JP2001189227A - Composite nickel conductor for forming electrode and layered ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an internal electrode thin, break of the electrode caused by nickel is excluded by preventing interlayer exfoliation be caused contraction difference in sintering of a dielectric layer and the internal electrode of a layered ceramic capacitor, whose main component is (CaSr/TiZr)O3-based non- reducing dielectric porcelain material, and generation of structural defects which are caused by oxidation of nickel. SOLUTION: Nickel of 99.5-80 wt.% and zirconate of 0.5-20 wt.% are unified in batch in granule, thereby constituting a nickel composite conductor for forming an electrode, of which conductor the internal electrode of a layered ceramic capacitor is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to (CaSr / Ti
Zr) Nickel composite conductor used for forming internal electrodes of multilayer ceramic capacitor mainly composed of O ₃ -based non-reducing dielectric ceramic material, and multilayer ceramic capacitor forming internal electrodes using the nickel composite conductor It is about.

[0002]

2. Description of the Related Art A nickel (Ni) electrode is a palladium (P) electrode.
d) Since non-reducing dielectric porcelain material of (CaSr / TiZr) O ₃ -based is already used instead of palladium because it has less oxidative expansion than electrodes and is advantageous for structural defects such as cracks. It has been proposed that an internal electrode of a multilayer ceramic capacitor as a component is formed of nickel (JP-A-10-335169).

In the multilayer ceramic capacitor, the dielectric layer starts shrinking at a temperature of 1000 ° C. or more, while the internal electrode shrinks at a temperature of 500 ° C. in view of the shrinkage rate depending on the firing temperature of the dielectric layer and the internal electrode. Since the shrinkage starts at a low temperature, a structural defect due to mutual delamination due to a difference in shrinkage between the dielectric layer and the internal electrode is likely to occur. Also,
Nickel particles are spheroidized with the sintering of the internal electrode in a high-temperature region, and the internal electrode is interrupted, so that poor current conduction and a decrease in DC breakdown voltage are easily induced.

In order to prevent this, conventionally, an internal electrode is formed by an electrode paste mixed with a resin binder together with nickel powder using a powder having the same composition as the dielectric layer as a common material,
Control of the contraction difference with the dielectric layer has been performed. However, this also makes it difficult to completely prevent the spheroidization of the nickel particles by sintering.
Problems remain with regard to thinning of the internal electrode formed to a thickness of 0 μm or less.

Further, it is said that the oxidation rate of nickel depends on the specific surface area of nickel. In particular, when an internal electrode is formed from a fine nickel powder, structural defects due to oxidation of the nickel powder occur frequently, so that mass production is required. Is difficult. This nickel oxidation rate has no effect even if a powder having the same composition as the dielectric layer is mixed as a common material.

[0006]

SUMMARY OF THE INVENTION The present invention relates to (CaSr
/ TiZr) O ₃ -based non-reducing dielectric ceramic material has a multilayer ceramic capacitor mainly composed of a dielectric layer and internal electrodes, which are mutually delaminated due to shrinkage due to sintering and structural defects caused by oxidation of nickel. It is an object of the present invention to provide a nickel composite conductor for forming an electrode, which can prevent the occurrence of the internal electrode and prevent the internal electrode from being interrupted by nickel and can cope with the thinning of the internal electrode.

Further, the present invention relates to (CaSr / TiZr) O ₃
To prevent delamination due to shrinkage due to sintering between dielectric layers and internal electrodes of multilayer ceramic capacitors containing non-reducible dielectric ceramic material as a main component and the occurrence of structural defects due to oxidation of nickel. Accordingly, it is an object of the present invention to provide a multilayer ceramic capacitor which can prevent the internal electrode from being interrupted due to the above, and can be configured to have a high capacity with a thin-film internal electrode.

[0008]

According to the nickel composite conductor for forming an electrode according to the first aspect of the present invention, (CaSr /
The non-reducing dielectric ceramic material of TiZr) _{O 3} system as forming an internal electrode of a multilayer ceramic capacitor as a main component, 0.5 and 99.5～80Wt% nickel
It is constituted by integrating 20 wt% of zirconate into particles.

