Anode and cathode lead wire assembly for solid electrolytic capacitors

#The present invention is directed to a lead wire assembly for solid electrolytic capacitors. More particularly, the present invention is directed to the attachment of cathode and anode lead wires to a solid electrolytic capacitor body.

#Solid electrolytic capacitors, as is well known in the art, commonly comprise a generally cylindrical capacitor body having an outer cathode layer surrounding an anode of film forming metal, e.g., tantalum.

#The anode is formed with an axially extending lead out rod or wire, to which an anode lead wire is subsequently attached, e.g., by welding, while a cathode lead wire is subsequently attached, e.g., by soldering, to the cathode layer.

#Other objects will be apparent from the following description and claims taken in conjunction with the drawings wherein

#FIG. 1 shows a sectional elevation view of a conventional solid electrolytic capacitor body

#FIG. 2 shows a lead wire assembly in accordance with the present invention

#With reference to the drawing FIG. 1 shows a cylindrical capacitor body 1 comprising a generally cylindrical sintered tantalum anode body 30 having an anode lead out rod 3 electrically connected thereto and extending in longitudinal axial alignment therewith. Anode body 30 is conventionally coated with a dielectric layer of tantalum pentoxide 32. A solid layer of manganese dioxide electrolyte 34 is provided over the dielectric layer 32 and cathode layer 36, e.g., a solderable film, e.g. silver, is provided over the electrolyte layer 34.

#With reference to FIG. 2, a lead wire assembly in accordance with the present invention is shown at 100 being formed of an integral resilient wire, e.g., made of solder coated nickel copperweld wire and the like, having a pair of wires 110 and 120 which extend substantially in the same direction and lie substantially in a common plane with anode lead out rod 3 of capacitor body 1. Wires 110 and 120 are shown substantially in a common plane with anode lead out rod 3 of capacitor body 1. Wires 110 and 120 are shown substantially parallel and wire 110 has a lateral portion 130 which extends transverse to anode lead out rod 3 of capacitor body 1 of the type shown in FIG. 1. Wire 120 has an arcuate portion 125 which is spaced from lateral portion 130 and lies in a plane transverse, i.e. at a 90.degree. angle, to the longitudinal axis of capacitor body 30 and to the common plane of wires 110, 120 and lead out rod 3.

#Capacitor body 30 nests centrally in the generally conforming arcuate member 125 as shown in FIGS. 2(b) through 2(e); FIG. 2(d) shows a form of arcuate member 125 which is not a true curve shape but which, as in the embodiments of FIGS. 2(b), 2(c) and 2(e) generally conforms to the shape of the capacitor body and partially surrounds the capacitor body, e.g. 1/8 to 1/2 the circumference, and is within the scope of the present invention. FIG. 2(c) shows a capacitor body 1' which is smaller than that of FIG. 2(b) and FIG. 2(e) shows a capacitor body 1" which is larger than that of FIG. 2(b). FIG. 2(b), where the capacitor body 1 closely conforms to the shape of arcuate member 125 is a preferred arrangement due to maximum contact, however, all of the arrangements of FIGS. 2(b) to 2(e) provide a good contact for subsequent soldering. In the practice of the present invention and with reference to FIGS. 2(a) and 3, capacitor body 1 is fixedly positioned as are the components of lead wire assembly 100 as hereinafter described. A force F is applied to wire 110 as shown in FIGS. 2(a) and 3. This force is transverse, i.e. perpendicular, to the common plane 101 of wires 110, 120, 130 and lead out rod 3 and is sufficient to provide contact between lateral portion 130 and anode lead out rod 3. While in contact, anode lead out rod 3 is conventionally welded to lateral portion 130, force F being sufficient to ensure a good weld. A force F' is applied to wire 120 as also shown in FIGS. 2(a) and 3 and this force is also transverse, i.e. at a 90.degree. angle, to the common plane 101 of wires 110, 120 and lead out rod 3 and this force is sufficient to provide a nesting contact between arcuate portion 125 and capacitor body 30 as shown in FIGS. 2(b) to 2(e). Due to the resilience of wire 120 and its cantilever mounting at 137, it is laterally moveable as indicated at 135, thus, enabling alignment of arcuate member 125 in a nesting contact with capacitor body 30 even if capacitor body 30 is somewhat irregular in shape or "out of line". Wire 110 is also cantilever mounted as indicated at 139 and is moveable in the direction of force F to enable close contact with anode lead out rod 3. As shown in FIG. 3 the common plane 101 of wires 110, 120, 130 and lead out rod 3 substantially contains the longitudinal axis 102 of capacitor body 1 and plane 107 substantially contains the capacitor body contacting arcuate member 125 and plane 107 is transverse to plane 101.