JP2523687B2 - Method of forming superconducting film pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] The present invention relates to a method for forming a superconducting film pattern on a substrate using a superconducting ceramic paste, which aims to improve the yield of the resulting superconducting film pattern. A substrate having a perovskite crystal structure is used as a substrate on which a pattern is to be formed.

[Industrial applications]

The present invention relates to a pattern forming method, and more particularly, to a method of forming a superconducting film pattern on a substrate using a superconducting ceramic paste. The method of the present invention can be advantageously used in the production of superconducting wiring circuits and the like.

[Conventional technology]

As is well known, recently, a ceramic high temperature superconducting material that exhibits superconductivity even at a temperature higher than liquid nitrogen temperature (77K) has been developed, and a wide range of research on film forming technology has been carried out for its wide use. ing. The superconducting film is usually formed in the form of a film pattern on a substrate such as a ceramic substrate, and for forming the film, a technique such as a paste sintering method, a sputtering method, a vapor deposition method, a plasma spraying method or the like is used. It is used.

Above all, the paste sintering method is easy to carry out,
It is mainly used in this technical field because of its advantages such as In the paste sintering method, generally, a raw material powder (this may be a powder of a superconducting material itself or a mixed powder of a starting material for forming a superconducting material) is mixed with an organic binder and an organic solvent to obtain a uniform mixture. By dispersing, the resulting paste-like material is applied on the substrate by a printing method such as a screen printing method, and finally, a coating film of this paste-like material is baked in the atmosphere at a high temperature of 800 to 1000 ° C. It can be carried out. The substrate used is a zirconia substrate, a high-purity alumina substrate (so-called FGA substrate), or the like, and the substrate has various shapes such as a rod shape, a sheet shape, and a plate shape. The superconducting film pattern and circuit thus obtained can be applied to circuits of electronic devices such as various IC substrates and hybrid circuits.

[Problems to be solved by the invention]

The above-mentioned paste sintering method, however, has the problem that the resulting superconducting films often do not exhibit sufficient superconductivity. That is, when this paste sintering method is carried out on a zirconia substrate or an FGA substrate, the substrate used is a general ceramics sintered body, and the particles are present at random on the substrate surface. Despite the fact that crystals of superconducting ceramics are formed inside, they often do not become superconductors because their orientations are not uniform.

Therefore, an object of the present invention is to align the orientation of the superconducting ceramics in the paste sintering method, and thus improve the yield of the obtained superconducting film pattern.

[Means for solving problems]

The present inventors, when forming a superconducting film pattern on a substrate using a superconducting ceramic paste, have a perovskite crystal structure, that is, the same crystal structure as the superconductor to be formed, It has been found that the above object can be achieved by using a substrate having

The substrate used in the present invention is preferably a substrate having a layered crystal structure. Examples of useful substrates having a perovskite crystal structure include lead titanate (PbTiO ₃ ), lead zirconate (PbZrO ₃ ), lead zirconate titanate (PbZrO ₃ —PbTiO ₃ ), and the like. As described above, these substrates can have various shapes such as a rod shape and a sheet shape.

The superconducting ceramic paste used in the practice of the present invention is not particularly limited as long as it can be applied and fired by the paste sintering method. As a typical useful ceramic paste, Y-Ba-Cu-O ceramics (where Y is Y, Sc, La, Ce, Pr, Nd, Sm, Eu, G
No. I selected from the group consisting of d, Tb, Dy, Ho, Er, Tm, Yb and Lu
IIa group element, and Ba can be a Group IIa element selected from the group consisting of Ba, Sr, Ca and Mg), for example YBa ₂ Cu ₃ O _X. it can. YBa
_{The 2} Cu ₃ O _X paste is, for example, Y ₂ O ₃ , CuO, and BaO powder as a starting material, the material is sintered to obtain a bulk of a superconductor, and the bulk is crushed to obtain an organic binder and It can be prepared by dispersing in an organic solvent.

[Work]

In the method of the present invention, a ceramic substrate having a perovskite type crystal structure is coated with a superconducting ceramic paste having a perovskite type crystal structure and fired, so that they are well compatible with each other, and therefore the orientation of the superconducting ceramics is improved. You can arrange. In fact, according to the method of the present invention, there is no inconvenience that a portion that should be an orthorhombic crystal becomes a cubic crystal as in the conventional method.

