JPH04220966A - Connecting wire and method and device for manufacturing the same - Google Patents

Abstract

PURPOSE:To provide a connecting wire for a superconducting device with less heat intrusion by forming the wire portion below the critical temp. from a superconducting material and the portion over the critical temp. from a good conductive metal, and forming the area between the two portions so that their densities vary gradually. CONSTITUTION:A connecting wire 8 is composed of a portion 8a consisting of a superconduct substance and a portion 8b consisting of an alloy chiefly containing Ag, etc., having a low electric resistance. At the boundary 8c, the two portions 8a, 8b are mixed with gradient, and the dia. of the boundary 8c shall be the same as the other parts. The end of the superconducting portion 8a is connected with a superconducting device, not illustrated, while the end of the alloy portion 8b is connected with a connector, not illustrated. When current flows. a temp. gradient is generated from the alloy portion 8b to the end of the superconducting portion 8a. The specific resistance of alloy portion 8b sinks with a sink of the temp. but the temp. remains higher than the superconducting portion 8b, being lower than in normal conductive state. Accordingly the connecting resistance decreases as a whole, which causes decrease of the heat intrusion.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection line that connects an electronic circuit using a superconducting material that operates in a low-temperature environment to an external circuit that operates at a normal temperature, and an apparatus and method for manufacturing the same.

0002

[Prior Art] Conventionally, so-called superconducting devices such as Josephson devices and magnetic flux quantum interference devices (SQUID), which operate in extremely low-temperature environments, are capable of ultra-high-speed operation and weak magnetic field detection that cannot be achieved with semiconductor devices. Because of this, it has been used in only a few limited fields.

0003

[Problem to be Solved by the Invention] By the way, it is relatively easy to maintain an extremely low temperature environment. For example, a high-quality cryostat can maintain liquid helium at an absolute temperature of 4.2 K for several weeks to several months. is possible. This is because once a low-temperature environment is created, there is no longer a cause for destroying the low-temperature environment by blocking heat from entering the environment. On the other hand, since superconducting devices only operate at extremely low temperatures, it is necessary to install the device in an extremely low temperature environment. However, since the signal from a superconducting device is amplified and used at room temperature, the signal line is electrically connected between the superconducting device set at an extremely low temperature and the peripheral circuitry installed at room temperature. It was necessary to connect. Usually, a good electrical conductor such as copper is used for this connection, but since a good electrical conductor is also a good thermal conductor, heat can enter through the electrical connection. At this time, the amount of invaded heat Q is the temperature difference Δt,
The thermal conductivity is ρ, the cross-sectional area of the connecting wire is S, and the length of the connecting wire is l
Then,

[0004] Q=kΔtSρ/l k is a specific constant

It is determined by the relationship: Therefore, if a thin conductor wire is used to prevent heat from entering, or if a metal such as stainless steel is used, which does not allow heat to pass through, the electric resistance increases, resulting in signal loss and noise generation. For this reason, it is common practice to connect a refrigerator that exceeds the amount of heat input and use electrical connections with good conductivity, resulting in a new problem in that an expensive and large refrigeration system is required.

Furthermore, even with superconducting devices that use high-temperature superconducting materials discovered in recent years, the operating temperature is now higher than 77 K, but the situation is the same, and it is still difficult to maintain a low-temperature environment. was one of the important keys for practical application.

[0007]

OBJECTS OF THE INVENTION In view of the above-mentioned circumstances, the present invention provides a connecting wire and an apparatus for manufacturing the same, which can realize a connection with a room-temperature part with low electrical resistance and little heat intrusion when operating a superconducting device. The purpose is to provide a manufacturing method.

[0008]

[Means for Solving the Problems] In order to achieve the object, the present invention according to claim 1 includes a superconducting device that operates at a low temperature and a peripheral circuit that operates near room temperature, and the superconducting device and In the connection line that electrically connects the peripheral circuit, the connection line is mainly composed of a superconducting material in a portion where the temperature environment of the line is below the critical temperature of the superconducting material, and where the temperature environment of the line is below the critical temperature of the superconducting material. The part connected to the circuit is mainly composed of metal that is a good conductor of electricity, and the junction of the two is at a part corresponding to just below the critical temperature, and the density of the two is gentle in the length direction of the line. The gist is what has changed.

