JPH0244662A - Electric terminal extending through sealed container - Google Patents

Abstract

PURPOSE:To prevent cracks from occurring in an airtightly sealed portion by extending an MI cable, having an aluminum sheath whose both ends or one end is airtightly sealed and insulated with powder member, through a sealed aluminum container and welding therebetween. CONSTITUTION:An MI cable 3, in which ceramics powder member is used as an insulator for an aluminum sheath, is extended through a vacuum sealed container 1 formed of aluminum, and the container 1 and the cable 3 are welded together airtightly by a laser. The difference between the thermal expansion coefficients occurring at that time is absorbed by the powder member as the insulator, because the thermal expansion coefficients are nearly equal, so that cracks will never produced in the airtightly sealed portion. Further, airtight sealing is effected at both ends or one end of the cable 3 by ceramics which chemically reacts with the insulating powder member so that the stress due to the expansion of the container 1 is not transmitted hence cracks will never occur. Thus, the cracks in the airtightly sealed portion due to the difference between the thermal expansion of the container and the cable is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application on r gi M] The present invention relates to a closed container penetrating electrical terminal that passes fT through a closed container such as a vacuum vessel or a pressure vessel.

[Conventional technology] Sealed electrical terminals used in closed containers such as vacuum vessels and pressure vessels are made by combining ceramic or glass insulators such as alumina with metals such as Kovar, which have a coefficient of thermal expansion similar to that of the insulators. Hermetic terminals are used. The reason why metals such as Kovar are used in hermetic terminals is 1. Normal metals have very different thermal expansion coefficients from ceramic or glass insulators, so a difference in thermal expansion occurs between the insulator and the metal due to temperature changes. This is because cracks will occur at the joint.

FIG. 7 shows an example of a conventional hermetic terminal. Connect a metal electrical terminal such as Kovar to the opening of the stainless steel container 101.
An insulator made of ceramics or glass for electrically insulating +0 by inserting 02 into it and fitting the cylinder 103 such as Kovar.
4 and seal. Electrical terminal 102 and insulator 10
4. Insulator +04 and cylindrical body 103 are each filled with brazing material +0
5 Join at 106. Brazing filler metal 105 used here
Reference numeral 106 indicates gold solder, silver solder, or a brazing material that does not require metallization treatment on the ceramics or glass to be joined. Furthermore, the cylindrical body 103 is welded to the container +01. Here, an electric terminal 102, an insulator 104. Since the cylindrical bodies 103 have similar coefficients of thermal expansion, even if the temperature changes, the electrical terminal +
No cracks occur between 02 and the insulator 104, and between the insulator 104 and the cylinder 103. Moreover, the cylinder 103 and the container 101 are
Because it has elasticity, it absorbs the difference in thermal expansion and does not crack even when the temperature changes.In this way, a through-hermetic electrical terminal that maintains airtightness even when the temperature changes is formed.

"Problem to be Solved by the Invention" Recently, containers made of aluminum or aluminum alloy, which are less likely to generate gas, have been increasingly used as ultra-high vacuum containers. Aluminum or aluminum alloy has a much lower melting point than Kovar, and if joined slowly, Aluminum 11 or aluminum alloy will melt.

As described above, although aluminum and Kovar have very different melting points, they can be welded by laser welding, which can rapidly heat and cool and quickly complete the bond. However, solidification cracks are likely to occur due to the thermal stress that occurs with rapid heating and rapid cooling, and airtight leaks are likely to occur. electric end j'
-112 is inserted, an insulator made of ceramics such as alumina or glass +13 is interposed, and the electrical end /' +12 is inserted.
It is assumed that the insulator 113 and the insulator 11:3 and the container II+ are joined by brazing materials 114 and 115.

Then, there is a large difference in thermal expansion between the aluminum or aluminum alloy container 111 and the insulator 113, and cracks occur between the two when the temperature changes.

