JPH04324687A - Base metal electrode material - Google Patents

Abstract

PURPOSE:To make an integrally calcining type ceramic element using a base metal for its internal electrode calcinable in an oxidizing neutral atmosphere and to obtain an internal electrode material for laminated ceramic elements which is inexpensive and has an excellent characteristic by adding a substance which discharges hydrogen at a temperature higher than a debindering temperature to the base metal electrode material. CONSTITUTION:An internal electrode is formed by using a base metal, such as Cu, Ni, Fe, Cr, Ti, etc., and internal electrode paste is prepared by using a metal hydride, such as titanium hydride, etc., as a hydrogen discharging material and adding an organic binder. A laminated element is formed by screen- printing the paste on a ceramic green sheet of lead zirconate titanate, piling up the green sheet thus prepared, and the laminate body is subjected to vacuum thermo-compression bonding. Then this internal electrode material for laminated type ceramic elements is obtained by calcining the laminated element thus obtained in an oxidizing neutral atmosphere. Therefore, a lead type laminated ceramic element which is inexpensive and highly reliable, has a stable dielectric characteristic, and uses a base metal for its internal electrode can be manufactured.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base metal electrode material used as an internal electrode material for a laminated ceramic element.

0002

[Prior Art] Conventionally, when manufacturing a monolithically fired multilayer ceramic element, Pt, Au, etc. are used as internal electrode materials.
, Ag, Pd, and other noble metals are used. However, such precious metals are expensive, and when used as internal electrodes, they lead to a significant increase in the cost of the product.
Cheap metals such as Cu are increasingly being used as internal electrode materials.

0003

[Problems to be Solved by the Invention] However, when firing such inexpensive materials such as Ni and Cu as internal electrode materials, it is necessary to perform the firing in a reducing atmosphere to prevent oxidation. Furthermore, when many dielectric and piezoelectric ceramics are fired in a reducing atmosphere, they are easily reduced and cannot provide sufficient insulation. In particular, lead-based dielectric and piezoelectric ceramics are easily reduced and have the disadvantage of not exhibiting their original electrical properties. In addition, as a reduction-resistant dielectric ceramic material,
Barium titanate-based materials have been developed, but they have drawbacks such as bias dependence of dielectric constant, temperature dependence, and change in capacitance over time, which are inferior to lead materials.

[0004] Therefore, in order to solve the problems in the prior art, it is an object of the present invention to provide an integrated firing type ceramic element with internal electrodes made of base metals such as Ni and Cu, which can be fired in an oxidizing and neutral atmosphere. The object of the present invention is to provide a base metal electrode material as an internal electrode material for a multilayer ceramic element that is inexpensive and exhibits excellent properties.

[0005]

[Means for Solving the Problems] In order to achieve the above object, according to the present invention, a base metal electrode material as an internal electrode material for a multilayer ceramic element releases hydrogen at a temperature equal to or higher than the debinding temperature. It is characterized by containing a substance.

In the present invention, a substance that releases hydrogen at a temperature above the debinding temperature is mixed with base metal powder and used as the base metal electrode material, or a metal hydride such as titanium hydride is used as the hydrogen releasing substance. Alternatively, the above-mentioned object can be achieved by using a base metal electrode material in which hydrogen is occluded in a base metal electrode powder as a hydrogen releasing substance, and by using the material as an internal electrode material for a multilayer ceramic element. Most metals absorb hydrogen. Hydrogen stored in metals is released when heated to high temperatures. Therefore, if a metal powder whose hydrogen release temperature is higher than the debinding temperature is used as the internal electrode material, hydrogen will be released only during sintering of the ceramic. In the laminated body, the released hydrogen gas is difficult to dissipate, so only the vicinity of the internal electrodes is maintained in a reducing atmosphere to prevent oxidation of the base metal internal electrodes.
Dielectric and piezoelectric ceramics can be fired in a neutral atmosphere. This makes it possible to manufacture an integrally fired ceramic element having base metal internal electrodes using lead-based dielectric or piezoelectric ceramics that have poor reduction resistance.

[0007] That is, the base metal electrode material of the present invention is
Base metals such as Cu, Ni, Fe, Cr, and Ti are used as internal electrodes and an organic binder is added to form an internal electrode paste. This is screen printed on a ceramic green sheet of lead zirconate titanate, and this is laminated. A laminated element is formed by vacuum heat and pressure bonding, and is then fired in an oxidizing and neutral atmosphere to form an internal electrode material for a laminated ceramic element. Alternatively, as an internal electrode paste, Cu, Ni, Fe
It is also possible to store hydrogen in a base metal such as Cr, Ti, etc., and add an organic binder thereto to use it as an internal electrode paste.