[0009] Furthermore, the invention as set forth in claim 2 is characterized in that the metal is an alloy mainly containing silver, and the superconducting material is an oxide superconducting material.

Furthermore, the invention according to claim 3 provides a vehicle tank in which alloy fine powder is stored, a vehicle tank in which superconducting fine powder is stored, and a mixing tank connected to each of the vehicle tanks through pipes. a forming die disposed below the mixer and configured to stretch the wire discharged from the mixer; The gist of the present invention is to include a cutter that cuts the stretched wire into an appropriate length, and a tunnel electric furnace adjacent to the cutter that burns the cut wire.

Furthermore, in the invention according to claim 4, one vehicle tank stores alloy fine powder, and the other vehicle tank stores superconducting fine powder, and each of the fine powders stored in each of the vehicle tanks The gist is that the wire rod is discharged from the mixer while its component ratio is adjusted, and the discharged wire is formed into a predetermined shape and length, cut, and then baked in a tunnel electric furnace.

0012

[Embodiment] An embodiment of the connection wire and its manufacturing apparatus of the present invention will be explained based on the drawings.

FIG. 1 is a perspective view showing the external appearance of an electronic device showing an embodiment of the present invention, FIG. 2(a) is a partially enlarged view of connection lines, and FIG. 2(b) is a connection corresponding to FIG. 2(a). FIG. 3 is a graph diagram showing the distribution of components forming a line.

In FIG. 1, reference numeral 1 denotes a low-temperature thermostat, and a superconducting device 2 is disposed below the interior 1a. Further, a refrigerator 3 is disposed outside the low-temperature constant temperature bath 1 so as to be able to communicate with the inside 1a of the low-temperature constant temperature bath 1 via a duct 4. Further, a peripheral circuit 5 is provided outside the low-temperature constant temperature chamber 1, and the peripheral circuit 5 and the superconducting device 2 are connected via a connecting portion 6.

The connecting portion 6 connects the normal temperature side wiring 7 attached to the peripheral circuit 5 side and the connecting wire 8 attached to the superconducting device 2 side via a connector 9 attached above the low temperature constant temperature oven 1. connected.

As shown in FIGS. 2(a) and 2(b), the connecting wire 8 includes a portion 8a made of a superconducting component (hereinafter referred to as a superconducting portion) and a portion 8a made mainly of silver or gold having low electrical resistance. The superconducting portion 8a and the alloy portion 8b are composed of a portion 8b (hereinafter referred to as the alloy portion) consisting of an alloy component, and the components of the superconducting portion 8a and the alloy portion 8b are mixed in a gradient manner at the boundary 8c between the superconducting portion 8a and the alloy portion 8b. ing. Further, the physical diameter at the boundary 8c of the connection line 8 is formed without being different from the diameter at other portions. Further, the end of the connecting wire 8 on the superconducting portion 8a side is connected to the superconducting device 2, and the end of the connecting wire 8 on the alloy portion 8b is connected to the connector 9.

By the way, since the connecting wire 8 used in the electronic device A having such a configuration connects the operating cryogenic part of the superconducting device 2 to the connector 9 which is close to room temperature,
A temperature gradient occurs from the end of the alloy portion 8b on the connector 9 side to the end of the superconducting portion 8a on the superconducting device 2 side. Heat enters according to this temperature gradient.

On the other hand, the specific resistance of the alloy portion 8b of the connecting wire 8 decreases as the temperature decreases, but the temperature is higher than the superconducting state of the superconducting portion 8a and lower than the normal conducting state. Therefore,
For the connection wire 8, if the superconducting portion 8a is used below the critical temperature (Tc) of superconductivity, and the alloy portion 8b is used in the region above the critical temperature, the overall connection resistance can be reduced, and, Heat intrusion is also reduced.

