JPH10223470A - Multilayer ceramic capacitors - Google Patents

Abstract

(57) [Problem] To provide a multilayer ceramic capacitor having a high creeping discharge starting voltage. SOLUTION: The distance from the lateral end face of the laminate to the outermost internal electrode layer 2a is made shorter than the distance to other internal electrode layers 2, and the longitudinal direction of the outermost internal electrode layer 2a is reduced. The length (a) is set to 0.25 to 0.75 times the length (G) in the longitudinal direction of the laminate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic capacitor.

[0002]

2. Description of the Related Art As shown in FIG. 7, a conventional multilayer ceramic capacitor is formed by laminating dielectric ceramic layers 100 and internal electrode layers 101 alternately so that the internal electrode layers 101 are exposed at opposing end faces. External electrodes 102 are provided on both end surfaces of the body so as to be electrically connected to the internal electrode layers 101.
Was formed. The internal electrode layers 101 were all the same size and shape, and had a parallel electrode structure.

In addition, since a high voltage is applied to a multilayer ceramic capacitor for medium and high pressures, a so-called creeping discharge may occur between external electrodes, in which a current flows along the surface of the dielectric ceramic layer.

Accordingly, a multilayer ceramic capacitor for medium and high voltage is required to have a high creeping discharge starting voltage.

[0005]

According to this structure, when used under a high voltage, the potential difference on the surface of the laminate becomes large, so that the creeping discharge starting voltage is low.

Accordingly, an object of the present invention is to provide a multilayer ceramic capacitor having a high creeping discharge starting voltage.

[0007]

In order to achieve this object, a multilayer ceramic capacitor according to the present invention comprises a plurality of dielectric layers and a plurality of internal electrode layers which are alternately arranged on an end face where the internal current layers face each other. A laminated body that is laminated so as to be exposed, and an external electrode provided on an exposed end face of the internal electrode layer of the laminated body, from the lateral end face of the laminated body to the outermost internal electrode layer The distance is made shorter than the distance to the other internal electrode layers, and the length of the outermost inner electrode layer in the longitudinal direction is set to 0.25 of the longitudinal length of the laminate.
Since the gradient of the potential on the surface of the laminate becomes gentle, the creeping discharge starting voltage is high.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated so that the internal electrode layers are exposed at opposing end faces. And an external electrode provided on an exposed end face of the internal electrode layer of the laminate, and a distance from a lateral end face of the laminate to the outermost internal electrode layer is set to another internal distance. A multilayer ceramic capacitor having a length shorter than a distance to an electrode layer and a length in a longitudinal direction of the outermost inner electrode layer being 0.25 to 0.75 times a length in a longitudinal direction of the laminate. Since the gradient of the potential on the surface of the laminate becomes gentle, the creeping discharge starting voltage is high.

According to a second aspect of the present invention, there is provided a laminated body in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated so that the internal electrode layers are exposed at opposing end faces, and An external electrode provided on an exposed end face of the internal electrode layer of the body, wherein the length of the outermost internal electrode layer in the longitudinal direction of the laminate is 0.01 to less than the longitudinal length of the laminate.
The multilayer ceramic capacitor is 0.25 times, and has a high creeping discharge starting voltage because the gradient of the potential on the surface of the multilayer body becomes gentle.

According to a third aspect of the present invention, the length of the second inner electrode layer from the outside in the longitudinal direction of the laminate is 0.75 times or less the longitudinal length of the laminate. Wherein the gradient of the potential on the surface of the multilayer body becomes gentle, so that the creeping discharge starting voltage is high.

According to a fourth aspect of the present invention, there is provided a laminate in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated, and an external electrode provided on an exposed end face of the internal electrode layer of the laminate. Wherein the outermost layer of the internal electrode layers is composed of two internal electrode layers connected to the different external electrodes on the same plane, and the outermost layer of one of the two internal electrode layers has a longitudinal length of one of the stacked bodies. The length in the direction is 0.25 to 0.75 times the length in the longitudinal direction of the laminate, and the length in the longitudinal direction of the other laminate is 0. 0
A multilayer ceramic capacitor in which the internal electrode layer is not in contact with the above two internal electrode layers, and the gradient of the potential on the surface of the multilayer body becomes gentle, so that the creeping discharge starting voltage is high. .

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is a sectional view of a multilayer ceramic capacitor according to the present embodiment, and FIG.
A sectional view and FIG. 3 are BB sectional views in FIG. 1. The dielectric ceramic layers 1 and the internal electrode layers 2 and 2a are alternately laminated, and the external electrode 3 is provided on the exposed end faces of the internal electrode layers 2 and 2a. Is formed.

As shown in FIGS. 2 and 3, the distance from the lateral end face of the laminate to the outermost internal electrode layer 2a is shorter than the distance to the other internal electrode layers 2, and the outermost layer is The length (a) of the internal electrode layer 2a in the longitudinal direction is 0.25 to 0.75 times the length (G) of the laminated body in the longitudinal direction.

