JPH01107594A - Manufacture of superconductive ceramic board - Google Patents

Abstract

PURPOSE:To obtain a superconductive ceramic board, in which high-speed transmission, minute-signal transmission and high-density mounting are, made possible, by printing a wiring circuit on a ceramic substrate with conductor paste of Ag or Au, baking the device at 850 deg.C or more, printing a superconductor wiring circuit on the conductor wiring circuit with superconductive ceramic paste, and baking the device at 1,050 deg.C or less. CONSTITUTION:A wiring circuit is printed on a ceramic substrate 3 with conductor paste of Ag or Au. The device is baked at 850 deg.C or more. Thereafter, a superconductor wiring circuit is printed on the conductor wiring circuit with superconductive ceramic paste. The device is baked at 1,050 deg.C or less. Thus, a high-speed signal without reflection and distortion can be transmitted without loss. The transmission of a minute signal can be ensured. There is no power loss. Power supply lines can be arranged at a high density. Reaction with a superconductor wiring layer can be suppressed. Therefore miniaturization is made possible.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention enables high-speed signal transmission and minute signal transmission,
The present invention relates to a method of manufacturing a superconducting ceramic substrate that prevents heat generation.

[Prior Art] A conventional method for fabricating ceramic substrates involves printing a circuit on an alumina green sheet with a high melting point conductor paste such as No-Hn, and heating it at 1500~1600 in a humid hydrogen atmosphere.
℃ firing method (hereinafter referred to as conventional method a), AU, AQ, Ag-Pd are deposited on a sintered alumina substrate.
, a method of printing a conductor paste such as Cu and firing it at 850 to 950°C in the air or an atmosphere (hereinafter referred to as "conventional method"), for example, for glass-ceramic composite materials.

AU, ACI, A11l-Pd, on green sheets made from materials that sinter at 800-1000℃.
There is a method (hereinafter referred to as conventional method C) in which a conductive paste such as C1l is printed, laminated and then fired in a wet nitrogen atmosphere.

Conventional method a has the advantage of highly reliable multi-layering by laminating green sheets, and is used for miniaturizing LSI circuit boards that require many input terminals. Since No--Hn has a high electrical resistance and is not suitable for miniaturizing wiring, it has the disadvantage that it cannot increase the packaging density.

In addition, the conventional method requires a low firing temperature and can also use resistors and dielectrics, so by repeating firing and printing according to this method, it is possible to create 5
~While it has the advantage of being able to create a six-layer multilayer hybrid circuit board, it has disadvantages such as the low multilayer limit due to printing, and the inability to increase packaging density because only two-dimensional wiring can be routed. There is.

In conventional method C, which is a method to compensate for the drawbacks of conventional method,
It is possible to fire the resistor if necessary, and the mounting density can be increased.The dielectric constant of the ceramic layer is 5 to 7, which is lower than that of alumina, making it suitable for high-speed signal transmission. However, since a conductor with a finite resistance value is used as the wiring material (this point is also the same for conventional methods a and b), high-speed operation elements (for example, GaA
When mounting a superconducting element (S-based element) or a superconducting element, major problems arise such as signal propagation delay, signal reflection, and transmission loss on the substrate.

Dempa Shimbun (dated May 12, 1986) describes a method for manufacturing superconducting ceramic substrates that solves the problems of these conventional ceramic substrates using oxide-based superconducting materials (Y-Ba-Cu-0 based materials). ) is made into a paste and alumina F'GA (Fine Grained Aluminum
na) A method of manufacturing a superconducting ceramic substrate by printing on a substrate and firing it (hereinafter referred to as conventional method d) is disclosed. This involves kneading superconducting ceramic powder made of Y-Ba-CO-0-based material with an organic binder to form a paste, forming a circuit on an alumina substrate by printing, etc., and baking it to form superconducting wiring. This is an attempt to solve the problems in .

[Problems to be solved by the invention] However, even in the case of the superconducting ceramic substrate according to the conventional method d, even if the superconducting ceramic substrate is wired with a 4fY-Ba-Cu-0 series superconducting ceramic material, thermal
If the superconducting state is broken due to electrical or mechanical causes and transitions to the normal conducting state, signal transmission and power supply will be impossible due to the high electrical resistance, which will cause serious problems to the entire system. The problem arises.

