JP2970838B2 - Polyimide substrate for superconducting materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide substrate made of a superconductive material, and more particularly, to 3,3 ', 4,4'.
- Ultra comprising as essential components of - a biphenyl tetracarboxylic acid component and p- phenylenediamine component polymer
The present invention relates to a polyimide substrate for a conductive material.

The polyimide substrate for a superconducting material of the present invention is preferably used as a substrate for ensuring good conductivity under various molding conditions at a high temperature for producing a superconducting material and under severe use conditions. It can be used.

[0003] In the present invention, the superconducting material, poly
Thin metal layer and high-temperature superconducting ceramic layer on imide substrate
High-temperature superconducting ceramic laminate
Means polyimide material.

[0004]

_2. Description of the Related Art Conventionally, a substrate (support) made of a ceramic-based inorganic material has been known as a heat-resistant substrate for a superconducting material. ZrO, MgO, Al ₂ O ₃ , SrTi
A ceramic plate such as O ₃ is used.
Substrates made of these ceramic-based inorganic materials are relatively heavy, rigid, and do not have sufficient strength.

In particular, when the substrate made of the above-mentioned ceramic-based inorganic material is to be reduced in weight and thickness, there is a problem that the mechanical strength of the substrate itself is significantly reduced due to the reduction in thickness.

[0006] That is, the various known substrate, be flexible, yet lightweight with heat resistance, ultra has high strength
Conductive materials could not be easily manufactured.

[0007]

In this technical field, a substrate for producing a superconducting material does not have the problems of the above-mentioned known technology, has good moldability, and has a superconductivity. It has sufficient heat resistance, mechanical strength, and stability at high temperatures to produce functional materials, and has sufficient durability under severe conditions at high and low temperatures. A lightweight substrate was expected. An object of the present invention is to provide a substrate that provides good conductivity under various molding conditions at high temperatures and under severe use conditions.

[0008]

That is, the present invention provides:
A polyimide substrate having a thickness of about 50 μm used for a superconducting material, wherein the polyimide is 3,3 ′, 4,4′-biphenyltetracarboxylic acid or its acid dianhydride alone or 3,3 ′, 4,4 '-Biphenyltetracarboxylic acid or its acid dianhydride and pyromellitic acid or its acid dianhydride, 3,3', 4,4'-benzophenonetetracarboxylic acid or its acid dianhydride, 3,3 ', 4 ,
An aromatic tetracarboxylic acid component selected from a mixed system of 4'-diphenylethertetracarboxylic acid or an acid dianhydride and p-phenylenediamine alone or p-phenylenediamine
An aromatic polyimide obtained by polymerization and imidization from an aromatic diamine selected from a mixture of phenylenediamine and diaminodiphenyl ether, diaminodiphenylmethane, or 2,2-bis (aminophenyl) propane, (1) Conditions of (2) and (3) (1) The thermogravimetric loss rate when left at 550 ° C. for 60 minutes in a helium gas atmosphere is 5% by weight or less, and (2) 30-300 ° C. The coefficient of linear expansion is 0.4 × 10 ⁻⁵ −
2.0 × 10 ⁻⁵ cm / cm / ° C. (3) Low temperature tensile strength in liquid nitrogen of 20-60 k
g / mm ² . And a metal thin layer and
The present invention relates to a polyimide substrate for a superconducting material on which a high-temperature superconducting ceramic layer is laminated .

The polyimide substrate of the present invention has a thickness of
About 50 μm, comprising 3,3 ′, 4,4′-biphenyltetracarboxylic acid or its acid dianhydride alone, or 3,3 ′, 4,4′-biphenyltetracarboxylic acid or its acid dianhydride Pyromellitic acid or its acid dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic acid or its acid dianhydride, 3,3', 4,4 '
An aromatic tetracarboxylic acid component selected from a mixed system of -diphenyl ether tetracarboxylic acid or an acid dianhydride and p-phenylenediamine alone, or p-phenylenediamine and diaminodiphenyl ether, diaminodiphenylmethane, or An aromatic polyimide obtained by polymerization and imidization from an aromatic diamine selected from a mixed system with 2,2-bis (aminophenyl) propane, which satisfies the above conditions (1) to (3) and usually It is in the form of a film. In the present invention,
(1)-
By combining with the condition of (3), stability is realized.
It can be manifested.

