JP2713305B2 - Superconducting connector - Google Patents

Description

The present invention relates to a superconducting connector. More specifically, the present invention relates to a superconducting connector, and more specifically, a superconducting ceramic is applied. The present invention relates to a superconducting connector used for a method of obtaining an electrical connection. INDUSTRIAL APPLICABILITY The superconducting connector of the present invention can be widely and advantageously used in the field of electronic equipment and the like.

[Conventional technology]

Recently, ceramic materials exhibiting superconductivity at a temperature of liquid nitrogen (77 K) or higher have been discovered, and research and development for applying these materials to various devices have been advanced. As one of the applications, there is an application to an electronic device, and a method of forming a superconducting element or a circuit is being studied. In order to make use of the superconducting characteristics of elements and circuits, it is necessary to realize superconductivity even in a portion where these are electrically connected to each other.

To date, examples of microconnectors aimed at such connections (hereinafter referred to as superconducting connections) have been found in Josephson computer implementations operating at liquid helium temperature (4.2K) (eg, SKLahiri et al. “Packag
ing Technology for Josephson Integrated Circuits ",
IEEE Trans.Components, Hybrids, and Manufacturing Te
chnology, vol. CHMT-5, no. 2 (1982) p.271-280.).
This microconnector has a cavity in a silicon wafer filled with mercury, and the pins sticking out of the circuit board are pushed into the mercury and cooled to the temperature of liquid helium, which causes the mercury to cool down. To fix the pins and obtain electrical connection.
In this connector, a pin-mercury-pin connection is made. Here, platinum is used as the pin,
A two-layer thin film made of palladium (base) and gold is formed at the tip (the part that comes into contact with mercury) (thickness is 1000 mm). These materials, however, do not exhibit superconductivity at liquid helium temperatures, and thus exhibit a resistance of the order of a few hundred μΩ across the pin-mercury-pin connection. The above-mentioned literature describes that from the viewpoint of the transmission characteristics of the circuit, such a resistance value can be practically ignored.
As described above, when the connector is used at a cryogenic temperature of 4.2 K, the resistance of the constituent material is extremely low, so that the constituent material does not have to be a superconductor.

[Problems to be solved by the invention]

However, since equipment using superconducting ceramics is used at a temperature of liquid nitrogen (77 K) or higher, the resistance of the constituent material of the connector cannot be ignored. For example, the electrical resistivity of platinum is about 80K
It is 1.9 μΩ-cm, which is 650 times or more the value at 10K (0.0029 μΩ-cm). (American Institute of Physics Hand
book, pp. 9-41). This means that the resistance of the connector connection
Increase to a level that cannot be ignored. For this reason, in connectors used at liquid nitrogen or higher,
It is essential that the material forming the connection exhibits superconductivity at the operating temperature or has a negligibly low resistance, and the contact is also a superconducting contact. ) Or close to it. That is, it is necessary to make the contact resistance less than the order of several hundred μΩ.

It is therefore an object of the present invention to realize a superconducting connector having a superconducting connector with a contact resistance of less than a few hundred μΩ.

[Means for solving the problem]

According to the present invention (first invention), the above object is achieved by providing a first contact piece having a contact surface coated with a superconducting ceramic material, and a counterpart having a contact surface coated with a superconducting ceramic material. A first contact force for slidably contacting the second contact piece and a second contact force for pressing and supporting the second contact piece against the first contact piece. This can be achieved by a superconducting connector characterized by having

The superconducting connector according to the present invention is characterized in that a superconducting ceramic material is coated on the surface of a pair of contact pieces, for example, a contact, a pin, etc. It is intended to realize the connection. And, in the present invention, when the contact portions are brought into contact with each other, after sliding them in a state where the smaller one is added,
It is characterized in that it is pressurized with a larger force (that is, a pressing force sufficient to obtain an electrical connection in a conventional general connector, that is, a force corresponding to a contact force). In the connector according to the present invention, for example, a contact having a coating film of superconducting ceramic is fixed to the housing of the connector. Then, insert the pin joined to the circuit board into the contact and butt them together with a small force.
In this state, one of the contact and the pin is slid.
Thereafter, a predetermined contact force is applied. At this time, a superconducting ceramic coating film is formed on the surfaces of the contacts and the pins, so that a superconducting connection is obtained. Although the superconducting connector of the present invention can be used in various fields, it is particularly advantageous to use it in electronic equipment.

