Dec. 31’ LEAD CONNECTION K. H_FOR ELECTRICAL APPARATUS Filed Sept. 1 ,_ 1945 Z7 2,413,539 3 Sheets-Sheet 1 \\\\\\\\\\ \ B dM // 1 . FIGURE KERMIT H. BALLARD INVENTOR. FIGURE 2 Arron/v5)’ Dec. 31, 1946‘ K. H. EALLARD 2,413,539 LEAD CONNECTION FOR ELECTRICAL APPARATUS Filed Sept. 1, 1943 3 Sheets-Sheet 2 FIGURE 3 KERMIT H. BALLARD , INVENTOR. BY ‘ATTORNEY Dec. 31, 1946.. K. H. BALLARD 2,413,539 - LEAD CONNECTION FOR ELECTRICAL APPARATUS Filed Sept. 1, 1943 32 3,5 33 3 Sheets-Sheet 3 _ 35] , . g4 ‘ -‘ \\\ I‘ / / / / / ‘ " ‘ B-B /A-A 3% ‘ / \40 “ / / 1y , . /‘ / [“__— c-c/ D-D/ FIGURE 4 I ‘\Q \\ \\ /33 / BAA ~~|| \ // % J I 4o FIGUQE 5 KERMIT’ H. BALLARD INVENTOR. BY A TTORNEY Patented Dec. 31, 1946 ‘2,413,539 UNITED STATES PATENT OFFICE 2,413,539 LEAD CONNECTION FOR ELECTRICAL APPARATUS Kermit H. Ballard, Perth Amboy, N. J ., assignor to E. I. du Pont de Nemours & Company, Wil mington, Del., a corporation of Delaware Application September 1, 1943, Serial No. 500,807 1 9 Claims. (Cl. 173-324) This invention relates to electrical capacitors or condensers and, more especially, to a new and improved terminal connection for attaching the electrical lead wires to the electrodes of the capacitor. My invention is particularly adapted for use in securing lead wires to electrical capacitors of the type described and claimed in my copending ap plications, Serial No. 461.302, ?led October 8, 1942, and Serial No. 494,627, ?led July 14, 1943, wherein the capacitor is formed with electrodes compris 2 I have now devised a new and improved at tachment means which permits the attachment of an electrical conductor or lead Wire to the metallic layer electrodes of an electrical capacitor in Such a manner that the resulting assembly is more rugged and wear-resistant than previously considered possible under circumstances wherein a wire must be attached to a ceramic silver sur face. The new and improved fastening method, and the improved joinder means and electrical capacitor resulting, is of such strength that when ing alternate layers of metallic silver separated the assembled capacitor is tested by applying ten by dielectric layers comprising a vitreous compo sion between the copper lead wires the failure sition, the entire construction being formed on a occurs by breaking of the lead wire when its ten supporting block preferably of ceramic material. 15 sile strength is exceeded, rather than by the pull However, it is not limited to utilization in con ing away of the lead wire from the silver electrode necting lead wires to electrical capacitors, but is surface. The strength of my improved electrical of general use wherever lead wires are to be fastening construction, particularly adapted for brought into electrical communication with me use in attaching lead wires to electrical capacitors tallic layers or surfaces on electrical apparatus 20 of the type speci?ed, will be appreciated when it generally. In fabricating electrical condensers of this type wherein layers of ceramic metallic silver are utilized as the electrodes considerable difficulty is understood that the ordinary No. 18 copper wire used as lead wires for such condensers will resist a tension of from 30 to 45 lbs. without breaking. has been experienced in attaching in electrical 25 Accordingly, it is one of the objects of this in communication with those electrodes lead wires vention to provide fastening or connection means which will possess satisfactory mechanical for securing a lead wire to a ceramic silver sur strength. In various constructions previously face, more especially for securing a lead wire to a utilized the lead wires or conductors have been soldered to exposed portions of the silver layer electrodes, but the soldered connections generally become disconnected, breaking the electrical con nection when the con-denser is subjected to even relatively slight vibration or mechanical han dling. In an effort to avoid this di?iculty lead wires have been attached to the base on which the condenser construction is supported in elec ceramic silver surface in an electrical capacitor, which fastening or connection means is of more rugged construction and more resistant both to wear and to tensile stresses than ever previously attainable. It is another object of this invention to render available a fastening means particu larly suitable for use in manufacturing electrical condensers of the type described in my previously referred-to copending applications. which fasten ing means possesses great strength and rigidity when subjected to deforming or separating in trical communication with the silver layer elec trodes by means of a low-melting glass serving as the cement. In another modi?cation of this 40 ?uences. A new and improved method for secur construction the end of the supporting ceramic ing these connections forms another object of base or tile is provided with sawed slots wherein my invention. These and still further objects of a bent-in portion of the lead wire may be ?tted this invention will be apparent from the ensuing before bringing it into communication with the disclosure of certain preferred embodiments silver electrode by soldering or by means of a low 45 thereof. melting glass cement. However, none of these My invention is best explained with reference methods of joining results in a construction pos to the attached drawings wherein Figure 1 is a sessing sui?cient mechanical strength and rug diagrammatic view taken approximately on the gedness to stand up when the capacitor is sub line I—I of Figure 5, looking in the direction of jected to severe twisting, when the lead wire is 50 the arrows, which view shows the tapered open deformed in use, or even when it is subjected to a ing in the ceramic block or tile member support straight pull of moderate force. Under these cir ing the glass or enamel dielectric and metallic cumstances the conductor becomes disconnected layer electrodes of the electrical capacitor, the from the metallic electrode and the usefulness of end of the conducting lead wire (not shown) the capacitor is destroyed. 