JP2012004029A - Metal terminal joint structure of superconducting wire rod and method for joining superconducting wire rod and metal terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal terminal joint structure of a superconducting wire rod that is joined well and capable of suppressing an increase in electric resistance at a solder joint, and a method for joining the superconducting wire rod to the metal terminal.SOLUTION: In a method of joining a superconducting wire rod to a metal terminal, a stabilizer tape 21 is joined on a protective layer 14 of a superconducting tape 1 comprising a substrate 11, an intermediate layer 12, a superconducting layer 13 and the protective layer 14 to form a stabilizer compounded superconducting tape 5, and a metal terminal 8 is joined on the stabilizer compounded superconducting tape 5. The stabilizer tape 21 has one surface plated with a first solder 21A and the other surface plated with a second solder 21B. The superconducting tape 1 is joined to the stabilizer tape 21 via the first solder 21A. The metal terminal 8 is joined on the stabilizer compounded superconducting tape 5 by the second solder 21B and a third solder 7 being intercalated in order. The second solder 21B and the third solder 7 have lower melting points than the first solder 21A.

Description

  The present invention relates to a metal terminal bonding structure of a superconducting wire and a method for bonding a superconducting wire and a metal terminal.

The RE-123 oxide superconductor discovered recently (REBa ₂ Cu ₃ O _7-x : RE is a rare earth element including Y) is extremely promising in practice because it exhibits superconductivity at liquid nitrogen temperature or higher. There is a strong demand for processing this into a wire and using it as a conductor for power supply. As a method of manufacturing an oxide superconductor as a wire, a metal that has high strength and heat resistance and can be easily processed into a wire is processed into a long tape shape, and the oxide superconductor is formed on the metal substrate. A method for forming a thin film has been studied.
In order to obtain an oxide superconductor as a wire, it is common to provide a stabilizing layer made of a highly conductive metal layer such as silver or copper on an oxide superconducting thin film (superconducting layer). The stabilization layer functions as a bypass that commutates the current of the superconducting layer when the superconducting layer attempts to transition from the superconducting state to the normal conducting state.

In order to apply such oxide superconducting conductors to practical equipment as wires, it is essential to establish a technology for connecting metal terminals and oxide superconducting wires to electrically connect external power sources and circuits to oxide superconducting wires. It is.
As a method of connecting an oxide superconducting wire and a metal terminal, a method of connecting a metal terminal via solder on a layer made of silver or a silver alloy formed on an oxide superconductor is disclosed (Patent Document 1). reference). Although it is not a method for connecting metal terminals, as a technique for connecting oxide superconducting wires, two oxide superconducting wires each having a superconducting layer and a stabilized silver layer provided in this order on a tape-like base material A technique is disclosed in which the surfaces of the stabilized silver layers are opposed to each other and connected via solder (see Patent Document 2).

JP-A-9-97637 JP 2000-133067 A

When a metal terminal is connected to an oxide superconducting wire as in the technique described in Patent Document 1, it is common to connect via a solder.
Although connection by solder is simple, there is a problem that electrical resistance (connection resistance) is generated at the solder connection portion. When the connection resistance is increased, the resistance is increased, and there is a possibility that the characteristic that the superconducting wire material has a low loss should be impaired. Further, when Joule heat generated in the solder connection portion by the connection resistance is conducted to the superconducting layer, the superconducting characteristics may be deteriorated. As an example of Joule heat generation due to connection resistance, a connection resistance of 1 μΩ was generated between the metal terminal and the oxide superconducting wire at a liquid nitrogen temperature (about 77 K) at which the oxide superconductor becomes superconductive and the resistance becomes 0. In this case, 1 W Joule heat is generated when 1 kA is energized. Therefore, it is desirable to reduce the connection resistance by reducing the thickness of the solder as much as possible.
In addition, when soldering is poor, if the wettability of the solder is poor, it is difficult to obtain a good connection and there is a problem that the connection resistance increases.

  Furthermore, the heat of the connection part due to heating at the time of solder connection is transmitted to the superconducting layer, and the superconducting characteristics may be deteriorated. In order to prevent deterioration of superconducting characteristics, solder connection in a short time is desirable. However, in a short time solder connection, it becomes difficult to obtain a good connection, which may lead to an increase in connection resistance. When a metal terminal is solder-bonded to an oxide superconducting wire in which a silver layer as a stabilization layer is provided on the superconducting layer and a copper tape is provided on the silver layer via solder. By heating at the time of solder connection, the solder joint between the copper tape and the silver layer may be remelted, and the copper tape may be peeled off.

  The present invention has been made in view of such conventional circumstances, and is a superconducting wire that is in a good bonded state in which no peeled portion or the like is generated and can suppress an increase in electrical resistance of a solder connection portion. An object of the present invention is to provide a metal terminal bonding structure and a method of bonding a superconducting wire and a metal terminal.