In this way, it is impossible to directly replace the stainless steel container/JIOI shown in FIG. 7 with the aluminum or aluminum alloy container II+ shown in FIG. 8, which is desired to be used, in view of solidification cracking.

"Means for Solving the Problems" Therefore, in order to eliminate the above-mentioned drawbacks, the present invention provides a sealed container such as a vacuum container formed of aluminum or an aluminum alloy, a sheath of aluminum or an aluminum alloy, and an aluminum oxide, aluminum oxide, etc. 17 MI cables with insulators made of ceramic powder such as magnesium and boron nitride were passed through.
Laser welding, TIG welding, brazing, etc. are used to form an airtight joint, and the difference in thermal expansion that occurs in this case is absorbed by the insulating powder and no cracking occurs.

Hermetic sealing is done by sealing the MI cable with glass, glass,
Plastics such as epoxy, magnesium oxide, etc.
Since the I cable's insulating powder is made of ceramics that undergo chemical reactions such as hydration, the hermetic seal is located at a distance from the vacuum vessel, and stress due to thermal expansion of the vacuum vessel is generated. If both ends of the M1 cable are sealed, even if the seal +1 part were to break due to the application of external force, even if one breaks, the other will not break. The remaining vacuum cannot be broken, and even if all the seals and lz parts are broken, it takes time for the air to pass through the powder in the MI cable, so work slowly.

Measures such as activating necessary protective devices are extremely effective in protecting the vacuum container.

Even when baking a vacuum container to cause degassing and obtain an ultra-high vacuum, the vacuum container and the M1 cable sealing part are separated, making it difficult for the baking heat to be transmitted to the hermetically sealed part. Does not break easily.

``Sakukawa'' MI cable (mineral insulated metal sheath cable) is an MI cable (mineral insulated metal sheath cable) that is hermetically sealed at both ends or one end and has an aluminum or aluminum alloy sheath with powder as an insulator. This is an electrical terminal that penetrates the airtight container and connects the wall of the airtight container and the MI cable sheath by welding to completely airtightly seal the airtight container such as a vacuum container.

"Example" The present invention will be described in detail below based on an example. In FIG. 1, an MI cable 3 having an aluminum or aluminum alloy sheath is connected to a connector (SMΔ-Il
It is connected to the NC type, N series, ST-I V, multi-pin connector) 4, and hermetically joined to the aluminum or aluminum alloy plate 2 by electron beam welding, TTG welding, brazing, etc. The plate 2 is hermetically joined to a vacuum vessel l made of aluminum or aluminum alloy by electron beam welding or the like.

In FIG. 2, both ends 5 and 6 of the M1 cable 3 are hermetically sealed, and FIG. 3 is a cross-sectional view of FIG. 2.

FIG. 4 shows an airtight sealing state of both ends 5 and 6 of the sheath 10, that is, an airtight sealing portion 15 formed by melting and mixing plastics such as glass and epoxy. Alternatively, an airtight seal is formed by inserting ceramics or the like that causes chemical reactions such as hydration into the insulator 12 of powder such as aluminum oxide, magnesium oxide, or boron nitride between the sheath 10 and the core wire 11. be.

In Figure 5, the screw 2 is inserted through the packing 23 made of insulating material.
In step 2, the screw 21 provided at the end of the MI cable 3 is tightened to mechanically seal it airtight.

In FIG. 6, layers 3a and 3s of nickel or the like are formed in advance on at least one surface of the outside of the sheath 10 or the inside of the through hole of the vacuum vessel 1 by a method such as plating, so that they are in +8 contact. This method makes laser welding easier, for example, and prevents solidification cracks from occurring in the welded portion. M.I.
A core wire 11 is passed from the end 5 of the cable 3 to the connector 4 through the end 6, and direct current or high frequency current may be passed through the connector 4 or vice versa. to the outside of the vacuum chamber, and conversely, to transmit external control signals, etc. to the inside. In particular, in the case of high frequency current, 10, 11, and 12 form a high frequency coaxial waveguide.

