and a single ground plane on the other side of the carrier. In Patent No. ₄,₆02,831, all ground conductors of the single row of _tri-lead cables (or a tri-lead flat cable) are terminated to the ground plane, singly in respective single width slots by welding such as laser welding. In Patent No. 4,655,515, each' row of cables (or each flat cable) has a contact carrier associated with it having signal terminals on one side and a single ground plane on the other, with each slot of the ground plane receiving a pair of side-by-side ground conductors therein for laser weld termination. Either ground plane is formed by first stamping the plurality of slots in a metal blank near one side edge of the blank, then folding over a portion of the blank along that side edge so that the slots now extend out to the newly formed edge to receive the conductor or pair of conductors. But with either ground plane, all grounds of a row of cables (or of the flat cable) are terminated only on the same side of the carrier, and each row of cables or flat cable requires its own contact carrier. Thus, either type of ground plane delimits or complicates the programmability of a double-row connector, and cannot be used in the double-row connector of aforementioned European No. 0211496.
It is desirable to provide a connector for tri-lead cable for high integrity high speed signal transmission using individual ground contact terminals which each receive two small diameter ground conductors in individual slots for separate spaced weld termination without substantially distorting the conductors.
It is also desirable to provide a contact for two conductor wires which includes a separate slot for each conductor, each for receiving a respective one of the conductors for individual weld termination, to eliminate both the necessity for gathering the two conductors to a side-by-side arrangement to be disposed along a single slot, and the necessity for carefully wiping the pair of wires together when being force-fit into a single slot in a manner whereby the conductors are held in a true side-by-side arrangement after being wiped into the slot.
It is further desirable to provide separate slots in a single contact for respective ones of a pair of conductors to reduce the necessary width of the weld joint when the welding is laser welding, to provide an assured laser weld joint without damaging the conductor wire.
According to the present invention, a stamped and formed contact terminal with a contact section proximate one end thereof, has .a spaced pair of parallel slots extending inwardly from the other end thereof to receive respective conductors thereinto to be held in interference fit therein for weld termination such as by laser welding. Each slot has at least at one axial location therealong a width slightly less than the diameter of the conductor and holds its conductor so that the top-most portion of its conductor is approximately coplanar with the top of at least one side of the slot.
According to one embodiment, the dual slot terminal of the present invention is made by stamping a terminal blank including a contact section and a tab portion extending rearwardly from a termination section, joined thereto by a narrower neck-portion and having a precisely selected width. Side portions of the termination section are bent upward forming low height vertical side walls, and the tab portion is bent backward at the neck portion to be disposed between the side walls and along the termination section, spaced from the side walls to define a pair of slots of precise width. The top of the bent-over tab portion is preferably coplanar with the top surfaces of the side walls, and edges along the slots are preferably swaged.
According to another embodiment, the dual slot terminal of the present invention is made by stamping a terminal blank including a contact section and a termination section rearwardly therefrom. A central boss is stamped upwardly from said termination section having a precisely selected width and precise parallel vertical side surfaces. In one embodiment, side portions of the termination section are bent'upwardly forming parallel low height vertical side walls spaced from the side surfaces of the central boss a selected distance to define a pair of slots of precise width. The top surface of the central boss is preferably coplanar with the top surface portions of the conductor wires disposed along the slots, and edges of at least the side walls along the slots are preferably swaged. In another embodiment, rounded bosses extend inwardly from high side walls to secure the conductors in the slots below the rounded bosses, with the top surface portions of the conductor wires coplanar with the top of the central boss.
It is an objective of the present invention to provide a terminal to terminate separately two small diameter conductors at one terminal location within a multiterminal connector, such as the pair of ground conductors of a tri-lead cable, which terminal can be located on either side of a contact carrier independently of locations of other signal and ground terminal means.
It is another objective of the present invention to provide a terminal to simplify the wire handling procedure prior to weld termination and it is still a further objective to enable assured laser weld termination of ground conductors.
It is yet another objective of the present invention to provide a dual slot terminal and a method for making such a terminal with slots of precisely controlled width for holding respective conductors in interference fit therein for laser weld termination.