On the other hand, the superconducting device 2 is generally used under the condition that the operating temperature T is T/Tc≦0.8, but if it is only used for connection, it is possible to use superconducting materials up to the very edge of the critical temperature. It is. Therefore, the superconducting part 8a and the alloy part 8 are separated from each other by setting the position below the superconducting transition temperature as the boundary 8c.
It is desirable to connect b. However, in reality, high-temperature superconducting materials cannot be fused by soldering or the like, unlike conventional superconducting materials. Furthermore, it is necessary for the connecting wire 8 to maintain mechanical strength by increasing the surface area where the superconducting portion 8a and the alloy portion 8b come in contact with each other at the boundary 8c, and by combining them topologically.

Based on these conditions, in the connecting wire 8 of the present invention, each component of the superconducting portion 8a and the alloy portion 8b is mixed in a gradient manner, so that the portion where the proportion of the alloy component is small is It is as if the alloy components enter into the gaps in the superconducting material, and conversely, in areas with a high ratio of alloy components, superconducting fine powder enters into the alloy components, and the contact area of both components is compressed. The bonding strength is dramatically increased compared to a bonded structure simply bonded by bonding or the like. Furthermore, since the structure of both components is intricate, the mechanical strength of the connecting wire 8 is mainly determined by the breaking strength of the superconducting material, and the strength is dramatically improved compared to simple crimping.

Therefore, the connection wire 8 of the present invention can reduce heat intrusion, which has been a problem with conventional connections. Furthermore, in the system shown in FIG. 1, the temperature distribution of the connecting wire 8 is determined almost entirely by heat intrusion from the outside, and considering that most of the amount of heat flowing through the connecting wire 8 is conserved, the superconducting portion 8a
The distance LS from the connector 9, which is the position where the superconducting device 2 and the alloy part 8b should be joined, is defined by the distance L connecting the superconducting device 2 and the connector 9, the respective temperatures T1 and T3, the superconducting material and the alloy material. If the thermal conductivity of is ps, pa,

00
22] LS>L[pa(T3-Tc)]/[ps(Tc
−T1)+pa(T3−Tc)]

It is determined by the relationship: Thermal conductivity p of the superconducting material shown here
s is considerably lower than the thermal conductivity of metals, which are generally good conductors; for example, in the case of yttrium-based superconducting oxides,
2.5 (W/m/K), which is overwhelmingly lower than the thermal conductivity of silver or copper, which is over 400. As a result, the thermal resistance of the connecting wire 8 can be increased, and the amount of heat flowing in can be reduced. can be reduced.

Next, a manufacturing apparatus for the connecting wire 8 of the present invention is shown in FIG.
The explanation will be based on.

In FIG. 3, 10 and 11 are vehicle tanks in which alloy fine powder and superconducting fine powder are stored, respectively, and pipe 1
It is communicated with the mixer 12 via 0a and 11a. Furthermore, flow rate regulators 10b and 11b are provided in the middle of the pipes 10a and 11a to adjust the amount of fine powder flowing out from the vehicle tanks 10 and 11, respectively.

As shown in FIG. 4, a partition wall 12a is provided inside the mixer 12, and a fine powder storage chamber 12b is connected to the ends of the respective pipes 10a and 11a of the vehicle tanks 10 and 11 through the partition wall 12a. , 12c are set. Further, a fine powder discharge port 12d is formed on the lower surface of the mixer 12. The fine powder storage chambers 12b and 12c are provided with shutters 12e and 12c so that the superconducting fine powder a and the alloy fine powder b sent from the vehicle tanks 10 and 11 can be stored and discharged.
12f is provided so that it can be opened and closed. This shutter 12
e and 12f are set to be located above the fine powder discharge port 12d with a predetermined distance therebetween.

On the other hand, below the mixer 12 is a forming die 13 through which the wire 8' discharged from the mixer 12 is stretched.
is provided below the molding die 13.
A feed roller 14 for conveying the green wire 8'' stretched by the green wire 3 and a cutter 15 for cutting the green wire 8'' into appropriate lengths are provided, respectively. Further, a tunnel electric furnace 16 for baking the cut green wire 8'' is arranged adjacent to the cutter 15.Furthermore, the flow rate regulators 10b and 11b, the mixer 12, the feed roller 14, and the cutter 15 are equipped with a fine powder. flow rate, or green wire 8”
A control device 17 is used to control the cross-sectional shape, length, etc.
It is connected to the.

