US2476592A - Cathodic deposition apparatus - Google Patents

Description

July 19, 1949. H. F. FRUTH CATHODIC DEPOSITION APPARATUS 3Sheets-Sheet 1 Filed Dec. 13, 1944 F3 [12 yen/01 fiazmederzcki'mih I By- July 19, 1949. FRUTH 2,476,592

CATHODIC DEPOSITION APPARATUS Filed D60. 13, 1944 3 Sheets-Sheet 2 i /bw; m x jforgeys.

July 19, 1949.

H. F. FRUTHY 7 CATHODI C DEPOS ITION APPARATUS Filed Dec. 15, 1944 3 Sheets-Sheet 3 4,2 415 i y |k l fizz e/fi er fizlfr'egyclz Fred/z Patented July 19, 1949 UNI STATES PATENT OFF l C E OATHDDIO-DEPOSI ION ARBARATIIS HalFfrederick Fruth, Skokieglll.

.l-Apnliee mn-D eem er 1 e i l N0. '568,.0Z9

:8 'cG eim 11 The e s n i vent n; pertains to a nov l and imp ed I appa atu e appl ng metal c ating to articles y m a s of catho i d qsiti e ema led fe thwqd -:sp1itterins- The L en eimiefzth p esent invent is :t pr v d a appara u :Q :th tim ndica ed capa l f effecting the ;coatin ,.in e ar :QQIDP meteiel production: of ;larg ;siuentitie of art cles in rail lemcient a and.-.exped iq :m nn r- More particularly, it is an object to provide such :an -appe at: fo me ti p-un eorm y th entire periph ra .ssurfee :ef each :O roup .ef articles.

"Another r bjeet is :t provide an appa atu :Q thecher c er 1 orth b v emb dy n an rt w-h em nt fo tu ninaeaeh ta oup-of a cle abou individual axes 6r Q h "th y .zate housed i eta-vacuum chemhenin orde ateexpos different: a r ion zef them to p sit n.

:Eurther objectsHand-advantages of the; invention will becom apparent a -th fol w n escripti n pr edsken :in c nnection wi zvth ccomp nyin redrawingsl in which:

Figure 7.1 shows an apparatus emb dyi th present 'ri-nventicn, theevacu ted-ve s ncluded Y im he sameiliein s hewn in-vert e lpsee ic a the as ci ted appara us zleeated eext r erly .of the vessel, :beine indicated sensual-1y :schematically.

Fi -1 is za-transvers sectiona :vi wcefzth avesselgin lud d; win th apnexatus i :1, the, same bein sh wn with: vp lttiona f @the r rcath d s ipportingst uetureLbmkenaway tmbetter illust at the interior arran ement rQfil'ih =perts- :Eis a ze er edzimement ry d ta i. a1 aview taken su s an ia l rte-lens :t lin s -sr nzfi e-1, Qend,sh w nestheenede;implan- ;E ;41is:a fra men ary detai vseetio a vi w taken substantially I along: the 1inei 4- 4 in;Fi g. 3.

Fr e ar detail perspectiv vvi wsshowinesre pectivel ene Q h "WQ1TK piece s p ortinepins included in theennenetu of. i s 1, end Qne :cf vthe eee eting n tched stemming heads.

'.E 5 and 8-,,are ;enlareedfiasm n y d tai ide-eelevetien -e the l e p rti nwefzthesupcases which th diseles d emanate i adapted pump il ;.2 t s a end with a po tio .Q t "cor broken away.

.Reierring mo e part ula l t th .e emple 'y embod ment of the v nvention il ustrated in th d aw n s, th sam .ha be n shown es inco rated in Janhepnenetus desi ned pr marily v o applyin m allic coatin t iesist re re I 9 Fig- 1, and ,see .alsoe core, illnstratedin detail in Fig. 9) Such use i ,..hQW Yer,. simply "i lu tra v o one f thev manyeuses-t wh e apparat embod in the pres einventiemmay e .pu Accord n ly, there is nointentiont Jim tthe inv ntion t tha particular use nor t0 the precise details, of struct r shown- O hecen remthe int ntion. i t ov r all analo ous .ns s alte nat v c nstru tio modifica on nd l ern t on fallin within the s irit {and scope of t the invention ,as e es ed intt ..e nendedQl ims.