M1 cable 3 sheath 10. By making the entire core wire 11 grade MI cable non-magnetic, even when a high magnetic field is applied to a vacuum container, such as an ultra-high vacuum container in a synchrotron radiation facility, it will be attracted by the magnetic field, causing distortions in the shape. Therefore, it is possible to obtain a through-hole electrical terminal that does not cause any damage.

[Effects of the Invention] Since the present invention is configured as mentioned above, even if there is a difference in thermal expansion between the waste container and the insulator of the MI cable, since the insulator is a powder, it will not be caused by thermal stress. No cracks will occur.

2. The hermetic sealing part of the MI cable is located in a place close to the vacuum container, so the hermetic sealing part will not crack due to the stress of thermal expansion caused by baking the vacuum container. 3. The sheath of the MI cable is made of aluminum or aluminum. Since it is an alloy, there is no difference in thermal expansion between the ultra-high vacuum container made of aluminum or aluminum alloy and the two, which are easy to weld, so cracks do not occur at the joint between the two due to baking or the like.

4. The MI cable has one or two airtight seals, and the MI cable is tightly filled with insulating powder, so even if the airtight seal breaks, the vacuum is unlikely to suddenly break. , extremely reliable.

As described above, the airtight sealing of the vacuum container is very good and extremely reliable.

21・ 2;3 ・・・・・・・・・・Sheath ・・・・・・・・・Core wire ・・・・・・・・・Insulating powder ・・・・・・・・・Hermetic sealing part 22... Neji ・・・・・・・・・Patsukin ・34... layer

[Brief explanation of the drawing]

Fig. 1 is a partially sectional view of a specific embodiment of the present invention; Fig. 2 is a sectional view of a part of another embodiment; Fig. 3 is a sectional view taken along the line XX of Fig. 2; Fig. 4 , FIG. 5, and FIG. 6 are partial cross-sectional views of another embodiment. ■ ... Vacuum container 2 ... Aluminum or aluminum alloy plate 3 ... MI cable 4 ... Connectors 5 and 6 ... Sealing of M1 cable end

Claims (1)

[Scope of Claims] (1) An electrical terminal provided through an MI cable in a closed container, wherein an MI cable having a thermal expansion coefficient that is the same as or close to that of the container is inserted into the opening of the container. (2) A closed container penetrating electrical terminal according to claim 1, wherein the MI cable is non-magnetic (3) The sealed container and the MI cable are made of aluminum or an aluminum alloy. The electrical terminal (4) penetrating the sealed container according to the first claim, wherein the wall of the sealed container and the sheath of the MI cable are joined by brazing, laser welding, or TIG welding. Closed container penetrating electrical terminal (5) Closed container penetrating electrical terminal according to claim 1, wherein the insulator of the MI cable is a powder (6) Fifth claim, wherein the powder is aluminum oxide, magnesium oxide, or boron nitride A sealed container penetrating electrical terminal (7) according to the first claim, in which the core wire of the MI cable is made of aluminum or an aluminum alloy; A closed container penetrating electric terminal (9) according to claim 8. A closed container penetrating electric terminal (10) according to claim 8, wherein the hermetic seal is glass sealing or plastic sealing. The closed container penetrating electrical terminal (11) according to claim 8, which is mechanically sealed.
The hermetically sealed electrical terminal (12) according to claim 8, wherein the hermetic sealing is a ceramic sealing that causes a chemical reaction with the insulating powder of the MI cable. A closed container penetrating electrical terminal (13) according to claim 1, in which a layer is formed on one end; (14) a closed container penetrating electrical terminal (14) in which the layer is made of nickel or formed by plating; A closed container penetrating electrical terminal (15) according to claim 1, electrically connected to an electrical connector, wherein the electrical connector is an SMA connector or a BN connector.
The closed container penetrating electrical terminal according to claim 14, which is a C connector or N series, or SHV or multi-pin connector (16) The closed container penetrating electrical terminal according to claim 1, wherein the sealed container is a vacuum container.