55 being adapted for securement in this tapered 2,413,539 3 opening. Figure 2 is a diagrammatic view show ing the end portion of the electrical conductor 4 able that the face edges l8 and IQ of tapered open ing l I make an angle of from approximately 75° to or lead wire, this end portion being suitably de 85° with the ?at edge 20 of the ceramic base 5, i. e. formed or upset to permit of it being inserted in with the horizontal. This angle (with surface ll the tapered opening shown in Figure 1. Figure 3 5 generally parallel to ?at edge 20) is indicated in is a diagrammatic view, taken approximately on the line I—I of Figure 5 and looking in the direc Figure 1 of the drawings. As illustrated, the en tirejinside portions of tapered opening l2 may be tion of the "arrows of .the complete assembly, this coated with the metallic layer material forming view showing the electrical conductor positioned the electrode 7 so that electrical conductivity be~ in the tapered opening and so held in electrical 10 tween the two is provided. communication with the silver layer electrode. > Referring now to Figure 2, this view illustrates Figure 4 is a plan view, some parts being cutaway 1 ‘the electrical conductor or lead wire which is to and some parts being shown in section in order be brought into communication with electrode to illustrate the construction more clearly, of a . layer 1' of the electrical capacitor. This conduct complete electrical capacitor of the type shown 15 ing member 2| is formed with an enlarged or up in my previously referred-to copending applica set head portion 22 and a tapered connecting por tions wherein the electrical lead wires are at tion 23 extending between the two. This upset tached to the silver layer electrodes as herein de head portion 22 may have adiameter at the larger scribed. In this ?gure the various letters A-—A, end approximately twice that of the diameter of IB-B, C—C, and D—D indicate the plane, indi- . cated by the corresponding markings on Figure 5, where the particular section is taken, the un shaded portion of Fig. 4 being in plan. Figure 5 the electric wire or conductor 2 I. In forming the connection, as shown in Figure 3 the enlarged upset end 22 of the electrical con ductor 2! is inserted ?rmly into the tapered open~ is a cross-sectional view, some parts being shown ing H in ceramic block 5 in such a way that the in elevation taken on the line 5-5 of Figure 4. 25 end surface 26 of the large end of the upset por Referring speci?cally to Figure 1, 5 denotes a ceramic base, tile or slab supporting member whereon the elements of an electrical condenser tion 22 is in close communicating contact with the metallic layer on the large inner base ii of the tapered opening II. In this way electrical com are positioned. These may include, as a mini munication‘ is provided between the conductor 2| mum, electrode layers 1 and 9 separated by dielec 30 and the electrode 1. . tric layer 8, this dielectric layer being preferably In order to secure satisfactory electrical con ,aformed of a vitreous composition. In usual prac ductivity and to hold the lead wire 2! securely in tice other electrode layers and other layers of position it is desirable to place a small amount of separating dielectric may be present, but as they solder in- the tapered opening surrounding the up form no part of this invention and need not be 35 set or enlarged end portion 22. While I prefer to described in order to explain it they are not shown utilize solder for this purpose, it is also possible in the drawings. This electrical capacitor or con merely to dip or immerse the enlarged end portion denser may be constructed as disclosed and 22 of the lead wire ii in a. conducting cement be claimed in my above-identi?ed copending applica fore introducing it into the tapered opening Ii, tions. 40 thh conducting cement serving to provide for As shown, at that portion of the ceramic base 5 electrical communication with the electrode 7 adjacent tapered’opening ll one of the electrode through the metallic layer l2 positioned in the layers 9 is spaced back from the opening to pre interior of tapered opening H, reliance being vent short-circuiting between electrodes. Of placed on the insulating cement later to be placed - course, either of the electrode layers 1 or 9 could in the un?lled portions of the tapered opening II to hold the lead wire securely in place therein. Neither the solder or conductive cement, nor the conductor or lead wire as shown in Fig. 3., In insulating paste or enamel which is positioned in practice one electrode layer will be spaced back at the tapered opening around the enlarged head the tapered opening I l for one lead wire connec 50 portion 22 