JP3089956B2 - Multilayer ceramic capacitors - Google Patents

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 In general, a multilayer ceramic capacitor is obtained by stacking ceramic green sheets and sheets on which an internal electrode paste is printed on ceramic green sheets, pressurizing to form a laminate, and then firing and sintering both ends of the sintered body. This is a structure in which an external electrode connected to the internal electrode is provided in the portion.

[0003] Medium to high voltage monolithic ceramic capacitors (1 kV
Or higher), a series electrode structure was formed, the voltage applied to each effective layer was reduced by half, and dielectric breakdown was less likely to occur.

[0004]

In the above-mentioned conventional configuration,
When used at a high voltage, the electric field tends to concentrate on the ends of the internal electrodes, and therefore, there is a problem that dielectric breakdown easily occurs at the ends of the internal electrodes.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a multilayer ceramic capacitor in which dielectric breakdown occurring at an end of an internal electrode is prevented and dielectric breakdown voltage is improved.

[0006]

In order to achieve this object, a multilayer ceramic capacitor according to the present invention comprises a first dielectric layer having a pair of first internal electrodes formed so as to reach opposite ends. A laminate in which dielectric layers on which second internal electrodes are formed alternately so as not to reach an end, and an external electrode formed on an end of the laminate, and a first internal electrode Are connected to the capacitor electrode, the external electrode and the capacitor electrode, and at least one lead electrode having a width smaller than the width of the capacitor electrode, and at least one floating electrode provided between the capacitor electrodes. The second electrode has a pair of capacitance electrodes and at least one of a width smaller than the width of the capacitance electrode, connecting the capacitance electrodes to each other.
And at least one floating electrode provided between the external electrode and the capacitor electrode. The floating electrode of the first internal electrode is connected to the second internal electrode via the dielectric electrode and the dielectric layer. The floating electrode of the second internal electrode is formed so as to face the lead-out electrode of the first internal electrode via a dielectric layer.

[0007]

According to this structure, the electric field concentration on the end of the internal electrode is reduced, so that the dielectric breakdown voltage is improved.

[0008]

【Example】

Embodiment 1 Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIGS. 1, 2, 3 and 4 are sectional views of a multilayer ceramic capacitor according to an embodiment of the present invention. A method for manufacturing the multilayer ceramic capacitor will be described.

First, a dielectric ceramic slurry is formed on a carrier film by a reverse roll coater.
After drying, a ceramic green sheet was formed. next,
The ceramic green sheet was peeled off from the carrier film, the internal electrode paste was printed and dried on the ceramic green sheet in a pattern Y shown in FIG. 5 by screen printing, and the ceramic green sheet was laminated thereon.
On this green sheet, the internal electrode paste was printed and dried while shifting the pattern Y shown in FIG. 5 in the length direction. By repeating this process, lamination was performed. On the upper and lower sides of the thus laminated ceramic green sheets, a predetermined number of ceramic green sheets on which the internal electrode paste was not printed were laminated as necessary. Next, the laminated ceramic green sheets were pressed and pressed together to form a laminate. Next, the laminated body was cut, binder-out and firing were performed, and then external electrodes were applied and baked, and Ni plating and Sn-Pb plating were performed to obtain a multilayer ceramic capacitor. The obtained multilayer ceramic capacitor has a capacitance of 100 pF, Q 12
00, IR 1 * 10 ¹³ Ω.

The dielectric breakdown voltage of this multilayer ceramic capacitor was measured, and the results are shown in Table 1.

[0012]

[Table 1]

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 in a pattern W shown in FIG. 6 by screen printing, and a ceramic green sheet is laminated thereon. The pattern W shown in FIG. 6 was shifted in the length direction on the 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. Thereafter, a multilayer ceramic capacitor was obtained in the same manner as in Example 1, but this was the conventional type.

The results of measuring the dielectric breakdown voltage of the obtained multilayer ceramic capacitor in the same manner as in Example 1 are shown in Table 1 below.

As apparent from Table 1, the multilayer ceramic capacitor of the present invention can improve the dielectric breakdown voltage.

In this embodiment, as shown in FIGS. 1 and 2, two kinds of internal electrodes 2a and 2b are alternately laminated with a dielectric ceramic layer 1 interposed therebetween to form a laminate. FIG. 3 is a cross-sectional view of the ceramic capacitor taken along the line AA in FIG. 2, and FIG. 4 is a cross-sectional view taken along the line BB of FIG. FIG.
As can be seen from the figure, the provision of the floating electrode 3 can reduce the concentration of the electric field as compared with the conventional case.

In the present embodiment, two lead-out electrodes 6 are provided for one capacitor electrode 5, but it is sufficient that electrical connection between the external electrode 4 and the capacitor electrode is established and electric field concentration hardly occurs. Also, four floating electrodes 3 are provided on one dielectric ceramic layer 1, but the larger and the larger the number, the more the electric field concentration can be eased. Further, in the present embodiment, the corners of the capacitance electrode 5 are rounded and the shape of the floating electrode 3 is also circular, but this is also for preventing the electric field concentration from occurring.

[0018]

As described above, according to the present invention, the dielectric breakdown voltage is improved by alleviating the electric field concentration on the end of the internal electrode.

[Brief description of the drawings]

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

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

FIG. 3 is a sectional view taken along line AA of the multilayer ceramic capacitor in one embodiment of the present invention.

FIG. 4 is a sectional view taken along line BB of the multilayer ceramic capacitor in one embodiment of the present invention.

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

FIG. 6 is a screen pattern diagram for printing a conventional internal electrode.

[Explanation of symbols]

 Reference Signs List 1 dielectric ceramic layer 2a internal electrode 2b internal electrode 3 floating electrode 4 external electrode 5 capacitance electrode 6 lead-out electrode

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01G 4/00-4/40 H01G 13/00-13/06

Claims (1)

(57) [Claims] 1. A first dielectric layer provided with two first internal electrodes extending to opposing ends, and a state in which one second internal electrode is not in contact with the ends. A laminate in which a plurality of the second dielectric layers provided in the above are alternately laminated, and an external electrode provided on an exposed end face of the first internal electrode of the laminate, wherein the first internal electrode Are respectively connected to the capacitor electrode, the external electrode and the capacitor electrode, and at least one lead electrode having a width smaller than the width of the capacitor electrode; and at least one floating electrode provided between the capacitor electrodes. The second electrode is formed of a pair of capacitance electrodes, at least one lead electrode connecting the capacitance electrodes and having a width smaller than the width of the capacitance electrodes, and the external electrode and the capacitance electrodes. At least one in between
And a floating electrode of the first internal electrode is formed so as to face a lead electrode of the second internal electrode via a dielectric layer, and the floating electrode of the second internal electrode is A multilayer ceramic capacitor formed so as to face the lead-out electrode of the first internal electrode via a dielectric layer.