Figure 1 is a double-row connector for signal transmission cable in which the present invention may be used;
Figure 2 is an exploded view of a terminal assembly usable with the electrical connector of Figure 1, using a dual slot terminal of the present invention;
'Figure 3 is an enlarged view of the embodiment of the dual slot terminal of Figure 2;
Figure 4 is a second embodiment of the invention;
Figures 5A to 5C illustrate the forming of the termination section of the dual slot terminal of Figure ₄;
Figures 6A and 6B illustrate the placement of conductors in the slots of the terminal of Figure 4 and weld termination of one of them;
Figure 7 is a cross-sectional view taken along lines 7-7 of Figure 5B and showing the laser weld termination joint of one of the conductors;
Figure 8 is a third embodiment of the present invention;
Figures 9A and 9B are perspective views of Figure 8;
Figures 10A and 10B illustrate another embodiment of the present invention; and
Figure 11 illustrates yet another embodiment of the present invention.

In Figure 1 is shown an electrical connector such as that of European Publication No. 0211496. Connector 20₀ comprises a terminal assembly 202 having a plurality of terminals disposed in passageways 204 extending rearwardly from the mating face 206 of the connector. Rearward sections of the terminals (not shown) extend along a contact-carrying portion 208 of the terminal assembly and are terminated to conductors of cables 210. A dielectric covering 212 is overmolded over the terminal assembly sealing the terminations and extending along cables 210, securing the cables to the connector to form a cable harness 214 and provide nondistorting strain relief. Also seen is a transverse bar 216 spaced rearwardly from covering 212 and joined to it by axial webs 218, bar 216 also being molded over the cables integrally with covering 212 and providing secondary nondistorting strain relief for the cables and also spacing and supporting them.
.Figure 2 shows a terminal assembly 10 usable in such a connector, which assembly comprises a premolded forward housing member 12, signal terminals 14 and ground terminals 16. Signal conductors 18 of cables 20 are stripped to be terminated to termination sections 22 of signal terminals 14, and pairs of ground conductors 24A,24B of cables 20 are stripped to be terminated to termination sections 26 of ground terminals 16. Contact sections 28 of ground terminals 16 are identical to contact sections 30 of signal terminals 14 and will be disposed along and secured within passageways 32 of housing 12 which extend from housing mating face 34 to contact-carrying portion 36. Termination sections 22,26 of signal and ground terminals 14,16 extend along contact-carrying portion 36, preferably in shallow recesses 38 thereof. Terminal assembly 10 is assembled by securing contact sections 28,30 of terminals 14,16 within passageways 32 of housing 12, then terminating conductors 18,24A,24B to appropriate ones of terminals 14,16, and thereafter molding a dielectric covering over the contact-carrying portion, the terminals and stripped conductors, and along end lengths of the cables. During overmolding, rear ends of passageways 32 are closed off by core pins in the mold which also hold terminals 14,16 firmly against the respective top or bottom surface of contact-carrying portion 36 of housing 1₂.
Each signal terminal 14 preferably includes a single conductor-receiving slot 40 which is of a width just less than the diameter of a corresponding signal conductor 18. Signal conductor 18 is then wiped carefully along and into slot 40 by appropriate apparatus such as that disclosed in U.S. Patent No. 4,649,636. Signal conductor 18 will be held by interference fit within slot 40 until being welded therein such as preferably by laser welding.
Each ground terminal 16, best seen in Figure 3, includes a spaced pair of parallel conductor- receiving slots 42A,42B extending forwardly from a rearward end 44 of terminal 16. Within each slot 42A,42B will be wiped a respective ground conductor 24A,24B as with signal conductor 18 in slot 40 of signal terminal 14 above. Best seen in Figures 6A, 6B and 7, slots 42A,42B are slightly less wide than the diameter of respective ground conductors 24A,24B, to hold them in interference fit therein until being welded therein such as preferably by laser welding. Slots 42A,42B preferably have lead- ins 46A,46B respectively to assist in receiving a respective conductor being wiped thereinto and minimize possible damage to the conductor wire which may typically have a diameter of about 0.010 inches.