of lead wire 2i in order to seal off the tion at one end of the ceramic base 5, and the entire construction, is shown in the drawings, as other spaced back at a similar tapered opening I I the arrangement of parts would be obscured for the other lead wire connection at the other thereby. This vitreous insulating enamel placed end of the ceramic base 5. in un?lled portions of the frusto-pyramidal open The ceramic supporting block 5 is provided, as 55 ing,“ provides the necessary electrical insula shown, with the previously referred-to tapered or tion and also serves to consolidate the Joint and be so spaced back, depending on which is to be brought into electrical communication with the wedge-shaped opening II which may be con protect it from corrosion. The use of vitreous in structed generally in the form of a slightly de sulating enamel in this way is disclosed and formed frustum of a pyramid. The larger base claimed in the copending application of Deyrup, l2 of this quasi-frustum of a pyramid (hereafter 60 Serial No. 479,156, ?led March 15, 1943, which ma for convenience the opening I l is termed frusto tured into Patent No. 2,398,176, on April 9, 1946. pyramidal, or a frustum of a pyramid), is at the Referring more especially to Figures 4 and 5, inner end. As shown, this opening may be formed the numeral 3| denotes one silver layer electrode with a much narrower slit l1 extending from the separated by dielectric layer 32 from another bottom of the tapered opening ll proper down 65 silver layer electrode 33. As shown, the two wardly through the ceramic base block 5. This silver layer electrodes are not coextensive in area, slit is not essential, but may be included for con and are, of course, respectively positioned back venience in manufacturing the block or for plac from the tapered openings H except when Joined ing the conductive metal layer or conductive ce to an electrical conductor at that tapered open- I menltlon the interior surfaces of the tapered open 70 ing as previously explained. A vitreous cover ing . coat 35 as disclosed, for example, in the co I have found that in order that the upset head pending application of Deyrup, Ser. No. 474,679. or end portion of the lead wire 2| (shown in Fig. ?ied February 4, 1943, may be applied over the 2) may be properly seated in the‘ tapered opening entire assembly after the lead wires 38 and 38 are II, as will .be subsequently explained, it is desir 75 positioned in identical tapered opening II in the 5 2,413,539 ceramic base 5 in electrical communication with the electrodes 3| and 32 as previously described. In these figures, for convenience in illustrating, the insulating enamel cover coat is not shown around the metallic lead wires 36 and 38, but in practice the insulating enamel is also applied around the tapered openings I l ?lled with the lead wires. The enamel may also be of an or ganic type as, for example, a wax or a resin 3 it is securely retained therein and is in electrical communication with said conductive layer on ‘the interior surfaces of said receptor opening. 2. The method of securing electrical lead wires to an electrical capacitor, said electrical capacitor comprising a ceramic base member on which there are mounted a plurality of layers of metallic electrodes and a plurality-of interposed layers of vitreous dielectric which comprises: providing such as one of the alkyd type (“Glyptal”). The 10 a plurality of electrical lead wires, the terminal cover coat may be applied to all parts of the elec portions of said lead Wires being formed in gen trical condenser before insertion of the electrical erally frusto-conical form; providing a plurality lead wires 36 and 38 by suitably masking the of receptor openings in said ceramic base mem tapered openings l l, which may be later sealed ber, said receptor openings being generally of off, if desired, after the electrical conductors have 15 frusto-pyramidal form; providing on the interior been positioned therein. ' surfaces of said frusto-pyramidal receptor open In forming the electrical connections the upset ings a plurality of metallic electrically conduc or enlarged terminal portions 39 and 40 of elec tive layers, each of said layers being in electrical trical conductors 36 and 38 are positioned in the communication with an electrode of said elec tapered openings ll provided in the base plate 20 trical capacitor; positioning said enlarged frusto 5, said generally frusto-pyramidal openings being constructed as shown in Figure 1 as described above. As shown in the latter ?gure. the metallic layer comprising the electrodes in each instance is extended over onto the inner surfaces i2 of tapered openings II, with which surfaces the enlarged head or upset terminal portions 39 and 40 of the conductors 36 and 38 are brought into conical head portions of each of said lead wires in said frusto-pyramidal receptor openings; and introducing an electrically conductive paste into un?lled portions of said receptor openings where by electrical communication is provided between said enlarged head portions, said interior metallic conductive layers, and each of said electrodes of said electrical capacitor. electrical communication by abutting directly 3. The method of securing an electrical lead up against those surfaces or through a conductive 30 wire to one of the electrodes of an electrical cement or solder, or by the use