A method for manufacturing the multilayer ceramic capacitor will be described. First, a dielectric ceramic slurry was formed on a carrier film by a reverse roll coater and dried to form a ceramic green sheet to be a dielectric ceramic layer 1. Next, the ceramic green sheet is peeled from the carrier film, the internal electrode layer paste is printed on the ceramic green sheet in a desired shape by screen printing, dried, and a ceramic green sheet is laminated thereon. The printing screen was shifted at regular intervals in the longitudinal direction, and the internal electrode layer paste was printed and dried. Next, a ceramic green sheet was stacked thereon again, and the internal electrode layer paste was printed and dried on the ceramic green sheet while returning the printing screen to its original position in the longitudinal direction. The process of printing by laminating the ceramic green sheets and alternately shifting the printing screen in the length direction was repeated a desired number of times. Then, the ceramic green sheets on which the internal electrode layer paste was not printed were laminated so as to be in upper and lower layers. The thus laminated ceramic green sheets were pressed and pressed against each other, cut into a desired size, binder-out, and fired. Thereafter, the external electrode 3 was applied to the exposed end face of the internal electrode layer 2 and baked, and Ni plating and Sn-Pb plating were performed to obtain a multilayer ceramic capacitor.

The obtained multilayer ceramic capacitor has a longitudinal dimension L of 3.2 mm, a capacitance of 10,000 pF, a T
An δ was 1.1% and IR was 1 × 10 ¹¹ Ω.

The thickness of the effective layer was 80 μm.
Table 1 shows the results of measuring the creeping discharge starting voltage using this multilayer ceramic capacitor.

[0017]

[Table 1]

Comparative Example 1 As a comparative example, a multilayer ceramic capacitor as shown in FIG. 7 was manufactured.

First, a dielectric ceramic slurry was formed on a carrier film by a reverse roll coater and dried to form a ceramic green sheet. Next, the ceramic green sheet is peeled off from the carrier film, the internal electrode layer paste is printed on the ceramic green sheet by screen printing, dried, the ceramic green sheet is laminated thereon, and the printing screen is lengthened on the green sheet. The paste was shifted in the direction and the internal electrode layer paste was printed and dried. Next, a ceramic green sheet was laminated thereon, and the internal electrode layer paste was printed and dried on the green sheet while returning the printing screen to its original position in the longitudinal direction. In this way, the printing screen was alternately shifted in the length direction, and printing lamination was repeated. Then, ceramic green sheets on which the internal electrode layer paste was not printed were laminated. The laminated ceramic green sheets were pressed and pressed against each other, cut into a desired size, binder-out, and fired. Thereafter, an external electrode 102 is applied to the exposed end face of the internal electrode layer 101 and baked, and Ni
Plating and Sn-Pb plating were performed to obtain a multilayer ceramic capacitor.

Using the obtained multilayer ceramic capacitor, the creeping discharge starting voltage was measured in the same manner as in the first embodiment, and the results are shown in Table 1.

As is clear from Table 1, the distance from the lateral end face of the laminate to the outermost internal electrode layer 2a is made shorter than the distance to the other internal electrode layers 2 and the outermost layer. By setting the length (a) of the internal electrode layer 2a in the longitudinal direction to 0.25 to 0.75 times the longitudinal length (G) of the laminate, the creeping discharge starting voltage is improved. .

(Embodiment 2) FIG. 4 is a cross-sectional view of a multilayer ceramic capacitor according to the present embodiment, in which a dielectric ceramic layer 10 and internal electrode layers 12, 12a and 12b are alternately stacked to form an internal electrode layer. External electrodes 13 are formed on the exposed end faces of 12, 12, 12b.

As shown in FIG. 4, the outermost inner electrode layer 1
The length (a) in the longitudinal direction of the laminated body of 2a is 0.01 to 0.25 times the longitudinal length (G) of the laminated body, and the longitudinal direction of the laminated body of the second internal electrode layer 12b from the outside is Of the length (G) of the laminate in the longitudinal direction (G) is 0.25 to 0.25.
It is 0.75 times.

This multilayer ceramic capacitor is manufactured in the same manner as in the first embodiment. The surface discharge starting voltage was measured using this multilayer ceramic capacitor, and the results are shown in (Table 2).

[0025]

[Table 2]

The conventional example is the result of measuring the creeping discharge starting voltage of the multilayer ceramic capacitor manufactured as described above.

As is clear from Table 2, when the length of the outermost inner electrode layer 12a in the longitudinal direction of the laminate is 0.01 to 0.25 times the longitudinal length of the laminate. It can be seen that the creeping discharge starting voltage has been improved. When the length of the second internal electrode layer 12b from the outside in the longitudinal direction of the laminate is 0.25 to 0.75 times the longitudinal length of the laminate, the creeping discharge start voltage can be further improved. Recognize.

