JP3493295B2 - Hermetic ceramic terminals - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airtight container such as a vacuum chamber or a liquefied gas tank used in a physics and chemistry apparatus, for example, which is used between an inside and an outside of the container. And to a hermetic ceramic terminal for inputting and outputting electricity. 2. Description of the Related Art Conventionally, in a hermetic container such as a metal hermetic container such as a vacuum chamber and a liquefied gas tank, an airtight ceramic terminal used for inputting and outputting electricity between the inside and the outside of the container is: For example, a cylindrical ceramic cylindrical body having a through hole in the center portion made of a ceramic material having excellent electrical insulation such as alumina ceramics, and a metal such as oxygen-free copper. A metal electrode rod which is inserted so as to hermetically close the through hole, and which is hermetically brazed and fixed so that both ends protrude forward and backward from the ceramic tubular body; and a metal such as an iron-nickel-cobalt alloy. And a metal ring-shaped fixture fitted and brazed to the outer peripheral surface of the ceramic cylindrical body, and a through-hole is previously formed in the container wall of the metal airtight container. The airtight ceramic terminal is inserted into the through hole with the rear end side of the electrode rod inside the container, and the fixing bracket is brazed or welded to the container wall by using joining means such as bolting. By air-tightly joining, the front end side of the electrode rod is attached to the airtight container with the outside facing outside, and the input and output of electricity inside and outside the airtight container via the electrode rod inserted into the through hole of the ceramic cylindrical body. The electrode rod and the airtight container are electrically insulated by a ceramic cylindrical body. [0003] However, this conventional hermetic ceramic terminal is generally made of a ceramic material such as alumina ceramics which forms a ceramic cylindrical body, and the surface thereof is hydrophilic. When the front end side of the electrode rod located outside the airtight container is used by exposing it to a humid atmosphere, the outer surface of the ceramic cylindrical body in this humid atmosphere has a large amount of moisture in the atmosphere. Adsorb and wet the outer surface with a continuous water film, and as a result, between the electrode rod of the hermetic ceramic terminal, the fixing bracket and the hermetic container through the outer surface of the continuously wet ceramic cylindrical body. There is a disadvantage that an electric leakage occurs. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an electrode through an outer surface of a ceramic cylindrical body due to moisture in an atmosphere even when used in a high humidity atmosphere. An object of the present invention is to provide a highly reliable hermetic ceramic terminal which does not cause a leakage between the rod, the fixing bracket and the hermetic container. [0005] The hermetic ceramic terminal of the present invention has an electrode rod hermetically fitted and fixed with both ends protruding forward and backward into a ceramic cylindrical body, and has an inner diameter of the electrode. The outer diameter of the rod, the outer diameter is adjusted to the end face of the ceramic cylindrical body, the electrode rod by an annular electrode mounting bracket narrowed down stepwise from the side of the ceramic cylindrical body to reduce the diameter. Attached to the ceramic tubular body, and an annular fixing metal fitting is hermetically fitted to the outer surface of the ceramic tubular body, and the ceramic cylindrical body between the fixing fitting and the front end side of the electrode rod. A heating resistor is provided on the outer surface or inside. According to the hermetic ceramic terminal of the present invention, since the heating resistor is disposed on the outer surface or inside of the ceramic cylindrical body from the annular fixing metal to the front end side of the electrode rod, By heating the outer surface of the ceramic cylindrical body by causing the heat generating resistor to generate heat, moisture on the outer surface of the ceramic cylindrical body is easily removed. A large amount of moisture is not adsorbed on the outer surface of the ceramic cylindrical body even when used in a wet atmosphere, and a water film is formed on the outer surface of the ceramic cylindrical body to continuously wet the surface. There is no. For this reason, no leakage occurs between the electrode rod of the hermetic ceramic terminal, the fixing bracket, and the hermetic container via the outer surface of the ceramic cylindrical body. Next, a hermetic ceramic terminal of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of an embodiment of an airtight ceramic terminal according to the present invention. In FIG. 1, reference numeral 1 denotes a ceramic cylindrical body, 2 denotes a metal electrode rod, and 3 denotes an annular fixture. These components constitute an airtight ceramic terminal, and the fixing bracket 3 is brazed or welded to a container wall W of an airtight container made of metal or the like indicated by a two-dot chain line.