The aromatic polyimide film preferably contains 3,3 ′, 4,4′-biphenyltetracarboxylic acid or its acid dianhydride in an amount of 50 mol% or more, particularly 60 mol% or more.
-100 mol% of an aromatic tetracarboxylic acid component and 50 mol% or more, particularly preferably 60 to 100 mol%, of p-phenylenediamine and diaminodiphenyl ether, diaminodiphenylmethane, or 2,2-
Bis (aminophenyl) propane is obtained from an aromatic diamine component containing 50 mol% or less, particularly 0 to 40 mol%.

The polyimide substrate of the present invention is preferably
3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride alone or 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride;
Aromatic tetracarboxylic dianhydride selected from 3 ', 4,4'-benzophenonetetracarboxylic dianhydride or a mixed system with 3,3', 4,4'-diphenyl-tertetracarboxylic dianhydride And p-phenylenediamine alone, or p-phenylenediamine and diaminodiphenyl ether, diaminodiphenylmethane, or 2,2
A high molecular weight, for example, a logarithmic viscosity, obtained by polymerizing an aromatic diamine component selected from a mixed system with -bis (aminophenyl) propane in an organic polar solvent;
A solution of an aromatic polyamic acid having a molecular weight of 5 or more is cast on a support to form a thin film of the solution, and then the solvent is gradually evaporated to dryness to contain about 15% by weight of the solvent. A solidified film is formed, the solid film is peeled from the support, and 2
It can be obtained by heating to a high temperature stepwise from 00 ° C. to a maximum heating temperature (for example, 450 ° C.) to perform drying and imidization.

The polyimide substrate of the present invention has a thermal weight loss rate of 5% by weight or less when left at 550 ° C. for 60 minutes in a helium gas atmosphere, and has a linear expansion coefficient of 0.4 × 30 to 300 ° C. 10 ^{−5 to} 2.0 × 10 ⁻⁵ cm / cm / ° C.
And a tensile strength in liquid nitrogen of 20 to 60 kg /
must be a mm ² approximately, thereby withstand heating of the substrate required for stacking step in the case of forming the conductive layer, moreover integral with the conductive layer by the heat treatment
It is possible to form a conductive material that is a laminate of BR>. When the thermal weight loss rate, the coefficient of linear expansion, and the strength at low temperature of the polyimide substrate are out of the above-mentioned ranges, the substrate may be damaged during the production or use of the conductive material, and the production of the substrate itself is difficult.

As a method of forming a superconducting material from a polyimide substrate according to the present invention, for example, a metal is directly formed on a polyimide substrate and then an oxide-based high-temperature superconducting ceramic, for example.
For example, a Y-Ba-Cu-O-based high-temperature superconducting ceramic or the like can be formed by a physicochemical method such as vacuum evaporation and sputtering. In the above-described vacuum deposition method, the temperature of the deposition substrate is 200 to 600 ° C., and the thickness of the deposited thin film layer is 2
It is preferably about 00-20000 °. In the sputtering method, the substrate temperature is preferably 200 to 450 ° C., and the thickness of the formed metal thin film layer is preferably about 200 to 20000 °. In the vacuum deposition method and the sputtering method, annealing is preferably performed at about 400 to 650 ° C. in order to increase the crystal orientation of the metal thin film. Of course,
Without being limited to these methods, if the polyimide substrate of the present invention is used, a good conductive material can be obtained without causing any problem in high-temperature heating (including heating to a high temperature and cooling from a high temperature) during production. Can be obtained.

[0014]

The present invention will be described below with reference to examples and comparative examples.

