GB1567695A

GB1567695A - Electrolytic capacitor with self-retaining lead assembly

Info

Publication number: GB1567695A
Application number: GB808977A
Authority: GB
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1976-02-27
Filing date: 1977-02-25
Publication date: 1980-05-21
Also published as: JPS5920627U; JPS52125759A; DE2706911A1; CA1092205A; NL7702059A; FR2342549A1; FR2342549B1; JPS6015334Y2

Description

(54) ELECTROLYTIC CAPACITOR WITH SELF-RETAINING LEAD ASSEMBLY (71) We, UNION CARBIDE CORPORATION, a corporation organized and existing under the laws of the State of New York, United States of America, of 270 Park Avenue, New York, State of New York 10017, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to resin coated electrolytic capacitors having terminal conductors configured to facilitate mounting and engagement with circuit boards and the like.

Resin coated solid state electrolytic capacitors are well known to the art and are described in United States Patent No.

3,646,404 which also describes a terminal conductor configuration generally suitable for circuit board installation. However, the terminal conductor configuration of this patent, and other previously known configurations, are not completely satisfactory in several important aspects e.g. the avoidance of accidental polarity reversal during installation, retention prior to soldering, uniformity of installation, and other aspects.

According to the present invention there is provided a resin-coated solid state electrolytic capacitor comprising an anode of film forming metal and an electrolytic dielectric oxide film thereon, a layer of semiconductive electrolyte on said film, and a conductive cathode layer on said electrolyte layer, a lead out rod connected to said anode, a resin envelope enclosing said anode and said layers, a pair of spaced termihal lead conductors extending in the same direction from the envelope, one of said pair of terminal lead conductors being the cathode lead conductor and having a strip-like portion and a longitudinal portion soldered to said cathode layer witb most of said longitudinal portion being embedded in the resin of said envelope, the other of said pair of said terminal lead conductors being the anode lead conductor, said anode lead conductor having a strip-like portion, a longitudinal portion substantially embedded in the resin of said envelope and a lateral portion welded to said anode lead out rod, said lateral portion and said lead out rod being embedded in the resin of said envelope, one of said strip-like portions being substantially wider than the other and terminating in a locking configuration which is pre-formed for self-engagement with a circuit board aperture of predetermined dimensions.

The present invention also provides a circuit board in combination with the capacitor of the invention the circuit board having a first aperture of a size which forcibly engages the pre-shaped end portion of said substantially wider strip-like portion and having a second aperture slightly larger than the other strip-like portion in surrounding relationship with said other strip-like portion.

The invention is described in more detail below making reference to the accompanying drawings in which: Figure 1 shows a cross-sectional elevation view of an electrolytic capacitor in accordance with the present invention, Figure 1 (a) shows a bottom view of the capacitor, Figure 2 through 4 illustrate steps during the manufacturing of capacitors of the type shown in Figure 1, and Figures 5(a), 5(b) and 5(c) illustrate certain terminal lead arrangements adapted for circuit board engagement in accordance with the invention.

The present invention will be more fully understood with reference to Figure 1 of the drawing which shows a sintered capacitor anode 10 made from tantalum, aluminum or other film forming metal having an attached metal lead out rod 20. An oxide layer is electrolytically provided on the surface of anode 10 and a semi conductive electrolyte layer and a cathode layer, e.g. silver, are applied on the oxide layer following conventional, known procedures. Anode and cathode terminal leads, indicated at 30 and 40 respectively, are bonded to the capacitor body by welding, as indicated at 35, and solder, as indicated at 45, and the assembly is enclosed within a resin envelope as indicated at 50 by conventional techniques. With further reference to Figure 1, cathode terminal lead 40 comprises a relatively narrow portion 60 which is arranged to loosely fit in the slightly larger aperture 62 of the conventional circuit board indicated at 64. Intermediate lateral portion 66 of cathode lead 40 is in contact with circuit board 64 as is the corresponding lateral portion 68 of anode lead 30.