(Embodiment 3) FIG. 5 is a cross-sectional view of a multilayer ceramic capacitor according to the present embodiment, in which a dielectric ceramic layer 21 and internal electrode layers 22, 22a, 22b are alternately laminated, and the internal electrode layer 22, External electrodes 23 are formed on the exposed end faces of 22a and 22b.

As shown in FIG. 5, the outermost inner electrode layer 2
2a and 22b are located on the same plane and are connected to different external electrodes 23, respectively. The length of one of the internal electrode layers 22a in the longitudinal direction is (b), and the length of the laminated body in the longitudinal direction is (b). (G) 0.25 to 0.75 times the length of the other internal electrode layer 22b in the longitudinal direction (a)
Is 0.01 to 0.2 of the length (G) in the longitudinal direction of the laminate.
It is made to be 5 times.

This multilayer ceramic capacitor is also manufactured in the same manner as in the first embodiment.

Using this multilayer ceramic capacitor, the creeping discharge starting voltage was measured, and the results are shown in Table 3.

[0032]

[Table 3]

The ones marked with * are the results of measuring the creeping discharge starting voltage of the multilayer ceramic capacitor manufactured according to the above (Comparative Example 1).

As is apparent from Table 3, the outermost internal electrode layers 22a and 22b are located on the same plane and are connected to different external electrodes 3, respectively. Is 0.25 to 0.75 times the longitudinal length (G) of the laminate, and the longitudinal length (a) of the other internal electrode layer 22b is (a). ) Is 0.01 to less than the longitudinal length (G) of the laminate.
0.25 times (however, a + b <G
), The creeping discharge starting voltage is improved.

(Embodiment 4) FIG. 6 is a cross-sectional view of a multilayer ceramic capacitor according to the present embodiment, which is the same as (Embodiment 3) except that the internal electrode layer structure is a series-parallel structure. , The outermost inner electrode layers 22c and 22d
Are connected to different external electrodes 23 which are located on the same plane and are different from each other, and the length (b) of one of the internal electrode layers 22c in the longitudinal direction of the laminate is equal to the longitudinal length (G) of the laminate. 0.25 to 0.75 times, and the length (a) of the other internal electrode layer 22d in the longitudinal direction of the laminate is 0.01 to 0.25 times the longitudinal length (G) of the laminate. (Where a + b <G), the creeping discharge starting voltage is improved.

[0036]

As described above, according to the present invention, a multilayer ceramic capacitor having an improved creeping discharge starting voltage can be obtained because the potential gradient between the external electrodes on the surface of the laminate becomes gentle.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a multilayer ceramic capacitor according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a sectional view taken along line BB in FIG. 1;

FIG. 4 is a longitudinal sectional view of a multilayer ceramic capacitor according to a second embodiment of the present invention.

FIG. 5 is a longitudinal sectional view of a multilayer ceramic capacitor according to a third embodiment of the present invention.

FIG. 6 is a longitudinal sectional view of a multilayer ceramic capacitor according to a fourth embodiment of the present invention.

FIG. 7 is a longitudinal sectional view of a conventional multilayer ceramic capacitor.

[Explanation of symbols]

 Reference Signs List 1 dielectric ceramic layer 2 internal electrode layer 2a internal electrode layer 2b internal electrode layer 2c internal electrode layer 2d internal electrode layer 3 external electrode

Claims (4)

[Claims] 1. A laminate comprising: a laminate in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated; and an external electrode provided on an exposed end face of the internal electrode layer of the laminate. The distance from the short-side end face to the outermost internal electrode layer is shorter than the distance to the other internal electrode layers, and the length of the outermost internal electrode layer in the longitudinal direction is set to the laminate. A multilayer ceramic capacitor having a length in the longitudinal direction of 0.25 to 0.75 times. 2. An outermost layer comprising: a laminate in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated; and an external electrode provided on an exposed end face of the internal electrode layer of the laminate. A multilayer ceramic capacitor in which the length of the internal electrode layer in the longitudinal direction of the laminate is 0.01 to 0.25 times the longitudinal length of the laminate. 3. The length of the second internal electrode layer from the outside in the longitudinal direction of the laminate is 0.7 times the longitudinal length of the laminate.
3. The multilayer ceramic capacitor according to claim 2, wherein the value is 5 times or less. 4. A laminate comprising a plurality of dielectric layers and a plurality of internal electrode layers alternately laminated, and an external electrode provided on an exposed end face of the internal electrode layer of the laminate. The outermost layer of the layers is composed of two internal electrode layers connected to the different external electrodes on the same plane, and the length of one of the two internal electrode layers in the longitudinal direction is the length of the laminated body. 0.25 to 0.75 of the longitudinal length of the body
The length of the other laminated body in the longitudinal direction is 0.01 to 0.25 times the longitudinal length of the laminated body, and the two internal electrode layers are not in contact with each other. Ceramic capacitors.