According to a second aspect of the present invention, there is provided a nickel composite conductor for forming an electrode, wherein zirconate is applied to the surface of nickel particles to integrate nickel and zirconate into particles. I have.

The nickel composite conductor for forming an electrode according to the third aspect of the present invention is formed by mixing nickel and zirconate and integrating them in a granular form.

According to a fourth aspect of the present invention, there is provided a nickel composite conductor for forming an electrode, wherein nickel and a zirconate salt containing one or both of calcium zirconate and strontium zirconate are integrated in a granular form. .

In the multilayer ceramic capacitor according to a fifth aspect of the present invention, the internal electrodes are made of a nickel composite conductor in which 99.5 to 80 wt% of nickel and 0.5 to 20 wt% of zirconate are integrated in a granular form. It is constituted by forming.

According to a sixth aspect of the present invention, there is provided a multilayer ceramic capacitor mainly comprising a (CaSr / TiZr) O ₃ -based non-reducing dielectric ceramic material, wherein zirconate is applied to the surface of nickel particles. It is constituted by forming an internal electrode with a nickel composite conductor in which nickel and zirconate are integrated in a granular form by being adhered.

The multilayer ceramic capacitor according to a seventh aspect of the present invention is configured such that the internal electrodes are formed by a nickel composite conductor in which nickel and zirconate are mixed and integrated in a granular manner.

In the multilayer ceramic capacitor according to an eighth aspect of the present invention, the internal electrodes are formed by a nickel composite conductor in which nickel and zirconate containing one or both of calcium zirconate and strontium zirconate and nickel are integrated. It is constituted by.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the accompanying drawings, the illustrated embodiment is a multilayer ceramic capacitor mainly composed of a (CaSr / TiZr) O ₃ -based non-reducing dielectric ceramic material. This shows a capacitor element in which a plurality of dielectric layers mainly composed of calcium acid and internal electrodes mainly composed of a composite conductor of nickel and zirconate are laminated and pressed and fired.

The internal electrodes are 99.5-80 wt% nickel and 0.5-20 wt% calcium zirconate.
(CaZrO ₃ ) and a nickel composite conductor by integrating them in a granular form, and formed by an internal electrode paste in which this nickel composite conductor is mixed with a resin binder. The nickel composite conductor reduces the difference in shrinkage due to sintering between the dielectric layer and the internal electrode, prevents the occurrence of structural delamination due to mutual delamination and oxidation of nickel, and the interruption of the internal electrode due to nickel. Can be prevented and the internal electrode can be made thinner.

Here, calcium zirconate is 0.5 wt.
% Or less, the difference in shrinkage due to sintering between the dielectric layer and the internal electrode is reduced, and the effect on nickel granulation is small. On the other hand, when the content of calcium zirconate is 20 wt% or more, the capacitance is reduced. From 99.5% to 80% by weight of nickel and 0.5% to 2%.
0 wt% calcium zirconate is preferred.

The nickel composite conductor has a particle size of 5 to 10 μm.
m and a zirconate powder having a particle size of 0.5 or less are weighed at a predetermined ratio, uniformly mixed by a ball mill by a dry mixing method, and then melted and solidified by plasma to form granules. Can be integrated.
Since the powder after the plasma treatment has strong agglomeration, it is preferable to mechanically dissolve the agglomeration of the particles and mix the particles with the resin binder.

In the plasma treatment, calcium zirconate is coated on nickel particles as shown in FIG. 1 to form coating type particles, or calcium zirconate is mixed with nickel particles as shown in FIG. It can be made as a type of particle. In any of these types, the same effect can be obtained by reducing the difference in shrinkage due to sintering between the dielectric layer and the internal electrode, and the particle size is preferably 0.3 μm or less.

As the zirconate, instead of calcium zirconate, strontium zirconate (SrZr
O ₃ ) or those containing any of O ₃ ) can be used. With any of these zirconates, an effect equivalent to that of calcium zirconate alone can be obtained.

In order to confirm the effectiveness of the internal electrode using the nickel composite conductor, 0.5 wt%, 2.0 wt%,
An internal electrode paste including a nickel composite conductor in which 5.0 wt%, 10.0 wt%, and 20.0 wt% of calcium zirconate were integrated with nickel particles was prepared (Example 1).
~ 5).

