JPS6142440B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an airtight container for electrical equipment and a method for manufacturing the same, and more particularly, the present invention relates to an airtight container for electrical equipment and a method for manufacturing the same, and in particular, the invention is made by airtightly joining an insulating case or insulating plate made of an inorganic insulator to a metal plate or metal case made of metal. This article relates to an airtight container for electrical equipment and its manufacturing method.

In general, vacuum containers for electrical equipment such as vacuum shields, disconnectors, vacuum fuses, and vacuum tubes, and airtight containers for airtightly storing semiconductors in electrical equipment such as power diodes, transistors, thyristors, and GTOs are made of alumina ceramics, etc. It is constructed by airtightly joining an insulating case or plate made of an inorganic insulator and a metal plate or case made of metal by brazing.

Therefore, it is desirable that the metal plate or metal case constituting a part of the conventional airtight container have a coefficient of thermal expansion similar to that of an inorganic insulator such as alumina ceramic, and generally Fe-Ni-Co alloy (Kovar ) and Fe-Ni alloys are used.

However, Fe-Ni-Co alloys and Fe-Ni alloys have thermal expansion coefficients of 4.5 to 7 × 10 -6 /°C, while inorganic insulators such as alumina ceramics have thermal expansion coefficients of 4 to 7 × 10 ^-6 /°C. 6.6×10 ^-6 /℃, each temperature (T)
The relationship between the coefficient of thermal expansion (α) in
The T characteristics do not necessarily match perfectly, and
The elastic modulus of Fe-Ni-Co alloy and Fe-Ni alloy is 1.4×
10 ⁴ Kg/mm ² (20℃), and the thermal stress σ [σ = ε. E(σ; Kg/mm ² , ε=Δ/
, E; Kg/mm ² ), Δ=Δα. ．． ΔT(Δ
;Elongation against temperature change ΔT, ;Original length,
Δα (difference in coefficient of thermal expansion between Kovar etc. and alumina ceramic)] increases. Therefore, in order to alleviate the thermal stress caused by brazing the two, it is necessary to reduce the thickness of the metal plate or metal case made of Fe-Ni-Co alloy, etc., or to make the metal plate etc. It has become necessary to provide a U-shaped stress relief section.

Furthermore, Kovar et al.
The drawback is that the price is high due to the limited amount of Ni resources.

The present invention has been made in view of the above-mentioned problems, and its purpose is to connect an insulating case or insulating plate made of an inorganic insulating material and a metal plate or metal case made of metal by connecting a bonding surface between the two. By interposing thin plate-like auxiliary members made of plastically deformable metal during the cooling process from the bonding temperature and joining by brazing, it is possible to achieve excellent airtightness and bonding strength, and to bond metal plates and metals made of metal. To provide an airtight container for electrical equipment whose case has a simple shape and is inexpensive. Embodiments of the present invention will be described in detail below with reference to the drawings.

The airtight container according to the present invention can be used to store contacts, fuses, etc. by keeping the inside of the container in a high vacuum, or by filling the container with an inert gas such as dry nitrogen gas to store power diodes, transistors, etc. It is used to house semiconductors such as thyristors and GTOs, and as shown in Fig. 1, an insulating case 1 made of an inorganic insulator such as alumina ceramic or crystallized glass is formed into a cylindrical shape, and on both ends thereof, as shown in FIG. Mo-Mn with a thermal expansion coefficient similar to that of alumina ceramics, etc.
-Austenitic stainless steel (hereinafter simply referred to as "stainless steel"), steel, or iron to form a metallized layer 2 made of Ti alloy, Mo-Mn alloy, etc., and close the open end of the insulating case 1 on each metallized layer 2. Disc-shaped metal plates 3, 3 made of metal such as,
A ring-shaped auxiliary member 4 is interposed between the joint surfaces of the two and airtightly brazed. Each auxiliary member 4 can be brazed in a vacuum atmosphere of 10 ^-4 Torr or less or in a non-oxidizing or reducing gas atmosphere such as hydrogen gas, and can be plastically deformed during the cooling process after brazing. It is made of copper or metal, and its wall thickness is 0.1 mm or more and 1 mm or less.
In addition, each metal plate 3 is made of non-magnetic material such as copper or stainless steel when preventing temperature rise caused by eddy current loss due to energization of various electrical devices housed in an airtight container. Iron, which is cheaper than copper or stainless steel, is used when the current carrying capacity of various electrical equipment is small and its influence is not a problem, and when mechanical strength is required, iron or stainless steel is used. If corrosion resistance is required, one made of stainless steel is used.

