JPH0426202B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic capacitor that can be made smaller and have a larger capacity by using a ceramic molded body having a plurality of through holes.

Ceramic capacitors have excellent high frequency characteristics, are small in size, have large capacity, and are highly reliable. For this reason, ceramic capacitors are used in many electronic devices, but in order to further increase the size and capacity of capacitors, it is required that the dielectric constant of the ceramic be increased. However, when ceramic dielectric materials have a high dielectric constant, the temperature change rate of the dielectric constant generally increases.
tanδ increases. For this reason, another method is to increase the specific surface area. For example, a multilayer ceramic capacitor is known in which a small size and a large capacity are achieved by stacking dielectric layers. By adopting the above structure, the specific surface area becomes extremely large, making it possible to achieve a small size and a large capacity. However, since multilayer capacitors are made of stacked ceramic sheets, it is difficult to control the film thickness of the sheets themselves, and the manufacturing equipment for this is expensive. Furthermore, since the electrodes are embedded and sintered at high temperatures, they are expensive. There were problems such as high prices.

The present invention improves the above problems by creating a structure that increases the specific surface area without relying on lamination.
The purpose is to obtain a small-sized, large-capacity ceramic capacitor.

That is, the ceramic capacitor of the present invention is
It has a structure in which a plurality of through holes are provided in a ceramic molded body, internal electrodes are embedded in the through holes, and external electrodes are installed on the surface of the ceramic molded body.

Hereinafter, the present invention will be described with reference to examples. As shown in FIGS. 1 and 2, a plurality of through holes 1A are provided in a ceramic molded body 1, and an insulating part 4 is installed in the center of the through holes 1A. Internal electrodes 2 are embedded in the upper and lower parts of the through hole 1A, and external electrodes 3 connected to the internal electrodes 2 are placed on the surface of the ceramic molded body 1 to form a ceramic capacitor. At this time, the insulating section 4 only needs to have a structure in which the upper internal electrode and the lower internal electrode are not in contact with each other, and may be a hollow structure or a structure filled with an insulator, dielectric material, or the like.

With the above structure, the specific surface area increases, so it is possible to make the device smaller and have a larger capacity.

The ceramic used in the present invention may be any ceramic commonly used as a capacitor, such as BaTiO ₃ , SrTiO ₃ , CaTiO ₃ ,
_PbTiO3 , _CaSnO3 , _BaSnO3 , _BaZrO3 ,
_CaZrO3 , _La2O3 , _{Nb2O5 , TiO2 ,} MgO, _{Fe2O3 ,}
etc. as main ingredients or as additives, optionally combined as necessary.

The shape of the ceramic molded body may be any shape such as a columnar shape, a disk shape, or a square shape, and the length and outer diameter can be arbitrarily set depending on the use.

The position of each through hole in the ceramic molded body is arbitrary, but for example, those located concentrically from the center of the molded body, those in a lattice shape, those in a radial shape, those in a honeycomb shape, or those in a random shape, etc. Can be mentioned.

Although the shape and number of the through holes are arbitrary, the number of holes needs to be arbitrarily set based on the outer diameter of the ceramic molded body and the diameter of the through holes. Of course, the greater the number of pores, the greater the specific surface area, which is preferable.

Any method may be used to create the through holes as long as a plurality of through holes can be obtained.For example, metal wires of a predetermined diameter and number are placed in a cylindrical mold, After filling the ceramic kneaded material, pressing, drying, and sintering, the metal wire is extracted by melting, fusing, drawing, etc. during or after firing to create a through hole, or by screw extrusion using a honeycomb die. For example, a method may be used in which a through hole is created by pressing the ceramic.

In addition, as another embodiment of the ceramic capacitor of the present invention, when an internal electrode is installed in the through hole 1A as shown in FIG. Then, approximately half of the internal electrodes 12 are connected to the external electrode 3 at the upper end of the ceramic molded body 1, and the other internal electrodes 12 are connected to the external electrode 3 at the lower end to form a ceramic capacitor. This structure increases the specific surface area, making it possible to increase the size and capacity.

Further, as shown in FIG. 4, an internal electrode 22 is embedded in the through hole 1A of the ceramic molded body 1, and an external electrode 3 connected to the internal electrode 22 is provided on the end surface of the ceramic molded body 1. A ceramic capacitor can also be formed by disposing opposing external electrodes 3 on the outer periphery.

Next, to briefly describe the manufacturing method of the present invention, BaTiO ₃ is used as a raw material as a main component, polyvinyl butyral is used as a binder, dibutyl phthalate is used as a plasticizer, and methyl ethyl ketone is added as a solvent to form a ceramic kneaded product. It was created. Here, the ceramic mixture is filled into a cylindrical mold with an outer diameter of 50μ and 50 metal wires.
After pressing at a molding pressure of 3Ton/ ^cm2 , the diameter is 10
A cylindrical molded product with a length of 8 mm was created and heated at 100℃.
Dry for 24hr. Next, the molded body containing 50 metal wires is fired in the atmosphere at 1300 to 1400℃ to sinter the ceramic and simultaneously dissolve and remove the metal, forming 50 through holes with a diameter of 45μ. A ceramic molded body having the following properties was obtained.

Next, after filling the center of the through hole with an insulator, the upper and lower parts are filled with Ag paste as internal electrodes, and the upper and lower surfaces of the ceramic molded body are filled with Ag paste as external electrodes connected to it.
Apply electrode paste and bake at approximately 800℃.
It was made into a ceramic capacitor.

The ceramic capacitor of the present invention obtained as described above has a dielectric constant at 25°C and 100KHz.
3000 or more and t _ao 〓 of 2.0% or less, and by using the structure of the present invention, the specific surface area becomes extremely large, so it is possible to easily achieve a small size and a large capacity. . Furthermore, since the manufacturing process is simpler than that of multilayer capacitors, process control is easier, costs can be reduced, and stable performance can be obtained, among other excellent effects. Although the present invention has been described with respect to a general ceramic capacitor, it is of course applicable to high frequency capacitors, semiconductor capacitors, and the like.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a ceramic capacitor of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. Longitudinal cross-sectional view. 1... Ceramic molded body, 1A... Through hole,
2, 12, 22...internal electrode, 3... external electrode,
4... Insulation section.

Claims (1)

[Claims] 1. A ceramic capacitor in which a plurality of through holes are provided in a ceramic molded body, internal electrodes are embedded in the through holes, and external electrodes are installed on the surface of the ceramic molded body.