The present invention was made to solve the above-mentioned problems, and has the following features: High-speed signals without reflection and distortion can be transmitted without loss, minute signals can be reliably transmitted, power lines can be densified without power loss. It has the following advantages: the reaction between the substrate and the superconducting wiring layer is suppressed and miniaturization is possible; even if the superconducting state is broken, signal transmission is possible through the conductor layer (Au layer or Ag layer), and the entire system can be recovered. An object of the present invention is to provide a method for hanging a superconducting ceramic substrate having a superconducting ceramic substrate.

[11! ! [Means for Solving Problem I] The present invention prints a wiring circuit using AQ or AU conductor paste on a ceramic substrate, and after firing at 850°C or higher, superconducting wiring circuit is printed on the conductor wiring circuit using superconducting ceramic paste. The present invention relates to a method for manufacturing a superconducting ceramic substrate by printing and firing at 1050°C or lower.

[Example] The ceramic substrate used in the present invention is not particularly limited as long as it is a ceramic substrate that has a heat resistance of at least the firing temperature, preferably about 12 sub degrees Celsius or more, and is commonly used as a circuit board. , as a specific example, even if $
fYSZ (yttrium stabilized zirconia) substrate,
Examples include substrates such as alumina substrates, strontium titanate substrates, and magnesia substrates.

The AQ or Au conductive paste used in the present invention may be of a high-temperature firing type that is generally used for forming circuits on a substrate, and may be used without particular limitation.

In the conductor paste, the average particle size of the metal particles is 1-
In addition to the above, there are also 3 to 30 items from the viewpoint of suppressing over-firing of the conductor layer and reaction between the conductor layer and the superconducting layer during firing of the superconducting paste, lowering the surface energy, and increasing the sintering temperature. preferable.

The conductor paste is printed as a wiring circuit on the ceramic substrate, and after drying, the paste is heated to 850°C or higher, preferably 930°C.
It is fired at ~960°C to form a conductor wiring circuit.

As the printing method, methods such as a screen printing method, a wiping method, and a transfer method can be used, but the screen printing method is preferable from the viewpoints of printing film characteristics, precision printability, mass productivity, and the like.

In the above firing, if the firing temperature is less than 850°C, it is not preferable because a diffusion reaction with the superconducting ceramic may occur during firing of the superconducting ceramic layer, or the substrate and the conductor layer may peel off.

There are no particular limitations on the firing atmosphere, firing time, cooling time, number of firings, etc., and for example, firing is performed in the air for 0.5 to 1.0 hours, and cooling is performed over 1.0 to 3.0 hours.

The thickness, line width, etc. of a metal wiring circuit cannot be defined unconditionally because they vary depending on the desired characteristics, but for example, if characteristics such as a ceramic wiring circuit board with high packaging density and high-speed signal transmission are desired. thickness 10~20
．． A line width of about 100 to 250 lines is usually adopted.

The superconducting ceramic paste used in the present invention is not particularly limited as long as it can be used to form a wiring circuit by printing and then firing to form a superconducting circuit; for example, Y
, Ba, , cu oxides and carbonates as YBa2C
u3 combined powder (and calcined this powder to form orthorhombic YBa
2Cu307-8 (single-phase powder), Y, Ba, CLI alcoholade to Y by alkoxide method
/Ba/Cu superconducting ceramic particles such as ultrafine powder prepared to have an atomic ratio of 1/2/3, an organic binder such as nitrocellulose or methyl methacrylate, butylcarpitol acetate, terpineol,
Those obtained by kneading with a solvent such as ethanol can be used.

There is no particular limitation on the mixing ratio in the crosstalk, but Y
92-99% by weight of powders of compounds such as SBa and CLI and superconducting ceramic particles, and 1-8% by weight of organic binders.
A solvent is used so that the viscosity is about 8,000 to 15,000 centimeters, and a material that has good leveling properties, does not cause pinholes, printing mesh marks, or smudges, improves dispersibility, and provides a smooth surface after firing. It is preferable to use

There is no particular limitation on the particle size of the powder of the above-mentioned 'f, Ba, C1, etc.-based compounds or the superconducting ceramic particles, but from the viewpoint of lowering the sintering temperature and increasing the reactivity with oxygen, it is preferable that the average particle size is 1.
~10I is preferable.