The longitudinal portion 70 of cathode lead 40 is bonded by solder to the cathode of the capacitor as previously described. Anode lead 30 is formed of a resiliently deformable metal such as "nickel silver" which is weldable to tantalum and solderable (typical composition: 55 %Cu, 2675V0Zn, 18%no, 025/00Mn) and has a relatively wide strip-like portion 72, a transverse "shoulder" portion 68 at the same level as the transverse portion 66 of cathode lead 40, a longitudinal portion 74, and a transverse portion 76 which is welded at 35 to anode lead out rod 20. As can be seen from Figure l(a), the relatively wide portion 72 of anode lead 30 has an end portion 78 which, upon entry into aperture 80 of circuit board 64, is resiliently deformed by the sides 83 of aperture 80, as indicated at 82, due to the relatively narrow width of aperture 80. Upon passing through aperture 80, resilient end portion 78 returns to its initial shape and engages the capacitor to circuit board 64 as shown at 85 in Figure l(a). The resilient deformation of locking configuration 78 is facilitated by lance cuts, as indicated at 84, in in relatively wide strip-like member 72. Upon insertion of the capacitor into circuit board 64, as described above, which can be done manually or automatically by machine, the capacitor is firmly held to circuit board 64 by the engagement of end portion 78 of anode terminal lead 30, and the contact of lateral portions 66 and 68 of the cathode and anode terminal leads. The capacitor can thus be conveniently joined to conductors 86 and 88 as indicated in Figure 1 by solder connections 90 and 92.

The capacitor body of the present invention is engaged to circuit board 64 bv aligning the relatively narrow strip-like cathode terminal lead 40 with the relatively smaller aperture 62 circuit board 64. End portion 60 of cathode lead 40 is surrounded by aperture 62 but fits loosely in aperture 62. The end portion 78 of relatively wide strip-like anode terminal lead 30 is spaced a predetermined distance from portion 60 of cathode lead 40 so as to be aligned with aperture 80 of circuit board 64.

The width of aperture 80 is narrower than the overall width 81 of end portion 78. Thus, end portion 78 is resiliently deformed upon passing through aperture 80 and is returned to its original shape after passing through aperture 80 and thus engages circuit board 64.

In view of the substantially different widths of the anode terminal lead 30 and cathode terminal lead 40, the likelihood of reversing the desired polarity upon engagement with circuit board 64 is obviated. In addition to ease of installation, the capacitor of the present invention is firmly engaged so that it will not fall free of the circuit board 64 prior to or during soldering.

With reference to Figure 2, a thin sheet of resilient, solderable metal such as previously mentioned hereinabove, about 0 010 inch to 0 020 inch thick, is suitably punched to obtain the configuration shown having a plurality of conductor pairs 100 attached to strip 110. The configuration of Figure 2 is subsequently subjected to a lancing operation to provide the lance cuts indicated at 84 in Figure 3, and a progressive die punch press operation to deform end portion 78 as shown in Figure 3 and 3A. Thereafter capacitors 10 are attached as shown in Figure 4, to anode leads 30 by welding lead out rods 20 thereto as indicated at 35. Subsequently, the assembly is conveniently dipped in molten solder to bond the cathode leads 40 to capacitors 10 and provide the solder coating shown at 45 in Figure 1. Following the solder-dipping step, the assembly is conveniently dipped in liquid resin, e.g. epoxy resin to provide a resin envelope as indicated at 50 in Figure 1 which enclsoes the capacitor 10, anode lead out rod 20 and most of the longitudinal portions of anode terminal lead 30 and cathode terminal lead 40. After forming the resin envelope 50, the conductor pairs 100 are cut at line 120 to obtain individual completed capacitors of the type shown in Figure 1. With reference to Figures 5(a), 5(b) and 5(c), these figures show different embodiments of end portion or locking configuration 78, which can be formed by conventional metal working techniques. In Figure 5(b), the embodiment disclosed engages circuit board 64 in a manner similar to the embodiment of Figure 1, i.e. the end portion 7811 is resiliently deformed and passes completely through aperture 8011 and thereafter returns to its original shape to engage circuit board 64. In the embodiment of Figure 5(a), end portion 781 is resiliently deformed and compressed and engages circuit board 64 by being "wedged" in aperture 8C1 which is suitably of a circular, rather than elongate cross-section. In the embodiment of Figure 5(c), end portion 78111 is tapered as shown at 81, suitably from about 5 to 100, and is wedged in aperture 80111 without any substantial deformation of end portion 78111. The slight taper of end portion 78111 enables a firm engagement with circuit board 64, particularly when the circuit board material is a thermosetting resin such as phenolic and glass epoxy materials.

