JPH06349666A - Multilayered ceramic capacitor - Google Patents

Abstract

PURPOSE:To prevent influence of an external circuit which is to be exerted upon a multilayered capacitor. CONSTITUTION:A first inner electrode 2 and a second inner electrode 3 are buried in ceramic dielectric material 1, and connected with an outer electrode 4 and an outer electrode 5, respectively. The first and the second inner electrodes 2, 3 consist of a plurality of conductor layers, which are connected with the same outer electrode every two adjacent conductor layers.

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 which can be used in a high frequency range.

[0002]

2. Description of the Related Art As shown in FIG. 5, a typical conventional monolithic ceramic capacitor has a ceramic dielectric 1 and first and second internal electrodes 2 and 3 alternately embedded therein.
It is composed of first and second outer electrodes 4, 5 connected to the first and second inner electrodes 2, 3. In this multilayer capacitor, capacitance is obtained by the facing of the first and second internal electrodes 2, 3. As another conventional multilayer capacitor, one having a structure shown in FIG. 6 is known. In the multilayer capacitor of FIG. 6, two second inner electrodes 3 are arranged between the first inner electrodes 2 and two first inner electrodes 2 are arranged between the second inner electrodes 3. Has been done. With this configuration, the current flowing through the internal electrodes 2 and 3 excluding the lowermost and uppermost portions is half that in the case of FIG.
Can be increased.

[0003]

By the way, in recent electronic circuit devices, electronic components are mounted on a circuit board at a high density. Therefore, the wiring conductor on the circuit board may have to pass under the multilayer capacitor. In such a case, a current based on stray capacitance (stray capacitance) between the internal electrode of the multilayer capacitor and the wiring conductor on the circuit board flows through the internal electrode, which lowers Q. Further, noise components may enter the circuit including the multilayer capacitor from the wiring conductor on the circuit board.

Therefore, an object of the present invention is to provide a monolithic ceramic capacitor capable of lowering the current density of the internal electrodes to increase the Q and reducing the influence of the external circuit.

[0005]

The present invention for achieving the above object comprises a dielectric having first and second main surfaces and side surfaces, and a plurality of conductor layers embedded in the dielectric. A multilayer ceramic capacitor having first and second internal electrodes and first and second external electrodes provided on an outer peripheral surface of the dielectric and connected to the first and second internal electrodes, The first internal electrode is divided into a plurality of groups for each of a plurality of conductor layers, the second internal electrode is also divided into a plurality of groups of each of a plurality of conductor layers, and the plurality of groups of the first internal electrode are divided. The present invention relates to a monolithic ceramic capacitor characterized in that are alternately arranged.

[0006]

According to the present invention, a plurality of conductor layers of the first and second internal electrodes are grouped and arranged alternately for each group. The uppermost conductor layer and the lowermost conductor layer of the conductor layers of the first and second internal electrodes do not directly contribute to obtain the desired capacitance, but are used to obtain the capacitance. It contributes to prevent the current based on the stray capacitance from flowing in the intermediate conductive layer, and further exerts an electromagnetic shield effect. In addition, the conductor layers of the internal electrodes are grouped in the central region as well, and a plurality (preferably two) of conductor layers are led out in the same direction, so that the current flowing in one conductor layer is determined based on the capacitance. It can be reduced to 1/2 and Q can be increased, that is, signal loss can be reduced.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a multilayer capacitor 10 according to an embodiment of the present invention will be described with reference to FIGS. This multilayer capacitor 10 is a ceramic (porcelain) dielectric 1 made of a material having a capacitance value C of 5.0 pF and a Q value of 2000 at 1 MHz.
And the first and second inner electrodes 2 and 3 and the first and second outer electrodes 4 and 5.

As is apparent from FIG. 1 in which the thicknesses of the external electrodes 4 and 5 are omitted, the dielectric 1 has a first main surface (upper surface) 8a and a second main surface (the upper surface) 8a opposed thereto. Bottom) 8b
And it has the 1st-4th side surface 9a, 9b, 9c, 9d, and is formed in a rectangular parallelepiped as a whole.