FIG. 2 is a half-cut sectional view of a second embodiment of the airtight container according to the present invention. , is a so-called butt seal in which an auxiliary member 4 is interposed between the two, whereas both end faces of the insulating case 1 on which the metallized layer 2 is formed and the peripheral end faces of the metal plates 5, 5 formed in a dish shape. are joined by a so-called edge seal, which is airtightly brazed with an auxiliary member 4 interposed between both end faces.

FIG. 3 is a half-cut sectional view of a third embodiment of the airtight container according to the present invention. 6 and insulation case 1
A cap-shaped metal plate 7 having a diameter suitably larger than the outer diameter of the cap is fitted between the two, and a metal plate 7 made of the same metal as the auxiliary member 4 described above and formed in a thin annular shape is fitted between the joint surfaces of the two. The auxiliary members 8 are interposed therebetween and are joined by a so-called compression seal, which is airtightly brazed.

Furthermore, FIGS. 4, 5, and 6 show the fourth, fifth, and sixth embodiments of the present invention, respectively.
This figure shows a half-cut sectional view of the embodiments, and the airtight containers of the fourth to sixth embodiments are different from those of the first to third embodiments, in which the insulating case 1 made of an inorganic insulator is connected to the auxiliary members 4 and 8.
In contrast, a case made of metal is sealed airtight by an insulating plate made of an inorganic insulator with an auxiliary member interposed between the metal case and the metal plates 3, 5, and 7 made of metal. It is composed of a closed system.

That is, the airtight container of the fourth embodiment is made of an inorganic insulator such as alumina ceramic formed into a substantially disk shape, and the airtight container of the first to third embodiments is attached to one end surface near the outer peripheral edge of the insulating plate 9. A metallized layer 10 made of the same metal as the metallized layers 2 and 6 is formed, and the metallized layer 10 and a metal case 11 formed in a cylindrical shape with a bottom (cup shape) are extended outwardly at the edge of the opening. The flange portion 11a provided as
An auxiliary member 12 having the same shape and made of the same metal as the auxiliary member 4 in the airtight container of the first embodiment is interposed between the flange portion 11a and the metallized layer 10, and then brazed. They are airtightly connected.

In addition, the airtight container of the fifth embodiment uses a so-called butt seal in the fourth embodiment, whereas the metallized layer 10 of the insulating plate 9 and the open end surface of the metal case 11 are assisted between the two. Member 12
They were joined airtightly by brazing with
Furthermore, the airtight container of the sixth embodiment has a metallized layer 13 formed on the outer peripheral surface of the insulating plate 9, and the metallized layer 13 and the vicinity of the opening of the metal case 11. The inner peripheral surface is provided by a so -called complex shyon seal, in which the auxiliary member 14 formed in a ring between the two is interposed and joined by the airtight.

In addition, in the airtight containers of the first to third embodiments, a case will be explained in which the insulating case 1 formed in a cylindrical shape is used, and in the airtight containers of the fourth to sixth embodiments, the insulating case 1 is formed in a cylindrical shape with a bottom. metal case 11
However, the case is not limited to this shape; for example, the case may be a rectangular parallelepiped insulating block with a recess on one side, or a rectangular parallelepiped box-shaped metal case. A case may also be used.