Example 1 Using 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and paraphenylenediamine in equimolar amounts,
Polymerization in N-methyl-2-pyrrolidone at 30 ° C. for 2 hours, and logarithmic viscosity (concentration: 0.5 g / 100 ml, solvent: N-methyl-2-pyrrolidone, measuring temperature: 30 ° C.)
An aromatic polyamic acid of 3.5 was produced. The polymerization solution had a polymer concentration of about 25% by weight and a solution viscosity at 100 ° C. of about 3000 poise.

Using the polyamic acid solution, a thin film of the above solution is formed on a support by a solution casting method (film forming temperature: 90 ° C.), and the solvent is gradually evaporated at a temperature of about 110 ° C. To form a solidified film of an aromatic polyamic acid containing about 15% by weight of a solvent. The solidified film is peeled off from the support, and is cured at a temperature of about 200 ° C. for about 30 minutes for about 30 minutes.
By heating at 0 ° C. for 15 minutes and at about 450 ° C. for 15 minutes, imidization was performed to form a 50 μm thick polyimide substrate.

The above-mentioned aromatic polyimide film had the following physical properties. Tensile strength (30 ° C.): 45 kg / mm 2 Tensile strength (in liquid nitrogen): 52 kg / mm 2 Elongation at break: 34% Tensile modulus: 843 kg / mm 2 End crack resistance (JIS C2318) : 51 kg / 20 mm Bending resistance Number of times MIT: 10,000 or more Glass transition temperature: 500 ° C. or more Heat shrinkage: 0.46% Linear expansion coefficient (cm / cm / ° C.): 1.1 × 10 −5 (30-300 ° C.) Water absorption: 1 0.1% by weight Thermal weight loss rate: 2.6% by weight (550 ° C. for 60 minutes in helium)

(Evaluation Experiment 1) Using a Cu metal target and the polyimide substrate, a copper thin film was formed on the film substrate by the following sputtering method. As the sputtering device, a magnetron type high frequency bipolar sputtering device was used. After fixing the film substrate on the substrate electrode, the inside of the vacuum chamber was evacuated to 1 × 10 ⁻⁴ pa or less, the substrate was heated to 300 ° C. for 1 hour, and degassing was performed. Sputtering was performed by introducing argon gas having a purity of 99.999% to the inside of the shite system at 0.5 pa. The substrate was heated to 200 ° C. A thin film of copper having a thickness of about 3000 ° was formed.

Next, a magnetron-type high-frequency bipolar sputtering apparatus was used for the Cu-laminated polyimide substrate.
A Y-Ba-Cu-O-based high-temperature superconducting ceramic film was formed by the following sputtering method. A high-temperature superconducting ceramic laminated film was formed under the conditions of a composition ratio of argon and oxygen (O ₂ / Ar + O ₂ = 0.5), 1 Pa, a substrate temperature of 550 ° C., a formation speed of 5 ° / sec, and a formed film thickness of 3000 °. As a target, a composition of Y _0.23 Ba _0.45 CuO _3-x was used. The critical temperature of the obtained high-temperature superconducting ceramic laminated polyimide film was 80K.

(Evaluation Experiment 2) Also, except that Pt was used instead of Cu as the metal material of the metal thin film laminated on the aromatic polyimide film,
A Y-Ba-Cu-O-based high-temperature superconducting ceramic film was formed in the same manner as in Evaluation Experiment 1. The critical temperature of the obtained high-temperature superconducting ceramic laminated polyimide film was 82K.

(Evaluation Experiment 3) A copper thin film was laminated on the polyimide substrate having a thickness of about 50 μm manufactured in Example 1 by a vacuum evaporation method using the following electron beam. After pre-heating the substrate as in Evaluation Experiment 1,
Using a Cu deposition source, substrate temperature 300 ° C, degree of vacuum 1 × 1
Vacuum deposition is performed at 0 ^-4 pa, instantaneous vapor deposition at 500Å / sec.
An aromatic polyimide substrate on which a copper thin film layer having a thickness of 3000 ° was laminated was formed. Next, a Y-Ba-Cu-O-based high-temperature superconducting ceramic laminated film was formed in the same manner as in Evaluation Experiment 1. The critical temperature of the obtained high-temperature superconducting ceramic laminated polyimide film was 81K.

