JPH0945573A - Multilayer ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a multilayer ceramic capacitor featured by suppressing the creeping discharge from occurring on the surface of ceramic and improving the creeping discharge start voltage. SOLUTION: A multilayer ceramic capacitor comprises a multilayer body of first and second green ceramic sheets 1 alternately stacked; each first sheet 1 having two first internal electrodes 2a, 2b extending to the mutually opposed ends, and each second sheet 1 having one second internal electrode not contacted with the end. External electrodes 4a, 4b are formed on the end faces of the multilayer body where the electrodes 2a, 2b are exposed. Each of the electrodes 2a, 2b has a smaller width at the side face of the central part than that at the other side face connected to the electrodes 4a, 4b.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Generally, a laminated ceramic capacitor is formed by stacking a ceramic green sheet and a sheet on which an internal electrode paste is printed on the ceramic green sheet, pressurizing the laminated body, and then firing the laminated body to both ends of the sintered body. This is a structure in which an external electrode connected to the internal electrode is provided.

Medium and high voltage monolithic ceramic capacitors (1 KV
In the above grades), a series-type electrode structure was formed, and the voltage applied to each effective layer was halved to prevent dielectric breakdown.

[0004]

However, the above-mentioned conventional structure has a problem that the creeping discharge starting voltage is low when used at a high voltage. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and to produce a monolithic ceramic capacitor having an improved creeping discharge starting voltage.

[0005]

In order to achieve this object, a monolithic ceramic capacitor according to the present invention is provided with a first dielectric material having two first internal electrodes provided on the surface so as to reach opposite ends. A layered body in which a plurality of layers and a second dielectric layer having a surface on which one second internal electrode is provided in an end portion in a non-contact state are alternately laminated, and the first layered body of the laminated body. An external electrode provided on an exposed end surface of the internal electrode, and at least one electrode of the first internal electrodes of at least one layer has a width of an end portion on a side connected to the external electrode, The width is shortened.

[0006]

With this structure, the gradient of the electric potential on the side surface between the external electrodes of the monolithic ceramic capacitor becomes gentler than in the conventional case, and the creeping discharge starting voltage is improved.

[0007]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

1, 2, 3 and 4 are cross-sectional views of a monolithic ceramic capacitor according to the present embodiment, in which a first internal electrode 2a, 2b and a second internal electrode 2a,
Of the first internal electrodes 2a,
External electrodes 4a and 4b are formed on the exposed end faces of 2b.

As shown in FIG. 1, the first internal electrodes 2a,
In 2b, the width of the central portion is shorter than the width on the side connected to the external electrodes 4a and 4b, and the distance between the two first internal electrodes 2a and 2b is smaller than the central portion. The side is longer. Here, it is desirable that the distance between the electrodes on the side surface is the same on the left and right.

Further, it is desirable that the corners of the first internal electrodes 2a, 2b and the second internal electrode 3 are curved in order to prevent dielectric breakdown.

A method of manufacturing this laminated ceramic capacitor will be described below. First, a dielectric ceramic slurry was formed on a carrier film by a reverse roll coater and dried to form a ceramic green sheet 1. Next, the ceramic green sheet 1 is peeled from the carrier film, and the internal electrode paste is screen-printed on the ceramic green sheet 1 by printing and drying using the pattern Y shown in FIG.
Formed 2b. Next, the ceramic green sheet 1 was laminated on this, the pattern W of FIG. 6 was shifted in the length direction on this, and the internal electrode paste was printed and dried to form the second internal electrode 3. In this way, with the ceramic green sheets 1 sandwiched therebetween, the pattern Y shown in FIG. 5 and the pattern W shown in FIG. 6 were alternately used, and this step was repeated until the desired number of layers were stacked.

Next, a predetermined number of ceramic green sheets 1 on which internal electrodes are not printed are laminated on the upper side and the lower side of the laminated body as described above to form an ineffective layer, which is pressed and pressure-bonded to each other. To obtain a laminate.

Next, this laminated body was cut, binder-out and fired, after which the external electrodes 4a and 4b were applied and baked, and Ni plating and Sn-Pb plating were carried out to obtain a laminated ceramic capacitor. This monolithic ceramic capacitor has a capacitance of 100 pF, Q1200, IR 1 * 10.
¹³ Ω.

The results of measuring the creeping discharge inception voltage using this monolithic ceramic capacitor are shown in (Table 1).

[0015]

[Table 1]

Further, in this embodiment, the width of the central portion is made shorter than the width on the side where all the first internal electrodes 2a, 2b are connected to the external electrodes 4a, 4b, and the two first internal electrodes 2a, 2b are connected. 1
The inter-electrode distance between the internal electrodes 2a and 2b is longer on the side surface side than on the central portion. However, if one of the first internal electrodes 2a and 2b has this structure, creeping discharge starts more than in the conventional case. It seems that the voltage can be improved.

Comparative Example 1 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 paste is printed and dried on the ceramic green sheet by screen printing in the pattern W of FIG. 6, and the ceramic green sheet is laminated on it.
The pattern W of FIG. 6 was shifted in the length direction on the green sheet, and the internal electrode paste was printed and dried. By repeating this process, lamination was performed. The laminated ceramic green sheets were pressed and pressed together to form a laminate. The subsequent steps are the same as in the first embodiment.

The results of measuring the creeping discharge inception voltage using the obtained monolithic ceramic capacitor in the same manner as in Example 1 are shown in Table 1.

As is clear from this (Table 1), the monolithic ceramic capacitor of the present invention was able to improve the dielectric breakdown voltage.

[0020]

As described above, according to the present invention, since the gradient of the electric potential on the side surface between the external electrodes of the monolithic ceramic capacitor becomes gentler than in the conventional case, the creeping discharge starting voltage is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a monolithic ceramic capacitor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a monolithic ceramic capacitor according to an embodiment of the present invention.

3 is an A- of the monolithic ceramic capacitor in FIG.
Section A

4 is a B- of the monolithic ceramic capacitor in FIG.
B sectional view

FIG. 5 is a pattern diagram for printing internal electrodes in an embodiment of the present invention.

FIG. 6 is a pattern diagram for printing internal electrodes according to an embodiment of the present invention.

[Explanation of symbols]

 1 Ceramic Green Sheet 2a First Internal Electrode 2b First Internal Electrode 3 Second Internal Electrode 4a External Electrode 4b External Electrode

Claims (2)

[Claims] 1. A first dielectric layer provided with at least two first internal electrodes on the surface so as to reach opposite ends, and at least one second internal electrode on the surface with a non-end. At least one layer is provided, including a laminated body in which a plurality of second dielectric layers provided in contact with each other are alternately laminated, and an external electrode provided on the exposed end surface of the first internal electrode of the laminated body. One of the first internal electrodes is a multilayer ceramic capacitor in which the width of the other end is shorter than the width of the end on the side connected to the external electrode. 2. The multilayer ceramic capacitor according to claim 1, wherein in at least one layer of the first internal electrode, a distance between two facing electrodes is longer in a side surface portion than in a central portion.