In order to solve the above problems, the present invention employs the following configuration.
The superconducting wire and metal terminal joining method of the present invention is a superconducting tape comprising a substrate, a superconducting layer provided on the substrate via an intermediate layer, and a protective layer provided on the superconducting layer. A stabilizing material tape is joined on the protective layer to form a stabilizing material composite superconducting tape, and a method of joining a superconducting wire and a metal terminal to join a metal terminal on the stabilizing material composite superconducting tape, wherein the stabilizing The chemical tape has a first solder plated on one surface and a second solder plated on the other surface, and the superconducting tape and the stabilizing tape are joined via the first solder. ,
The metal terminal is formed by joining the stabilizing material composite superconducting tape with the second solder and the third solder interposed in this order, and the melting point T ₂ of the second solder and the melting point T _{3 of} the third solder. Is lower than the melting point T ₁ of the first solder.
In the method for joining a superconducting wire and a metal terminal according to the present invention, the melting point T ₁ of the first solder, the melting point T ₂ of the second solder, and the melting point T ₃ of the third solder are 250 ° C.> T ₁ > T ₂ = it is preferable to satisfy a relation of T _3.
In the method for joining a superconducting wire and a metal terminal according to the present invention, the stabilizing material composite superconducting tape is stacked on the protective layer of the superconducting tape with the stabilizing material tape in contact with the first solder side, It is also preferable that the second solder is formed by heating and pressing with a pair of heating / pressurizing rolls, and the thickness of the second solder is 10 μm or less.

The superconducting wire metal terminal junction structure of the present invention comprises a base material, a superconducting tape provided on the base material via an intermediate layer, and a protective layer provided on the superconducting layer; A stabilizer tape provided on the protective layer of the superconducting tape via a first solder, and a metal provided on the stabilizer tape with a second solder and a third solder interposed in this order. The stabilizer tape has one surface plated with the first solder and the other surface plated with the second solder, and the melting point T _{2 of} the second solder. The melting point T ₃ of the third solder is lower than the melting point T ₁ of the first solder.
In the metal terminal junction structure of the superconducting wire of the present invention, the melting point T ₁ of the first solder, the melting point T ₂ of the second solder, and the melting point T ₃ of the third solder are 250 ° C.>T1> T2 = T3. It is preferable to satisfy the relationship.
In the superconducting wire metal terminal bonding structure according to the present invention, it is also preferable that the thickness of the second solder is 10 μm or less.

The superconducting wire and metal terminal joining method according to the present invention includes a stabilizer tape in which a first solder is pre-plated on one surface and a second solder is plated on the other surface on the superconducting tape. In addition, a metal terminal is connected to the second solder on the stabilizer tape via the third solder. Since the second solder on the stabilizer tape is thinly and uniformly plated on the stabilizer tape instead of hand solder as in the conventional method, the wettability of the third solder is improved and the metal terminal is attached. It can be connected stably and satisfactorily. Therefore, it is possible to suppress an increase in the electrical resistance of the connection portion as a good bonded state as compared with the case where the metal terminal is connected via solder by hand solder as in the conventional method.
Further, in the method for joining the superconducting wire and the metal terminal of the present invention, the melting points of the second solder and the third solder for joining the stabilizer tape and the metal terminal are the first ones for joining the superconducting tape and the stabilizer tape. It was set as the structure which becomes lower than melting | fusing point of solder. Thereby, it can suppress that a 1st solder fuse | melts and the stabilization material tape peels from a superconducting tape by the heating at the time of solder joining of a metal terminal.

Furthermore, in the method for joining a superconducting wire and a metal terminal according to the present invention, the melting point T ₁ of the first solder, the melting point T ₂ of the second solder, and the melting point T ₃ of the third solder are 250 ° C.> T ₁ > T ₂ = T _When it is set as the structure which satisfy | fills the relationship of ₃ , it can suppress that the heating at the time of joining of 1st-3rd solder transfers heat, a superconducting layer deteriorates, and a superconducting characteristic falls.
In the method for joining a superconducting wire and a metal terminal according to the present invention, the superconducting tape and the stabilizing material tape are superposed via a first solder and joined by heating and pressurizing with a pair of heating / pressurizing rolls. The solder thickness is preferably 10 μm or less. By adopting such a configuration, when the superconducting tape and the stabilizing material tape are passed through the heating / pressurizing roll, the second solder having a melting point lower than that of the first solder is melted and fluidized to stabilize the stabilizing material. Outflow to the side of the tape or the superconducting tape can be suppressed. Further, by setting the thickness of the second solder to 10 μm or less, it is possible to suppress an increase in connection resistance of the solder joint portion, and it is also possible to reduce the thickness of the superconducting wire and suppress the deterioration of the mechanical strength.

The metal terminal junction structure of the superconducting wire of the present invention has a configuration in which a metal terminal is provided via a third solder on a second solder plated on a stabilizer tape. Since the second solder on the stabilizer tape is widely and uniformly formed by plating, the wettability of the third solder provided thereon is improved, and the connection state of the metal terminals is stable and in a good state. can do. Therefore, it can be set as the metal terminal junction structure of the superconducting wire which can suppress the increase in the electrical resistance of the connection part.
In the superconducting wire metal terminal bonding structure according to the present invention, when the thickness of the second solder is 10 μm or less, it is possible to suppress an increase in the connection resistance of the solder bonding portion, and to make the superconducting wire thin. And deterioration of mechanical strength can be suppressed.

It is a schematic perspective view which shows 1st Embodiment of the metal terminal junction structure of the superconducting wire of this invention. It is a schematic block diagram which shows an example of the manufacturing apparatus used for the joining method of the superconducting wire of this invention of this invention, and a metal terminal.

