US2451877A - Method of manufacturing oscillator plates - Google Patents

Description

Oct. 19, 1948. w. H. E. sAMuELSoN 2,451,877

METHOD OF MANUFACTURING OSCILLATOR PLATES Filed ot. e, 1945 @je Y'MM,

ATTORNEYS Patented Oct. 19, 1948 man t'orporation;I (Sarlisle;

fof Pennsylvania. j

Pai., a: corporation` spoliation october 6, 1945, 'serial No '6265720 1 This invention 'relates 'to the fmanufactureof quartz oscillator plates and the "like, andinas for its "object certain improvements in the method of :depositing lmsof m'etal on quartzffo'scillator plates andthe like. "Quartz "oscillator plates teridto lose factivitv onageing, `for 'rexam'p'le`, 'by beingfstoredl Various treatments `Aof 'the Aplates have been 'proposed to restore the activity of 'the plates, 'at 'least iirlarge' part. Among. such `treatments isY thatof `'sputter'- in'g the Ypfates 'witlrfa'suitabl'e metal, v'such as "'gol'd: The Lmost common method is to cover the plates' completely with a thin `layer 'or coating if"'. gfolol;` not only the y'surfaces'of 'thetv/o major sdes'or faces but falso the lsurfaces 'of the :edge portions ofthe-.plates For oscillatingpurposesthe plates must 'have high tel-ectric'al Iresistance Fbetwe'r'ithe surfaces of theitwofmajor l'faces'air'id lit is, therefore, necessary to `remove thewg'ol'd from'- the' edges oftheplat'es.I This@isusuallydoneb'yabrading thegold ffrom ithe'edgefportions `of the fplats. As a result -of fthe 'abrading "operation, 'the soil"-V lator plates 'a're' yfrequently scratched, and?tliis'"in turn impairs their oscillating characteristics;

The all-gold Icoated"osoillatcnr' 'plates 'tendto have 'further .undesired characteristics; Fori Sexample', they 'tend toA have l:a lower "atctivitythan that or the uncoated, but funaged, "plates Some of `the coated oscillator plates "also" 'tend yto fo'scll late with a :spurious frequency. 'This latter "trait is especially ldetrimental because-its 'oc'currerue-` is'er'ratic,'unpredictableandnot necessarilyrepr ducible even inthe same oscillatorplate l"millincoated quartz oscillator plate which exhibits 'fno' spurious frequency may lshow one 'orfmo'r'e after being covered with gold. f 4As a result 1of 'iny investigations,y I fhavefdlsbv covered that iffthe -quartz Aoscillator" plates are' coated with metal fin a `certain' manner, 'disad' vantageso'f the-kind enumerated 'may bcvlargely overcome. The thin film, coating Ior layer ofvv metal-maybe deposited on the oscllator'platesain suchfa manner as toiniake unnecessary th'e'"'cus'-" tomary abradingoperation on. the edge Tp'orti'rs and? thus minimize greatly thelfancesofsciatch ingf or` otherwise impaiiing the tw'o main surfaces of the oscillator plates. -In accordance with Ythe method tof lthe "present invention, -a iilm of a suitablemetal iis `."dep'osite"d falce of-each plate Yand av'similarlm of netali's deposited -on fa "spot on Vtl'ie other major Nvface'. of each plate.

Theltwomain sides or surfacesfthe'oscillator platesfarezadvantageously coveredisimultaocousiy 3- claims. (chaos-.imm

With metal in the manner indicated.' Thisc'an beld'onelinV sucli la Way "that the fside of thefplate containing the'- spot wur contain no metamc deposit lother"thari the spot. "This Vspotis l advantagusly 16C-'ated dertllylU-'th Oscillator plate and. `premiati;zlofiIpredeterimmedfsizefdepend lrig iipon "the size Earid"intended use 'of fthe' "oscillatorp'lfate. 1"