While in the foregoing description, the anode termihal lead conductor has been described as having a relatively wide striplike portion and a locking configuration, and the cathode terminal lead conductor as having a relatively narrow strip-like portion, it is within the scope of this invention that this arrangement be reversed. That is, the cathode lead terminal conductor can have a relatively wide strip-like portion and locking configuration while the anode terminal lead conductor has a relatively narrow strip-like portion.

WHAT WE CLAIM IS: 1. A resin coated solid state electrolytic capacitor comprising an anode of film forming metal and an electrolytic dielectric oxide film thereon, a layer of semiconductive electrolyte on said film, and a conductive cathode layer on said electrolyte layer, a lead out rod connected to said anode, a resin envelope enclosing said anode and said layers, a pair of spaced terminal lead conductors extending in the same direction from the envelope, one of said pair of terminal lead conductors being the cathode lead conductor and having a strip-like portion and a longitudinal portion soldered to said cathode layer with most of said longitudinal portion being embedded in the resin of said envelope, the other of said pair of said terminal lead conductors being the anode lead conductor, said anode lead conductor having a strip-like portion, a longitudinal portion substantially embedded in the resin of said envelope and a lateral portion welded to said anode lead out rod, said lateral portion and said lead out rod being embedded in the resin of said envelope, one of said strip-like portions being substantially wider than the other and terminating in a locking configuration which is pre-formed for self-engagement with a circuit board aperture of predetermined dimensions.

2. A capacitor in accordance with claim 1 wherein each of said pair of terminal lead conductors has an intermediate transverse lateral portion at a common level between their respective strip-like portions and longitudinal portions.

3. A capacitor in accordance with claim 1 wherein the substantially wider strip-like portion is pre-shaped to provide an end portion which is resiliently deformable substantially independently of the rest of said strip-like portion.

4. A capacitor in accordance with claim 2 wherein the substantially wider strip-like portion is pre-shaped at a predetermined distance from the intermediate lateral transverse portion thereof to provide an end portion which is resiliently deformable substantially independently of the rest of said substantially wider strip-like portion.

5. A circuit board in combination with the capacitor of claim 1, said circuit board having a first aperture of a size which forcibly engages the pre-shaped end portion of said substantially wider strip-like portion and having a second aperture lightly larger than the other strip-like portion in surrounding relationship with said other strip-like portion.

6. A circuit board in combination with the capacitor of claim 4, said circuit board being in contact with the intermediate lateral transverse portions of each of said terminal lead conductors and having a first aperture of a size which resiliently deforms and engages the pre-shaped end portion of said substantially wider strip-like portion and having a second aperture slightly larger than the other strip-like portion in surrounding relationship with said other strip-like portion.

7. A capacitor in accordance with Claim 1 substantially as described herein with reference to Figures 1 to 4 or Figure 1 modified according to any one of Figures 5(a) (b), or(c).

8. A combination in accordance with Claim 5 substantially as described herein with reference to Figure 1(a) or that Figure modified according to any one of Figures 5(a).

(b) or (c).

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the cathode terminal lead conductor as having a relatively narrow strip-like portion, it is within the scope of this invention that this arrangement be reversed. That is, the cathode lead terminal conductor can have a relatively wide strip-like portion and locking configuration while the anode terminal lead conductor has a relatively narrow strip-like portion. WHAT WE CLAIM IS:

1. A resin coated solid state electrolytic capacitor comprising an anode of film forming metal and an electrolytic dielectric oxide film thereon, a layer of semiconductive electrolyte on said film, and a conductive cathode layer on said electrolyte layer, a lead out rod connected to said anode, a resin envelope enclosing said anode and said layers, a pair of spaced terminal lead conductors extending in the same direction from the envelope, one of said pair of terminal lead conductors being the cathode lead conductor and having a strip-like portion and a longitudinal portion soldered to said cathode layer with most of said longitudinal portion being embedded in the resin of said envelope, the other of said pair of said terminal lead conductors being the anode lead conductor, said anode lead conductor having a strip-like portion, a longitudinal portion substantially embedded in the resin of said envelope and a lateral portion welded to said anode lead out rod, said lateral portion and said lead out rod being embedded in the resin of said envelope, one of said strip-like portions being substantially wider than the other and terminating in a locking configuration which is pre-formed for self-engagement with a circuit board aperture of predetermined dimensions.

(b) or (c).