The hermetic ceramic terminal is fixed to the container wall W of the hermetic container by joining with screws or the like. The ceramic tubular body 1 is made of a ceramic having excellent electrical insulation properties, such as alumina ceramics, and is a tubular body such as a cylindrical body having a through hole 1a at the center. A metal electrode rod 2 is provided in the through hole 1a.
a is hermetically sealed, and both ends thereof are fitted and fixed by projecting forward and backward from both ends of the ceramic cylindrical body 1, and the hermetic ceramic terminal is mounted on the outer peripheral surface on the front end 2 a side of the electrode rod 2. An annular fixing metal fitting 3 for fixing the fixing device 3 to the container wall W of the airtight container with the outside facing is attached. The ceramic base 1 functions as a support for electrically supporting the electrode rod 2 between the electrode rod 2 and the airtight container. When the electrode base 2 is made of, for example, alumina ceramic, a raw material powder such as alumina, silica, magnesia, and calcia is used. It is manufactured by filling into a shaped press die, pressing it and molding, and firing this molded product at a temperature of about 1600 ° C. The ceramic tubular body 1 has a front side,
That is, an electrode mounting metallized metal layer 4 made of, for example, molybdenum-manganese metallization is formed on one end surface on the side located outside the airtight container, and the electrode rod 2 is attached to the electrode mounting metallized metal layer 4. An annular metal fitting 5 for attaching to the ceramic tubular body 1 is attached via a brazing material such as silver brazing. The electrode mounting metallized metal layer 4 functions as a base metal for brazing the electrode mounting bracket 5,
For example, if it consists of molybdenum-manganese metallization,
A metal paste obtained by adding an organic binder and a solvent to molybdenum powder and manganese powder is printed and applied on the front end face of the ceramic cylindrical body 1 by a conventionally known screen printing method, and is fired at a high temperature of about 1500 ° C. Thereby, it is adhered and formed on one end surface of the ceramic tubular body 1. The electrode mounting metallized metal layer 4 is
If a metal such as nickel having excellent wettability with a brazing material is applied to the surface thereof by plating to a thickness of about 1 to 10 μm, an electrode mounting metal
Can be brazed firmly. Therefore, it is preferable that a metal such as nickel having excellent wettability with a brazing material is applied to the surface of the electrode mounting metallized metal layer 4 by plating to a thickness of about 1 to 10 μm. The annular electrode mounting bracket 5 brazed to the electrode mounting metallized metal layer 4 is made of, for example, a metal such as an iron-nickel-cobalt alloy.
A ring-shaped member whose outer diameter is adjusted to the end surface of the ceramic tubular body 1 so that the diameter is reduced stepwise from the side of the ceramic tubular body 1;
An electrode rod 2 is inserted into the inside thereof with its front end 2a side protruding and brazed via a brazing material such as silver brazing. The electrode mounting bracket 5 is a ceramic cylindrical body 1.