The first method for manufacturing an airtight container having the above configuration is as follows.
Taking the embodiment as an example, first, one metal plate 3 is supported horizontally, and one auxiliary member 4, the insulating case 1, the other auxiliary member 4, and the other metal plate are placed on this metal plate 3. The plates 3 are placed one on top of the other with a ring-shaped solder plate interposed between their joint surfaces, as shown in FIG. 1, to temporarily assemble an airtight container. Next, the temporarily assembled airtight container,
Stored in a heating furnace that can be maintained in a vacuum atmosphere at a pressure of 10 ^-4 Torr or less or a non-oxidizing or reducing gas atmosphere such as hydrogen gas, and heated to a temperature of 500 to 600°C or higher at 1050°C or higher.
Heating is performed at a temperature below 0.degree. C., and air-tight brazing is performed at the same time as degassing of each component. As shown in FIG. 7, in which the horizontal axis represents the processing time (H) and the vertical axis represents the furnace temperature (°C), the heating furnace is cooled from the brazing temperature T ₁ to the auxiliary member 4. The plastic deformation temperature T ₂ is lowered to the optimum plastic deformation temperature T 2 , this plastic deformation temperature T ₂ is maintained for a predetermined holding time h required for plastic deformation of the auxiliary member 4 , and then the inside of the furnace is cooled again to lower the plastic deformation temperature. The desired product can be obtained by removing the airtight container after cooling from T ₂ to room temperature T ₃ .

Here, the insulating case 1 or the insulating plate 9 made of an inorganic insulating material such as alumina ceramic, and the metal plates 3, 5, 7 or the metal case 11 made of a metal whose thermal expansion coefficients do not necessarily match each other are airtightly joined to each other by using copper. Alternatively, by interposing thin-walled auxiliary members 4, 8, 12, and 14 made of iron between the joint surfaces of both members and brazing them, excellent airtightness and joint strength can be obtained, and the metal plates 3, 5, The reason why it is possible to obtain an airtight container in which the shape of the metal case 7 or the metal case 11 can be simplified is considered to be due to the following reasons.

In other words, the tensile strength and elongation of copper and the tensile strength and elongation of iron with respect to temperature are shown by curve A ₁ in Figure 8, where the horizontal axis is the temperature °C, and the vertical axis is the tensile strength (Kg/mm ² ) and elongation (%). , A ₂ and curves B ₁ and B ₂ , it is known that the tensile strength decreases as the temperature increases, and the elongation almost increases as the temperature increases. In this way, copper and iron have almost the same mechanical properties, so below,
Regarding the case where the auxiliary members 4, 8, 12, and 14 are made of copper, the apparent elastic modulus of copper is determined from the above-mentioned relational expression between stress σ and elastic modulus E and from FIG.
It is known that it is as small as about 30 Kg/mm ² at 200°C, and as small as about 46 Kg/mm ² even at 0°C. Therefore, it is thought that this is because the thermal stress generated by brazing the copper and the inorganic insulating material such as alumina ceramic becomes smaller based on the difference in thermal expansion coefficient between the two and the temperature change.

In addition, in the manufacturing method when the auxiliary members 4, 8, 12, and 14 are made of copper, the reason why the cooling process from the brazing temperature to room temperature after brazing in the furnace is maintained at a predetermined temperature for a predetermined time is as follows. It is based on what you say.

In other words, copper at a constant temperature and a constant load (7.3Kg/
The creep elongation with respect to the loading time under the condition (tensile load of mm ²
Curves A and 400℃ respectively.
As shown in B and C, at temperatures below 200°C, there is almost no creep elongation, in other words, no plastic deformation to relieve thermal stress occurs.
It can be seen that under high temperature conditions of 300°C and 400°C, this is caused by maintaining the load time.

Therefore, after brazing in the furnace, the brazing temperature T ₁ is lowered to the plastic deformation temperature T _{2 by cooling in the furnace, this plastic deformation temperature T 2 is} maintained for a predetermined holding time h, and then the temperature is lowered again. By cooling in the furnace to lower the plastic deformation temperature T ₂ to room temperature T ₃ , the residual thermal stress caused by joining the two can be almost completely reduced to zero.

In this case, the higher the plastic deformation temperature T ₂ is, the faster the residual thermal stress caused by the temperature drop from the brazing temperature T ₁ to the plastic deformation temperature T ₂ can be brought to zero, and the holding time h can be shortened. However, the residual thermal stress caused by the temperature drop from the plastic deformation temperature T ₂ to the room temperature T ₃ increases.

