US3069585A

US3069585A - Tensioned cross wire grid having soldered crossing points

Info

Publication number: US3069585A
Application number: US843578A
Authority: US
Inventors: Katz Helmut
Original assignee: Siemens and Halske AG
Current assignee: Siemens and Halske AG
Priority date: 1958-10-16
Filing date: 1959-09-30
Publication date: 1962-12-18
Anticipated expiration: 1979-12-18

Description

Dec. 18, 1962 H. KATZ 3,069,585

TENSIONED qRoss WIRE GRID HAVING SOLDERED CROSSING POINTS Filed Sept. 30, 1959 United tates tice 3,069,535 TENSIONED CROSS WERE G HAVING SOLDERED CROSSKNG POINTS Helrnut Katz, Munich, Germany, assignor to Siemens and Halske Aktiengesellschaft Berlin and Munich, a corporation of Germany Filed Sept. 30, 1959, Ser. No. 843,578 Claims priority, application Germany Oct. 16, 1958 3 Claims. (Cl. 313348) This invention is concerned with a frame grid of the cross wire type comprising at least two layers of tensioned parallel wires made of tungsten, molybdenum and the like, positioned superposed so that the wires of diiferent layers extend at a desired angle, such wires being soldered together at the crossing points and having for this purpose, inter alia, a coating of at least one metal.

Planar frame grids of this kind have been extraordinarily useful in the case of disk type tubes. Such grids exhibit in operation of the corresponding tubes in addition of the best mechanical and heat conducting properties negligibly low inductivity and therefore permit operation with limit frequencies which cannot be reached at all with grids lacking the punctiform soldering.

For soldering the common crossing points of the grid wires together, it is in the interest of simplification of the operations and for obtaining very exact grids, generally necessary to provide the wires with a solderable coating, such coating melting upon soldering. However, such metal coatings frequently have the drawback that they assume in operation, by strong heating, be it due to slight spacing from the cathode or to current connected thereto, a considerable temperature at which the metallic coatings can vaporize. Accordingly, metals, having a relatively high melting point are used to form the coatings, gold being an example of such metals. On the other hand, the melting point must not be so high that the tungsten wire, which is in a tensioned grid subjected to considerable tensile stress, suifers detrimental recrystallization. The art is for these reasons bound to a maximum temperature which preferably shall not exceed 1000 C.

It is in view of this situation the aim and object of the invention to avoid metals with high vapor pressure, that is, metals which at such operating temperatures disturb a vacuum of Torr and less due to vaporization, and to permit nevertheless production of such grids at temperatures below 1000 C.

This object is, in connection with a frame grid of the cross wire type having at least two layers of tensioned parallel wires made of tungsten and directly superposed so that the wires of dilferent layers extend at a desired angle, with the wires at the crossing points soldered together, and using for the soldering, inter alia, a coating of at least one metal, according to the invention realized by employing a metal coating for the grid wires which contains in the range of the crossing points in addition to titanium at least one further metal adapted to form with the titanium below about 1000 C. a liquid phase required for the soldering without exhibiting a disturbing vapor pressure for a vacuum of 1( Torr or less.

Particularly suitable for applying this measure in connection with titanium are the metals copper and nickel, each of which forms with titanium a liquid phase respectively at 875 C. and 955 C.

The invention will now be explained with reference to the accompanying drawing wherein:

FIG. 1 shows in purely schematic manner a frame grid of the tensioned cross wire type according to the invention; and

FIG. 2 illustrates likewise diagrammatically the method of producing such a grid with the aid of an interposed foil.

The production of such a grid proceeds from a layer of titanized wires upon which is wound the second layer of nickel plated or copper plated wires. Upon the titanized layer is moreover placed an annular nickel plated or copper plated tungsten member or ring, such annular member serving as a carrier for the grid, and the resulting assembly is suitably heated to a temperature such as to produce alloy formation between titanium and copper (875 C.) or between titanium and nickel (955 C.), respectively, depending upon the given combination of parts. The liquid phase formed thereby solders the individual components together.