At the same time, an internal electrode paste containing only nickel powder (Comparative Example 1) and an internal electrode paste containing a nickel composite conductor in which 30.0 wt% of calcium zirconate was integrated with nickel particles (Comparative Example 2) were prepared. . Internal electrode paste containing 90 wt% of nickel powder and 10.0 wt% of calcium zirconate (conventional example)
Was prepared.

The oxidation characteristics of each sample were measured by a thermal analyzer under a measurement atmosphere in the atmosphere. As the oxidation characteristics, each sample was gradually heated from room temperature to 700 ° C., and the oxidation amount at 700 ° C. was obtained from the oxidation curve of nickel at that time, and the acid acceleration from room temperature to 700 ° C. was obtained.

At the same time, each of the above-mentioned internal electrode pastes is printed on a dielectric sheet having a thickness of 11.0 μm, and a 260-layer dielectric sheet is alternately laminated with the internal electrodes to obtain a laminated dielectric. The body under N ₂ / H ₂ atmosphere
The shrinkage was measured by firing at a temperature of 300 ° C. When the average value of each test item was calculated from 10 samples of each sample, it was as shown in Table 1 below.

[0026]

[Table 1]

As is apparent from Table 1, as the amount of calcium zirconate increases, nickel is less liable to be oxidized, and the acid acceleration is smaller.

Further, each laminated dielectric of the conventional example, the comparative example 1 and the example 2 was photographed by a micrograph at each firing temperature of 800 ° C., 1000 ° C. and 1300 ° C. As shown in FIGS. 3 to 5, the micrographs show that the growth of nickel particles started at 800 ° C. in the conventional dielectric of FIG. 3 and the laminated dielectric according to Comparative Example 1 of FIG. In the laminated dielectric according to Example 5 of Example 5, the growth of nickel particles was 800.
It can be seen that the sintering is delayed without starting at ℃.

Next, the occurrence rate of structural defects, the capacitance, the DC breakdown voltage, and the thickness of the internal electrode were measured for each of the laminated dielectrics manufactured as described above, and the results were as shown in Table 2 below. .

[0030]

[Table 2]

As is evident from Table 2, as the amount of calcium zirconate increases, the incidence of structural defects decreases and the thickness of the electrode can be reduced.

Further, the laminated dielectrics according to the conventional example and Example 2 were photographed with a microscope photograph. Fig. 6 and Fig. 7
As shown in FIG. 6, the thickness t _{1 of the} internal electrode is 1.5 μm in the laminated dielectric according to the conventional example of FIG. 6, whereas the thickness t _{1 of the} electrode in the laminated dielectric according to the second embodiment in FIG.
₂ is 1.0 μm, which is thin and uniform. This is largely due to the effect of preventing the electrode from being spheroidized due to the oxidation characteristics of the nickel powder and the thickness of the internal electrode.

However, when the amount of calcium zirconate is increased as in Comparative Example 2, the capacitance is significantly reduced because the amount of nickel is small.

In addition to the above, the occurrence of structural defects in a laminated dielectric having an internal electrode formed by an internal electrode paste including a nickel composite conductor in which 2 wt% of strontium zirconate (Example 6) is integrated with nickel particles. The ratio, capacitance, DC breakdown voltage, and thickness of the internal electrode were measured, and the results were as shown in Table 3 below.

[0035]

[Table 3]

As is evident from Table 3, strontium zirconate (Example 6) has the same effect as calcium zirconate.

[0037]

As described above, according to the nickel composite conductor for forming an electrode according to the present invention, 99.5 to 80% by weight of nickel and 0.5 to 20% by weight of zirconate are integrated into particles. Accordingly, mutual delamination due to a shrinkage difference due to sintering of the dielectric layer and the internal electrode of the multilayer ceramic capacitor mainly composed of a (CaSr / TiZr) O ₃ -based non-reducing dielectric ceramic material, It is possible to prevent the occurrence of structural defects due to oxidation and to prevent the internal electrode from being interrupted by nickel, thereby producing an electrode-forming conductive paste capable of coping with the thinning of the internal electrode.