M a'presentlyipreferredpractioe offtheihvenelmetl l c'lrnsarefdeposited on theloscil- 1 tes iy'? rneah's 4fof: fa high voltage across a neta' node 'androne cram/ore metal'oathodes operatinsfirrfnfevacuated chamber vhavling the necessaryijelectricalconnections" lThe cathode disintegratesfa'd tliemetl of *which it Eis' -made is de` posited oritenfdsto Vdeposit :upon the anod'e'as :an extremely thinA "and homogeneous film. i A `hat sheet ror -'plate' Pof aluminum 'is advantageously lhplyedsfthef ano'de; the anodebeing punched with" `a plurality" `of-'spaced :holes of la 'size 'correspendingLto'thefmetdilicspots tothe placed on the oscillator plates. The cathodes are advantazontally liiis'xosed and :equidistanuy spaced beti'cfof fthe ivetoh; "YIhe oscillator lates nnra'node; each plate` beirg centered *over one "ofi theinoItfsintnef'anode` 4*Phenopersurface 'ofi each oscillator Aplte iis'fcoinpletely exposd,"fas is so much ofitlelower surface ofeach oscillator plate: ove'f'the holes.` r AThe remainder `of "the llower surfacefof thel oscillatorplaies'is `inl cdntactwith the iuninumiarode randliis, therefore, masked off;

Thefohaniber i'suvcuated Vin the usualvrnanner and fnignvoltage lcz'irrent fi'sj" passed Y:aomss the anode and 'ca'tlo'des This causes 'the gold inthe cathodes fgradalll-y fofdisintegrate, A fillingv the climber withleoidfvapor'wiiicndeposits or tends tcdeposit on tiiefaiuminmn'anode and-,therefore deposits i s; nini on fthe exposed upper' surface fof' th" sciuetorplstesand so much-of the-under surf ce f"the'oscillator plates asis Aexposed by tllholesin'ithfjluniinum anode.`

'Thifintetiori 'will "be better understood by referring to Athe 'accompanying drawing," taken in conifiiiidtlori with ithe following `desc1"iption, in \'v1'iit-:`liL-"V 1" Y" 'Figl 1 is a-sidfelevation' Tin" ysection jon the 'line IL-Qlofiof fahffa-pparatus illustrative of a ln'actice'offthef-imrerltiong v i l "Fig-12 isaplanvievvpartlyinsectin and partlv inw'rfiameritary Lsections of the same apparatus; Fig. 3\is"'a diagrammaticIrepresentationof the;

iriir'x-ialllamlfangdientfofthe apparatus;

Referring rst to Fig. 1, the apparatus shown comprises a glass bell-jar or cover III, dening a chamber II. The lower circumferential edge secured thereto by means of a nut 48 turned tightly on the upper threaded portion of the conductor rod.

Vertical support 36 is advantageously constructed in the same manner as vertical support 35. It is therefore unnecessary to describe its construction in detail. It consists of a rod 55 threaded at both ends to receive nuts 56 and 51,

and thereby hold in place truncated insulator 58, nut.59, slotted shoulder 60 of lower aluminum plate 28, cylindrical insulator 6I and slotted portion I2 of the bell-jar fits snugly within an annular groove I3 of a rubber gasket I4 resting on a metal base I5. The bell-jar and rubber gasket are readily removable as a unit from the steel base.

One end of a conduit I6 is nonleakably screwed into an opening I1 in base I5, thus communicating with chamber II, and the.

other end of the conduit connects with a source of vacuum, not shown. 1

The parts located within chamber II- comprise a pair of spaced metallic cathodes and 2| and a metallic anode 22 midway between the two, all horizontally disposed to base I5. In a presently preferred practice, the cathodes are formed of gold and the anode of aluminum. Thus, upper cathode 20 is formed of a thin sheet of gold or gold foil23 underlying an appropriately supported upper aluminum plate 24, the overlying edge portion 25 of the gold sheet being bent upwardly and over the top of the edge portions 0f a glass plate 26 resting on the top'of the upper aluminum plate. In similar fashion, lower cathode 2| is also formed of a thin sheet of gold or gold foil 21 overlying an appropriately supported lower aluminum plate 28, the overlying edge portion 29 of the gold sheet being bent downwardly and over the top of the edge portion of an appropriately supported glass `plate 30 located immediately below the lower aluminum plate.