BaCO3, Y2O as raw materials for superconducting ceramic particles
An example of the process for preparing the superconducting ceramic paste using No. 3 and CuO is shown in FIG. The raw materials are dry mixed in a predetermined ratio, a solvent such as ethanol is added, and the mixture is mixed and pulverized in a ball mill for several hours to several tens of hours. After that, the solvent is splashed and the usual 950
By calcination at ~1000℃ for about 24 hours, Y/Ba
A superconducting ceramic having a /CO composition ratio of 1/2/3 in atomic ratio is prepared. However, even if the composition ratio of Y/Ba/Cu is 1/2/3, superconducting properties will not be exhibited unless the crystal system is orthorhombic.
It is necessary to conduct sufficient heat treatment at 0° C. in pure oxygen (approximately 90 vol 1% or more). This calcination and heat treatment is performed so that the powder is single-phase and its composition is YBaz cu3o 7-6.
And it is repeated until it becomes an orthorhombic crystal.

The single-phase YBaz culo 7-8 and orthorhombic crystals were confirmed because the powder X-ray diffraction analysis results matched the X-ray diffract pattern shown in Figure 3, and the electrical resistance at room temperature was several tens of thousands. This can be done by confirming that -ΩC■.

The superconducting ceramic produced by the above method is pulverized into a fine powder with an average particle size of 1 to 10 -, the above organic binder and the above solvent are added to this, and a superconducting ceramic paste is formed by mixing for several hours to several tens of hours. It can be grown.

The superconducting ceramic paste is formed as a wiring circuit by printing on the Ag wiring circuit, and after drying, the paste is heated to 1050°C.
It is then fired to form a superconducting wiring circuit.

As the printing method, methods such as a screen printing method, a wiping method, and a transfer method can be used, but the screen printing method is preferable from the viewpoints of printing film characteristics, precision printability, mass productivity, and the like.

In this firing, if the firing temperature exceeds 1050° C., separation of the superconducting ceramic phase will occur and the superconducting properties will deteriorate, which is not preferable.

Note that firing the superconducting ceramic paste requires sufficient burnout of organic matter, formation of a superconducting phase, supply of sufficient oxygen, etc., so firing at at least 800 to 900°C is required. It becomes necessary.

There are no particular limitations on the firing atmosphere, firing time, cooling time, number of firings, etc.
It is baked for 4 hours and cooled for 8 to 30 hours.

The superconducting ceramic substrate manufactured in this way has a 1.
A low electrical resistance of X10-4 to 4X10-4 ΩC1 can be maintained.

An example of the manufacturing process of a superconducting ceramic substrate by the method of the present invention is shown in FIG.

Next, a method for manufacturing a superconducting ceramic substrate according to the present invention will be explained based on examples.

Example 1 100g of dry mixed mixture of 52.0% by weight of BaCOs, 15.1% by weight of Y2O3, and 32.9% by weight of CuO was added with 15% of ethanol as a solvent.
01d.

In addition, the mixture was mixed and ground in a ball mill for about 24 hours. After that, the solvent was scattered and the temperature was 24°C at 950-1000°C in the atmosphere.
Y/Ba/C
A superconducting ceramic having a composition ratio of u in an atomic ratio of 1/2/3 was produced.

The resulting superconducting ceramic has a diffract pattern determined by powder X-ray diffraction that matches the X-ray diffract pattern shown in Figure 3, and an electrical resistance of 55 Ω/C1 at room temperature.
Met.

Next, the obtained superconducting ceramic was ground into a fine powder with an average particle size of 2-, and 3 g of nitrocellulose as an organic binder and a total of 30 m of butylcarpitol acetate, terpineol, and ethanol were added as a solvent to 50 g of this fine powder. In addition, the mixture was kneaded for several hours to obtain a superconducting ceramic paste.

A wiring circuit was printed on the YSZ substrate using Ag paste for high temperature firing with an average Ag particle size of 13ρ, and after drying, it was fired at 900°C for about 1 hour to form an Ag paste with a thickness of about 10 mm and a width of about 250 mm.
A layer was formed on a ceramic substrate. The same wiring circuit as the AQ layer was printed on the Ag layer using the above-mentioned superconducting ceramic paste, as shown in FIG. 4, and baked in the atmosphere at 800° C. for about 18 hours to obtain a superconducting ceramic substrate. In the figure, (1) is a superconducting ceramic layer, (2 is a conductor layer, (3)
represents a ceramic substrate.

FIG. 5 shows the relationship between the temperature ('k) and the wiring resistance (Ωε■) of the obtained superconducting ceramic substrate. From Figure 5, as the electrical resistance decreases from room temperature, it decreases linearly due to metallic changes, but it begins to drop rapidly near point B (90°k), and completely reaches O at point A (8G''k). I know what will happen.