Hereinafter, an embodiment of a metal terminal bonding structure of a superconducting wire according to the present invention will be described.
FIG. 1 is a schematic perspective view showing a first embodiment of a metal terminal bonding structure of a superconducting wire according to the present invention. The superconducting wire metal terminal joint structure 10 of the present embodiment shown in FIG. 1 is a stabilizing material composite superconducting composed of a long superconducting tape 1 and a soldering stabilizing tape 2 provided on the superconducting tape 1. A tape 5 and a metal terminal 8 provided on the end portion of the stabilizing material composite superconducting tape (superconducting wire) 5 via a third solder 7 are provided.

  The superconducting tape 1 is configured by laminating an intermediate layer 12, a superconducting layer 13, and a protective layer 14 in this order on a long tape-like base material 11.

The base material 11 may be any material that can be used as a base material for ordinary superconducting wires, and is preferably in the form of a long plate or sheet, and is preferably made of a heat-resistant metal. Among heat resistant metals, an alloy is preferable, and a nickel (Ni) alloy or a copper (Cu) alloy is more preferable. Among them, Hastelloy (trade name, manufactured by Haynes Co., Ltd.) is suitable for commercial products, and has different amounts of components such as molybdenum (Mo), chromium (Cr), iron (Fe), cobalt (Co), etc. Any type of C, G, N, W, etc. can be used.
What is necessary is just to adjust the thickness of the base material 11 suitably according to the objective, Usually, it is preferable that it is 10-500 micrometers, and it is more preferable that it is 20-200 micrometers. By setting the lower limit value or more, the strength is further improved, and by setting the upper limit value or less, the overall critical current density can be further improved.

The intermediate layer 12 controls the crystal orientation of the superconducting layer 13 to prevent the metal element in the base material 11 from diffusing into the superconducting layer 13, and the physical layer between the base material 11 and the superconducting layer 13. It functions as a buffer layer that alleviates the difference in characteristics (thermal expansion coefficient, lattice constant, etc.). The material of the intermediate layer 12 is preferably a metal oxide whose physical characteristics show intermediate values between the substrate 11 and the superconducting layer 13. Specifically, preferred materials for the intermediate layer 12 are Gd ₂ Zr ₂ O ₇ , MgO, ZrO ₂ —Y ₂ O ₃ (YSZ), SrTiO ₃ , CeO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , Gd _2. Examples thereof include metal oxides such as O ₃ , Zr ₂ O ₃ , Ho ₂ O ₃ , and Nd ₂ O ₃ .
The intermediate layer 12 may be a single layer or a plurality of layers. For example, the layer made of the metal oxide (metal oxide layer) preferably has crystal orientation, and when it is a plurality of layers, the outermost layer (layer closest to the superconducting layer 13) is at least It preferably has crystal orientation.

A bed layer may be interposed between the intermediate layer 12 and the base material 11. The bed layer has high heat resistance and is used for reducing interfacial reactivity, and is used for obtaining the orientation of a film disposed thereon. Such a bed layer is arranged as necessary, and is made of, for example, yttria (Y ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₃ , also referred to as “alumina”), or the like. Is done. The bed layer is formed by a film forming method such as a sputtering method, and has a thickness of 10 to 200 nm, for example.

Furthermore, in this invention, it is good also as a structure where the diffusion prevention layer was interposed between the base material 11 and the bed layer. The diffusion preventing layer is formed for the purpose of preventing the diffusion of the constituent elements of the substrate 11, and is composed of silicon nitride (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₃ ), rare earth metal oxide, or the like. The thickness is, for example, 10 to 400 nm. Note that since the crystallinity of the diffusion preventing layer is not questioned, it may be formed by a film forming method such as a normal sputtering method.
In this way, by interposing the diffusion preventing layer between the base material 11 and the bed layer, when forming other layers such as an intermediate layer 12 and a superconducting layer 13 which will be described later, inevitably heating or heat treatment is performed. As a result, when receiving a thermal history, it is possible to effectively suppress a part of the constituent elements of the base material 11 from diffusing to the superconducting layer 13 side through the bed layer. As an example of the case where a diffusion preventing layer is interposed between the base material 11 and the bed layer, a combination using Al ₂ O ₃ as the diffusion preventing layer and Y ₂ O ₃ as the bed layer can be exemplified.

  The intermediate layer 12 may have a multi-layer structure in which a cap layer is further laminated on the metal oxide layer. The cap layer has a function of controlling the orientation of the superconducting layer 13, diffuses the elements constituting the superconducting layer 13 into the intermediate layer 12, and reacts the gas used when the superconducting layer 13 is laminated with the intermediate layer 12. It has a function to suppress. Further, the orientation of the cap layer is controlled by the metal oxide layer.

The cap layer is formed through a process of epitaxially growing on the surface of the metal oxide layer, and then growing the grains in the lateral direction (plane direction) (overgrowth) and selectively growing the crystal grains in the in-plane direction. The ones made are preferred. Such a cap layer has a higher degree of in-plane orientation than the metal oxide layer.
The material of the cap layer is not particularly limited as long as it can exhibit the above functions, but specifically, preferred examples include CeO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , Gd ₂ O ₃ , and Zr ₂ O. ₃ , Ho ₂ O ₃ , Nd ₂ O _{3 and the} like. When the material of the cap layer is CeO ₂ , the cap layer may contain a Ce—M—O-based oxide in which part of Ce is substituted with another metal atom or metal ion.