[0008]

[Effects of the Invention] As described above, according to the base metal electrode material of the present invention, it is possible to manufacture a lead-based multilayer ceramic element using a base metal as an internal electrode, and a multilayer capacitor can be manufactured using a lead-based dielectric ceramic material. By doing so, it is possible to provide an inexpensive element with stable dielectric properties and high reliability. Furthermore, if a lead-based piezoelectric ceramic material is used as the base metal electrode material, a multilayer piezoelectric element can be manufactured at low cost. In particular, since the voltage applied to piezoelectric elements is high, electromigration (electron migration) occurs in conventionally used Ag-Pd-based internal electrodes, causing reliability problems. Furthermore, according to the base metal electrode material of the present invention, it is possible to use metals such as Ni, Fe, Cr, and Ti that do not easily cause electromigration as internal electrodes, thereby improving the reliability of the multilayer piezoelectric element. It can be significantly improved.

Furthermore, when firing an element having a base metal internal electrode, it is necessary to keep the oxygen partial pressure in the firing atmosphere extremely low, so a reducing gas such as hydrogen or carbon monoxide is conventionally used. However, according to this invention, elements with base metal internal electrodes can be fired in an atmospheric furnace or simple atmosphere furnace, so it is not necessary to go to a firing furnace. Effects such as being able to reduce equipment costs can be obtained.

0010

EXAMPLES Next, examples of the base metal electrode material of the present invention will be described. Example 1 Ni powder with an average particle size of 1 μm was used as a base metal internal electrode, and 10% by weight of titanium hydride was added as a hydrogen releasing substance and mixed well. Further, ethyl cellulose and butyl carbitol were mixed and dissolved in a ratio of 1:10 to obtain an organic binder. 45% by weight of an organic binder was added to the mixture of Ni and Ti-H2 powders, and the mixture was kneaded with three rolls to uniformly disperse the inorganic materials. Furthermore, about 30% by weight of butyl carbitol was added to adjust the viscosity to 500 poise to obtain an internal electrode paste. For comparison, an internal electrode paste containing only Ni powder without adding titanium hydride was also prepared in the same manner. Ceramic green sheet is 1μ
20% by weight of water, 0.5% by weight of dispersant, and 20% of organic binder in lead zirconate titanate (PZT) powder ground to
% by weight was added to form a slurry, and this slurry was molded to a thickness of 100 μm using a doctor blade.

Lead zirconate titanate (
The internal electrode paste was printed on a PZT ceramic green sheet to a thickness of 20 to 25 μm using a screen printing method, and 100 sheets of this were laminated and bonded under vacuum heat and pressure to form a laminated element. The obtained laminated device is heated in air at a temperature of 2
The temperature was raised to 50°C and held for 48 hours to remove the binder. Sintering was performed at 1200° C. for 1 hour in air and nitrogen. In addition, as shown in FIGS. 1 and 2,
An appropriate number, for example, four laminated elements 1 are placed on the center setter 3 on the table 5, and the laminated elements 1 on the setter 3 are separated from the table 5 by four spacers 4.
It was covered with a sagger 2 placed on top, and differences in characteristics such as electric capacity and dielectric loss were investigated. The results are shown in Table 1 below.

0012

[Table 1]

In the above table, titanium hydrogen (Ti-H
When 2) was not added, many delaminations occurred, probably because nickel (Ni) was oxidized and the volume increased. Further, the capacitance is very small, less than 1%, and Ni does not function as an internal electrode. When titanium hydride is added and fired in a nitrogen atmosphere, the capacitance is 97% of the calculated value expected from the multilayer element specifications, indicating that the internal electrodes are almost completely formed. . In addition, even when the laminated element is fired in the atmosphere while covered with a sagger, good dielectric properties are obtained, dielectric loss is small, and reduction of the piezoelectric ceramic does not occur.

Example 2 Ni powder with an average particle size of 1 μm was placed in a pressure vessel, and after the inside of the vessel was vacuum degassed, hydrogen gas was introduced at a pressure of 10 kg/cm2.
has been introduced. Place this container in a constant temperature bath at a temperature of 200℃ for 2 hours.
It was left to stand for 4 hours to allow hydrogen to be absorbed into the Ni powder. In the same manner as in Example 1, an organic binder was added to hydrogen-absorbing Ni powder to obtain an internal electrode paste, which was printed on green sheets, 100 sheets of which were laminated, and vacuum heat and pressure bonded to form a laminated element. The resulting laminated device was subjected to binder removal and firing in the same manner as in Example 1. The results are shown in Table 2 below.

[0015]

[Table 2]

As can be seen from Table 2, good dielectric properties were exhibited only when Ni powder occluded with hydrogen was used, and the effects of the present invention are clearly evident.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of firing a base metal electrode member of the present invention.

FIG. 2 is a partially sectional side view of the embodiment of FIG. 1;

[Explanation of symbols]

1 Laminated element 2　　　Sagger bowl 3 Setter 4 Spacer 5 Table

Claims (3)

[Claims] 1. A base metal electrode material comprising a substance that releases hydrogen at a temperature equal to or higher than the debinding temperature. 2. The base metal electrode material according to claim 1, wherein a metal hydride such as titanium hydride is used as the hydrogen releasing substance. 3. A base metal electrode material characterized in that a base metal electrode powder in which hydrogen is occluded in the base metal electrode powder itself is used as a hydrogen releasing substance.