JPH07120598B2 - Multilayer capacitor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement in a multilayer capacitor, and more particularly to a multilayer capacitor having an improved internal electrode structure.

[Conventional technology]

As is well known, a laminated capacitor is configured by using a sintered body obtained by laminating a plurality of ceramic green sheets with an internal electrode material interposed therebetween and integrally firing them. An example of this known multilayer capacitor is shown in a sectional view in FIG. In the multilayer capacitor 1, the ceramic sintered body 2
Internal electrodes 3a to 3e are arranged therein so as to overlap with each other with a ceramic layer 4 interposed therebetween. The external electrodes 5a, 5b are formed on the opposite end faces of the sintered body 2, and the external electrodes 5a, 5b are formed.
Are electrically connected to the internal electrodes 3a, 3c, 3e and 3b, 3d, respectively.

By the way, the internal electrodes 3a to 3e are generally composed of a noble metal such as Ag or Ag-Pd. This is because the firing of the ceramic sintered body 2 is exposed to a high temperature atmosphere, so that it is necessary to use a material having a high melting point and that it is difficult to be oxidized during firing.

However, since Ag and Ag-Pd are fairly expensive materials,
In recent years, a multilayer capacitor using a base metal such as nickel or copper as an internal electrode material has been receiving attention.

[Technical problem to be solved by the invention]

At present, the base metals actually used as the internal electrode materials are nickel and copper.

However, when nickel is used as the internal electrode material, there is a problem that the bonding strength between the internal electrode and the ceramics layer is low, and delamination and layer peeling easily occur.

On the other hand, when copper is used as the internal electrode material, it is difficult to control the firing profile and the melting point is low (1060 ° C), so it is necessary to use a non-reducing ceramic material that can be fired below that temperature. Therefore, there is a problem that the types of ceramic materials that can be used are limited.

The object of the present invention is to solve the above problems in a multilayer capacitor using a base metal as an internal electrode material, while using nickel or nickel-copper alloy as an internal electrode material, the bonding strength between the internal electrode and the ceramics is improved. high,
It is to provide a multilayer capacitor in which delamination or the like hardly occurs.

[Means for solving technical problems]

According to the present invention, a plurality of internal electrodes are arranged in a ceramic sintered body so as to overlap with each other via a ceramic layer, and a pair of internal electrodes are connected so as to be connected to a predetermined internal electrode in order to extract a capacitance between the internal electrodes. A multilayer capacitor having external electrodes provided on the side surface of a sintered body is characterized by having the following configuration.

That is, the internal electrode is made of nickel or a nickel alloy, and the internal electrode is joined to the ceramic layer via an intermediate layer made of a nickel-copper alloy or a nickel-copper alloy and copper. To do.

[Action]

An intermediate layer made of nickel-copper alloy or nickel-copper alloy and copper, which is firmly bonded to nickel or nickel alloy, is provided between the internal electrode made of nickel or nickel alloy and the ceramic layer. The nickel-copper alloy or the intermediate layer made of the nickel-copper alloy and copper contains copper and thus is firmly bonded to the ceramic layer. That is, the internal electrode made of nickel or a nickel alloy is indirectly bonded to the ceramic through the intermediate layer having excellent bonding strength with the ceramic layer, thereby increasing the bonding strength between the ceramic and the internal electrode. There is.

[Explanation of Examples]

 Hereinafter, non-limiting examples of the present invention will be described.

Example 1 First, BaCO ₃ , CaCO ₃ , ZrO ₂ and TiO ₂ having a purity of 99% or more were used as a non-reducing material constituting a ceramic sintered body, and a composition formula {(Ba _0.90 Ca _0.10 ) 0} _1.01 ( Ti _0.80 Zr _0.20 ) O ₂ was weighed. The weighed raw material powder was mixed and calcined to obtain a dielectric ceramic raw material powder.

To this dielectric ceramic raw material powder, 15% by weight of a mixed aqueous solution containing an organic binder, a dispersant and an antifoaming agent was added,
Water was further added in an amount of wt% and mixed and pulverized with a ball mill to prepare a slurry.

