Патент USA US2295759код для вставки
Sept. 15, 1942. C. L. SCHEER 2,295,759 CAPACITOR Filed June 30, 1939 / ////////////////////////// ?/////////// Gttomeg Patented Sept._ .15, 1942 - 2,295,759 UNITED STATES PATENT OFFICE &295.759 CAPACITOB Charles L. seheer, naddon?eld. N. J., a??ig?'?or to ne“Ilo Corporation of America, a oorpor?_tion oi w?re Application I??ne 30, 1939, Serial No. 282.299 5 Claims. (Cl. 175-41) i ~ This invention relates to capacitors oi the type treated illms, may be said to lose their identity wherein the armatures comprise metal applied in a fineiy divided state to the mica or other dielec ' tric. and to methods oi' making such capacitors. and form a sheet characterized by the substan tially `perfect physical and electrical continuity of the molecules of which it is constituted. This desired result is achieved in accordance with the method of the invention by subjecting a dielec The principal object ot the invention is to pro vide an improved capacitor, of the general type' tric. element. upon which the opposite metallic described. which exhibits a lower power !actor than has heretotore been thought possible oi practicai achievement. Another and important object of the present armature layers have been deposited, to a rela tively high temperature for a period su?iclently long to produce softening and virtual ?ow of the invention is to provide a simple, inexpensive and trouble-free method of accomplishing the afore metal, so that a welding, i'using, commingling or recrystallization of the formerly separate, or said object, and one which iends itself readily to the mass production oi! capacitors of the general partly separated. molecules or globules of the metal is e ected. as indicated by the smooth sur iaces B in . 2. This improved smoothness is type described. Other objects and advantages will be apparent usually evidenced in the ?nished ?lm by its sur face sheen. While the method ot the invention will be de accompanying drawing. wherein scribed as applied to a metallic iilm which has r'igure 1 is a sectional view ot part oi a capaci 20 been deposited on the mica by thermal evapora tor and illustrates the lack oi homogeneity in the tion. distiilation or sublimation, it will be appar metallic iilms oi the prior art; ent to those skilled in the art that the invention Figure 2 is a view of the capacitor ot Fig. 1 is likewise applicable to metallic ?lms which have been deposited by means of the Schoop spray subsequent to being treated in accordance with the principle oi the invention and illustrates the 25 process, or by electroplating methods, or by cathodic disintegration, or by substantially any homogeneity and physical continuity of the me other'h?own method or process for creating and tallic films; applying' metal in a ?nely divided state. Figure 3 shows, in sectional elevation, one ior?n In carrying the invention into eiiect, the mica of an apparatus for depositing metal in a ?nely divided state upon mica or other dielectric ele 80 2 is ?rst split to the required thickness and cut to size. The individual mica plates are then pref~ ments; erably provided each with a punched ori?ce 4 ad Figure 4 shows, in front elevation, a rack for jacent one end thereof, whereby they may be supporting a number of dielectric elements in the . and the invention will be best understood by ref erence to the following speci?cation and to the Suspended on pins E, which project rearwardly apparatus of Fig. 1; Flgure 5 is a cross-sectional view taken on the 35 from a !rame I which is provided with apertures ?o individual to the discrete mica plates. As shown more clearly in Figs. 4 and 5, the dimen sions or apertures ?o are somewhat less than those of the mica elements so that the side edges and top edge |4 oi' each element are e?fectively sliielded by the marginai edges IS of the frame which surrounds each mica element. When all of the mica elements are in place in the frame 8, line 5-5 of Fig. 4; and Figure 6 is a side elevational view of an ele mental capacitor constructed in acoordance with „ the principle of the invention. The present invention is predicated upon the fact, revealed by microscopic examination, that the metallic "mms" or "layers"` or "surface coat ings” of the prior art lack perfect physical con amasking plate ?s, which' is provided with a to the fact that such ?lms are usually applied to 45 number of apertures zu, is clamped tightly over the !rame as by bolts 22. The apertures 20 in the mica or other base in the form ot spray, vapor the masking plate ?s are preferably of the same or solution constituted oi discrete globules, or spaced apart molecules of metal which, as indi- ` size, but are oil'set in the vertical direction from the apertures I? in the frame 8 whereby the mar cated at A, Fig. l, to a substantial degree retain ' tinuity and homogeneity. This may be attributed their physical identity and haphazard distribu 50 ginal side and bottom edges ?z', l4', respectively, of the mica surface opposite the surface contain ing the masked edges i2 and !4, are exposed. With the mica plates mounted on írame 8 and masked by the masking plate !8 in the manner direct current resistance ot the metallic ?lms and is also manifest in the' ?nished capacitor-8 by the 55 above described, the assembly is supported on a substantial power factor which they exhibitvin suitable bracket 24 (Fig. 3) ?xed to the base tion when the deposition process has been com pleted. This lack of physical continuity and homogeneity is manifest by the relatively high use. h The present invention contemplates and its practice provides, a metallic ?lm wherein the dis ' 26 oi' an evacuable enclosure 28. Asvillustrated in Fig. 3, the enclosure 28 comprises an inverted vessel 30 adapted to be clamped to the base 26 crete globules of metal,_char_acteristic oi un 60 as by bolts u. suitable gaskets 34 are provided 2 ascunsa to ensure a gas-tight seal between the base !I and the vessel u. An outlet !I communicates with the interier of the enclosure and is con nected with a suitable pump, not shown, for evaculatinz the vessel. A valve u is provided for restoring atmospheric pressure when the mica has been processed. Supported in spaced rela two elemental capacitors, each of which