The thickness of the intermediate layer 12 may be appropriately adjusted according to the purpose, but is usually 0.1 to 5 μm.
When the intermediate layer 12 has a multi-layer structure in which a cap layer is laminated on the metal oxide layer, the thickness of the cap layer is usually 0.1 to 1.5 μm.

The intermediate layer 12 is formed by physical vapor deposition such as sputtering, vacuum vapor deposition, laser vapor deposition, electron beam vapor deposition, ion beam assisted sputtering (hereinafter abbreviated as IBAD method), chemical vapor deposition (CVD), or the like. Method: Thermal coating decomposition method (MOD method); It can be laminated by a known method for forming an oxide thin film such as thermal spraying. In particular, the metal oxide layer formed by the IBAD method is preferable in that the crystal orientation is high and the effect of controlling the crystal orientation of the superconducting layer 13 and the cap layer is high. The IBAD method is a method of orienting crystal axes by irradiating an ion beam at a predetermined angle with respect to a crystal deposition surface during deposition. Usually, an argon (Ar) ion beam is used as the ion beam. For example, the intermediate layer 12 made of Gd ₂ Zr ₂ O ₇ , MgO, or ZrO ₂ —Y ₂ O ₃ (YSZ) can reduce the value of ΔΦ (FWHM: full width at half maximum) that is an index representing the degree of orientation in the IBAD method. Therefore, it is particularly suitable.

The superconducting layer 13 can be widely applied to those composed of a superconductor having a generally known composition, and is preferably composed of an oxide superconductor. Specifically, a material made of REBa ₂ Cu ₃ O _y (RE represents a rare earth element such as Y, La, Nd, Sm, Er, Gd) can be exemplified. Further, other oxide superconductors, for _{example, Bi 2 Sr 2 Ca n-} 1 Cu n for _{O 4 + 2n + δ} becomes may be used in compositions such as those made of other oxide superconductors having high critical temperatures representative Of course.
The superconducting layer 13 can be laminated by physical vapor deposition such as sputtering, vacuum vapor deposition, laser vapor deposition, electron beam vapor deposition, chemical vapor deposition (CVD), thermal coating decomposition (MOD), etc. Of these, laser vapor deposition is preferred.
The superconducting layer 13 has a thickness of about 0.5 to 5 μm and preferably a uniform thickness.

  The protective layer 14 laminated on the superconducting layer 13 is formed as a layer made of a metal material having good conductivity, such as Ag, and low contact resistance with the superconducting layer 13. The thickness of the protective layer 14 is preferably 1 to 30 μm. The protective layer 14 can be formed by a known method, but it is preferable to form the protective layer 14 by a sputtering method.

  The soldered stabilizer tape 2 laminated on the protective layer 14 of the superconducting tape 1 includes a stabilizer tape 21, a first solder 21A plated on one surface of the stabilizer tape 21, and a stabilizer. The second solder 21B is plated on the other surface of the material tape 21. The soldered stabilizer tape 2 is laminated on the protective layer 14 of the superconducting tape 1 in the order of the first solder 21A, the stabilizer tape 21 and the second solder 21B.

The stabilizer tape 21 is made of a highly conductive metal material that is in the form of a long tape. When the superconducting layer 13 attempts to transition from the superconducting state to the normal conducting state, the current of the superconducting layer 13 together with the protective layer 14 is obtained. Functions as a bypass to commutate.
The metal material constituting the long tape-shaped stabilization tape 21 is not particularly limited as long as it has good electrical conductivity, but copper alloy such as copper and brass (Cu-Zn alloy), stainless steel, and the like. It is preferable to use a relatively inexpensive material, and copper is more preferable because it has high conductivity and is inexpensive. The thickness of the stabilizing tape 21 is preferably 10 to 300 μm. By setting the lower limit value or more, a higher effect of stabilizing the superconducting layer 13 can be obtained, and by setting the upper limit value or less, the superconducting wire can be thinned.

The melting point T ₁ of the first solder 21, the melting point T ₂ of the second solder 21 B, and the melting point T ₃ of the third solder 7 preferably satisfy the relationship of T ₁ > T ₂ , T ₃ , and 250 ° C.> T ₁ > It is preferable to satisfy the relationship of T ₂ = T ₃ .

First solder 21A is not particularly limited as long as the melting point T ₁ is higher than the second solder 21B to be described later, the melting point T ₁ is preferable to use a solder of 250 ° C. or less. By melting point T ₁ of the first solder 21A is used solder 250 ° C. or less, when complexed with the superconducting tape 1 and the solder with stabilizing material tape 2 described later, the superconducting layer 13 is deteriorated by soldering heat Can be suppressed. Examples of the first solder 21A include lead-free solders such as Sn—Cu based alloys and Sn—Ag based alloys. The first solder 21A is formed on one surface of the stabilizing material tape 21 by a plating method. The thickness of the first solder 21A can be adjusted as appropriate, and is not particularly limited, but is preferably 10 μm or less because the wire can be thinned.