Next, the obtained slurry was formed into a sheet by a doctor blade method to obtain a green sheet having a thickness of 35 μm.

On the other hand, as shown in FIG. 3, on the carrier film 11,
The intermediate layer 12 made of a nickel-copper alloy has a thickness of 0.05 μm, and the internal electrode 13 made of nickel has a thickness of 0.6 μm on the intermediate layer 12.
An intermediate layer 14 made of a nickel-copper alloy was again deposited on the internal electrode 13 to a thickness of 0.05 μm to a thickness of 0.05 μm by vapor deposition to obtain an electrode pattern.

The electrode pattern produced as described above was thermally transferred onto the above-mentioned green sheet.

Next, a plurality of green sheets to which the electrode patterns were transferred were laminated and thermocompression bonded in the thickness direction to obtain a laminated body. A conductive paste for forming an external electrode, to which nickel powder and zinc borosilicate glass were added, was applied to the opposite end surface of the obtained laminate from which the internal electrode pattern was drawn out.

Next, the obtained laminate was heated to a temperature of 350 ° C. in the atmosphere to burn the organic binder, and then the oxygen partial pressure was 10 ^−9.
The laminated capacitor shown in FIG. 1 was obtained by firing at 1300 ° C. for 2 hours in a reducing atmosphere using a mixed gas of H ₂ —N ₂ and H ₂ O of up to 10 ⁻¹² MPa.

As is apparent from FIG. 1, in the obtained multilayer capacitor, the plurality of internal electrodes 13 are arranged in the ceramic sintered body 15 so as to overlap with each other with the ceramic layer 16 interposed therebetween. Each internal electrode 13 is joined to each ceramic layer 16 with intermediate layers 12 and 14 interposed therebetween. Note that 17a and 17b indicate external electrodes.

The specifications of the multilayer capacitor obtained as described above are as follows.

External dimensions Width: 3.2mm Length: 1.6mm Thickness: 1.2mm Ceramic unit thickness: 20μm Total number of effective dielectrics: 19 Counter electrode area per layer: 1.3mm ² Multilayer capacitor obtained as above and conventional The multilayer capacitor was evaluated according to the following procedure.

First, the capacitance (C) and the dielectric loss (tan δ) were measured by applying a voltage of 1 kH ₂ and 1 Vrms to the multilayer capacitor of each sample using an automatic bridge type measuring device. Next, in order to measure the insulation resistance (R),
A voltage of 50 V was applied for 2 minutes using an insulation resistance meter. Then, the CR product of the electrostatic capacity (C) and the insulation resistance (R) was obtained.

For comparison, a conventional multilayer capacitor having no intermediate layer formed was prepared as a comparative example, and the electrical characteristics were measured in the same manner.

The results are shown in Table 1 below.

As is clear from Table 1, in the multilayer capacitor of Example 1, since the intermediate layer made of Ni-Cu alloy is provided between the internal electrode and the ceramic layer, the dielectric loss is improved and the electrostatic loss is improved. It can be seen that the capacitance also increased from 0.16 μF to 0.19 μF.

When observing the inside of the multilayer capacitors of these samples, delamination occurred between the internal electrodes and the ceramic layers in the multilayer capacitor of the comparative example, but neither layer peeling nor delamination occurred in the multilayer capacitor of this example. It was found that the bonding strength between the internal electrode and the ceramics layer was increased by providing the intermediate layer.

Example 2 In the same manner as in Example 1, a green sheet having a thickness of 35 μm was formed.

On the other hand, as shown in FIG. 4, on the carrier film 11,
The first intermediate layer 12a made of copper has a thickness of 0.03 μm, and the second intermediate layer 12b made of nickel-copper alloy has a thickness of 0.03 μm.
The inner electrode 13 made of nickel has a thickness of 0.5 μm, and the second intermediate layer 14b made of a nickel-copper alloy has a thickness of 0.03 μm on the inner electrode 13.
The first intermediate layer 1 made of copper on the intermediate layer 14b with a thickness of m.
4a was vapor-deposited to a thickness of 0.03 μm to form an electrode pattern.