As shown, upper aluminum plate 24 and lower aluminum plate 28 are;held in position by two oppositely located vertical supports and 3E,

the former being provided with an electrical conductor. Thus, support 35 consists of a vertically disposed conductor rod 31 threaded at both ends, the lower end of which extends through an' opening in base I5 andthe upper end of which extends through a slotted opening 38 in a shoulder portion 39 of upper aluminum plate`24. The conductor rod is held in positi-onby means of a nut 40 secured well above the lower end of the rod, an insulating washer 4I being disposed between'the nut and the lower side of base I5, and a truncated porcelain insulator 42, the lower portion of which is reduced in sizeto fit snugly in the same open-- ing of the base through which the rod extends, thus forming a shoulder portion 43 resting upon the base, The truncated porcelain insulator fits around an enlarged lower section of the conductor rod, the upper end of the enlarged section being threaded to receive a stop nut 44. The conductor rod extends through a slotted opening in a shoulder portion 45 of lower aluminum plate 28 which rests on the nut. A cylindrical porcelain insulator 46 nts around the upper and reduced section 41 of the conductor rod, the lower end of the insulator resting one the top of shoulder portion 45 of lower aluminum plate 28. The upper end of the` insulator terminates at the upper threaded end of the conductor rod. Shoulder portion 39 of upper aluminum plate 24 is located on the upper end of.` the insulatorand is shoulder 62 of upper aluminum plate 24, In the construction shown, however, vertical support 36 is not designed to form part of an electrical circuit.

Returning to vertical support 35, its electrical connection is provided by means of a high Voltage line 65, connectible with a source of current,

' not shown, and a terminal 66 secured to conductor rod 31. The terminal is disposed between nut 40 and a securing nut 61' on the lower end of the conductor rod.

Turning next to anode 22, it will be noted that it is held in position by three spaced vertical supports 10, 1I and 12. They are similar in construction, except thatl the latter is connectible electrically with the source of high voltage current to be employed. Thus, vertical support 12 consists of a vertically disposed conductor rod 13 threaded at both ends, the'lower end of which extends through an opening in base I5 and the upper end of which extends through a slotted opening 14 in a shoulder portion 15 of aluminum plate 22. The conductor Irod is held in position by means of a nut 1B secured to the lower end of the rod, an insulating bushing 11, which fits snugly in the hole in the base, a cylindrical porcelain insulator 1.8 and a nut 19 secured to the upper end of the-conductor rod. The electrical connection is provided by means of a high voltagevline 8D, connectible with the source oi high voltage current, and a terminal BI. The terminal is disposed between nut 16 and insulating bushing 11.

Still referring to anode 22, which, as stated, is an aluminum plate. in a presently Apreferred practice of the invention, it will be noted that its top portion is: subdivided into a plurality of rectangular recesses spaced from one another by relatively narrow criss-cross top portions 86 of the aluminum plate. The rectangular recesses are preferably of a size easilyto accommodate rectangular quartz oscillator plates 81. While rectangular recesses are shown, it will be obvious that they may be circular or in other desired conguration. In the construction shown, each recess is provided-with a centrally located hole 88. preferably of predetermined size so as to make possible a sputtered spot of predetermined size. An advantage of the recess is that when an oscillator plate* is placed therein, it is automatically centered or aligned with the hole in the recess so that the spotof the oscillator plate to be sputtered is centrally located.

Referring again to anode 22, as more particularly illustrated in Fig. 6, a modified practice is shown in part. It may be desirable to sputter a spot on both major faces vof the oscillator plates. This may be accomplished, for example, by placing a mask 89'on the top of anode 22, the mask being provided with a plurality of suitably lspaced holes III),` preferably juxtaposed to holes 88 in the anode proper.

Glass plate 30, which is located immediately below and preferably in contact with lower aluminum plate 28 forming a part of the lower cathode construction, is freely supported on three Vertically disposed and spaced supports 9|, 92 and 93, resting on base I5. The supports may, for example, be formed of cylindrical porcelain, such as used in the other vertical supports. The supports for the glass plate may merely rest on the base, although they may be secured thereto, if desired.