Second solder 21B is not particularly limited as long as a low melting point _{T 2} than the first solder 21A, for example, eutectic solder such as Pb-Sn-based alloy, the lead-free solder such as Sn-Bi alloy thereof It is done. The first solder 21B is formed by plating on the surface (the other surface) opposite to the surface on which the first solder 21A of the stabilizing material tape 21 is plated. By providing the second solder 21B, the metal terminal 8 is joined via the third solder 7 to the stabilizing material composite superconducting tape (superconducting wire) 5 in which the superconducting tape 1 and the stabilizing material tape 2 with solder are integrated. In this case, the third solder 7 can stably and uniformly spread on the second solder 21B formed on the uppermost surface of the superconducting wire 5, and the wettability of the third solder 7 can be improved. And the metal terminal 8 are in a good connection state, and an increase in connection resistance can be suppressed.
The thickness of the second solder 21B is preferably 10 μm or less. By setting the thickness of the second solder 21B to 10 μm or less, in the superconducting wire and metal terminal joining method described later, the superconducting tape 1 and the soldered stabilizer tape 2 are overlapped and passed through the heating / pressure roll. In doing so, it is possible to suppress the second solder 21B having a melting point lower than that of the first solder 21A from melting and flowing and flowing out to the side of the stabilizing tape 21 or the superconducting tape 1 side. Further, by setting the thickness of the second solder 21B to 10 μm or less, not only can the wire be thinned, but also an increase in the connection resistance of the solder joint can be suppressed.

The third solder 7 is not particularly limited as long as a low melting point T ₃ than the first solder 21A, may be the same as the second solder 21B. Among these, it is preferable that the second solder 21B is formed of a solder having the same composition as the second solder 21B because the manufacturing cost can be suppressed and the manufacturing can be easily performed. The third solder 7 may be formed by hand solder, or may be formed on one surface of the metal terminal 8 by a plating method. The thickness of the third solder 7 is not particularly limited, but a thinner one is preferable because it can suppress an increase in connection resistance of the plated joint, and is preferably 2 to 10 μm, for example.
By setting lower than the melting point T ₁ of the melting point T ₃ of the melting point T ₂ and the third solder 7 first solder 21A of the second solder 21B, the metal terminal 8 to the stabilizer complex superconducting tape (superconducting wire) 5 It is possible to prevent the first solder 21 </ b> A from being melted and peeling the stabilizing material tape 21 from the superconducting tape 1 during heating at the time of joining.

  The metal terminal 8 is preferably formed of a metal having high conductivity, and examples thereof include gold, platinum, silver, copper, or an alloy containing at least one of these metals, and copper is particularly preferable. The size of the metal terminal 3 is not particularly limited and can be adjusted as appropriate. The metal terminal 8 is preferably formed with a lead portion (not shown) for conducting the metal terminal 8 and the external excitation power source.

The superconducting wire metal terminal joint structure 10 of the present embodiment is configured such that the metal terminals 8 are provided on the second solder 21B plated on the stabilizing material tape 21 via the third solder 7. Since the second solder 21B on the stabilizing material tape 21 is uniformly formed on the entire upper surface of the stabilizing material tape 21 by plating, the wettability of the third solder 7 provided thereon is improved, and the metal terminal The connection state of 8 can be made stable and good. Therefore, it can be set as the metal terminal junction structure of the superconducting wire which can suppress the increase in the electrical resistance of the connection part.
In the superconducting wire metal terminal joint structure of the present embodiment, when the thickness of the second solder 21B is 10 μm or less, an increase in the connection resistance of the solder joint can be suppressed, and the superconducting wire 5 can be made thin to suppress the deterioration of the mechanical strength.

Next, an embodiment of a method for joining a superconducting wire of the present invention and a metal terminal, which is a method for producing a superconducting wire metal terminal connecting structure of the present invention, will be described.
First, the superconducting tape 1 having the above-described configuration and the soldering stabilizer tape 2 are prepared. Next, the superconducting tape 1 and the soldered stabilizer tape 2 are overlapped and joined so that the protective layer 14 of the superconducting tape 1 and the first solder 21A of the soldered stabilizer tape 2 are in contact with each other. For joining the superconducting tape 1 and the soldered stabilizer tape 2, it is preferable to use a manufacturing apparatus having a configuration as shown in FIG.

FIG. 2 is a schematic configuration diagram showing an example of a manufacturing apparatus used for manufacturing a stabilizing material composite superconducting tape in the method of bonding a superconducting wire and a metal terminal according to the present embodiment.
The manufacturing apparatus shown in FIG. 2 has a delivery reel 9a for feeding the superconducting tape 1, a delivery reel 9b for feeding a soldering stabilizing tape 9b, a superconducting tape 1 sent from the delivery reel 9a and the delivery reel 9b, and a soldered stable. A pair of heatings for heating and pressurizing a preheating furnace 3 for heating the chemical tape 2, and a composite material 6 in which the superconducting tape 1 heated in the preheating furnace 3 and the stabilizing material tape 2 with solder are superposed. It is composed of pressure rolls 4 and 4 and a take-up reel (not shown) for winding the stabilizing material composite superconducting tape (superconducting wire) 5 heated and pressurized by the heating and pressure rolls 4 and 4. .

