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2,139,640 Patented Dec. 6, 1938 PATENT OFFICE ‘ UNITED STATES’ 2,139,640 METHOD FOR METALIZING SURFACES Eugen Mall, Stuttgart-Bad Cannstatt, and Wal tcr Dorn, Stuttgart, Germany, assignors to Rob ert Bosch Gesellschaft mit beschri'mkter Haf tung, Stuttgart, Germany No Drawing. Application March 17, 1937, Se rial No. 131,532. In Germany March 30, 1936 13 Claims. (CI. 41-18) The invention relates to a method for metaliz~ ing surfaces by the purely thermal vaporization of metal in vacuo, in which the metal to be va porized is heated in an evacuated vessel until it vaporizes, and the vapour is also precipitated in vacuo directly on the surface to be metalized. In this method in order to keep certain places on the surfaces to be metalized free from the depo sition of metal, stencils have hitherto been em ployed to cover the surfaces at the places in ques tion. Such stencils have the drawback that they also become coated withthe metal, so that the places left free by the stencils increase in size in course of time. It is thereforenecessary to change the stencils very frequently. In a con tinuous vaporizing method, in which metal-free and metalized places alternately succeed each other on a running band,‘ the stencils have also the drawback that they must be arranged to run iii) with the surface to be treated with vaporized metal. ' According to the invention, the places to be kept free from metal are made in a substantially simp'er manner by their being covered before the metalizing with a substance, and which on heat 25 ing in vacuo produces vapours. It has been. found that no metal precipitate is formed at such places. This is to be ascribed to the very hot molecules of metal vapour when vaporizing in 0 vacuo liberating vapours from the substance ap plied at the places to be kept free from metal, which form a cushion against the penetration of the molecules of metal vapour; The substance applied at the places to be kept free from metal is preferably in a liquid or semi liquid state. As substances for preventing the precipitation of metal, hydrocarbons or hydrocarbon-like sub stances come principally in question. Greases 40 and oils have been found very suitable. Halogen derivatives of the hydrocarbons, and further, al cohols, such for instance as glycerine, as well as resins, waxes, paraiiins and other organic sub stances, are however also suitable. ‘ As for example in the case of grease, even the . slightest traces of grease su?lce to prevent a deposit of the metal, the desired end can even be obtained with extremely thin layers or films of grease. The use of very thin layers is espe 60 cially advisable, because thereby the edges of 45 the layer are prevented from running and pro ducing metal edges on the surface which are blurred. For the technical production of the metal de 55 posit while leaving certain places free, the pre cipitation inhibiting layer is applied to the sur face to be metalized by printing or impressing it thereon. Any desired design can be obtained by this means in the metal layer in the simplest way, either by printing the design itself, in which case the design copy remains free from metal, or by ~ printing with a negative of the design whereby then the design itself is formed as-the metal deposit. For the printing, not only the oils customary in printing, but also any other oil can be em ployed. Where it is desired to obtain very sharp edges, substances are preferably used whose sur face tension is small at the temperatures em ployed, so that the edges do not become indis .10 tinct. Besides oils, greases, such for instance as petroleum jelly, and also resins and waxes or other organic substances may be used in the very thinnest layers for the printing. ' If it is a question of metalizing bands or strips, 15 for instance paper bands, one can for example, when using a very thin grease layer, ?rst print the paper of a whole roll with the design in grease, and wind it up again, without the non printed parts thereby becoming greasy. The roll 20 is then introduced into the vaporizing apparatus, the strip or band unwound from the roll, led past the vaporizing nozzle, and again wound up. In cases where it is desired to get sharp metal edges, it is however better to do the printing'or impressing in the vacuumized vaporizing appa ratus directly before the vaporizing, so that the grease has no time for its edges to become blurred. The method is applicable for imprints or im pressions of all kinds, thus for instance for ad vertising purposes on wrapping paper, or for sim ilar purposes.’ Further, it is very suitable for making metal ized paper, such as can be employed for the con struction of electrostatic condensers. By mark ings according to definite paper lengths, made for example with grease, metal-free marks can‘ be provided in the manufacture of metalized paper, which subsequently, when assembling a condens er, give an indication of the wound up effective 40 length of the paper. As in these condensers the metalized paper must usually have an edge free from metal, this edge may also be made by greas ing or by applying any other precipitation-inhib iting substance, before the vaporizing. The method described may also be used for the manufacture of condensers in which the metal deposit is applied to plates of mica or plates of a ceramic material. In this case, the places on the plates that are to be kept clear of metal are 50 covered with the substances mentioned before the metalizing operation. ‘ ' The method is also suitable for the manufac ture of resistances. If, for example, thin layers of metal are applied to strips of insulating ma. 55 terial by vaporizing metal, the metal coating of the strip represents an ohmic resistance. This resistance can be increased by the metal layer running in meandering form on the strip or band. Forthis purpose, it is only necessary to print the 2 2,139,640 band in meandering form w;th a precipitation the surface to said metalizing operation to pre inhibiting substance, such for instance as grease, cipitate metal on the uncoated portion of said surface. 