-.In the illustrated ,nse of the invention, the co s ll! arenoneeonduc ve, he nemadeofihend fired fier mic or the like. .Each v. ore w is .of el ngated ,tubulariorm ..(see Eig. 9) with its exterior molded in sct we hreadedshape. frosu hscrewthreaded exterior portioneoteachrsuch s mispplied a .thincverallcoating ll .of metal, by the apparatu herein=,dis 10se.d. EInme ing r s t r in;.accordanc,e with themethod disclosed in my .copending "application Serial No. 534,037, filed May 4, 1944, now abandoned, the metal coating n su aeere .is .cut awa in re helic dine a f rexammeamng theet p f th threades ea t0,leave.a he1ix. of thin metal which has .a high resistance fromend to end of the core. Further detailing ofcthat process is,v hcwever unnecessery heresince the ,concern for the pnesent is simply w tht eeppanetus fo app y n th ve all. metal coating.

To applythe desired coatingl l' on the cores in, they, are, in the presently disclosed apparatus, subjected ,to ,theaction of dispersed electronic emission from, a.., cathode comprised of the metal whicheisutocompose thecoating. For that purpose the cores i l0, are received in a vacuum-tight vessel, here s hownlEigs. 1:.and 2) as a heavy glass bowl v!2,e q11 ipp,ed with ,a glass cover ,14 wh ehhwhenfremovedhvexp se lthe e rei ie ofthe. howl fOILEBSYi access. The annular edge 9 lip portions l2a,. Uh of. thelcowl and cover respectively present accurately gro und opposed that fa s. A as et L5,: greased.,.if. ne ssary may: be interposed between the surfaces to insure ,an efiectual hermetic sealwhen the cover is. in; place.

,The ,vacu im chamber 7 l6 defined by the bowl en eev n 12 His v cnetedbye suite v um Eli hump =,eenneeted vwith the chamber It by an electrically conductive metal conduit i8 passing through a sealing plug [9 in the upper central portion of the cover. A shutoii valve 20 may be interposed in this conduit and a suitable vacuum gauge 2! connected to indicate the pressure prevailing in the conduit and chamber.

Within the vacuum chamber [6 is a cathode consisting of a plurality of wires 22 depending in spaced parallel relation. These wires are composed of the metal which is to be deposited,

usually a noble metal such, for example, as platinum or platinum-iridium alloy. As here shown, the cathode wires 22 are arranged at spaced intervals in two circular series (see Fig. 2) with the wires comprising the inner series located substantially midway between successive ones of the wires in the outer series. Such location of the cathode wires is utilized in order to facilitate grouping of a generally circularly arranged cluster of work pieces In about each cathode wire and with each circular cluster or group of work pieces merging into the next, and centered on its corresponding one of the cathode wires. Such location of the work pieces or cores i ll with reference to the several cathode wires afiords exposure of a maximum number of work pieces to emission for each cathode, together with maximum equalization of deposit on each work piece.

The upper ends of the cathode wires 22 are, in the present instance, bent laterally as shown and hooked loosely in eyes 23a fashioned in the outer ends of laterally extending lead wires 23."The inner ends of these lead wires are all secured to a central terminal 24 and are enclosed by individual insulating sleeves 25, the wires 23 and terminal 24 constituting a spider for suspending the wires 22 at the desired points. The sleeves 25 rest on a horizontal metal supporting plate 26 whichin turn rests on the upper ends of studs 21 rising from a lower transverse metal supporting plate 28. The latter plate is fixed by clamping screws 29, threaded in U-shaped brackets 31!, to lugs 3| on the interior of the bowl l2. The cathode wires 22 pass down through holes 26a in the upper plate 25 and terminate short of the lower plate 28. Apertures 28a in the. latter register with the lower ends of each of the cathode wires.