The apparatus described m-ay be operated as follows in the practice of the invention:

With bell-jar l0 removed, a quartz oscillator plate 8l is placed in each recess 85 of anode 22. The bell-jar is then returned to cover the anodecathodes-assembly and chamber Il is evacuated through conduit I6 to a suitable subatmospheric pressure. High voltage current is next applied across terminals 66 and BI and thus across cathode and anode 22 and across anode 22 and cathode 2|. 'This causes gold foil 23 o-f cathode 20 and gold foil 21 of cathode 2l gradually to disintegrate, lling chamber I'I with sputtered gold vapor. Some of the gold vapor is deposited on exposed surfaces of the quartz oscillator plates to form a thin and homogeneous film. The top and edge and the bottom circular spot surfaces,

being the only portions of the oscillator plates thus exposed, are therefore covered with gold in this manner. After a suitable interval of time, enough to deposit the desired amount of gold, the application of current is discontinued and the vacuum broken; after which the bellejar is removed and the treated oscillator plates are removed. In Figs. 4 and 5, the deposit is shown as a top and edge lm 95 and a bottom spot 96.

If, on the other hand, it is desired to sputter a spot on each major face of loscillator plates 81, mask 89 is placed on the top of anode 22. sputtering of gold from cathodes 20 and 2l takes place, spots 89 are also placed on the oscillator plates. Portions of the oscillator plates covered by the mask willV then obvlbusly not be sputtered with the gold. When the spots are centered in the manner indicated, they provide electrode contacts, which brings the electric field to the center of the oscillator plates where it does the most good.

While in the practice described above high voltage cathode sputtering is employed, it will be clear to those skilled in this art that other means may be employed to deposit the film of metal in the manner desired. Arc sputtering may also be used. Pencils of the metal to be deposited may be brought together with a suitable electromotiveforce applied between them. A voltage may be f from a heated container in the chamber, or thermal evaporation of the metal, for example, as a coating from heated tungsten filament. It Will thus be clear to those skilled in this art that the practice of the invention lends itself readily to a number of highly useful modifications.

claim:

l. The method of simultaneously producing by cathode sputtering electrode coatings on the opposed major faces of an oscillator plate, which consists in supporting the plate with one major face resting downwardly on an apertured ancdic support in bridging relation to the aperture whereby said face is partially shielded and partially exposed, exposing at least a part of the opposed major face of the plate, and cathode sputtering metallic coatings on the exposed areas of said plate by passing a high voltage across said anodic support and a coating-metal-disintegrating cathode.

2. The method of simultaneously producing -by cathode sputtering electrode coatings on the opposed major faces of an oscillator plate, which consists in supporting the plate with one major face resting downwardly on an apertured anodic support in bridging relation to the aperture whereby said face is partially shielded and partially exposed, exposing the entire opposed major face of the plate, and cathode sputtering metallic coatings on the exposed areas of said plate by passing a high voltage across said anodic support and a coating-metal-distintegrating cathode.

3. The method of simultaneously producing by cathode sputtering electrode coatings on the opposed major faces and side edges of an oscillator plate, which consists in supporting the plate with one major face resting on an apertured anodic support in bridging relation to the aperture whereby the support-engaging face is partially shielded and partially exposed, exposing the entire opposed major face and the side edges of the plate, and cathode sputtering metallic coatings on the exposed areas of said plate by passing a high voltage across said anodic support and a coating-metal-disintegrating cathode.

WALLACE H. E. SAMUELSON.

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

UNITED STATES PATENTS Number Name Date 1,099,934 Rafn et al June 16, 1914 1,765,413 Fruth June 24, 1930 1,848,630 Hulbert Mar. 8, 1932 2,239,642 Burkhardt Apr. 22, 1941 `2,249,933 Bechmann July 22, 1941 2,256,771 Berghaus et al Sept. 23, 1941 2,313 ,059 Hight Feb. 29, 1944

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