According to the multilayer ceramic capacitor of the present invention, 99.5 to 80% by weight of nickel and 0.5 to 2%
By forming an internal electrode with a nickel composite conductor obtained by integrating 0 wt% zirconate into particles, (Ca
Sr / TiZr) O ₃ -based non-reducing dielectric ceramic material as a main component, a multilayer ceramic capacitor mainly composed of a dielectric layer and internal electrodes, mutually delaminated due to shrinkage due to sintering, and structural defects caused by oxidation of nickel. Of the internal electrode can be prevented, and the internal electrode can be prevented from being interrupted by nickel, and a thin film-shaped internal electrode can be formed to achieve a high capacity.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a structure of a nickel composite conductor for forming an electrode according to an example of the present invention.

FIG. 2 is an explanatory view schematically showing a structure of a nickel composite conductor for forming an electrode according to another example of the present invention.

FIG. 3 shows a sintering state of a laminated dielectric according to a conventional example of 800.
It is the microscope photograph image | photographed at each baking temperature of 1000 degreeC, 1000 degreeC, and 1300 degreeC.

FIG. 4 shows a sintering state of the laminated dielectric according to Comparative Example 1 of 800.
It is the microscope photograph image | photographed at each baking temperature of 1000 degreeC, 1000 degreeC, and 1300 degreeC.

FIG. 5 is a micrograph taken at each of the sintering temperatures of 800 ° C., 1000 ° C., and 1300 ° C. in a sintered state of the laminated dielectric according to Example 2 of the present invention.

FIG. 6 is a micrograph showing the thickness of an internal electrode when a laminated dielectric according to a conventional example is fired at 1300 ° C.

FIG. 7 shows a laminated dielectric according to the second embodiment of the present invention,
5 is a photomicrograph of the thickness of the internal electrode when fired at ℃.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Koji Tanaka, 151 Maeda, Hirasawa, Nikaho-cho, Yuri-gun, Akita Prefecture Inside TDCMCC Co., Ltd. (72) Inventor Kiyoshi Ito 1-13-1 Nihombashi, Chuo-ku, Tokyo Inside TDK Corporation (72) Osamu Otani Inventor F-term (reference) 1-13-1 Nihonbashi, Chuo-ku, Tokyo 5E001 AB03 AC09 AE00 AE01 AE03 AH01 AH09 AJ01 5G301 AA14 AA30 AB20 AD07 AD10 AE02 5G303 AA01 AB11 AB12 BA06 BA09 CA01 CB06 CB32 CB35 CB39

Claims (8)

[Claims] 1. A nickel composite conductor for forming an internal electrode of a multilayer ceramic capacitor comprising a (CaSr / TiZr) O ₃ -based non-reducing dielectric ceramic material as a main component.
A nickel composite conductor for electrode formation, wherein nickel of 5 to 80 wt% and zirconate of 0.5 to 20 wt% are integrated in a granular form. 2. The nickel composite conductor for forming an electrode according to claim 1, wherein the zirconate is adhered to the surface of the nickel particles to integrate nickel and zirconate in a granular form. 3. The nickel composite conductor for electrode formation according to claim 1, wherein nickel and zirconate are mixed and integrated in a granular form. 4. The method according to claim 1, wherein zirconate containing one or both of calcium zirconate and strontium zirconate and nickel are integrated in a granular form.
The nickel composite conductor for electrode formation according to any one of the above. 5. A multilayer ceramic capacitor mainly composed of a (CaSr / TiZr) O ₃ -based non-reducing dielectric ceramic material, wherein 99.5 to 80 wt% of nickel and 0.5%
A multilayer ceramic capacitor, wherein an internal electrode is formed of a nickel composite conductor in which 〜20 wt% of zirconate is integrated in a granular form. 6. The internal electrode according to claim 5, wherein the zirconate is applied to the surface of the nickel particles, and the internal electrode is formed by a nickel composite conductor in which nickel and zirconate are integrated in a granular manner. Multilayer ceramic capacitor. 7. The multilayer ceramic capacitor according to claim 5, wherein the internal electrode is formed of a nickel composite conductor in which nickel and zirconate are mixed and integrated in a granular form. 8. The internal electrode is formed of a nickel composite conductor in which zirconate containing one or both of calcium zirconate and strontium zirconate and nickel are integrated in a granular form. Multilayer ceramic capacitors.