The electrode rod 2 is hermetically inserted into and fixed to the ceramic cylindrical body 1, and when the electrode rod 2 is attached to the ceramic cylindrical body 1, the difference in thermal expansion coefficient between the ceramic cylindrical body 1 and the electrode rod 2 is caused. It acts to absorb and reduce the stress generated. The electrode rod 2 brazed to the electrode mounting bracket 5 is a cylindrical body made of a highly conductive metal such as oxygen-free copper, and penetrates through the electrode mounting bracket 5 and the ceramic cylindrical body 1. The two ends are fitted and inserted into the hole 1a so as to protrude forward and backward from the electrode mounting bracket 5 and the ceramic tubular body 1 and are brazed and fixed to the electrode mounting bracket 5 or the ceramic. By being brazed and fixed to the through-hole 1a of the tubular body 1, it is fitted and fixed in the through-hole 1a of the ceramic tubular body 1. The electrode rod 2 acts as a conductive path for inputting and outputting electricity to and from the airtight container. Electricity input and output to and from the airtight container flows through the electrode rod 2. A metallized metal layer 6 for attaching a fixing metal is applied to an outer peripheral surface of the ceramic cylindrical body 1 which is an outer peripheral surface.
, A fixing bracket 3 is attached by brazing via a brazing material such as silver brazing. The metallized metal layer 6 for attaching the fixing member is made of a metal having a high melting point such as molybdenum-manganese metallization, and functions as a base metal for attaching the fixing member 3 to the ceramic cylindrical body 1. For example, in the case of molybdenum-manganese metallization, a metal paste obtained by adding and mixing an appropriate binder and a solvent to molybdenum powder and manganese powder is applied onto the outer peripheral surface of the ceramic tubular body 1 by printing, and this is applied at a temperature of about 1500 ° C. By firing, it is formed on the outer surface of the ceramic tubular body 1. Note that the metallized metal layer 6 for attaching the fixing bracket is used.
When a metal such as nickel having excellent wettability with a brazing material is applied to the surface thereof by plating to a thickness of about 1 to 10 μm, the fixing metal 3 is firmly attached to the metallized metal layer 6 for mounting the fixing metal. Can be attached. Therefore, the metallized metal layer 6 for attaching the fixing metal is formed by plating a metal such as nickel having excellent wettability with the brazing material on the surface thereof by plating to a thickness of 1 to 10 mm.
It is preferable to apply the coating to a thickness of about μm. The annular fixture 3 brazed to the metallized metal layer 6 for attaching the fixture is made of, for example, iron-nickel-metal.
It is made of a metal such as a cobalt alloy. Its inner diameter is adjusted to the outer diameter of the ceramic cylindrical body 1 and its outer shape is adjusted to a through hole of the container wall W of the airtight container. A part of the inner peripheral surface of the annular member is hermetically brazed to the metallized metal layer 6 for attaching the fixing metal through a brazing material such as silver brazing. The portion of the fixing bracket 3 to be attached to the container wall W is not limited to the shape fitted into the through hole of the container wall W as shown in FIG. It may be shaped to be worn. The fixing member 3 functions as a fixing member for fixing the hermetic ceramic terminal to the container wall W of the hermetic container, and is joined to the container wall W of the hermetic container by brazing, welding, or the like, thereby forming the hermetic ceramic terminal. The terminal is fixed to the airtight container with the front end 2a side of the electrode rod 2 facing outward. The ceramic tubular body 1 is further exposed to the outside of the hermetic container by the fixing fitting 3 at the front end 2a of the electrode rod 2.