The dual slot terminal 50 of Figure 4 has a termination section shown being formed in Figures 5A and 5B. Terminal 50 is stamped from a sheet of metal such as phosphor-bronze alloy, Copper Alloy 511 having a thickness of, for example, 0.007 inches. Forward contact section 52 may be of the receptacle type shown in Figure 4. Prior to forming, it is preferred to swage top side edges 58A,58B of termination section 60 and.bottom side edges 62A,62B of tab portion 56. In Figure 5B, side portions of termination section 60 are bent upward to form side walls 64A,64B, and in Figure 5C tab portion 56 is bent up and then back along surface ₆₆ of termination section ,60, forming two slots 68A,68B in termination section 60. It may be advantageous to reduce the thickness of the metal blank at neck portion 54 to facilitate bending. Swaged edges 58A,58B and 62A,62B are disposed along tops of slots 68A,68B and will cooperate to form axially extending lead-ins to receive respective conductors being wiped thereinto, while neck portion 5₄ being narrower than tab portion 56 and also tapered now defines initial lead-ins 70 at the cable-proximate end of termination section 60.
In Figures 6A and 6B, stripped conductors 72A,72B are shown first partially wiped into interference fit within respective slots 68A,68B, and then fully wiped thereinto. Conductor 72A is terminated by weld joint 74A which is preferably a laser weld joint. Figure 7 illustrates conductors 72A,72B in interference fit between sides of tab portion 56 and respective opposing side walls 64A,64B and showing weld joint 74A of conductor 72A to terminal 50.
The dual slot terminal 80 of Figure 8 has a termination section 82 shown being formed in Figures 9A and 9B. Termination section 82 has a central boss 84 stamped upwardly therefrom which extends axially and has precise vertical side surfaces 86A,86B and a substantially planar top surface 87. Side walls 88A,88B may be higher than the top surface of central boss 84 and may have rounded bosses extending inwardly towards central boss 84 centered slightly above its top surface to provide the necessary narrow slot width at one axial location to hold conductor wires in interference fit in slots 90A,90B. Edges 52A,52B may be deburred; and swaging of edges 94A,94B as in terminal 50 of Figure 6C, and either swaging or bending, or both, of corners 96A,96B is preferred to form axially extending lead-ins and initial lead-ins respectively to assist wiping of respective conductor wires into slots 9A,90B. Terminal ₈0 of Figure 9B is believed to be easier to manufacture, with good control of slot width.
In Figures 10A and 10B, another embodiment of the present invention is shown. Similarly to terminal 80 of Figure 8, dual slot terminal 100 has a central boss 102 struck up from termination section 104. Rounded bosses 106 are struck upward from side portions of termination section 104. Side walls 108 are then bent vertically upwardly from the side portions forming slots 110 such that rounded bosses 106 extend inwardly centered slightly above the plane of top surface 112 of central boss 102. When conductor wires 114 are wiped along and into slots 110, each wire 114 is forced downward between a rounded boss 106 and side surface 116 of central boss 102 and is held in slot 110 by rounded boss 106. Figure 10B also shows a laser weld joint 118 of one of the conductor wires 114 to terminal 100.
Figure 11 illustrates still another embodiment of a dual slot terminal of the present invention, terminal 120.
The dual slot terminal of the present invention can be made in several specific ways with minor variations in the ultimate structure, without depart:ing from the spirit of the invention and the scope of the claims. Such a terminal would most commonly be used as a ground terminal for a tri-lead cable to receive a pair of ground wires associated with the same signal conductor. But the terminal can be used to receive ground conductors from two cables, or even signal conductors from two different cables were it desired for the terminal to conduct an electrical signal from either one of a pair of cables.