Coacting with the cathode wires 22 is an anode, comprising, in the present instance, a metal disk 32 rested on the bottom of the bowl I2 (see Figs. 1, 3 and 4). The diameter of the anode plate is in the present instance somewhat less than that of the imaginary circle on which the outer group of cathode wires is located and somewhat more than that on which the inner group is located (see Fig. 2). Moreover, the anode 32 is spaced from the lower ends of the cathode wires and the apertured plate 28 is interposed between the cathode wires and anode so that it acts more or less as a barrier screen. With such an arrangement, application of high potential between anode 32 and-cathode 22 serves, when the chamber I6 is evacuated, to effect electronic emission from the cathode wires in a more or less cloudlike dis ersion so that a thin coating of the particles emitted from the cathodes is deposited on objects placed in the dispersion zone.

High potential may be applied between the anode and cathode electrodes 32, 22 from any suitable source. In the present instance a transformer 33 is indicated in Fig. 1 for that purpose. Such transformer includes a primary winding 34 connected to a suitable source of alternating current by lines Ll, L2 in series with a regulating rheostat 35. The end terminals of the transformer secondary winding 36 are connected by leads 3? and 38 with the anode and cathode respectively.

The lead 31 extends to a terminal stud 39 embedded in the bottom wall of the bowl l2 and passing through the same. On the upper end of the stud 39 is fixed a resilient contact arm 43 (Figs. 1 and 3) having its inner end curled to press firmly in contact with the face of the anode 32.

On the other hand, the lead 38 is connected to the metal conduit 18, the latter having a resilient terminal strap 4| fixed to it and pressed against the cathode terminal 24. The transformer 33 may be arranged to furnish an output voltage of any desired value as, for example, 9,000 volts from a conventional volt supply line.

The cores or work pieces II! are, as heretofore noted, strategically located with reference to the cloud of electrons emitted by the cathode wires 22 in circularly arranged groups or clusters about the several cathode wires. Supporting or locating pins 42 are provided to position the cores in that manner. Such pins are upright in order that the cores may be telescoped down over the same and thus positioned with the core axes paralleling each other as well as the axes of the cathode wires 22.

With the cores or work pieces I0 arranged as set forth above, provision must be made to turn each one through substantially ninety degrees about its longitudinal axis in the course of the deposition of coating in order that such coating may be substantially uniform about the entire peripheries of the individual cores. Otherwise the deposit on the portions of the cores remote from the cathode wires 22 would be substantially less than that on the portions directly exposed. On the other hand, the fact that the chamber [6 must be hermetically sealed during the operation of the apparatus makes the provision of any exteriorly operable mechanical drive connection for turning the cores difiicult to provide while still retaining adequate sealing. To interrupt the coating process by removing the cover l4 and turning the cores would slow up production inordinately.

To resolve the difiiculty noted above, provision has been made in the present apparatus for turning each of the supporting pins42, together with the core or cores on it, at will, and through a preset angle, without the necessity of actual access to the interior of the evacuated vessel or mechanical drive connection to the pins. For that purpose each pin 42 has fixed to it intermediate its ends a downwardly facing Wedge-shaped head 43 (Fig. 5). Coacting stationary heads or bushings 44 are fixed to the plate 28. Each of these heads 44 has a longitudinal bore 44a receiving the lower end of its associated pin 42. The upper faces of the heads 44 are notched transversely as indicated at 45, the shape of the notches being complemental to that of the coacting wedgeshaped heads 43.

Initially the pins 42 are located (as shown in Fig. 7) with the wedge-shaped heads 43 of each bridging the notch 45 in the corresponding stationary head below it. The edges of the wedgeshaped heads are preferably slightly rounded, as are the'upper edges of the heads 44, so that the parts will rest, as indicated in Fig. 7, with heads 43 poised in unstable equilibrium. Then. to turn the pins 42 through an angle of ninety degrees it is. only necessary to jar the structure. Upon so doing thevv heads 43 areijarred out of their state of equilibrium and slide down into the complementalnotchesli, coming to rest in the position of'Figrt. As the wedge shaped heads 43 slide downv into the notches 45', the notch walls cam the-heads, turningthe latter along with their attached pins through a quarter revolution.