In the superconducting connector of the present invention, the formation of a coating film of a superconducting ceramic material on the surface of a contact piece such as a contact or a pin is performed by, for example, a paste sintering method, a sputtering method, an evaporation method, a plasma spraying method, or the like. This can be done advantageously using techniques. Above all, it is recommended to use the paste sintering method because it has advantages such as easy implementation. In the paste sintering method, a raw material powder (which may be a powder of a superconducting material itself or a mixed powder of a starting material for forming a superconducting material) is generally mixed with an organic binder and an organic solvent and uniformly dispersed. Then, the obtained paste is coated on the object to be coated by a printing method such as a screen printing method.
It can be performed by firing at a high temperature of 0 to 1000 ° C.

The superconducting ceramic paste used for forming the superconducting coating film is not limited as long as it can be applied by a paste sintering method and fired. As typical useful ceramic pastes, Y-Ba-Cu-O-based ceramics (where Y is Y, Sc, La, Ce, Pr, Nd, Sm, Eu, Gd, T
III, selected from the group consisting of b, Dy, Ho, Er, Tm, Yb and Lu
Ba can be a group a element, and Ba is Ba, Sr, Ca and M
can from the group consisting of g is a II a group metal selected), can be mentioned for instance YBa ₂ Cu ₃ O _X. YBa ₂ C
u ₃ O _X pastes, for example, a Y ₂ O _3, CuO and BaO powder starting material, and sintering the raw material to obtain a bulk superconductor, organic binder and organic by grinding the bulk It can be prepared by dispersing in a solvent.

In the superconducting connector of the present invention, the contact / pressing of the contact pieces, that is, a first contact force for slidably bringing the first contact piece into contact with the second contact piece, and a second contact force. The biasing of the second contact force for pressing and supporting the contact piece against the first contact piece can be performed by using various biasing means. According to the findings of the present inventors, as described in the following examples, by using a contact / pressing mechanism using a spring as a biasing means for the first and second contact forces, particularly, Advantageous results can be obtained.

Furthermore, the above-described object is achieved by the present invention (second invention)
According to the present invention, there is provided a superconducting connector which obtains an electrical connection by pressing first and second contact portions having a contact surface coated with a superconducting ceramic material, wherein the first and second contact portions are at room temperature. Holding the pieces detachably, deforming the first and second contact pieces at a temperature below the transition temperature of the superconducting ceramic material,
This can be achieved by a superconducting connector having a biasing member made of a shape memory alloy that presses with a contact force that makes the contact between the contact surfaces become a superconducting contact.

The superconducting connector according to the present invention forms a coating film of a superconducting ceramic material on the surface of a contact piece, for example, a contact, a pin, etc., and contacts and presses each other, similarly to the above-described invention. This aims to realize a superconducting connection. The present invention is characterized in that when the contact portions are brought into contact with each other, they are pressed and brought into contact with each other using a shape memory alloy (hereinafter referred to as SMA). In the connector of the present invention, for example, a contact having a superconducting ceramic coating film on a connector housing and a pin for moving the contact and / or a pin of a circuit board are provided.
Install SMA contact / pressing mechanism. Then, the pins joined to the circuit board are inserted and cooled to the temperature of liquid nitrogen. When the SMA expands, the contacts and / or the pins are pressed and pressed. Thereby, a superconducting connection can be realized.

The superconducting connector of the present invention can also be advantageously used in the field of electronic equipment, similarly to the above-described invention, and the formation of the superconducting coating film on the surface of the contact piece can be similarly performed. It can be carried out.

One of the features of this superconducting connector is that the contact / pressing mechanism is manufactured from SMA. The composition and components of the SMA used here are not particularly limited.
Examples include Ni alloy, Cu ₃ Al alloy, CuAlNi alloy, CuZnAl alloy, and others. In other words, the composition and composition of the SMA will be determined by the temperature range to which the connector is applied, since the temperature at which the contact pieces are pressed can be adjusted by changing the composition of the SMA. Such SMA is used after being processed into a shape suitable for acting as a contact / pressing mechanism. A preferable shape of the contact / pressing mechanism is, for example, a ring shape, and two contact pieces are inserted into a ring of the ring to form a SM.
Both are contacted and pressurized as a result of the expansion of A. The “contact / pressing mechanism” referred to here is, in other words, the urging member of the present invention, and therefore, while holding the first and second contact pieces detachably at normal temperature, the superconducting ceramic At temperatures below the transition temperature of the material, it deforms and presses the first and second contact pieces with a contact force such that their contact becomes a superconducting contact.