In order to produce the stabilizing material composite superconducting tape (superconducting wire) 5 by integrating the superconducting tape 1 and the soldering stabilizing tape 2, the protective layer 14 of the superconducting tape 1 and the soldering stabilizing tape 2 are used. as a state to be opposed to the first solder 21A it is, transported into the preheating furnace 3, and heating these tapes 1,2 to melting point above T ₁ of the first solder 21A, overlay is heated in the preheating furnace The superconducting tape 1 and the material to be composited 6 which is the soldering stabilizing tape 2 are pressed through a pair of heating / pressurizing rolls 4 and 4 and cooled to a melting point T ₁ or less of the first solder 21A. Then, the first solder 21A is solidified under heating, the superconducting tape 1 and the stabilizing material tape 2 with solder are joined, and the stabilizing material composite superconducting tape (superconducting tape) 5 can be continuously produced at high speed.

Heating temperature in the preheating furnace 3 is not particularly limited as long as the melting point above T ₁ of the first solder 21A, deterioration of the superconducting tape 1 of the superconducting layer 13 by heating, the second solder 21B of solder with a stabilizing material tape 2 It is preferable to set the temperature to 240 to 300 ° C.

The heating temperature in the heat and pressure roll 4, 4 is not particularly limited as long as the melting point _{T 1} than the first solder 21A, preferably made 160 to 220 ° C..
As the material of the heating / pressurizing rolls 4 and 4, a material usually used as a pressurizing roll can be used. However, since deterioration due to pressurization of the superconducting layer 13 of the superconducting tape 1 can be suppressed, silicone is used. A soft material such as rubber is preferred. Further, since the heating / pressurizing rolls 4 and 4 are formed from a soft material such as silicone rubber, the solidification position of the first solder 21A can be easily optimized by adjusting the hardness of the rubber. A good bonding interface can be obtained.
Although the pressure at the time of the pressurization in the heating / pressurizing rolls 4 and 4 is not particularly limited, it is preferable to set the pressure to 10 to 200 MPa since deterioration of the superconducting layer 13 of the superconducting tape 1 can be prevented.

  In the present embodiment, as described above, the thickness of the second solder 21B plated on the stabilizing material tape 21 is set to 10 μm or less, so that the composite material 6 passes through the heating / pressurizing rolls 4 and 4. In doing so, the second solder 21B having a melting point lower than that of the first solder 21A melts and flows, flows out to the side surface of the stabilizing material tape 1 and around the composite material 6, and the second solder 21B loses. Can be prevented. Furthermore, the superconducting wire 5 can be thinned by setting the thickness of the first solder 21A to 10 μm or less.

In order to effectively solidify the first solder 21A under pressure by the heating / pressurizing rolls 4 and 4, the composite material 1 is heated / pressurized at the timing when the first solder 21A is lowered to the solidification temperature. It is necessary to adjust the temperature gradient and the tape linear speed (conveyance speed) so that the rolls 4 and 4 come near. In the manufacturing apparatus of the present embodiment shown in FIG. 2, the outlet side of the preheating furnace 3 is elongated in a bowl shape, and the precombined material to be preheated at a position within 20 mm before the meshing position of the heating and pressure rolls 4 and 4 is obtained. 6 comes out of the preheating furnace 3 and is immediately wound around the heating / pressure rolls 4 and 4. Thus, the first solder 21A which has been heated to melting point above T ₁ in the preheating furnace 3, has a structure that does not coagulate before the heating and pressing roll 4,4. Moreover, the solidification position of the 1st solder 21A can be made more downstream by raising a tape linear velocity. The tape linear velocity is preferably 50 m / h or more.

Moreover, the manufacturing apparatus used for manufacturing the stabilizing material composite superconducting tape (superconducting wire) 5 in this embodiment is not limited to the manufacturing apparatus shown in FIG. A step roll can also be provided. By providing a step roll, a length (grounding region) where tension is applied while the bonded stabilizing material composite superconducting tape (superconducting wire) 5 is grounded on the heating / pressurizing rolls 4 and 4 is secured. Can do. Thereby, even when the solidification position of the first solder 21A is behind the meshing position of the rolls 4 and 4, the composite material 6 can be joined without causing large peeling.
As described above, the stabilizing material composite superconducting tape (superconducting wire) 5 can be manufactured.

Next, the metal terminal 8 is joined via the third solder 7 on the second solder 21 </ b> B of the stabilizing material composite superconducting tape (superconducting wire) 5.
The metal terminal 8 can be formed by ordinary soldering by the third solder 7 to the superconducting wire 5 and may be joined by hand soldering, or the third solder 7 is plated on the joining surface of the metal terminal 8 in advance. The metal terminal 8 may be installed so that the surface on which the third solder 7 is formed is in contact with the surface of the second solder 21B of the superconducting wire 5 and then cooled and joined after heating.

In the superconducting wire and metal terminal joining method of the present embodiment, since the second solder 21B formed by plating is formed on the upper surface of the superconducting wire 5, the third solder 7 is uniformly formed on the second solder 21B. Since the wettability of the third solder 7 can be improved, the solder joint surface between the superconducting wire 5 and the metal terminal 8 can be made uniform, and a good connection state can be obtained. Thereby, compared with the case where it joins directly by hand solder like the conventional method, it suppresses that the dispersion | variation in the joining state by a manufacturing process arises, and with the superconducting wire 5 in a stable good connection state stably. The metal terminal 8 can be joined. Moreover, since the connection state of a superconducting wire and a metal terminal can be made favorable, an increase in connection resistance can be suppressed.
Furthermore, the method of connecting the superconducting wire and the metal terminal of this embodiment, by setting lower than the melting point T ₁ of the melting point T ₃ of the melting point T ₂ and the third solder 7 of the second solder 21B first solder 21A, It is possible to prevent the first solder 21 </ b> A from melting and the stabilizing material tape 21 from being peeled from the superconducting tape 1 during heating when joining the metal terminal 8 to the superconducting wire 5.