In general, the electrical resistance after firing of a superconducting ceramic paste using particles having an average particle size of IJJl+ or more cannot exhibit good characteristics unless the firing temperature is 790° C. or higher.

Next, in order to examine the effects when superconductivity transitions to normal conductivity, this superconducting ceramic substrate was held at 80 @,
102 to 104, which is an excessive current exceeding the critical current (Jc)
A/d was applied to examine changes in wiring resistance of the superconducting ceramic wiring board.

In this example, which has a conductor layer (Ag), the electrical resistance of the wiring became that of a metal because the main conduction is transferred from the superconductor layer to the conductor layer as the superconducting state is destroyed. In this example, the conductor layer (Ag) has a resistance of approximately 2.5×10'Ω at room temperature.
C1 but close to 1006 about 0.2X 10'Ω
It becomes C1. Therefore, when input and output terminals are provided on both the superconducting layer and the conductor layer, the electrical resistance of the superconducting ceramic wiring board is approximately 10-7ΩC1 even if it transitions to a normal conductive state.
It was possible to prevent heat generation and function as a substrate.

Comparative Example 1 Example 1 except that the superconducting paste was printed after drying the Ag paste without baking it in the Ag layer forming process.
A wiring board was prepared in the same manner as above. The electrical resistance of the fabricated substrate showed only metallic resistance characteristics even when the temperature was lowered to near the helium temperature.

Comparative Example 2 The average particle size of ^0 particles is about 0.5I! When I printed and fired a wiring circuit using Irl's Ag paste,
At temperatures above 850°C, oversintering occurred and a thick film could not be formed. Therefore, A13 was baked at 800℃ for 10 minutes.
A layer was formed, and a superconducting ceramic paste was printed and fired, but if the firing temperature was higher than 770°C, the AQ layer would oversinter, making it difficult to form a film, and if the firing temperature was lower than 770°C, it would be difficult to sinter the superconducting ceramic. The electrical properties of the obtained superconducting ceramic substrate were significantly lower than those of Example 1.

In addition, in Example 1 and Comparative Examples 1 and 2, examples will be mainly described in the case where a Y-Ba-Cu-0 based superconducting ceramic material is manufactured as a superconducting ceramic material having an oxygen-deficient perovskite structure. However, Y-B
Some of the a-Cu-0 series elements are La%S-1Eu, G
d, Dy, Ho, E", Tm, Yb1Lu, CI
, Ft' substitution, or by adding a new quaternary or higher superconducting ceramic material, the initial objective could be achieved.

[Effects of the Invention] By providing electrical elements formed of a superconducting ceramic material and a high-temperature sintered AQ or Au metal material on a substrate according to the method of the present invention, and providing electrical elements on the substrate, high-speed signals can be generated. A superconducting ceramic substrate that enables transmission, minute signal transmission, and high-density mounting, and generates little heat.It maintains low electrical resistance even when the superconducting state is broken and transitions to the normal conductive state, and the RAM on the board A superconducting ceramic substrate can be used to prevent problems such as data loss and signal transmission being impossible.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the manufacturing process of a superconducting ceramic substrate according to the method of the present invention, FIG. 2 is a diagram showing an example of the manufacturing process for obtaining a superconducting ceramic paste used in the method of the present invention, and FIG. The figure is an X-ray diffraction diagram of an example of a superconducting ceramic material used in the method of the present invention, FIG. 4 is an explanatory diagram of an example of a superconducting ceramic substrate obtained by the method of the present invention, and FIG. 3 is a graph showing the relationship between the substrate temperature (0k) and the electrical resistance (Ωcl) of the superconducting ceramic substrate according to Example 1. FIG. (Drawing codes) (1): Superconducting ceramic layer (2): Conductor layer (3): Ceramic substrate agent Masu Oiwa Yuten 1
Figure 2nd 3rd $ Enmity

Claims (2)

[Claims] (1) A superconductor in which a wiring circuit is printed on a ceramic substrate using conductor paste of Ag or Au and fired at 850°C or higher, and then a superconducting wiring circuit is printed on the conductor wiring circuit using superconducting ceramic paste and fired at 1050°C or lower. A method of manufacturing a ceramic substrate. (2) The method according to claim (1), wherein the average particle size of the metal particles in the conductive paste is 1 μm or more.