(Operation)

To confirm the operation of the superconducting connector according to the present invention,
The present inventors conducted the following experiment.

As shown in FIG. 3, rod-shaped test pieces A and B made of Y—Ba—Cu—O ceramic were crossed at a right angle, and a resistance was measured while applying a force (see arrow) to them. The measured value was defined as the contact resistance. The superconducting ceramic Y, Ba
The composition ratio of Cu and Cu was 1: 2: 3 (molar ratio). Each of the above two test pieces A and B was a liquid nitrogen temperature (77K).
It was previously confirmed that the sample exhibited a very low resistance value of about several μΩ.

The test apparatus schematically shown in FIG. 3 was replaced with liquid nitrogen (not shown).
The contact resistance was measured while increasing the pressure (contact force). The results obtained are shown in FIG. The figure shows measured values after the contact resistance is reduced to about several hundred μΩ or less. When the contact force is 1 kgf, the contact resistance is approximately 200 μΩ, and when the contact force is 2 kgf, the contact resistance is approximately 5 μΩ. Next, when the contact force is reduced from this state, the rate of increase in the contact resistance is smaller than when the contact force is increased, and shows a low value of about 50 μΩ at 0.3 kgf. From these results, it can be seen that, in an actual connector, after a contact piece, for example, a contact and a pin are brought into contact with a large force, a very low contact resistance is maintained even if the force is reduced. However, as shown in FIG. 4, the contact force to be applied first needs to be 1 kgf or more, which is a force that cannot be practically applied to an electronic device connector as the object of the present invention. By the way, as shown in FIG. 4, when superconducting contact is obtained with a large force, superconducting contact can be obtained even if the contact force is reduced to some extent. It is considered that this is because the surfaces of the contact and the pin were bonded at the atomic level under a large contact force.
From this, it is conceivable to slide the contact and the pin as a method of obtaining the same effect as providing a large contact force. However, when the superconducting ceramics are slid under a large contact force as in a normal connector, individual particles constituting the ceramics may be remarkably dropped. Dropout of particles leads to destruction of the coating film, resulting in a decrease in the number of connection repetitions and a decrease in reliability. As a result of various studies, the present inventors have found that, after sliding the contact and the pin under a relatively small contact force, a low contact resistance can be realized by increasing the contact force to a predetermined value. The present invention as described above has been completed.

Further, as described above, when the contact force is increased, the contact exhibits a contact resistance of approximately 200 μΩ at 1 kgf and a contact resistance of approximately 5 μΩ at 2 kgf. From these results, it can be seen that in the actual connector, a low contact resistance can be obtained by bringing the contact and the pin into contact with a force of 1 to 2 kgf. However, as shown in FIG. 4, the contact force to be applied needs to be 1 kgf or more.
Conventionally, if a spring contact is pressed against a pin at the same time, the force is so large that it cannot be practically applied to an electronic device connector as the object of the present invention. However, as disclosed in the present invention (second invention),
Such a force is not a problem if a force is applied to the pin for each contact of the housing. The present invention seeks to obtain a superconducting connection by pressing each contact against each pin with a large force independently, and applies a force to each pin independently. Does not occur. The present inventors have found use of SMA to generate such a force, and have completed the present invention.

〔Example〕

The present invention will now be described with reference to the accompanying drawings for several embodiments.

FIG. 1 shows a preferred example of a superconducting connector according to the present invention together with its contact pressure generating mechanism. As shown in FIG. 1 (A), the superconducting connector includes a circuit board 1, a spring-type pin moving device (as a contact / pressing mechanism, that is, a "first and second contact force" in the present invention). 7) and the circuit board 4 are arranged in this order. The pin moving device 7 is mounted in a housing (not shown), and is fixed to the circuit board 1 by an L-shaped cross-sectional member, and is pressed to press the pins 5 provided on the lower surface of the circuit board 4. Spring (in the figure, a member bent in the shape of a letter “C” in the opposite direction to the contact 2) is implanted, and a sliding plate that slides on the L-shaped cross-section member, and a vertical portion of the L-shaped cross-section member slides. It is configured to include a spring provided between the left side of the plate and pulling the sliding plate to the left, and a positioning jig (not shown) for determining a position of the sliding plate. Note that the positioning jig can be realized by a common-sense feed mechanism, for example, a feed screw that is attached to this spring and passes through a screw hole formed in a vertical portion of the L-shaped cross-section member and abuts on the left end of the sliding plate. is there. By the rotation of the feed screw, the position of the sliding plate can be arbitrarily determined.