of both expedients, capacitor, said electrical capacitor comprising 'a' thus providing direct electrical communication plurality of electrode plates separated by layers between electrode 3| and lead wire 36. and be of dielectric positioned on an insulating base tween electrode 33 and lead wire 38. The solder which comprises: providing an electrical lead to provide electrical communication, or the con 35 wire with an enlarged head portion; forming in ductive cement, may. as previously explained, be said insulating base a generally tapering receptor then incorporated in the un?lled portions of opening, said opening being larger toward the the tapered openings l I in order to provide bet interior of said insulating base than it is ad ter electrical communication between conductors jacent the external surfaces thereof; providing 36 and 38 and the interior metal-coated surfaces 40 on the interior surfaces of said receptor open l2 of tapered openings H, the latter being in ing an electrically conductive layer in electrical direct electrical circuit with the respective elec communication with said electrode to be con trodes 36 and 38. nected; positioning said enlarged head portion It is obvious that while I have described my of said electrical lead wire in said tapering re improved electrical connection and the method of 4. ceptor opening; introducing a conductive mate forming this connection with particular refer rial into un?lled portions of said receptor open ence to electrical capacitors or condensers, it may ing surrounding said enlarged head portions of be used in other apparatus for other purposes, said lead wire, whereby electrical communication wherever lead wires or metallic conductors are is provided between said lead wire and said elec to be brought into electrical communication with trode through the interior conductive layer of metal surfaces or layers. said receptor opening; and covering the resulting Various changes may be incorporated in my attachment with an electrically insulating mate preferred embodiment as above described and rial, whereby said electrical connection may be these changes insofar as they come within the electrically sealed from current leakage losses. scope of my invention, are intended to be com 4. The method of securing an electrical lead prehended in the claims. wire to a metallic electrode surface which com I claim: prises: providing an electrical lead wire having 1. Securement means for securing an electrical at its terminal portion an enlarged head portion lead wire in electrical communication with an generally in frusto-conical form; providing in electrode surface which comprises: an electrical 60 the base member supporting said metallic elec lead wire provided with an enlarged head portion trode surface a generally frusto-pyramidal re generally in the form of a frustum of a cone; ceptor opening, the larger portion of said frusto an insulating member provided with a receptor pyramidal receptor opening being positioned to opening, said receptor opening being generally ward the interior of said base member; providing in the shape of a frustum of a pyramid, the nar 65 on the interior surfaces of said frusto-pyramidal rower end section of said frustum of a pyramid receptor opening a metallic conducting layer, said being adjacent the external surface of said in metallic conducting layer being in electrical com sulating member; an electrically conductive layer munication with said metallic electrode; position positioned on the interior surfaces of said re~ ing said frusto-conical head portion of said lead ceptor opening in electrical communication with 70 wirein said frusto-pyramidal receptor opening; the electrode surface which is to be brought into ?lling unoccupied portions of said frusto-pyram_ electrical communication with said lead wire; idal receptor opening with solder, whereby elec and means for positioning said generally irusto trical communication is provided between said conical head portion of said electrical lead wire head portion of said lead wire, said interior con in said receptor opening in such position that 75 ductive surface, and said metal electrode, and 2,413,539 7 ' 8 \ placing in other unoccupied portions of said "terior of said insulating base than it is adjacent the external surfaces thereof; providing on the frusto-pyramidal opening a vitreous insulating I enamel, whereby said lead wire is securely re interior surfaces of said receptor opening an elec tained in position in said frusto-pyramidalopen trically conductive layer‘ in electrical communi ing. cation with said electrode to be connected; then dipping said enlarged head portion of said elec trical lead wire in conductive paste, and then 5. The method of securing electrical leadwires to an electrical capacitor, said electrical capaci tor comprising a ceramic base member on which there are mounted a plurality of layers of me positioning said enlarged head portion in said tapering receptor opening, said conductive paste serving to establish electrical communication be tween said lead wire and said electrode through the interior conductive layer of said receptor opening; and covering the resulting attachment with an electrically insulating material, whereby said electrical connection may be electrically sealed from current leakage losses. tallic electrodes and a plurality of interposed lay ers of vitreous dielectric which comprises: pro viding a plurality of electrical lead wires, the terminal portions of said lead wires being formed in generally frusto-‘conical form; providing a plu rality of receptor openings in said ceramic base member, said receptor openings being generally of frusto-pyramidal form; providing on the in 8. The method of securing an electrical lead - terior surfaces of said frusto-pyramidal receptor wire to one of the electrodes of an electrical ca openings a plurality of metallic electrically con pacitor, said electrical capacitor comprising a Q - ductive layers, each of said layers being in elec_ plurality of electrode plates separated by layers trical communication with an electrode of said of dielectric positioned on an insulating base electrical capacitor; positioning said enlarged which comprises: providing an electrical lead frusto-conical head portions of each of said lead wire with an enlarged head portion; forming in wires in said frusto-pyramidal receptor openings; said insulating base a generally tapering receptor and introducing a mass of solder into un?lled 25 opening, said opening being larger toward the in portions of said receptor openings whereby elec terior of said insulating base than it is adjacent trical communication is provided between said the external surfaces thereof; providing on the enlarged head portions, said interior metallic interior surfaces of said receptor opening an elec conductive layers, and each of said electrodes of trically conductive layer in electrical communica said electrical capacitor, and said lead wires are 30 tion with said electrode to be connected; then securely held in position in said receptor open dipping said enlarged head portion of said elec ings. trical lead wire in conductive paste, and then 6. The method of securing electrical lead wires positioning said enlarged head portion in said to an electrical capacitor, said electrical capacitor tapering receptor opening, said conductive paste comprising a ceramic base member on which serving to' establish electrical communication be there are mounted a plurality of layers of metallic tween said lead wire and said electrode through electrodes and a plurality of interposed layers of the interior conductive layer of said receptor vitreous dielectric which comprises: providing a opening; positioning solder in un?lled portions plurality of electrical lead wires, the terminal of said tapering receptor opening to assist in portions of said lead wires being formed in gen 40 holding said lead wire securely in position in said erally frusto-conical form; providing a plurality receptor opening. of receptor openings in said ceramic base mem 9. The method of securing an electrical lead ber, said receptor openings being generally of wire to one of the electrodes of an electrical ca frusto-pyramidal form; providing on the interior pacitor, said electrical capacitor comprising a surfaces of said frusto-pyramidal receptor open plurality of electrode plates separated by layers ings a plurality of metallic electrically conductive of dielectric positioned on an insulating base layers, each of said layers being in electrical com-I which comprises: providing an electrical lead munication with an electrode of said electrical wire with an enlarged head portion; forming in capacitor; positioning said enlarged frusto-coni~ said insulating base a generally tapering receptor cal head portions of each of said lead wires in opening, said opening being larger toward the in said frusto-pyramidal receptor openings; intro terior of said insulating base than it is adjacent ducing a mass of solder into un?lled portions of the externalsurfaces thereof; providing on the said receptor openings whereby electrical com interior surfaces of said receptor opening an elec munication is provided between said enlarged trically conductive layer in electrical communi head portions, said interior metallic conductive , cation with said electrode to be connected; dip layers, and each of said electrodes of said elecping said enlarged head portion of said electrical trical capacitor; and ?lling other unoccupied por lead wire in conductive paste, and then position tions of said receptor openings with an insulat ing said enlarged head portion in said tapering ing vitreous enamel which serves to insulate and receptor opening, said conductive paste serving securely retain in place in said receptor openings 60 to establish electrical communication between said electrical lead wires. 7 said lead wire and said electrode through the in 7. The method of securing an electrical lead terior conductive layer of said receptor opening; wire to one of the electrodes of an electrical ca positioning solder in un?lled portions of said pacitor, said electrical capacitor comprising a tapering receptor opening to assist in holding plurality of electrode plates separated by layers said lead wire securely in position in said receptor of dielectric positioned on an insulating base opening; and ?lling other un?lled portions of which comprises: providing an electrical lead said receptor opening with a vitreous insulating wire with an enlarged head portion; forming in enamel which serves to insulate said connection said insulating base a generally tapering receptor and hold the members thereof securely in place. opening, said opening being larger toward the in . , , KERMIT H. BALLARD.