It is understood, of course, that the combinations of components may be modified as required, especially in view of the grid carrier which is simultaneously soldered into place; for example, a tungsten ring provided with a titanium coating may be placed upon the copper plated or nickel plated wire layer, as a carrier therefor.

In case it is desired that both wire layers be provided with a titanium coating, a foil 2, such as shown in FIG. 2 may be placed between the layers to serve as an alloying member. There is first formed the wire layer 1, upon which is placed the foil 2, for example, made of nickel, and such foil is formed by pressure exerted by a suitable tool, for example, molybdenum wires 3 wound in spaced relationship, so that the foil 2 is caused to sag at spaces between the wires 1. The second layer of titanized wire 4 is thereupon wound in place. The foil 2 now engages one wire layer along the generatrix of the cylindrical wire thereof while engaging the other layer only at the crossing points. The alloy will be formed at suitable temperature only at these points of engagement, also for the grid frame 5, thereby effecting the punctiform soldering.

Depending upon the manner in which the grid is built into the tube, none of these alloyed points will be facing the cathode side.

The foil parts remaining after the soldering are removed by applying a strong air blast or mild sanding or by suitable cauterizing.

It is understood, of course, that the use of the materials for the individual parts can also be modified in this method; for example, wires can be nickel plated and a foil of titanium may be used. The use of particular materials will depend upon a given application of the grid.

Changes may be made within the scope and spirit of the appended claims which define what is believed to be new and desired to have protected by Letters Patent.

I claim:

1. A frame grid of the tensioned cross wire type comprising a metallic carrier for supporting at least two directly superposed wire layers each having parallel wires made of material selected from the class consisting of tungsten, molybdenum and the like, the wires of the respective layers embracing a desired angle and being soldered together at the crossing points thereof and also being soldered to said carrier by the aid of a coating of metal provided thereon, said metal coating containing within the areas of said crossing points titanium and at least one further metal which is adapted to form with the titanium below 1000 C. a liquid phase for effecting the soldering and which does not have a vapor pressure disturbing for a vacuum of 10" Torr and less.

2. A tensioned cross wire type frame grid according to ciaim 1, wherein the metal coatings of the grid wires contain Within the areas of the crossing points titanium and in addition thereto a metal selected from the class of metals consisting of copper and nickel.

3. A tensioned cross wire type frame grid according to claim 1, wherein the solder consists of an alloy of titanium and a metal selected from the class of metals consisting of copper and nickel.

References Cited in the file of this patent UNITED STATES PATENTS 2,304,990 Ewing Dec. 15, 1942 2,577,103 Brian Dec. 4, 1951 2,628,046 Hart Feb. 10, 1953 2,661,029 Walsh Dec. 1, 1953 2,874,449 De Rooy et a1. Feb. 24, 1959 FOREIGN PATENTS 1,147,733 France June 11, 1957

Claims

1. A FRAME GRID OF THE TENSIONED VCROSS WIRE TYPE COMPRISING A METALLIC CARRIER FOR SUPPORTING AT LEAST TWO DIRECTLY SUPERPOSED WIRE LAYERS EACH HAVING PARALLEL WIRES MADE OF MATERIAL SELECTED FROM THE CLASS CONSISTING OF TUNGSTEN, MOLYBDENUM AND THE LIKE, THE WIRES OF THE RESPECTIVE LAYERS EMBRACING A DESIRED ANGLE AND BEING SOLDERED TOGETHER AT THE CROSSING POINTS THEREOF AND ALSO BEING SOLDERED TO SAID CARRIER BY THE AID OF A COATING OF METAL PROVIDED THEREON, SAID METAL COATING CONTAINING WITHIN THE AREAS OF SAID CROSSING POINTS TITANIUM AND AT LEAST ONE FURTHER METAL WHICH IS ADAPTED TO FORM WITH THE TITANIUM BELOW 1000*C. A LIQUID PHASE FOR EFFECTING THE SOLDERING AND WHICH DOES NOT HAVE A VAPOR PRESSURE DISTURBING FOR A VACUUM OF 10-6 TORR AND LESS.