(Evaluation Experiment 4) Pt was laminated on an aromatic polyimide film (substrate) in the same manner as in Evaluation Experiment 2, and then a high-temperature superconducting ceramic laminated film was formed by vacuum evaporation. Using a deposition source of Y, Ba, and Cu, while slightly introducing oxygen,
Vacuum deposition is performed at a vacuum degree of 1 × 10 ⁻⁴ pa or less at a substrate temperature of 550 ° C., and a film thickness of Y—Ba—Cu—O is increased to 5000 °.
Lamination of high temperature superconducting ceramics was continued. Heat-treated at 400 ° C. for 2 hours in an oxygen stream to obtain Y— Ba— Cu—O
-Based high-temperature superconducting ceramics laminated aromatic polyimide film was manufactured. The critical temperature of the obtained high-temperature superconducting ceramic laminated polyimide film was 82K.

Comparative Example 1 A polyimide substrate was manufactured in the same manner as in Example 1 except that 4,4'-diaminodiphenyl ether was used as the aromatic diamine instead of paraphenylenediamine. The physical properties of this polyimide substrate were as follows. Linear expansion coefficient cm / cm / ° C .: 4.0 × 10 ⁻⁵ (30 to 300 ° C.) Water absorption: 1.3% by weight Thermal weight loss rate: 15% by weight (550 ° C. for 60 minutes in helium)

(Evaluation Experiment 5) Using the polyimide film (substrate) of Comparative Example 1 , Pt was laminated on the substrate in the same manner as in Evaluation Experiment 2, and then a high-temperature superconducting ceramic laminated film was formed by vacuum evaporation. Formed. Using a vapor deposition source of Y, Ba, and Cu, vacuum deposition is performed at a substrate temperature of 550 ° C. with a degree of vacuum of 1 × 10 ⁻⁴ pa or less while slightly introducing oxygen. -Lamination of Cu-O-based high-temperature superconducting ceramics was continued. Heat treatment at 400 ° C for 2 hours in an oxygen stream,
A Y- Ba- Cu-O-based high-temperature superconducting ceramic laminated aromatic polyimide film was produced. In the obtained laminated film, lamination integration of the ceramic layer and the polyimide substrate was poor.

[0025]

According to the present invention, it is possible to obtain a substrate which gives a good conductive material under various molding conditions at a high temperature for producing a conductive material or under severe use conditions.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B32B 15/08 B32B 15/08 R 18/00 18/00 C

Claims (1)

(57) [Claims] 1. A thickness of about 50 μm used for a superconducting material.
A polyimide substrate, wherein the polyimide is 3, 3 ',
4,4'-biphenyltetracarboxylic acid or its acid dianhydride alone, or 3,3 ', 4,4'-biphenyltetracarboxylic acid or its acid dianhydride and pyromellitic acid or its acid dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic acid or its acid dianhydride, or a mixed system with 3,3', 4,4'-diphenylethertetracarboxylic acid or its acid dianhydride An aromatic tetracarboxylic acid component and p-phenylenediamine alone, or an aromatic diamine selected from a mixture of p-phenylenediamine and diaminodiphenyl ether, diaminodiphenylmethane, or 2,2-bis (aminophenyl) propane Aromatic polyimide obtained by polymerization and imidation from the following, (1)
(2) and (3) conditions (1) The thermogravimetric reduction rate when left at 550 ° C. for 60 minutes in a helium gas atmosphere is 5% by weight or less, (2) Linear expansion coefficient at 30 to 300 ° C. Is 0.4 × 10 ⁻⁵ −
2.0 × 10 ⁻⁵ cm / cm / ° C. (3) Low temperature tensile strength in liquid nitrogen of 20-60 k
g / mm ² . And a metal thin layer and
A polyimide substrate for superconducting materials on which a high-temperature superconducting ceramic layer is laminated .