〔Example〕

Example 1 15.3 g of Y ₂ O _{3 having} a particle size of 1 μm, 48.6 g of BaO having a particle size of 1 μm and 36.0 g of CuO 36.0 g having a particle size of 3 μm were added with 1.5 g of polymethyl methacrylate (PMMA) binder, 20 g of terpineol and 50 g of methyl ethyl ketone (MEK), Mix on ball mill for 72 hours. The obtained mixture was put into a liquor machine and kneaded, and MEK was scattered to obtain a superconducting ceramic paste SCZ-1. This paste was screen-printed on a PbZrO ₃ —PbTiO ₃ -based substrate, dried, and then baked in the air at 950 ° C. for 12 hours. A superconducting film pattern was formed on the substrate.

When the electric resistance of the obtained superconducting film pattern was measured by a four-terminal method in liquid nitrogen, it was found that the resistance was zero. Furthermore, when the crystal structure of this sample was examined by X-ray diffraction, it was confirmed to be a perovskite type.

Furthermore, in order to confirm that the yield of superconducting ceramics is improved when using the PbZrO ₃ -PbTiO ₃ based substrate compared to when using the conventional FGA substrate, we used two different types of substrates. The above procedure was repeated. The yield of superconducting ceramics means the proportion (%) of the superconducting ceramics in the superconducting film pattern, which was evaluated by measuring the magnetization of the sample using a vibrating sample magnetometer (VSM). The results shown in Table 1 below were obtained.

Example 2 The procedure described in Example 1 above was repeated. However, in the case of this example, Y ₂ O ₃ is 16.7 g, BaO is 33.3 g, CuO is 50 g, and PMMA is 1.5 g.
g, and terpineol was used in an amount of 20 g. When the obtained superconducting ceramic paste SCZ-2 was screen-printed and fired in the same manner as in Example 1, a superconducting film pattern having the same characteristics as in Example 1 was formed.

With respect to this sample, the yield of the superconducting ceramics was evaluated in the same manner as in Example 1, and the results shown in Table 2 below were obtained.

Example 3 The procedure described in Example 1 above was repeated. However, in this example, Y ₂ O ₃ was used in an amount of 15 g, BaO in an amount of 50 g, CuO in an amount of 35 g, PMMA in an amount of 2.0 g, and terpineol in an amount of 25 g. When the obtained superconducting ceramic paste SCZ-3 was screen-printed and fired in the same manner as in Example 1, a superconducting film pattern having the same characteristics as in Example 1 was formed.

With respect to this sample, the yield of the superconducting ceramics was evaluated in the same manner as in Example 1, and the results shown in Table 3 below were obtained.

Example 4 15.3 g of Y ₂ O _{3 having} a particle size of 1 μm, 48.6 g of BaO having a particle size of 1 μm and 36.0 g of CuO 36.0 g having a particle size of 3 μm, and methyl ethyl ketone (MEK).
50 g was added and mixed on a ball mill for 48 hours.
Then, a powder having MEK scattered was used to form a green compact at a pressure of 200 MPa. This green compact was fired at 950 ° C. for 12 hours in the atmosphere. After firing is completed, it is crushed to a particle size of 0.
The powder was 5 μm. When this powder was subjected to X-ray diffraction,
It was found to have a perovskite type superconducting phase.

PMMA binder 3 was added to 100 g of the powder prepared as described above.
g, terpineol 25 g and MEK 50 g, and add it with a ball mill.
Mix for 24 hours. Subsequent processing is carried out as described in Example 1 above for superconducting ceramic paste.
SCZ-4 was obtained, and this paste was screen-printed to obtain a superconducting film pattern. The characteristics of this superconducting film pattern were the same as in the case of Example 1 above.

With respect to this sample, when the yield of the superconducting ceramics was evaluated in the same manner as in Example 1, the results shown in Table 4 below were obtained.

[Effects of the Invention] According to the present invention, since the pattern of the ceramic superconducting film having the same perovskite type crystal structure is formed on the ceramic substrate having the perovskite type crystal structure, the yield of the obtained superconducting film pattern can be significantly improved. Can be improved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Nobuo Kamehara, Nobuo Kamehara, 1015 Kamiodanaka, Nakahara-ku, Kawasaki, Kanagawa, Fujitsu Limited (72) Inventor, Koichi Niwa, 1015, Kamiodanaka, Nakahara-ku, Kawasaki, Kanagawa 56) References JP-A 64-5041 (JP, A) JP-A 1-186696 (JP, A)

Claims (2)

(57) [Claims] 1. When forming a superconducting film pattern on a substrate using the superconducting ceramic paste, the superconducting ceramic paste is screen-printed with lead titanate, lead zirconate and titanate zirconate. A method for forming a superconducting film pattern, which comprises coating on a substrate having a perovskite type crystal structure selected from the group consisting of lead, and then firing the pattern of this paste coating film. 2. The forming method according to claim 1, wherein the substrate has a layered crystal structure.