  The superconducting wire metal terminal connection structure and the superconducting wire and metal terminal joining method of the present invention have been described above. In the above embodiment, each part of the superconducting wire metal terminal connection structure, the superconducting wire and the metal terminal. The configuration of each part of the apparatus used in this joining method is an example, and can be appropriately changed without departing from the scope of the present invention.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited to these Examples.

Example 1
"Production of superconducting tape"
Gd ₂ Zr ₂ O ₇ (GZO) having a thickness of 1.2 μm is formed on a tape-shaped Hastelloy (trade name, manufactured by Haynes, USA) substrate having a width of 10 mm and a thickness of 0.1 mm by an ion beam assisted sputtering method (IBAD method). : Intermediate layer) was formed, and then CeO ₂ (cap layer) having a thickness of 1.0 μm was formed by a pulse laser deposition method (PLD method). Next, a 1.0 μm-thick GdBa ₂ Cu ₃ O ₇ (superconducting layer) is formed on the CeO ₂ layer by the PLD method, and a 10 μm-thick silver layer (protective layer) is further formed on the superconducting layer by the sputtering method. A tape was prepared.

"Production of superconducting wire (stabilized composite superconducting tape)"
One surface of a copper tape having a thickness of 100 μm and a width of 10 mm is plated with Sn—Cu alloy (melting point 235 ° C.) as a first solder at a thickness of 2 to 4 μm, and Sn—Pb—Ag alloy (melting point) as the second solder. A soldered stabilizer tape plated with a thickness of 180 to 190 ° C. at a thickness of 2 to 4 μm was prepared.
Next, using the apparatus shown in FIG. 2, the first solder side of the soldering stabilizer tape was joined onto the silver layer (protective layer) of the superconducting tape to produce a superconducting wire. Incidentally, the superconducting tape and the bonding of the solder with a stabilizing material tape, the pre-heat oven temperature 260 ° C., the heat and pressure roll as silicone rubber, heating temperature 220 ° C., heated and pressed at a pressure 100 MPa, linear velocity 100m / H. When the second solder surface of the superconducting wire after fabrication was observed, it was in a uniform state with no peeling or loss.

"Joining superconducting wire and metal terminal"
A Sn-Pb-Ag alloy (melting point: 180 to 190 ° C.) with a part of a copper metal terminal having a width of 10 mm, a height of 1 mm, and a length of 50 mm as a third solder at the end portion of the superconducting wire produced above. ) And was joined by hand soldering at a thickness of about 10 μm. The solder joint was an area having a width of 1.0 mm and a length of 50 mm from the end of the superconducting wire.
In addition, by the same procedure as described above, three superconducting wires and metal terminal joint structures were further produced, and a total of four superconducting wires and metal terminal joint structures were obtained.

(Comparative Example 1)
A superconducting tape is produced in the same manner as in Example 1, and a copper tape having a width of 10 mm is joined onto the silver layer (protective layer) of this superconducting tape via solder of Sn—Cu alloy (melting point 234 ° C.). A superconducting wire was prepared.
Next, a part of a copper metal terminal having a width of 10 mm, a height of 1 mm, and a length of 50 mm is used at the end of the produced superconducting wire on a copper tape, using a Sn—Pb—Ag alloy (melting point: 180 to 190 ° C.). The film was joined by hand soldering at a thickness of about 10 μm. The solder joint was an area having a width of 1.0 mm and a length of 50 mm from the end of the superconducting wire.
In addition, by the same procedure as described above, three superconducting wires and metal terminal joint structures were further produced, and a total of four superconducting wires and metal terminal joint structures were obtained.

"Evaluation"
The superconducting wire and the metal terminal joint structure produced in Example 1 and Comparative Example 2 were peeled off by applying mechanical force to the superconducting wire and the metal terminal, and the solder joint (width 1.0 mm × length 50 mm). The difference in gloss of the solder joints is observed with a microscope, the joint area P in the solder joints and the non-joint area Q (parts with different gloss) are obtained, and the ratio P / (P + Q) × 100 of the joint areas in the solder joints. (%) Was calculated. The results are shown in Table 1. In Table 1, Samples 1 to 4 show the respective superconducting wires and metal terminal bonded structures produced in the first to fourth times in the above Examples and Comparative Examples.

  In the connection method between the superconducting wire and the metal terminal according to the first embodiment of the present invention, the solder joint is bonded in a wider area than in the first comparative example, and there is less variation due to the manufacturing process, and a good bonding state is obtained. It is clear that it can be obtained stably.