In addition, the above-mentioned plastic deformation temperature T ₂ and holding time h
differs depending on the type of metal used as the auxiliary members 4, 8, 12, 14. For example, when the auxiliary members 4, 8, 12, 14 are made of carbon steel or stainless steel, the horizontal axis shows the temperature T. In Figure 10, where the vertical axis is the thermal stress σ, the creep rates of carbon steel and stainless steel are shown by curves A and B, respectively. It can be seen that the temperature is about 500℃ or more, and the temperature of stainless steel is about 600℃ or more. Therefore, from the relationship between the creep rate curve and the plastic deformation temperature T ₂ mentioned above, in the case of carbon steel, thermal stress can be alleviated to a certain extent by setting the plastic deformation temperature T ₂ to 500°C. However, in the case of stainless steel, the plastic deformation temperature T ₂ becomes high, making it difficult to alleviate thermal stress.

Furthermore, the plastic deformation temperature T ₂ when copper and alumina ceramic are brazed, and the theoretical residual thermal stress generated by brazing the two, are heat treated at each plastic deformation temperature T _{2 and} then at room temperature T ₃ .
The relationship between the percentage of residual thermal stress that actually occurs in , that is, the residual thermal stress ratio (%), is shown in Figure 11, where the horizontal axis is the plastic deformation temperature T ₂ (℃) and the vertical axis is the residual thermal stress ratio (%). It becomes like curve A shown in . Therefore, when brazing copper and alumina ceramic, the optimum plastic deformation temperature T ₂ is considered to be in the range of about 250°C to 350°C.

Also, the holding time (h) at the plastic deformation temperature T ₂ when copper and aluminum ceramic are brazed
The relationship between and the residual thermal stress ratio (%) is expressed as
In the figure, the plastic deformation temperature T ₂ is 250℃,
Curves A, B and C are shown at 300°C and 400°C. Therefore, the plastic deformation temperature when copper and alumina ceramic are brazed
It can be seen that the holding time h of T ₂ may be about 2 hours.

In addition, the insulating case 1 or insulating plate 9 made of an inorganic insulator such as alumina ceramic and the metal plates 3, 5, 7 or metal case 11 made of metal are connected, and an auxiliary member 4 made of copper is connected between the joint surfaces of the two.
Thickness t of auxiliary members 4, 8, 12, 14 when brazed with 8, 12, 14 interposed
The relationship between the adhesion strength ratio (times) of various metals, where the adhesion strength when directly brazing alumina ceramic and Kovar is 1, is shown on the horizontal axis for the auxiliary members 4, 8, 12, and 14 made of copper. In Fig. 13, where the plate thickness t (mm) is taken and the vertical axis is the adhesive strength ratio (times), the metal plates 3, 5, 7 or the metal case 11 made of Kovar, iron, and stainless steel are A and B, respectively. and C. Therefore, auxiliary members 4, 8, 1 made of copper are interposed between the bonding surfaces of alumina ceramic etc. and various metals.
Nos. 2 and 14 can be bonded well by setting their wall thickness to 1.1 mm or more and less than 1 mm.

In addition, a metallized layer was formed on the end face of a cylindrical alumina ceramic with an outer diameter of 60 mm and a thickness of 5 mm, and this metallized layer and a metal plate made of stainless steel were
An auxiliary member made of copper with a wall thickness of 0.25 mm is interposed between the joint surfaces of the two, and brazing is performed by heating at 950°C in a vacuum atmosphere with a pressure of 10 ^-4 Torr or less. After brazing, the material is cooled in a furnace. The bond strength was determined by lowering the furnace temperature to 300℃, holding the plastic deformation temperature at 300℃ for 2 hours, and then cooling it down to room temperature in the furnace.
The adhesive strength was 1.5 to 2.3 times that of the one obtained by directly brazing Kovar and alumina ceramic.