In the operation of the disclosed apparatus, the bowl I2 is firstof: all loaded with uncoated resistor cores It. For that purpose the cover I4, plate 26 and cathode elements supported by the latter are removed and a pair of cores lllslipped down over each pin 42. The loaded'pins are turned individually so that. the heads 43 on them bridge the notches 45 as shown in Fig.7. Having thus loaded the jar with work pieces the cathode wire and supporting structure 22, 23, 24, 25 and 26 are insertedand the cover i replaced. The vacuum pump I] is'thenstarted and continued in operation. as may be required to obtain, and maintain, adesired degree of vacuum, as for example 0.10 mm; of mercury.

Withthe. chamber It thus evacuated, high potential is applied between cathode and anode electrodes 22, 32, resulting in a cloudlike or dispersed emission of particles from the cathode wires 22. These deposit onthe cores Ill, coating the same with the metal of which the cathode wires. are composed. The thickness of coating given dimensions, applied potential and cathode metal, The coating thus applied has a high degree of overall continuity even when very minute in thickness, and can if desired even be substantially a unimolecular layer, that is to say, a layer one molecule in thickness.

After a time interval has elapsed, corresponding to a desired thickness of coating, the operator shakes or strikes the bowl l2 to jar it. The poised heads A3 are thus shaken from their position of unstable equilibrium and slide down into the notches 45, turning the cores about their respective axes through substantially ninety degrees. Since the bowl I2 is transparent, the operator can observe the several cores to be sure that each head 43 has been displaced as desired. Should any remain unl'moved he has only to hit the bowl again.

The deposition is continued with the cores in their new position until a desired degree of coating has been completed. Thereupon the power is shut off, the pump I! stopped and cover l4 taken off for removal of the coated cores. A new set of cores may then be put in and the process repeated. No other change is required except for replacement of the cathode wires 22 from time to time as they disintegrate in course of continued use. Being simply loosely suspended from the eyes 230., it is but the work of a moment to replace them.

I claim as my invention:

1. In an apparatus for applying a metallic coating to work pieces by cathodic deposition, the combination of means defining a hermetically sealed chamber and equipped with means for evacuating the same, a cathode support for suspending a plurality of cathode wires in depending relation therefrom within said chamber, an anode plate in said chamber arranged in spaced relation normal to said wires, means for applying high potential between said support and anode plate to effect emission from said wires, means for supporting a plurality of work pieces in circular groups clustered about respective ones of the wires with the groups centered on the associated wires, and means for supporting additional cathode wiring spaced about the assembly of cluster so that deposition takes place simultaneously on the respective opposite sides of substantially all of said work pieces.

2. In an apparatus for applying a metallic coating to articles by cathodic deposition, the combination of a vessel having an opening through which work pieces may be inserted and a closure for such opening adapted to hermetically seal the same, means for evacuating said vessel, means for supporting a cathode Wire within the vessel, an anode plate of extensive face area located in said vessel in position to be spaced from and substantially normal to a cathode wire carried by said supporting means, an apertured metallic barrier plate disposed in substantial parallelism with said anode plate between the latter and the adjacent and of a cathode wire carried by said support, means for applying high potential between said support and anode plate, whereby to effect a dispersed electronic emission from said cathode wire, and means for supporting a plurality of work pieces from said barrier plate in a cluster about said wire.

3. In an apparatus for applying a metallic coating to articles 'by cathodic deposition, the combination of a vessel having an open top in which work. pieces may be inserted and a closure adapted to hermetically seal said vessel, means for evacuating said vessel, means for supporting a cathode wire vertically within the vessel, an anode plate of extensive face area located in said vessel normal to said cathode wire and spaced from the same, means for applying high potential between said support and plate, whereby to effect a dispersed electronic emission from said cathode wire, and a plurality of upright work piece supporting pins clustered about said wire and adapted to have hollow work pieces telescoped down over individual ones thereof.

