JPH07201633A - Multilayer ceramic capacitor and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] A multilayer ceramic capacitor with reduced insulation resistance defects by preventing creeping discharge on the ceramic surface and preventing discharge between internal electrodes and external electrodes not connected. The purpose is to create. A dielectric ceramic layer 1 is formed between opposed internal electrodes 2, and an insulator portion other than the opposed internal electrodes 2 is a glass layer 3 of an insulator having a higher breakdown voltage than the dielectric ceramic layer 1. As a result, insulation resistance failure can be prevented in the moisture resistance load test, and the cutting margin and the ineffective layer thickness can be reduced, so that a small-sized high-capacity multilayer ceramic capacitor 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 monolithic ceramic capacitor and a method of manufacturing the same, and more particularly to a monolithic ceramic capacitor for medium and high voltage.

[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 it to form a laminated body, and then firing it 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
Since the creeping discharge is likely to occur on the surface of the dielectric ceramic, the distance between the electrodes is increased by increasing the dimension of the dielectric ceramic to prevent the creeping discharge.

[0004]

However, in the above conventional structure, when used at a high voltage, the distance between the electrodes must be increased in order to prevent creeping discharge on the surface of the dielectric ceramic. There is a problem that the shape becomes large and the cost becomes high. In addition, there is a problem that discharge is likely to occur between the internal electrode and the external electrode that is not connected, and defective insulation resistance is likely to occur.

The present invention solves the above-mentioned conventional problems by preventing creeping discharge on the surface of the dielectric ceramic layer,
It is another object of the present invention to produce a monolithic ceramic capacitor in which defective insulation resistance is reduced by preventing discharge between the internal electrode and an external electrode which is not connected.

[0006]

In order to achieve this object, according to the present invention, laminated internal electrodes are connected to predetermined external electrodes every other layer, and a portion between the opposed internal electrodes is a dielectric ceramic layer. Insulators other than between the opposing internal electrodes are made of an insulator having a higher breakdown voltage than the dielectric ceramic layer.

[0007]

According to the structure of the present invention, therefore, creeping discharge is unlikely to occur on the surface of the dielectric ceramic layer, and discharge is unlikely to occur between the internal electrode and the external electrode which is not connected. Defects are reduced.

[0008]

【Example】

(Embodiment 1) FIGS. 1 and 2 are sectional views of a monolithic ceramic capacitor according to an embodiment of the present invention. 1 and 2, 1 is a dielectric ceramic layer, 2 is an internal electrode,
Reference numeral 3 denotes a glass layer made of an insulating material having a higher breakdown voltage than the dielectric ceramic layer 1, 4 denotes external electrodes, and the stacked internal electrodes 2 are connected to predetermined external electrodes 4 every other layer, and the internal electrodes 2 facing each other are provided. A dielectric ceramic layer 1 is formed between them,
The glass layer 3 is formed except between the opposing internal electrodes 2. The glass layer 3 is also formed on both outer surfaces.

Since the glass layer 3 having a higher breakdown voltage than the dielectric ceramic layer 1 is formed except for the opposing portions of the internal electrodes 2 as described above, defective insulation resistance can be reduced even in a humidity resistance load test, and the dielectric ceramic layer can be reduced. No creeping discharge is likely to occur on the surface of No. 1.

Next, a method of manufacturing the monolithic ceramic capacitor will be described. First, the dielectric ceramic paste 9 is printed and dried on a carrier film by a screen which is continuously patterned in a rectangular shape by screen printing, and then the glass paste 3 is printed and dried on a portion where the dielectric ceramic paste 9 is not printed. Then, the green sheet 5 as shown in FIG. 3 was formed. Next, the internal electrode paste 2 was printed and dried on the green sheet 5 of FIG. 3 by screen printing to form a green sheet 5 having the internal electrodes 2 as shown in FIG. Next, the green sheets 5 having a plurality of internal electrodes 2 were laminated in a positional relationship as shown in FIG. A predetermined number of green sheets prepared only from the glass paste on which the internal electrodes 2 were not formed were laminated on the upper and lower sides of the thus laminated green sheets 5. The laminated green sheets were pressed and pressed together to form a laminated body. Then disconnect
Binder out and firing are performed, and then the external electrode 4 is applied and baked, and Ni plating and Sn-Pb plating are performed,
A monolithic ceramic capacitor was used.

The obtained monolithic ceramic capacitor has an electrostatic capacity of 10000 pF, Tan δ 1.0% and an insulation resistance of 1 ×.
It was 10 ¹¹ Ω.

Using this monolithic ceramic capacitor,
The results of a moisture resistance load test in which a voltage of 500 V is applied in an environment of 0 ° C. and 95% are shown in (Table 1). 5 × 10
Insulation resistance was considered to be ⁸ Ω or less.

(Comparative Example 1) A dielectric paste was applied on a carrier film by a reverse roll coater and printed to prepare a ceramic green sheet. Next, the internal electrode paste was printed by screen printing on the ceramic green sheet peeled from the carrier film and dried, and the ceramic green sheet was laminated thereon. After that, printing and drying of the internal electrode paste and lamination of the ceramic green sheets were repeated, pressed and pressed together to form a laminate. The subsequent steps are the same as in the first embodiment.

The results of a moisture resistance load test carried out in the same manner as in Example 1 using the obtained monolithic ceramic capacitor are shown in (Table 1).

[0015]

[Table 1]

As is clear from this (Table 1), the laminated ceramic capacitor of the present invention was able to prevent defective insulation resistance in the moisture resistance load test.

[0017]

As described above, according to the present invention, the insulating portion other than between the opposing internal electrodes is made of an insulating material having a higher withstand voltage than the dielectric ceramic layer, thereby preventing insulation resistance failure in the moisture resistance load test. Since the cutting margin and the ineffective layer thickness can be reduced, a small-sized and high-capacity monolithic ceramic capacitor can be manufactured.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view of the same monolithic ceramic capacitor.

FIG. 3 is a plan view of a state in which a green sheet is created to make the monolithic ceramic capacitor.

FIG. 4 is a plan view showing a state in which internal electrodes are formed on a green sheet to make the same multilayer ceramic capacitor.

FIG. 5 is an explanatory view showing a laminated state for making the same laminated ceramic capacitor.

[Explanation of symbols]

 1 Dielectric ceramic layer 2 Internal electrode 3 Glass layer 4 External electrode

Claims (2)

[Claims] 1. A laminated internal electrode is connected to a predetermined external electrode every other layer, a dielectric ceramic layer is formed between opposed internal electrodes, and an insulator portion other than the opposed internal electrodes is formed of the dielectric ceramic layer. Multilayer ceramic capacitor made of an insulator that has a higher breakdown voltage than the layers. 2. An insulating paste having a higher breakdown voltage than the dielectric ceramic is printed on a portion where the dielectric ceramic paste is not printed, by printing the dielectric ceramic paste on a screen which is continuously patterned in a rectangular shape. Printing and drying to produce a green sheet, and on the dielectric ceramic layer in the green sheet,
The internal electrode paste is printed on every other space in the longitudinal direction of the dielectric ceramic layer, dried, and the green sheets and the insulating sheets on which the internal electrodes are printed are stacked and then pressed to be fired as a laminate, A method for manufacturing a monolithic ceramic capacitor, which comprises a step of applying external electrodes connected to internal electrodes to both ends of the sintered body.