The obtained electrode pattern was thermally transferred onto a green sheet in the same manner as in Example 1. Thereafter, a multilayer capacitor was obtained by the same procedure as in Example 1.

That is, in the multilayer capacitor obtained in this example, the intermediate layers were the first intermediate layers 12a and 14a made of copper arranged on the ceramic side, and the first intermediate layers made of nickel-copper alloy arranged on the internal electrode side. The multilayer capacitor has the same structure as that of the multilayer capacitor prepared in Example 1 except that the multilayer capacitor is composed of a composite of the two intermediate layers 12b and 14b.

The specifications of the multilayer capacitor obtained as described above are as follows.

External dimensions Width: 3.2 mm Length: 1.6 mm Thickness: 1.2 mm Unit thickness of ceramic layer: 20 μm Total number of effective dielectrics: 19 Counter electrode area per layer: 1.3 mm ^{2 of} Example 2 obtained as above The electrical characteristics of the multilayer capacitor were measured in the same manner as in Example 1. For comparison, a conventional multilayer capacitor provided with no intermediate layer was prepared as a comparative sample, and the electrical characteristics were measured under the same conditions. The results are shown in Table 2 below.

As is clear from Table 2, in the multilayer capacitor of Example 2, since the first and second intermediate layers are provided between the internal electrodes and the ceramic layer, the dielectric loss is reduced from 2.3% to 0.2%. It can be seen that this is improved and the capacitance is increased from 0.16 μF to 0.20 μF. As for CR product, 5000ΩF to 5800
It can be seen that it has been increased to ΩF.

Further, when the inside of the multilayer capacitor of Example 2 and the comparative example was observed, peeling and delamination occurred between the internal electrodes and the ceramic layer in the multilayer capacitor of the comparative example. On the other hand, in the multilayer capacitor of Example 2, delamination did not occur at all even if it was peeled off, so that the first and second intermediate layers were interposed between the internal electrode and the ceramic layer, It can be seen that the bonding strength between the internal electrodes and the ceramic layer is increased.

〔The invention's effect〕

As described above, according to the present invention, the bonding strength between the internal electrode made of nickel or a nickel alloy and the ceramic layer is the nickel-copper alloy or the nickel-copper alloy interposed between the internal electrode and the ceramic layer, and It is effectively enhanced by the copper intermediate layer. Therefore, it is possible to prevent the occurrence of layer peeling and delamination in a multilayer capacitor using nickel or nickel alloy, which is an inexpensive base metal material, as an internal electrode material, and further, characteristics such as capacitance, dielectric loss and CR product can be obtained. Be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a multilayer capacitor prepared in Example 1, FIG. 2 is a cross-sectional view showing an example of a conventional multilayer capacitor, and FIG. 3 illustrates internal electrodes and intermediate layers prepared in Example 1. FIG. 4 is a side view for explaining the internal electrodes and the intermediate layer prepared in the second embodiment. In the figure, 12 and 14 are intermediate layers, 13 is an internal electrode, 15 is a ceramic sintered body, 16 is a ceramic layer, 17a and 17b are external electrodes, 12a and 14a are first intermediate layers, and 12b and 12b are second electrodes. The intermediate layer of FIG.

Claims (1)

[Claims] 1. A ceramic sintered body, a plurality of internal electrodes arranged in the ceramic sintered body so as to overlap with each other with a ceramic layer interposed therebetween, and a predetermined amount for extracting a capacitance between the internal electrodes. In a multilayer capacitor comprising a pair of external electrodes provided on the side surface of the sintered body so as to be electrically connected to the internal electrodes, the internal electrodes are made of nickel or nickel alloy, and the internal electrodes, A multilayer capacitor, which is joined to the ceramic layer with an intermediate layer made of nickel-copper alloy or nickel-copper alloy and copper interposed therebetween.