JPS59175541A - Cathode structure for magnetron - Google Patents

Abstract

PURPOSE:To weld a fine powder or plate of getter metal to almost the entire part of external edge surface of end hat with sufficient intensity by providing a brazing material reservoir to the cylindrical end region of end hat and integrally fixing it to the stem lead line by the brazing material. CONSTITUTION:An eyelet type end hat 10 is provided with a brazing material reservoir at the cylindrical end region 11 thereof and the stem lead wire 7 and end hat 10 are integrally brazed to a brazing material layer 13 extended vertically from said brazing material reservoir 12. However, the brazing material resservoir 12 is formed by making narrower the external diameter of end region of cylindrical part 11 than the external diameter of other region and the ring shaped sintering brazing material 14 is engaged with the brazing material reservoir 12 before the brazing. This sintering brazing material 14 melts when it is heated in the high frequency induction furnace and runs downward vertically, forming the brazing material layer 13. Thereby, the end hat and stem lead wire are placed in contact with the brazing material layer in the wider area and is strongly welded. Moreover, fine powder or plate of getter metal can be welded strongly to the external edge of end hat.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a cathode assembly for a directly heated magnetron.

Conventional Structure and Problems A directly heated magnetron used in a microwave oven or the like usually has a built-in cathode structure as shown in FIG. This cathode structure consists of a spiral cathode 1 made of thorium kungste/
, first and second eyelet-shaped end hats 4 and 6 made of molybdenum, which are soldered to one end edge and the other end edge of the cathode 1 with solder layers 2 and 3, respectively, and the stem insulating base 6 are hermetically sealed. A p% first end hat 4 consisting of first and second stem lead wires 7 and 8 made of penetrating molybdenum is soldered to the inner edge of the first stem lead wire 7 through a solder material layer 9. , the second end hat 5 is arc welded to the inner edge of the second stem lead wire 8. In such a cathode structure, the second end hat 5 is arc welded to the inner edge of the second stem lead wire 8. After arc welding, the cathode 1 and the first end hat 4 are sequentially mounted at predetermined positions, and then a liquid brazing material mixed with molybdenum powder, ruthenium powder, and a binder such as nitrocellulose is applied to the brazing material layer 2. , 39, and heat-melt the solder material.

However, the first end hat 4 and the first stem lead wire 7 fitted into its center hole are fixed by a thin brazing material layer 9 formed on the outer end surface of the first end hat 4. Therefore, there was a drawback in that it was difficult to obtain sufficient adhesion strength. Furthermore, when a large number of fine powders of getter metal such as titanium are welded to the outer end surface of the first end hat 4, the solder layer 9 becomes an obstacle. This is because the outer end surface of the filler metal layer 4 has a large number of unevenness microscopically, so that the fine powder can be welded there with sufficient adhesion strength, but the solder layer 9 has a very smooth surface. Therefore, the fine powder cannot be welded thereto with sufficient sticking strength.

OBJECTS OF THE INVENTION It is an object of the present invention to be able to firmly solder the first neck tip to the inner end edge of the first stem lead wire, and to make it possible to firmly solder the first neck tip to the inner edge of the first stem lead wire. The object of the present invention is to obtain a cathode structure in which a getter metal fine powder 1' or a plate can be welded to substantially the entire area with sufficient adhesion strength.

Structure of the Invention In the cathode structure of the present invention, the tip region of the cylindrical portion of the eyelet-like end hat is provided with a solder material reservoir having a smaller outer diameter than other regions, and the solder material hanging from the solder material reservoir is provided. The wire and the stem lead wire are integrally brazed to the layer, and this will be explained in detail below with reference to the embodiments shown in the drawings.

DESCRIPTION OF THE EMBODIMENTS The cathode structure shown in FIG. 2 is different from the cathode structure shown in FIG. 1 in that the cathode structure shown in FIG. 2 is different from the cathode structure shown in FIG. 10 is a 1/1 m iron material reservoir 1 in the tip region of the cylindrical portion 11.
2 and a layer of brazing material 13 hanging down from this brazing material reservoir 12.
Therefore, the first stem lead wire 7 and the first stem node 10 are brazed together. However, the solder material reservoir 12 is obtained by making the outer diameter of the tip region of the cylindrical portion 11 smaller than the outer diameter of other regions.
As shown in FIG. 3, a ring-shaped sintered solder material 14 is fitted into the solder material reservoir 12 before soldering.

15 is a fine powder of getter metal made of titanium or the like which is heat-welded to the outer end surface of the first end hat 1o, and is maintained in a powder state.

The ring-shaped sintered brazing material 14 is made of, for example, ruthenium (Ru
) powder and molybdenum (MO) powder mixed at a total weight ratio of 3:7, or a Ru-MO alloy powder. The material is placed in a mold together with a binder such as a nitrocellulose solution and compressed to 100%
It becomes a sintered body by undergoing heating texture at a temperature of 0 to 15008C. The sintered brazing material 14 is supported in a fitted state in the solder material reservoir 12 as shown in FIG. A material layer 13 is formed.

Effects of the Invention Since the yin-dong structure of the present invention is constructed as described above, the first
The head knot and the first stem lead wire are in contact with the solder material layer over a large area and are firmly soldered together.

The outer end surface of the first end/% throat is no longer covered by the solder material layer, and the getter metal fine powder or plate can be firmly welded to the outer end surface.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a conventional magnetron cathode assembly, FIG. 2 is a side sectional view of a magnetron cathode assembly according to the present invention, and FIG. 3 is a side sectional view of 9 parts of the same cathode assembly before soldering. It is a diagram. 1...Cathode, 7,8...Stem lead wire, 5゜10...End hat, 11...
...Cylindrical part, 12...Brazer material reservoir, 13...
...Brazing material layer.

Claims (1)

[Claims] An eyelet-shaped end hat fixed to the inner end edge of the stem lead wire in order to support and fix one end edge of the spiral cathode is inserted into the tip region of the cylindrical part into which the inner end edge is completely fitted. , the stem lead wire and the end hat are integrally soldered together by the solder material layer hanging down from the solder reservoir. Cathode structure for magnetron.