A heating resistor 7 composed of a metallized resistor layer containing a refractory metal powder such as tungsten, molybdenum or rhenium and an inorganic insulating powder such as aluminum oxide is provided on the outer surface on the side or in the vicinity thereof to supply power. Both ends are exposed on the outer surface of the ceramic tubular body 1 so that the width of the ceramic tubular body 1 is 0.2
A lead terminal 8 for supplying power to the heating resistor is provided with a brazing material such as silver brazing on both exposed ends of the heating resistor 7. Has been attached through. The heating resistor 7 generates Joule heat by supplying electric power via the lead terminal 8, thereby heating the outer surface of the ceramic tubular body 1 to about 40 to 100 ° C. It functions to prevent moisture in the atmosphere from adsorbing to the outer surface of the state body 1. When the outer surface of the ceramic tubular body 1 is heated by the heating resistor 7 generating Joule heat as described above, the heat effectively causes moisture to be adsorbed on the outer surface of the ceramic tubular body 1. In addition to being easily prevented, the outer surface of the ceramic tubular body 1 is always in a dry state. As a result, a leak between the front end 2a of the electrode rod 2 of the hermetic ceramic terminal and the fixture 3 and the hermetic container. Does not occur. The shape and arrangement of the heat generating resistor 7 can heat the outer surface of the ceramic cylindrical body 1 on the front end 2a side of the electrode rod 2 from the fixing fitting 3 to a temperature of about 40 to 100 ° C. over the entire circumference. There is no particular limitation as long as it is not limited, but it is substantially at a depth of 0.05 to 0.5 mm from the outer surface of the ceramic tubular body 1 between the fixing fitting 3 of the ceramic tubular body 1 and the front end 2a side of the electrode rod 2. When the heating resistor 7 is arranged with a uniform pattern density, the heating resistor 7 can be well protected from the external atmosphere, and the outer surface of the ceramic tubular body 1 can be uniformly insulated. It is possible to efficiently heat the area between the fixing fitting 3 on the outer surface of the ceramic cylindrical body 1 and the front end 2a of the electrode rod 2. Therefore, the heating resistor 7 is connected to the front end 2 a of the electrode rod 2 by the fixture 3 of the ceramic tubular body 1.
From the outer surface of the ceramic tubular body 1
It is preferable to dispose them at a depth of 0.5 mm with a substantially uniform pattern density. Such a heating resistor 7 is formed, for example, by forming two through-holes in an Alnami ceramic green sheet wound around the outer peripheral surface of a cylindrical molded body when the ceramic cylindrical body 1 is manufactured. At the same time, a resistor paste containing a refractory metal powder such as tungsten, molybdenum or rhenium and an alumina powder, both ends of which are extended to the surface side of the green sheet through through holes,
The center portion is disposed inside the vicinity of the outer surface of the ceramic tubular body 1 by printing and applying a meandering pattern or the like as shown in a development view in FIG. 2 on the inner surface of the green sheet. . The heating resistor 7 is formed by plating a metal such as nickel having excellent wettability with a brazing material to a thickness of about 1 to 10 μm on the exposed surfaces of both ends by plating. The lead terminals 8 can be firmly brazed to the exposed ends of the body 7. Therefore, the heating resistor 7
It is preferable that a metal such as nickel having excellent wettability with a brazing material is applied to the exposed surfaces of both ends by plating to a thickness of about 1 to 10 μm. The lead terminals 8 brazed to the exposed ends of the heating resistor 7 are made of a metal such as an iron-nickel-cobalt alloy, for supplying power to the heating resistor 7 from outside. Function as a terminal, lead terminal 8
Is connected to an external power supply, power is supplied to the heating resistor 7, whereby the heating resistor 7 generates Joule heat. Thus, according to the hermetic ceramic terminal of the present invention, the fixture 3 is fixed to the hermetic container by joining it to the container wall W of the hermetic container, and the input and output of electricity inside and outside the hermetic container via the electrode rod 2. Further, power is supplied to the heating resistor 7 disposed on the ceramic tubular body 1 through the lead terminal 8, whereby the heating resistor 7 generates Joule heat and the ceramic tubular body 1 is heated. Accordingly, even when used in a high-humidity atmosphere, a large amount of moisture does not adhere to the outer surface of the ceramic tubular body 1, and the outer surface of the ceramic tubular body 1 is always in a dry state. Electricity input / output between the inside and outside of the airtight container without causing