A contact 2 acting as a first contact piece is attached to a circuit board 1 as shown, and has a superconducting ceramic coating 3 on a portion of its contact surface. The shape of the contact may be the shape of the contact shown in FIG. 2 or another conventional shape, if necessary. Further, the pins 5 of the circuit board 4 of the LSI module acting as the second contact piece have a superconductive ceramic coating film 6 on the entire surface.

In the illustrated superconducting connector, at the stage of FIG. 1 (A), the sliding plate of the pin moving device 7 is stopped to the right by a positioning jig. In this state, there is a wide gap between the pressing spring and the corresponding contact 2, and the pin 5 of the circuit board 4 is loosely inserted into this gap.

Next, at the stage of FIG. 1 (B), the sliding jig is moved leftward by operating the positioning jig. With the movement of the sliding plate, the pressing spring moves to the left to push the pin 5 to the left, and further presses the pin 5 against the contact 2. Positioning jig, the deflection of the probe member 2 which is pressed by interposing a pin by pressing spring, defines the position of the sliding plate to produce a repulsive force of equal magnitude F ₁ to the first contact force. At this time, the force applied to the sliding plate is a state of static balance in which the sum of the leftward spring force pulling the sliding plate and the rightward reaction force against the positioning jig is equal to the rightward repulsive force resulting from the deflection of the contact 2. It is in. In other words, a leftward _first contact force of magnitude F1 equal to the first contact force of the sliding plate is urged. The position of the sliding plate, that is, the position determined from the sum of the amount of deflection of the contact 2 and the amount of deflection of the pressing spring, can be calculated or experimentally obtained in advance. With the first contact force being urged, the pins 5 of the circuit board 4 are slid up and down as shown by the arrow C in the figure. In addition, it is also possible to slide the contact 2 instead of the pin 5 or both of them as needed.

After the completion of the sliding under the pressure, as shown in FIG. 1C, the positioning jig is operated again to move the sliding plate to the left. Movement amount, the deflection of the probe member 2 is pressed by the pressing spring, the predetermined second distance causing repulsive force F ₂ equal size to the contact force. As a result, the pin 5 is pressed and supported by the contact 2 with the second contact force.

Next, the whole is immersed in liquid nitrogen 8 as it is. Since a coating film of superconducting ceramics is formed on the surfaces of the contact 2 and the pin 5, respectively, the desired superconducting connection is completed.

Using the superconducting connector shown in FIG. 1, the change in the contact resistance due to the contact force was evaluated as in the case of FIG. The contacts and pins used here were each made of alumina, and had the same Y-Ba-Cu-O-based ceramic coating layer on the surface as described in Example 1 below. As can be understood from the results shown in the graph of FIG. 5, after the contact and the pin are pressed and slid with a force of 0.2 kgf,
When the contact force is reduced to 0.05 kgf and the surrounding area is filled with liquid nitrogen and the contact force is increased again, the contact resistance is about 60 μΩ at a load of 0.3 kgf, which is much higher than that without sliding. Indicates a low value. Further, the contact resistance shows almost the same change when the pressing force is applied and when it is released. The results confirm the effectiveness of the method according to the invention. It should be noted that the force to be applied at the time of sliding needs to be 0.1 kgf or more, as is clear from the graph shown in FIG. The upper limit of this force is determined by the degree of friction of the ceramic material and the detachment of the particles, and is individually determined by the composition of the ceramic material and the like. But 0.6kgf
In the hatched area (D in the figure) which exceeds the above, ceramic wear is remarkable.
kgf, especially 0.2 to 0.4 kgf.

FIG. 2 also shows a preferred example of the superconducting connector according to the present invention. The circuit boards 1 and 4 and the contacts 2 and the pins 5 respectively correspond to those of FIG. 1 and are substantially the same except that the shape of the contacts 2 is slightly different. In this example, as shown in FIG. 2A, a ring-shaped pin moving device 9 is used as a contact / pressing mechanism. Each of the pin moving devices 9
It is made of TiNi alloy (SMA) and has one contact 2 and one pin 5 inside, and is fixed to a housing (not shown) via an optional mounting means (not shown). . At this stage, the contact 2 and the pin 5 are out of contact.

Next, as shown in FIG. 2 (B), when the entire connector is immersed in liquid nitrogen 8, the pin moving device 9
A, the contact 2
The pin is pressed strongly. That is, when cooled to the temperature of liquid nitrogen, the SMA is deformed and the contact 2
And the pin 5 are pressurized, thereby realizing a superconducting connection.