As described above, the present invention provides an insulating case or an insulating plate made of an inorganic insulator or a metal case made of an inorganic insulator with a metallized layer formed on the joint surfaces, and a metal plate or metal case made of metal, in a cooling process from the brazing temperature between the respective joint surfaces. Since it is airtightly joined by brazing with a thin plate-like auxiliary member made of plastically deformable metal interposed in the airtight container of electrical equipment made of inorganic insulators and metals, which have significantly different coefficients of thermal expansion, It is possible to improve the properties and bonding strength. Moreover, the airtight container can be made into a simple shape and inexpensive. Further, the metal material for forming the metal plate or the metal case can be arbitrarily selected depending on the purpose of use of the electric device, the atmosphere in which it is used, and the like.

In addition, in the cooling process from the brazing temperature, a brazing material is interposed between the joint surfaces of an insulating case made of an inorganic insulator with a metallized layer formed on the joint surface, or a metal plate or metal case made of an insulating plate and metal. An airtight container for electrical equipment is temporarily assembled by interposing a thin plate-like auxiliary member made of plastically deformable metal, and the temporarily assembled airtight container is placed in a vacuum atmosphere of 10 ^-4 Torr or less or a non-oxidizing or reducing gas. The furnace is placed in a furnace with an atmosphere for brazing, the temperature inside the furnace is lowered from the brazing temperature to a predetermined temperature, this predetermined temperature is maintained for a predetermined time, and then the temperature inside the furnace is lowered from the predetermined temperature to room temperature. As a result, residual thermal stress can be reduced to almost zero, and an airtight container with excellent bonding strength, impact resistance, etc. can be obtained.

[Brief explanation of the drawing]

1, 2, 3, 4, 5 and 6 are a first embodiment, a second embodiment, a third embodiment, respectively, of airtight containers for electrical equipment according to the present invention. FIG. 7 is an explanatory diagram of heat treatment in the manufacturing method according to the present invention, and FIG. 8 is a diagram showing the tensile strength and elongation at each temperature of copper and iron. FIG. 9 is an explanatory diagram showing the relationship between creep elongation and loading time of copper. FIG. 10 is an explanatory diagram showing thermal stress at each temperature of carbon steel and stainless steel.
Figure 1 is an explanatory diagram showing the residual thermal stress ratio at the plastic deformation temperature of copper, Figure 12 is an explanatory diagram showing the residual thermal stress ratio with respect to the holding time of copper at each plastic deformation temperature, and Figure 13 is an explanatory diagram showing the residual thermal stress ratio at each plastic deformation temperature of copper. FIG. 3 is an explanatory diagram showing the relationship between wall thickness and adhesive strength ratio. 1... Insulating case, 2... Metallized layer, 3...
...Metal plate, 4...Auxiliary member, 5...Metal plate, 6...
... Metallized layer, 7... Metal plate, 8... Auxiliary member, 9... Insulating plate, 10... Metallized layer, 11
... Metal case, 12 ... Auxiliary member, 13 ... Metallized layer, 14 ... Auxiliary member.

Claims (1)

[Claims] 1. A process of cooling an insulating case made of an inorganic insulator or an insulating plate and a metal plate or metal case made of a metal with a metallized layer formed on the joint surfaces from the brazing temperature between the respective joint surfaces. An airtight container for electrical equipment, characterized in that the container is airtightly joined by brazing with a thin plate-like auxiliary member made of a plastically deformable metal interposed therebetween. 2 A brazing material is interposed between the joint surfaces of an insulating case made of an inorganic insulator with a metallized layer formed on the joint surface, or an insulating plate and a metal plate or metal case, and the plasticity is reduced during the cooling process from the brazing temperature. Temporarily assemble an airtight container for electrical equipment by interposing thin plate-like auxiliary members made of deformable metal, and place the temporarily assembled airtight container in a vacuum atmosphere of 10 ^-4 Torr or less or a non-oxidizing or reducing gas atmosphere. The furnace is placed in a furnace for brazing, the temperature inside the furnace is lowered from the brazing temperature to a predetermined temperature, this predetermined temperature is maintained for a predetermined time, and then the temperature inside the furnace is lowered from the predetermined temperature to room temperature. A method for manufacturing an airtight container for electrical equipment, characterized by: