JPH0113406Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a ceramic capacitor that is small and has a large capacity.

(Conventional structure and its problems) In recent years, there has been a remarkable movement toward miniaturization and weight reduction of electronic devices, and the ceramic capacitors used in many electronic devices are also required to be small and large in capacity. ing. As a capacitor that meets this demand, a multilayer ceramic capacitor having a structure as shown in FIG. 1 has been developed and is now widely used, and the demand for it is rapidly increasing.

Such a multilayer ceramic capacitor has internal electrodes 2 whose main component is a noble metal such as palladium embedded in a ceramic dielectric material 1, increasing the electrode area and increasing the distance between the electrodes from several tens of microns to several hundred microns. By narrowing the
The capacitor is small and has a large capacity.

However, in conventional multilayer ceramic capacitors, the internal electrodes must be embedded in the ceramic dielectric material and sintered at the same time as the ceramic dielectric material. It is necessary to use a stable material that will not melt or react with the ceramic material even at the high temperatures required for sintering the material.

Ceramic dielectric materials whose main components are barium titanate, titanium oxide, calcium titanate, magnesium titanate, etc., with various additives added thereto are widely used. The sintering temperature for these is approximately 1200°C to 1400°C, and therefore, for the reasons mentioned above, platinum or palladium, which is stable even at such high temperatures but is extremely expensive, is used as the internal electrode. The material costs for the internal electrodes accounted for most of the total material costs for multilayer ceramic capacitors.

Furthermore, increasing the dielectric constant of the ceramic dielectric material is also an effective means for achieving smaller size and larger capacity. Known grain boundary layer insulation layer type,
Alternatively, when surface reoxidation type semiconductor capacitor materials are used, the apparent dielectric constant of these materials is very large, so it is possible to further reduce the size and increase the capacitance. However, when applying these semiconductor capacitor materials to multilayer ceramic capacitors, these materials are fired in a reducing atmosphere and then copper oxide is diffused in order to insulate the grain boundary layer, or very close to the electrodes. It has been impossible to fabricate multilayer ceramic capacitors with internal electrodes because only the thin ceramic portions need to be reoxidized.

(Purpose of the invention) The present invention has a laminated structure to achieve small size and large capacity, but it does not require internal electrodes to be embedded in the ceramic dielectric material and sintered at the same time as the ceramic dielectric material. The present invention provides a multilayer ceramic capacitor that can use inexpensive silver, silver-based alloys, nickel-based alloys, or the like.

(Structure of the invention) The present invention uses a ceramic capacitor material to prepare a sintered body with a U-shaped cross section in advance, and to prevent the inner and outer peripheral surfaces from being electrically connected to each other. After applying electrode paste at intervals, and inserting a plate-shaped ceramic that fits into the element body space, the applied paste is heat-treated to make it conductive.

(Description of an embodiment) An embodiment of the present invention is shown in FIG. Reference numeral 4 shown in FIG. 2a is a U-shaped ceramic obtained by sintering a ceramic dielectric material, preferably a semiconductor capacitor material, and the inner and outer peripheral surfaces of the ceramic are as shown in FIG. 2b. Apply electrode pastes 5 and 6 to the electrode pastes 5 and 6. 4' in FIG. 2c is a plate-shaped ceramic made of a ceramic dielectric material (the same material as the U-shaped element 4) or a high-strength material such as alumina. It has a shape that can fit into the space. This plate-shaped ceramic 4'
As shown in FIG. 2d, after being fitted onto the element body 4, heat treatment is performed to metallize the pastes 5 and 6. After that, a part of the element body shown in FIG. 2 d is covered with an insulator 7 such as glass and used as the structure shown in FIG. Cover the second layer with insulating resin 9.
The structure shown in Figure f is used.

(Effects of the invention) As explained above, according to the invention, inexpensive silver, silver-based alloys, nickel-based alloys, etc. can be used as internal electrode materials instead of extremely expensive precious metals such as palladium and platinum. This makes it possible to supply small, large-capacity ceramic capacitors at low cost.

Furthermore, after forming the electrode, it is possible to adjust the capacitance by a simple method of removing a part of the electrode on the outer peripheral surface.

Furthermore, by making the plate-shaped element shown in Figure 2c from a high-strength material such as alumina, even if the element shown in Figure 2a is made of a relatively weak semiconductor capacitor material, the strength can be improved. This is something that can be improved.

As mentioned above, it is possible to construct a ceramic capacitor similar to a laminated type using semiconductor capacitor materials, which have conventionally been difficult to manufacture, and it is possible to create a small, large-capacity ceramic capacitor in a simple manner. It has great industrial value because it can be supplied at low cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional multilayer ceramic capacitor, and FIG. 2 is a sectional view showing the manufacturing steps of an embodiment of the present invention. 4... U-shaped ceramic, 4'... Plate ceramic, 5, 6... Paste (electrode), 7... Insulator, 9... Resin.

Claims (1)

[Scope of utility model registration request] A paste made of an electrode material is applied to the inner and outer circumferential surfaces of a sintered body made of a ceramic dielectric having a U-shaped cross section at intervals so as not to be electrically conductive to each other, and A ceramic capacitor characterized in that a plate-shaped ceramic is fitted into the U-shaped inner space of a crystal body and heat-treated so that the applied paste becomes an electrode.