In order to manufacture the connecting wire 8 using the manufacturing apparatus constructed as described above, first, alloy fine powder is stored in the vehicle tank 10, and superconducting fine powder calcined in advance is stored in the vehicle tank 11. This superconducting fine powder is, for example, prepared by preparing yttrium-based oxide superconducting powder or behimus-based oxide superconducting powder with a particle size of around 1 μm, and kneading each of these powders with an organic binder to create a vehicle. has been done.

Next, each fine powder stored in the vehicle tanks 10 and 11 is sent to the mixer 12 while its component ratio is adjusted by the flow rate regulators 10b and 11b.
2, the wire 8' is discharged to the forming die 13.

At this time, as shown in FIG. 4(A), each fine powder sent to the mixer 12 closes the shutter 12e on the side of the fine powder storage chamber 12c and discharges only the superconducting fine powder a from the fine powder outlet 12d. After discharging a predetermined amount of superconducting fine powder a, the shutter 12f is closed to stop discharging the superconducting fine powder a, as shown in FIG. 4(B), and at the same time, as shown in FIG. 4(C), , the shutter 12e is opened to discharge the alloy fine powder b from the fine powder discharge port 12d. Then, the shutter 12e
, 12f and the fine powder discharge port 12d, the superconducting fine powder a and the alloy fine powder b are discharged in a mixed state.

[0031] In this manner, the component ratio of the wire rod 8' can be determined by simply changing the mixing ratio of the two. Also, how to change this mixing ratio,
That is, the opening and closing operations of the shutters 12e and 12f are performed at the final target position, that is, at the position where the temperature of the connecting wire 8 is just below the critical temperature of the superconducting material, and the composition ratio of the superconducting part 8a and the alloy part 8b is adjusted. Needless to say, it is set so that it changes in a gradient manner.

The wire rod 8' is drawn out as a green wire 8'' while being shaped into a suitable cross-sectional shape by the forming die 13. At this time, the drawn out green wire is kneaded with an organic binder, so it is flexible. Therefore, the green wire 8'' can be easily cut to a predetermined length by the control device 17 via the cutter 15. Further, at this time, it is also possible to give the green wire 8'' a predetermined shape as a predetermined connection line 8, for example, a spiral shape or a bent shape corresponding to the connector position.

The cut green wire 8'' passes through the tunnel electric furnace 16 while being baked and becomes the connecting wire 8.
is formed. At this time, in the tunnel electric furnace 16, the green wire 8 is heated at 900 to 1050 degrees in an oxygen atmosphere.
By firing ", the final target connecting wire 8 is formed.

By the way, since the control of each of these processes can be performed centrally from the monitoring of material feed, it can be performed extremely easily using a small personal computer. Further, regarding the molding of the green wire state, it is necessary to take into consideration heat shrinkage during firing in advance, but this can also be easily molded by registering and controlling it in the control device 17. Furthermore, the superconducting fine powder that is the raw material is a pre-fired material that is pulverized and then passed through a filter after being sorted in a magnetic field at a low temperature so that the particle size is uniform, so that it flows well and there is no unevenness in drawing.

On the other hand, the material for the alloy portion 8b should be one that will form an alloy when the binder evaporates when fired in an electric furnace in an oxygen atmosphere, and will not cause oxidative deterioration or adversely affect the firing of the superconducting material. good. A material that meets this purpose is preferably a material whose main component is silver or gold as described above, but pure silver or pure gold may also be used if the firing temperature is appropriate. However, in general, in order to take advantage of the characteristics of superconducting materials, a firing temperature is set that will most easily bring out the characteristics, and the alloy composition is determined by adding a small amount of platinum etc. so that the melting point etc. matches the set firing temperature. It is desirable to do so. In addition, copper, which is the main component of superconducting materials and is a good conductor of electricity, can provide mechanical bonding strength, but
It seems that good results cannot be obtained because it has the property of changing the composition ratio of superconducting materials.