com prises a. sheet of mica 2 and a pair of discrete metal films B which have been treated in accord ance with the present invention to e?ect a com mingling of the formerly separate, or partly separatedmolecules or globules of metal. Comparative tests of evaporated-metal ?lms before and after the described heat treatment tion above the base 2', as on rods 40 which ex showed a reduction of the order of substantially tend between and along the frames C-il which support the mica, are a plurality of tungsten or 10 ?fty percent in direct current resistance. Tests of complete capacitors showed a reduction in other refractory metal ?laments u which are each bent in a convenient form suitable for hold ing a piece u of the metal to be evaporated and deposited upon the exposed areas of the opposite surfaces of the mica. The number and spacing of the illaments 42 containing the metal to be evaporated is pref erably such that all of the mica plates are thor oughly and substantially equally bathed in metal power factor of the order of seventy-?ve percent. By way of example, a number of untreated (but its evaporation and deposited upon the mica. temperature of the order of from substantially substantial freedom from occluded gases and for eign solids is achieved at the lowest pressure 275° C. to substantially 325° C. for a period su?l ciently long to cause softening and virtual ?ow otherwise similar capacitors) exhibited a power factor of the order of .0006-.0008 at 1000 kilo cycles. whereas those treated in accordance with the present invention exhibited a power factor of .0001 to .0003. The foregoing description of the presently pre-~ vapor. The ?laments 42 are preferably con 20 ferred apparatus and means for achieving the obiects of the invention should be interpreted as nected to a common source of heating current, illustrative and not in a limiting sense except as not shown, so that when the enclosure 20 has required by the prior art and by the spirit of the become evacuated, evaporation of all of the metal appended claims. elements 44 occurs, thereby effecting the coating What is claimed is: of both sides of each mica plate simultaneously. 25 1. Method of decreasing the dielectric iosses The absolute pressure maintained in the en oi a capacitor comprised of a pair of conductive closure 28 during evaporation of the metal ?lm-like armatures constituted of metal in a should, for optimum results, preferably be no ?nely divided state and adhering to the opposite higher and preferably less than 0.0001 mm. of mercury (one-tenth of a micron). However, the 30 surfaces of an interposed dielectrlc layer, said method comprising subiecting said capacitor to a use of vacuum pressure considerably higher than temperature sufnciently high and for a period suf one-tenth of a micron may be employedas it has ?ciently long to cause softening and virtual ?ow been discovered that by varying the degree of of the metal. vacuum up to, say, two microns. the ultimate 2. Method of decreasing the dielectric iosses capacitance of the elements may be varied over 85 oi a capacitor comprised of a pair of conductive a substantial range. The general rule is the ?lm-like armatures constituted of metal in a higher the vacuum, the higher the ultimate ca ?nely divided state and adhering to the opposite pacitance. This phenomenon obtains by reason surfaces of an interposed dielectric layer, said of the relative quantity of gas and other foreign substances which are occluded in the metal during 40 method comprising subjecting said capacitor to a of the metal. mentioned. 3. Method of decreasing the dielectric losses of The deposition of the metal having been com 45 a capacitor comprised of a pair of conductive pleted the vacuum is broken by opening the valve film-like armatures constituted of metal in a u, the frames 8 are taken from the brackets 24, ilnely divided state and adhering to the opposite the masks !8 are lifted and the now coated mica surfaces of an interposed dielectric layer, said plates 2 are removed. subsequently and in ac cordance with the invention, these metallized di 50 method comprising subjecting said capacitor to a temperature of the order of from substantially electric plates are subiected to a temperature suf 275" C. to substantialiy 325° C. for a period of the order of from substantially flfteen to thirty minutes. lent results have been achieved simply by placing 55 4. Method of manufacturing a capacitor which comprises depositing a ?lm constituted of metal a batch of several hundred of these plates 2 ?clent to cause a welding, fusing, commingling or recrystallization of the moleculesor globules of which the metal ?lms are constituted. Excel in a tray in an ordinary oven (not shown) and in a ñnely divided _state upon the opposite sur subjecting them to temperatures of the order faces of a dielectric element, and subsequently subjecting said deposited ?lm to a temperature of 275-325° C. for a period of from, say, ?fteen to thirty minutes. The temperature and dura 60 su?lciently high and for a period su?lciently long to cause softening and virtual ?ow of said metal. tion of this heat treatment are not especially critical but may vary somewhat as determined by the nature of the metal and thickness of the 5. Method of manufacturing a capacitor which comprises mounting a dielectric element and a piece of metal in a vacuum, then subjecting said applied ?lms. Twenty minutes at apprcximately 300° C. is usually su?icient where the ?lm is silver 65 metal to a temperature sumcient to cause thermal evaporation of the metal whereby to cause it to and of a thiclmess of the order of a few one be deposited in the form of a ?lm upon the op millionths of an inch. The heating may be done posite surfaces of said dielectric element, and in vacuo, if desired, or partly in vacuo and partly subsequently subiecting said coated element to a at atmospheric pressure; however, as above indi cated, excellent results have been achieved on a 70 temperature sumciently high and for. a period sumciently long to cause virtual flow of the metal commercial scale in an ordinary oven Operating at substantially atmospheric pressure. Flg. 6 shows a capacitor comprising a stacir of constituting said ?lm. ' CHARLES L. SCHEER.