a leakage between the electrode 3 and the front end 2a side of the electrode rod 2 and between the airtight container to which the fixture 3 is fixed and the front end 2a side of the electrode rod 2 To Can Nau. It should be noted that the hermetic ceramic terminal of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described example, the heating resistor 7 is provided near the outer surface of the ceramic tubular body 1, but the heating resistor 7 is provided on the outer surface of the ceramic tubular body 1. In this case, in addition to the metallized resistor including the refractory metal powder such as tungsten, molybdenum and rhenium and the inorganic insulating powder such as aluminum oxide as the heating resistor 7, lanthanum boride and ruthenium oxide may be used. A thick film resistor containing a resistance material and glass, or a thin film resistor such as nichrome or tantalum nitride can be employed. When the heating resistor 7 is formed of a thick film resistor containing a resistance material such as lanthanum boride or ruthenium oxide and glass, for example, the outer surface of the ceramic cylindrical body 1 is made of lanthanum boride or ruthenium oxide. A resistor paste containing a resistor material and glass may be printed and applied in a predetermined pattern and baked at a temperature of about 800 to 1000 ° C. to be disposed on the outer surface of the ceramic cylindrical body 1 in a predetermined pattern. When the heating resistor 7 is formed of a thin-film resistor such as nichrome or tantalum nitride, for example, a thin-film technique such as a sputtering method is used on the outer surface of the cylindrical ceramic body 1 to form the heating resistor 7 from nichrome or tantalum nitride. The thin film thus formed is applied, and the applied thin film is etched into a predetermined pattern by using a photolithography technique, so that the thin film is disposed on the outer surface of the ceramic cylindrical body 1. The heating resistor 7 is connected to the ceramic cylindrical body 1.
In order to protect the heating resistor 7 from an external atmosphere, the heating resistor 7 may be further coated with a coating layer made of glass or resin. Further, in the above-described example, the heating resistor 7 is formed in a meandering pattern. However, the heating resistor 7 may be formed in a spiral pattern along the outer surface of the ceramic cylindrical body 1 or in a pattern having another shape. May be formed. According to the hermetic ceramic terminal of the present invention,
Since the heating resistor is arranged on the outer surface or inside from the fixing fitting of the ceramic cylinder to the front end side of the electrode rod, the ceramic is heated by heating the heating resistor to heat the ceramic cylinder. Since moisture can be effectively and easily prevented from adsorbing on the outer surface of the cylindrical body,
Even when the airtight ceramic terminal is used in a high humidity atmosphere with the front end side of the electrode rod as the outside of the airtight container, a large amount of moisture does not adsorb on the outer surface of the ceramic cylindrical body in the high humidity atmosphere. Since the outer surface of the cylindrical body is always in a dry state, as a result, a water film is not formed and does not continuously wet the outer surface of the ceramic cylindrical body. Leakage does not occur between the front end side of the vehicle and the fixture and the airtight container. As described above, according to the present invention, even when used in a high-humidity atmosphere, due to moisture in the atmosphere, the electrode rod is fixed to the fixture and the airtight container through the outer surface of the ceramic cylindrical body. A highly reliable hermetic ceramic terminal without occurrence of electric leakage could be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an example of an embodiment of an airtight ceramic terminal of the present invention. FIG. 2 is a developed view showing a pattern of a heating resistor disposed on the hermetic ceramic terminal shown in FIG. [Description of Signs] 1 ··· Ceramic cylindrical body 2 ··· Electrode rod 2a · · · Front end 3 ··· Fixing bracket 7 ··· Heating resistor W · ··· of airtight container Container wall

Claims (1)

(57) [Claims 1] An electrode rod is hermetically inserted and fixed in a state where both ends are projected forward and backward into a ceramic cylindrical body .
The diameter is the outer diameter of the electrode rod, and the outer diameter is the ceramic cylindrical body.
In accordance with the end face of the ceramic cylindrical body,
Ring-shaped electrode
Attach the electrode rod to the ceramic cylindrical body with the fitting
And an annular fixing metal fitting is hermetically fitted to the outer surface of the ceramic cylindrical body, and on the outer surface or inside of the ceramic cylindrical body from the fixing metal fitting to the front end side of the electrode rod. An airtight ceramic terminal having a heating resistor.