4. In an apparatus for applying a metallic coating to articles by cathodic deposition, the combination oi a vessel having an opening in which work pieces may be inserted and a closure for such opening adapted to henmetically seal said vessel, means for evacuating said vessel, means for supporting a cathode wire vertically within the vessel, an anode plate of extensive face area located in said vessel beneath said wire and spaced from the same normal to a cathode wire carried by said supporting means, means for applying high potential between said support and plate, whereby to efiect a dispersed electronic emission from said cathode wire, a plurality of upright work piece supporting pins clustered about said wire and adapted to have hollow work pieces telscoped down over individual ones thereof, and means for imparting rotational adjusting movement to each of said supporting pins, said latter-named means including complemental surfaces arranged for relative rotation into a position of registered engagement under the influence of gravity bias, and interfering means for keeping said complemental surfaces normally out of engagement but for releasing them as an incident to mechanical jarring of said vessel.

5. In an apparatus for applying a metallic coating to a work piece by cathodic deposition, the combination of a vessel adapted to be evacuated, means including anode and cathode electrodes within said vessel for setting up a dis persed electron emission from said cathode, and means contained wholly within the interior of said vessel for imparting a predetermined turning movement to a work piece located within the vessel, whereby to expose successively different portions of the work piece to the emission from said cathode, said latter-named means including a first member stationarily mounted at the bottom of said vessel and a second member pivoted thereto for rotatively supporting said Work piece, said members having an inclined surface therebetween and further including means for triggering said members for increasing engagement thereof at said inclined surface under the weight of said work piece.

6. In an apparatus for applying metallic coating to a work piece by cathodic deposition, the combination of a vessel adapted to be evacuated and equipped with electrodes for effecting a dispersed emission of electrons from a portion of coating metal placed therein, an upright supporting pin adapted to have a generally tubular work piece telescoped down over the same, a head on said pin fixed thereto intermediate the ends of the pin and presenting a downwardly facing wedgeshaped portion, and a stationary supporting head mounted within said vessel and having a central bore therein for reception of the lower portion of said pin, said stationary head having a transverse V notch in its upper face complemental in shape to the wedge-shaped portion of the first-mentioned head, whereby the pin may be positioned with said wedge-shaped portion of the first-mentioned head extending transversely of said notch and thus poised in unstable equilibrium for turning of said pin through substantially ninety degrees as the wedge-shaped portion of the first-mentioned head slides down into said notch when the pin and head thereon are jarred out of their position of unstable equilibrium.

7. In an apparatus for applying metallic coating to a work piece by cathodic deposition, the combination of a vessel adapted to be evacuated,

means including anode and cathode electrodes within said vessel for setting up a dispersed electron emission from said cathode, means including a rotatable gravity biased carrier for a work piece,

manually alignable surfaces for supporting said carrier in an elevated position, said surfaces being temporarily restrained against movement but arranged to be misalined upon jarring of said vessel to cause dropping of said carrier under the influence of gravity, said alignable means having inclined mating surfaces thereon to produce a predetermined turning movement of said carrier and work piece as an incident to said dropping, such turning movement serving to expose successively different portions of the work piece to emission from said cathode.

8. In an apparatus for applying a metallic coating to articles by cathodic deposition, the combination of a vessel having an opening through which work pieces may be inserted and a closure for such opening adapted to hermetically seal the same, means for evacuating said vessel, a plurality of cathode wires arranged in parallel spaced relation in said vessel, an anode plate of extensive face area located substantially flatly in the bottom of said vessel in position to be spaced from and substantially normal to said cathode wires, spaced parallel cathode wires carried by said supporting means, means for applying high potential between said wires and said plate, whereby to effeet a dispersed electronic emission from said cathode wires, and means for supporting a cluster of work pieces about each of said wires, said clusters being merged so that a given work piece lies within the zone of electron dispersion from more than one of said cathode wires.

HAL FREDERICK FRUTH.

REFERENCE S CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,090,926 Lutz Mar. 24, 1914 1,163,329 Edison Dec. '7, 1915 2,043,966 Whiston June 9, 1936 2,186,380 Hirsch Jan. 9, 1940 FOREIGN PATENTS Number Country Date 375,275 Germany May 8, 1923

Images