Claims

1. A contact terminal (16,50,80,100,120) for use in a connector (2₀₀) for transmitting electrical signals with high reliability and uniformity having a forvard contact section (28) for mating with a corresponding contact and a rearward termination section (26,60,82,104) for wire conductor termination, characterized in that the rearward termination section includes a spaced pair of conductor-receiving slots (42A,42B; 68A,68B; 90A,90B; 110,110) extending forwardly from a rearward end thereof to terminate a pair of conductor wires (24A,24B: 72A,72B; 114,114) each said slot having a width at least at one axial location selected to be just less than a respective said conductor wire and defined by inside surface portions of opposing side wall means to hold a said conductor wire in interference fit therein at said at least one axial location without substantially distorting the wire, to be terminated by welding.

2. A contact terminal as set forth in claim 1 further characterized in that each said slot '(42A,42B; 68A,68B; 90A,90B; 110,110) has a depth approximately equal to the diameter of a said conductor wire (24A,24B; 72A,72B), so that top portions of said conductor wire held therein are approximately coplanar with top surface means of adjacent portions of said termination section (26,60,82,104) on at least one side of said slot, for laser weld termination.

3. A contact terminal as set forth in claim 1 further characterized in that the edges at the tops of said slots are swaged (58A,58B,62A,62B) to define lead-ins for wiping thereinto respective said conductor wires.

4. A contact terminal (50,80,100) as set forth in claim 1 further c:haracterized in that said termination section (60,82,104) includes a raised central portion (56,84,112) having parallel vertical side walls facing outwardly, each to define an inside side wall of a respective one of said pair of slots (68A,68B; 90A,90B; 110,110), and further includes upstanding walls (64A,64B; ₈8A,88B: 108,108) parallel to said raised central portion (56,84,112) and spaced laterally from said vertical side walls thereof, each to define an outside side wall of a respective one of said pair of slots (68A,68B; 90A,90B; 110,110).

5. A contact terminal (100) as set forth in claim 4 further characterized in that each said upstanding wall (₁₀₈) extends higher than said raised central portion (₁12) and has at least one inwardly directed rounded boss (₁06) centered just above adjacent top surface portions of said raised central portion (112) and spaced from the corresponding said vertical side wall (116) thereof a distance selected to be just less than the diameter of said conductor wire (114) and also spaced above the bottom of said slot a height selected so that when said conductor wire (114) is wiped into said slot (110) and held by and below said rounded boss (106), top portions of said conductor wire (114) disposed therein are approximately coplanar with said adjacent top surface portions of said raised central portion (112) .

6. A ground connection of terminal means and a pair of ground wires of a tri-lead electrical cable (20), characterized in that said terminal means is a discrete contact terminal (16,50,80,100,120) having a forward contact section (28) for mating with a corresponding contact terminal and further having a rearward termination section (26,60,82,104) including a pair of conductor-receiving slots (42A,42B; 68A,68B; 90A,90B; 110,110) extending forwardly from a rearward end thereof and spaced apart a distance about equal to the distance between said pair of ground wires (24A,24B; 72A,72B; 114,114) of said cable (20), each said slot has a width at least at one axial location selected to be just less than a respective said ground wire and defined by inside surface portions of opposing side wall means, and each said ground wire (24A,24B,72A,72B,114) is disposed in a respective said slot (4_2A,42B,68A,68B,90A,90B,110) and held in interference fit therein at said at least one axial location and terminated thereto by a weld joint (74A,118).

₇. A method of making an electrical contact terminal (50,80,100), comprising the steps of:

stamping a terminal blank from sheet metal having a contact section at a forward end thereof and a termination section (60,82,104) at a rearward end thereof, said termination section having a central portion and side portions therealong;

forming said contact section;

forming a raised central portion (56,84,112) in said central termination section portion such that said raised central portion has a substantially planar top surface (87) a height above the surface of said central termination section portion therearound, and further has precise vertical side surfaces; and

bending said side portions to be vertically upstanding side walls (64A,64B; 88A,88B: 108,108), each a selected distance from a respective said side surface of said raised central portion (56,84,112), said selected distance being selected so that each slot (68A,68B; 90A,90B; 110,110) formed between an inwardly facing surface of a said upstanding side wall (64A,64B,88A,88B,108) and a said side surface of said raised central portion (56,84,112) has a width at least at one axial location just less than the diameter of a conductor wire (72A,72B,114) to be terminated to said contact terminal (50,80,100), whereby a pair of said wires are holdable in interference fit in respective said slots to be thereafter terminated thereto by welding.

8. A method as set forth in claim 7 wherein said step of forming a raised central portion comprises striking a central boss (84) upwardly from said central portion of said termination section (82).

₉. A method as set forth in claim 7 wherein said step of stamping includes stamping a tab portion (56) extending rearwardly from said central portion of said termination section (60), and said step of forming said raised central portion comprises bending said tab portion (56) back along said termination section (60) and thereabove.

₁₀. A method as set forth in claim 7 further including the step, prior to said bending step, of striking rounded bosses (106) upwardly along said side portions at selected locations such that after said bending of said side portions, said rounded bosses (106) extend inwardly centered above the plane of said top surface of said raised central portion (112).