5. A method of metalizing surfaces by the thermal vaporization of metal in vacuo compris ing applying to a portion of the surface a, thin ?lm-like coating of an organic substance liber ating vapours when heated in vacuo, and then subjecting the surface to said metalizing opera tion to precipitate metal on the uncoated portion 10 of said surface. 6. A method of metalizing surfaces by the thermal vaporization of metal in vacuo com before the vaporization, so as to cover those places which are to remain free from metal in the vaporizing. Paper bands metalized in mean ders in this way can be rolled up into rolls, and very useful ohmic resistances for electro-techni cal purposes are thus o‘zained which are excel lent-hv adapted, for exar ole, for combination of 10 resistances and capacities. Electrical disc coils may also be made in a cor responding way. It is only necessary to make longitudinal stripes, for instance with grease, on a strip of insulating material. On the succeed 15 ing vaporizing, metal stripes are produced be tween the grease strips and on the winding up of the paper, form disc coil windings, which can be connected together in parallel, or, for exam pie for producing very high voltages, in series. The method described is also suitable for mak ing cinematograph ?lms when the picture to be projected is applied to a transparent ?lm band in the form of a met :11 grid or screen. The places left free between the points of the grid are first imprinted with a precipitation inhibiting sub stance, such as grease. The ?lm is then treated with metal vapour. Pictures made in this way prising a-ppTying to a portion of the surface a thin coating of a precipitation-inhibiting substance 15 of low surface tension at the temperature of treatment and liberating vapours when heated in vacuo, and then subjecting the surface to said metalizing operation to precipitate metal on the uncoated portion of said surface. 20 7. A method of metalizing surfaces by the thermal vaporization of a metal in vacuo, com prising printing a portion of the surface in vacuo with a vaporizable precipitation inhibiting sub stance, and then subjecting the surface to said 25 metalizing operation to precipitate metal on the unprinted portion of said surface. 8. A method of metalizing strips or bands have the advantage that the metalized opaque points strongly reflect the light and do not ab sorb it, like the black places in the present ?lms do. When however less absorption takes place, the ?lm is less strongly heated during the pro which consists in printing a portion of the surface of the strips or bands with a vaporizable sub 30 jection. cipitate metal on the unprinted portion thereof. The method described can also be employed for sound-?lm records, by causing for example an oil-bearing member preferably of flexible ma terial, to oscillate with light friction on the ?lm band to correspond to the recorded sound oscil lations, and thereby mark a touch of oil on the 40 ?lm band running past, the limits of which vary corresponding to the sound oscillations. After this recording, the band is developed by metal vaporization, and can then be employed in known manner with incident or transmitted light for . the sound reproduction. We declare that what we claim is: l. A method of metalizing surfaces by the ther~ mal vaporization of metal in vacuo comprising applying to a portion of the surface a thin coat ing of a precipitation~inhibiting substance liber~ ating vapours when heated in vacuo, and then stance inhibiting precipitatlon, and then treating said bands or strips with a metal vapour to pre 9. A method of manufacturing metalized pa. pers which are provided with a design, picture or legend, comprising printing the design picture or legend on the paper in a vaporizable precipi tation inhibiting substance, and thereupon metal izing the portion of the paper not covered there by by thermal vaporization of metal in vacuo. 10. A method of manufacturing metalized pa pers which are provided with a design picture or legend comprising printing, all the paper ex cept the design picture or legend with a vapor izable precipitation inhibiting substance, and 45 thereupon metalizing the portion of the paper not covered thereby by thermal vaporization of metal in vacuo. 11. Method of making a band or strip or in sulating material coated with metal, for exam 50 ple, paper for roll condensers comprising ap plying a thin coating of a vaporizable precipita-_ subjecting the surface to said metalizing opera tion to precipitate metal on the uncoated por tion of said surface. 2. A method of metalizing surfaces by the ther mal vaporization of metal in vacuo comprising said band or strip and then metalizing the un coated portions of the material by thermal va porization of metal in vacuo. applying to a portion of the surface a thin coat in" of a precipitation-inhibiting substance in a 12. A method for thamanufacture of dielectric condensers comprising applying to at least one ‘ uid or semiliquid condition which liberates va pours on heating in vacuo, and then subjecting the surface to said inetalizing operation to pre~ ‘ate metal on the uncoated portion of said surface. 3. A method of metalizing surfaces by the thermal varxirization of metal in vacuo compris ine applying to a portion of the surface a thin coating of a hydrocarbon or hydrocarbon-like substance and then subjecting the surface to said inctaiizing operation to precipitate metal on the uncoated portion of said surface. 4. A method of metalizing surfaces by the thermal vaporization of metal in vacuo compris ing applying to a portion of the surface a thin coating of a grease or oil, and then subjecting tion inhibiting substance at spaced points along 65 edge of a strip of paper or the like a thin coat ing of a vaporizable precipitation inhibiting sub 60 stance and then metalizing the uncoated portion of the paper by thermal vaporization of metal in vacuo. 13. A method for the manufacture of metallic reactances comprising applying a thin coating of a vaporizable precipitation inhibiting sub stance in meandering form to a portion of the surface of an insulating material and then metal izing said insulating material by thermal va porization of metal in vacuo whereby the metal is 70 deposited on the uncoated portion of said insu ‘rating material in meandering form. EUGEN MALL. WALTER DORN.