In the above description, a circular wire was used as the wire, but it goes without saying that it can be formed into an elliptical cross section or a sheet shape depending on the shape of the forming die 13. In addition, by adjusting the wire feeding speed and die shape in conjunction with adjusting the mixing ratio of each fine powder, it is possible to form wire rods with non-uniform diameters. 9 is the alloy part 8b on the boundary 8c side.
It is also possible to reduce electrical resistance by making the diameter thicker than the diameter of .

Furthermore, although it has been described here that the connection between the superconducting portion 8a and the alloy portion 8b with a density gradient is located just below the critical temperature of the superconducting material, the connecting wire 8 of the present invention The manufacturing method allows alloy components to be arbitrarily placed in other necessary parts, so for example, many alloy components can be placed to connect to the superconducting device 2, which operates at extremely low temperatures, to facilitate soldering. It is also possible to

[0038]

[Effects of the Invention] As explained above, in the connecting wire of the present invention, the component in the portion where the temperature environment of the line is below the critical temperature of the superconducting material is mainly the superconducting material, and the component in the part where the temperature environment of the line is below the critical temperature of the superconducting material; The part connected to the peripheral circuit is mainly made of metal that is a good conductor of electricity, and the junction between the two is located just below the critical temperature, and the density of the two is low in the length direction of the line. Due to the gradual change, when operating a superconducting device,
It is possible to realize a connection with a room-temperature part that has low electrical resistance and little heat intrusion.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the appearance of an electronic device showing an embodiment of the present invention.

FIG. 2 shows a connection line of the present invention, FIG. 2(a) is a partially enlarged view of the connection line, and FIG. 2(b) is a graph showing the distribution of components forming the connection line corresponding to FIG. 2(a). It is a diagram.

FIG. 3 is a schematic diagram of a manufacturing apparatus for manufacturing the connection wire of the present invention.

FIG. 4 is a schematic cross-sectional view showing the operation of the mixer.

[Explanation of symbols]

2...Superconducting device 5...Peripheral circuit 8...Connection line 8a...Superconducting part 8b...Alloy part 8c...boundary 9...Connector 10b, 11b...Flow rate regulator 10, 11...Vehicle tank 10a, 11a...pipe 12...Mixer 13... Molding die 15...Cutter 16...Tunnel electric furnace 17...Control device

Claims (4)

[Claims] 1. A connection line that electrically connects the superconducting device and the peripheral circuit, comprising a superconducting device that operates at a low temperature and a peripheral circuit that operates near room temperature,
The connecting wire is mainly made of superconducting material in the portion where the temperature environment of the line is below the critical temperature of the superconducting material, and the portion connected to the peripheral circuit at the critical temperature or above is made of metal mainly consisting of a good electrical conductor. A connection line characterized in that the junction between the two is at a portion corresponding to just below the critical temperature, and the density of the two changes gently in the length direction of the line. 2. The connecting wire according to claim 1, wherein the metal is an alloy mainly composed of silver, and the superconducting material is an oxide superconducting material. 3. A vehicle tank in which alloy fine powder is stored, a vehicle tank in which superconducting fine powder is stored, a mixer connected to each of the vehicle tanks through pipes, and a mixer located below the mixer. a forming die that is positioned below the forming die and set to stretch the wire discharged from the mixer; and a forming die that is placed below the forming die and the wire drawn by the forming die is made into an appropriate length. 2. The connecting wire manufacturing apparatus according to claim 1, comprising at least a cutter for cutting, a tunnel electric furnace for baking the cut wire adjacent to the cutter, a flow rate regulator, and a control device. 4. One vehicle tank stores alloy fine powder, and the other vehicle tank stores superconducting fine powder, and each fine powder stored in each vehicle tank is mixed with its component ratio adjusted. 2. The method of manufacturing a connecting wire according to claim 1, wherein the wire rod discharged from the container is formed into a predetermined shape and a predetermined length, cut, and then baked in a tunnel electric furnace.