For the dielectric 1 in which the first and second internal electrodes 2 and 3 are buried, a conductive paste (palladium paste) is applied to a green sheet (ceramic green sheet) made of a temperature-compensating dielectric ceramic composition. It is formed by stacking things, pressing them, and baking them. As shown in FIG. 3, the first and second internal electrodes 2 and 3 made of wide strip-shaped conductor layers are the first and second main surfaces 8a of the dielectric body 1,
It is arranged parallel to 8b.

The first and second internal electrodes 2, 3 are each composed of a plurality of conductor layers, which are grouped so that two adjacent layers are led out to the same side surface. That is, the first
The second internal electrodes 2 and 3 are alternately led out to the first side face 9c and the second side face 9d by two layers. The first outer electrode 4 is connected to the first inner electrode 2 at the first side surface 9a, and the first, third and fourth side surfaces 9a, 9c, 9d and the first and second side surfaces 9a, 9c and 9d are provided at the left end of the dielectric 1. It is formed of a conductor film so as to cover the second main surfaces 8a and 8b. The second external electrode 5 is formed of a conductor film so as to cover the second, third and fourth side surfaces 9b, 9c and 9d and the first and second main surfaces 8a and 8b at the right end portion of the dielectric 1. Has been done.

The first and second outer electrodes 4, 5 of the multilayer capacitor 10 are shown in FIG. 4 in order to investigate the effect of grouping the first and second inner electrodes 2, 3 for every two conductor layers. As described above, the wiring conductors 21 and 22 of the measurement substrate 20 are soldered, and the ground wiring conductor 23 is further passed under the multilayer capacitor 10 to form a measuring device 2 including a network analyzer.
4 is connected, an AC signal of 1 GHz is passed between the external electrodes 4 and 5 of the multilayer capacitor 10, and the impedance Z = R + jXc (where R is a real part and Xc is an imaginary part) of the multilayer capacitor 10 is measured, When Q, i.e., -Xc / R, was determined, Q was 58.

For comparison, in the conventional multilayer capacitor shown in FIG. 5, when the same measurement as that of the multilayer capacitor 10 of the example was carried out, Q was 40. Also, when the same measurement as in the example was performed on the conventional multilayer capacitor of FIG. 6, Q was 55. As is clear from the above measurement results, by adopting the structure of this embodiment, the structure shown in FIG.
Not only can the effect of reducing the current density of the internal electrodes 2 and 3 be obtained as in the structure of No. 1, but the influence of external circuits such as the ground wiring conductor 23 can be prevented by the uppermost and lowermost internal electrodes, and Q can be reduced. Can be increased.

Further, the uppermost and lowermost conductor layers of the internal electrodes 2 and 3 can prevent not only a decrease in Q (increase in signal loss) but also a noise component from entering the capacitor.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a multilayer capacitor according to an embodiment of the present invention.

FIG. 2 is a sectional view of the multilayer capacitor showing a portion corresponding to line AA in FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is a plan view showing a characteristic measuring device for a multilayer capacitor.

FIG. 5 is a sectional view showing a conventional multilayer capacitor.

FIG. 6 is a sectional view showing another conventional multilayer capacitor.

[Explanation of symbols]

 1 Dielectric 2, 3 Internal electrode 4, 5 External electrode

Front page continuation (72) Inventor Atsushi Masuda 6-16-20 Ueno, Taito-ku, Tokyo Within Taiyo Denki Co., Ltd. (72) Inventor Riichi Toba 6-16-20 Ueno, Taito-ku, Tokyo Solar induction Within the corporation

Claims (1)

[Claims] 1. A dielectric having first and second main surfaces and side surfaces, first and second internal electrodes composed of a plurality of conductor layers embedded in the dielectric, and an outer periphery of the dielectric. A first surface provided on the surface and connected to the first and second internal electrodes
And a second external electrode, wherein the first inner electrode is divided into a plurality of groups for each of a plurality of conductor layers, and the second inner electrode is also a plurality of groups for each of a plurality of conductor layers. And a plurality of groups of the first internal electrodes are alternately arranged.