Next, the manufacture and use of the superconducting connector of the present invention will be described.

Example 1 Superconducting connector of FIG. 1: The dimensions of the contacts were 0.5 mm thick, 3 mm wide and 20 mm long, and the dimensions of the pins were 1.5 mm diameter and 25 mm long.
The contact and the pin were made of alumina, respectively, and the raw alumina contained 0.25% by weight of MgO and 0.025% by weight of Cr ₂ O.
₃ was added. The superconducting ceramic material coated on the surfaces of the contact and the pin is a Y-Ba-Cu-O-based material (molar ratio: Y: Ba: C
u = 1: 2: 3) and is, was formed into a film as follows: particle size 1μm Y ₂ O ₃ 13.5g, polyethyl methacrylate in CuO36.0g of BaO48.6g and particle size 3μm particle size 1 [mu] m (PM
MA) 1.5 g binder, 20 g terpineol and 50 g methyl ethyl ketone (MEX) were added and mixed on a ball mill for 72 hours. The obtained mixture was put in a raikai machine and kneaded, and MEK was scattered to obtain a superconducting ceramic paste. This paste was brushed on the surfaces of the contact and the pin, dried, and fired at 950 ° C. for 12 hours in the air. A superconducting ceramic coating was formed on the contacts and pins.

The contact thus prepared was fixed to a polybutyl terephthalate (PBT) housing. On the other hand, the pins were bonded to the alumina substrate so that the heads protruded from the surface. This was inserted into the housing, and the pin was pressed against the contact with a force of 0.1 kgf by a pin moving device provided at the top of the housing. Then, the contact and the pin were slid by moving the substrate up and down. Then the contact force
The pin was pressed against the contact until it reached 0.3 kgf. This connector was immersed in liquid nitrogen, and the resistance between the upper part of the pin and the lower part of the contact was measured. As a result, a value of about 60 μΩ was obtained. When the pin was not slid, the resistance at a contact force of 3 kgf was 1 Ω or more, which was unacceptable.

Example 2 A superconducting connector of FIG. 2 A contact and a pin were manufactured in the same manner as in Example 1. In this example, a ring-shaped pin moving device made of a Ni-50% Ti alloy was fixed in a PBT housing, and a contact was inserted and fixed so as to be in contact with the pin moving device. Then, an LSI module model in which the pins were bonded to the alumina substrate was made,
A pin was inserted between the contacts. This was immersed in liquid nitrogen, and the resistance between the pins of the LSI module model and the connector pins was measured. As a result, a value of less than 100 μΩ was obtained, confirming the effect of the present invention.

〔The invention's effect〕

According to the present invention, it is possible to realize a superconducting connection exhibiting a contact resistance of less than several hundred μΩ when used at a temperature of liquid nitrogen or higher.

[Brief description of the drawings]

1 and 2 are cross-sectional views each showing a preferred example of a superconducting connector according to the present invention, FIG. 3 is a schematic view showing measurement of contact resistance, and FIG. FIG. 5 is a graph showing a change in contact resistance due to a contact angle, and FIG. 6 is a graph showing a change in contact resistance due to a contact angle during sliding. . In the figure, 1 is a circuit board, 2 is a contact, 3 is a superconducting ceramic coating film, 4 is a circuit board, 5 is a pin, 6 is a superconducting ceramic coating film, 7 is a pin moving device, and 8 is a liquid. Nitrogen.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-110566 (JP, A) JP-A-60-112090 (JP, U) JP-A-63-69496 (JP, U) JP-A-63-69 196566 (JP, U) Actually open 1981-18669 (JP, U)

Claims (2)

(57) [Claims] 1. A first contact piece having a contact surface coated with a superconducting ceramic material is slidably contacted with a second contact piece having a contact surface coated with a superconducting ceramic material. Superconducting, comprising means for urging a first contact force to be applied, and a second contact force for pressing and supporting the second contact piece against the first contact piece. connector. 2. A superconducting connector for obtaining an electrical connection by pressing first and second contact pieces having a contact surface coated with a superconducting ceramic material, wherein the first and second contact pieces are at room temperature. The contact piece is detachably held, and the first and second contact pieces are deformed at a temperature equal to or lower than the transition temperature of the superconducting ceramic material so that the contact between the contact surfaces becomes a superconducting contact. A superconducting connector having an urging member made of a shape memory alloy pressed by force.