(Example 2)
A plurality of superconducting tapes were produced in the same manner as in Example 1 above.
Next, Sn—Cu alloy (melting point 234 ° C.) as a first solder is plated at a thickness of 2 to 4 μm on one surface of a copper tape having a thickness of 100 μm and a width of 10 mm, and Sn—Pb—Ag as a second solder. Soldered stabilizer tapes of Samples 1 to 5 in which an alloy (melting point: 180 to 190 ° C.) was plated at a thickness shown in Table 2 were prepared.
Next, using the apparatus shown in FIG. 2, the first plated side of the soldered stabilizer tape of Samples 1 to 5 is joined onto the silver layer (protective layer) of the superconducting tape, and the superconducting wires of Samples 1 to 5 are joined. Was made. The superconducting tape and soldered stabilizer tape are joined at a preheating furnace temperature of 260 ° C., and the heating / pressurizing roll is made of silicone rubber, heated and pressurized at a heating temperature of 220 ° C. and a pressure of 100 MPa, and a linear velocity of 100 m / h.
By observing the second solder surface of each of the produced superconducting wires of Samples 1 to 5, the following criteria were used. The results are shown in Table 2.
○: There was no peeling or loss, and it was in a uniform state.
X: There was peeling and loss (solder flow to the side surface of the wire), and it was in a non-uniform state.

  From the results in Table 2, when the thickness of the second solder is 10 μm or less, the second solder is melted when the superconducting tape and the soldered stabilizer tape are joined by passing the heating / pressurizing roll. Thus, it was confirmed that the formation failure of the second solder can be suppressed by flowing to the side surface side of the tape.

Furthermore, Sn-Pb-Ag with a part of a copper metal terminal having a width of 10 mm, a height of 1 mm, and a length of 50 mm as a third solder at the end on the second solder of the superconducting wires of Samples 1 to 3 prepared above. By using an alloy (melting point: 180 to 190 ° C.) and joining by hand solder with a thickness of about 10 μm, samples 1 to 5 of superconducting wires and metal terminal joined structures were produced. The solder joint was an area having a width of 10 mm and a length of 50 mm from the end of the superconducting wire.
Next, the bonding state of the superconducting wires of Samples 1 to 3 and the metal terminal bonding structure was observed by the same method as in Example 1. As a result, by making the thickness of the second solder 10 μm or less, the surface of the stabilizing material composite superconducting tape manufactured using a heating / pressurizing roll is uniform on the upper surface of the stabilizing material tape without peeling or loss. Since the second solder is formed in such a state, when the metal terminal is joined to the second solder via the third solder, the wettability of the third solder is improved and the solder joint portion is in a good joined state. It was confirmed that

  DESCRIPTION OF SYMBOLS 1 ... Superconducting tape, 2 ... Soldered stabilizer tape, 3 ... Preheating furnace, 4 ... Heating / pressurizing roll, 5 ... Stabilizing material composite superconducting tape (superconducting wire), 6 ... Composite material, 7 ... No. 3 solder, 8 ... metal terminal, 10 ... metal terminal bonding structure, 11 ... base material, 12 ... intermediate layer, 13 ... superconducting layer, 14 ... protective layer, 21 ... stabilizer tape, 21A ... first solder, 21B ... second solder.

Claims (6)

A stabilizer tape is bonded onto the protective layer of the superconducting tape comprising a base material, a superconducting layer provided on the base material via an intermediate layer, and a protective layer provided on the superconducting layer. And stabilizing material composite superconducting tape,
A method of joining a superconducting wire and a metal terminal to join a metal terminal on the stabilizing material composite superconducting tape,
The stabilizer tape has a first solder plated on one surface and a second solder plated on the other surface,
The superconducting tape and the stabilizer tape are joined via the first solder,
The metal terminal is formed by joining the second solder and the third solder in this order on the stabilizing material composite superconducting tape,
The second solder melting point T ₂ and the third solder melting point T ₃ is the bonding method of the superconducting wire and a metal terminal, characterized in that below the melting point T ₁ of the first solder. The melting point T ₁ of the first solder, the melting point T ₂ of the second solder, and the melting point T ₃ of the third solder satisfy a relationship of 250 ° C.> T ₁ > T ₂ = T _3. A method of joining the superconducting wire and the metal terminal according to 1. The stabilizing material composite superconducting tape is formed by superimposing the stabilizing material tape on the protective layer of the superconducting tape while contacting the first solder side, and heating and pressing with a pair of heating / pressurizing rolls. Formed,
The method of bonding a superconducting wire and a metal terminal according to claim 1 or 2, wherein the thickness of the second solder is 10 µm or less. A superconducting tape comprising a substrate, a superconducting layer provided on the substrate via an intermediate layer, and a protective layer provided on the superconducting layer;
A stabilizer tape provided on the protective layer of the superconducting tape via a first solder;
A metal terminal provided with the second solder and the third solder interposed in this order on the stabilizer tape;
The stabilizing material tape has the first solder plated on one surface and the second solder plated on the other surface,
The second solder melting point T ₂ and the third solder melting point T ₃ is replaced by a metal terminal connection structure of the superconducting wire, characterized in that below the melting point T ₁ of the first solder. 5. The melting point T ₁ of the first solder, the melting point T ₂ of the second solder, and the melting point T ₃ of the third solder satisfy a relationship of 250 ° C.> T 1> T 2 = T 3. Metal terminal junction structure of superconducting wire.   The metal terminal junction structure of a superconducting wire according to claim 4 or 5, wherein the thickness of the second solder is 10 µm or less.

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