JPS6285419A - Reduction and reoxidization type semiconductor porcelain capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a reduction-reoxidation type semiconductor ceramic capacitor.

(Prior Art) An example of a conventional reduction-reoxidation semiconductor ceramic capacitor that is of interest to the present invention is disclosed in, for example, Japanese Patent Laid-Open No. 144116/1983. A conventional reduction and reoxidation type semiconductor ceramic capacitor 1 shown in FIG. 5 includes a plate-shaped reduction and reoxidation type semiconductor ceramic unit 2, and the reduction and reoxidation type semiconductor ceramic unit 2 has a semiconductor portion 2a exposed at one end surface. and a re-oxidized layer 2b exposed on both surfaces and the other end surface. Furthermore, the semiconductor portion 2 of the reduction and reoxidation type semiconductor ceramic unit 2
A first electrode 3 is formed on the surface of the reoxidized layer 2b, and a second electrode 4 is formed on the surface of the reoxidized layer 2b. Then, capacitance is formed between the first electrode 3 and the second electrode 4. In this reduction and reoxidation type semiconductor ceramic capacitor 1, the equivalent circuit is shown in FIG. 6, as shown in FIG.
A capacitor with a capacity twice that of s can be obtained, and a large capacity can be expected.

(Problems to be Solved by the Invention) However, in such conventional reduction and reoxidation type semiconductor ceramic capacitors, the resistance due to the semiconductor portion of the reduction and reoxidation type semiconductor unit, that is, the equivalent direct resistance is large.
Not only is its high frequency characteristic inferior, but it also cannot provide the large capacity it was designed for.

Therefore, the main object of the present invention is to provide a small-sized, large-capacity reduction-reoxidation type semiconductor ceramic capacitor.

(Means for Solving the Problems) The present invention provides a reduction and reoxidation type semiconductor ceramic unit having a semiconductor portion and a reoxidation layer exposed on the surface, and at least two electrodes formed on the surface of the semiconductor portion. A reduction and reoxidation semiconductor magnetic capacitor comprising an internal electrode formed in an internal semiconductor portion of the unit and connected to one of the electrodes.

(Function) Since the internal electrode is formed within the semiconductor portion of the reduction-reoxidation type semiconductor unit, its internal resistance and capacitance are connected in parallel between the internal electrode and the second electrode. Furthermore, since the internal electrode is connected to the first electrode different from the second electrode, the internal resistance and capacitance connected in parallel between the first electrode and the second electrode are taken out.

(Effects of the Invention) According to the present invention, since the internal resistances are taken out in a parallel-connected form, the equivalent series resistance can be reduced. Therefore, deterioration of high frequency characteristics can be suppressed, and the calculated capacity can be obtained. Moreover, since the opposing area of the electrodes forming the capacitor is increased, a reduction-reoxidation type semiconductor ceramic capacitor with a small size and large capacity can be obtained.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

(Embodiment) FIG. 1 is a sectional view showing an embodiment of the present invention. This reduction and reoxidation type semiconductor ceramic capacitor IO includes a plate-shaped reduction and reoxidation type semiconductor ceramic unit 12. This reduction/reoxidation semiconductor ceramic unit 12 includes a semiconductor portion 12a and a reoxidation layer 12b covering the entire circumference of the semiconductor portion 12a, with the semiconductor portion 12a not being exposed and the reoxidation layer +2b covering both surfaces and both ends thereof. exposed on the surface. Note that this reoxidized layer 12b has a dielectric constant necessary for forming a capacitor.

Furthermore, a first electrode 14 is formed on the surface of the reoxidation layer 12b of the reduction and reoxidation type semiconductor ceramic unit 12. In this case, the first electrode 14 is formed on the surface of one end portion of the unit 12.

On the other hand, the second electrode 16 is spaced apart from the first electrode 14 and has a reoxidation layer! 2b.

Further, an internal electrode 18 is formed inside the semiconductor portion 12 a of the reduction-reoxidation type semiconductor ceramic unit 12 , and one end of this internal electrode 18 is connected to the first electrode 14 .

As a result, the internal resistance and capacitance of the reduction-reoxidation type semiconductor ceramic unit 12 are connected in parallel between the first electrode 14 and the internal electrode 18 .

Furthermore, the internal resistance and capacitance connected in parallel are the first
is taken out between the second electrode 14 and the second electrode 16.

Therefore, this reduction and reoxidation type semiconductor ceramic capacitor 1
0, the internal resistances are connected in parallel compared to the conventional example shown in Fig. 5, and the equivalent series resistance can be reduced.As a result, the deterioration of the high frequency characteristics can be reduced and the capacity can be maintained as calculated. is obtained. Moreover, compared to the conventional example,
Since the opposing area of the electrodes forming the capacitor becomes large, the capacitance becomes large.

"■ First, a raw material with a composition ratio of 87 mol % BaTiO and 13 mol % BaZrO is used, and the thickness is 500 μm and the height is 7 mm.
, a ceramic green sheet with a width of 9 mm,
Two sheets were formed.

Then, at the center of the main surface of one of the ceramic green sheets, an electrode paste mainly made of a high melting point metal material such as palladium, which is the material of the internal electrode 18, was printed in a size of 6 mm vertically and 8 mm horizontally.

Then, so that the printed side of the electrode paste is on the inside,
Stack two pieces of Ceramic Green Sea 1, 80
℃ and 20 t/cJ.

Further, one end of the crimped product was cut to expose the electrode paste from one end, and the electrode paste was fired at 1350° C. for 2 hours.

Next, the fired product was mixed with 15% by volume of hydrogen and 85% by volume of nitrogen.
A reduction heat treatment was performed at 1100° C. for 1 hour in a reducing atmosphere to convert the material into a semiconductor, thereby forming a semiconductor portion 12a.

Then, heat treatment was performed in air at 900° C. for 1 hour to form a reoxidation layer 12b on the surface of the semiconductor portion 12a, thereby forming a reduction and reoxidation type semiconductor ceramic unit 12.

Then, on the surface of the reduction-reoxidation type semiconductor ceramic unit 12, an electrode paste such as silver, which is the material of the first electrode I4 and the second electrode JK16, was applied and baked.

In this case, the electrode paste in the UNISO 1-12 is formed as an internal electrode 8, and the first electrode 14 is connected to this internal electrode 18.

As shown in FIG.
．． It was formed with dimensions of 75m5. Further, in this reduction/reoxidation type semiconductor ceramic capacitor 10, the first electrode 14 is formed with a dimension of 0°511+ from one end toward the center, and the second electrode 16 is formed with a dimension of 0.8 mm from the first electrode I4. Further, the internal electrodes 18 are formed with a gap of 4.61. It was formed with dimensions of 5° and 21A.

Electrode 14 of this reduction-reoxidation type semiconductor ceramic capacitor 10
When the capacitance between the second electrode 16 and the second electrode 16 was measured,
Its capacitance was 300 nF.

This is compared to a conventional reduction and reoxidation type semiconductor ceramic capacitor of the same size as this example but without internal electrodes.
This means that the capacity has doubled. Moreover, the equal series resistance was smaller than that of the conventional one.

In the above-mentioned experimental example, the first electrode 14 was formed with a non-ohmic electrode, and the internal electrode 18 was formed with an electrode paste mainly made of a high-melting point metal material, but in this invention, the first electrode 14 For example, the internal electrodes 18 may be formed by ohmic baked electrodes made of an electrode paste mainly made of aluminum or the like, or the internal electrodes 18 may be formed by injecting molten metal.

Furthermore, as shown in FIG. 4, a multilayer structure in which a plurality of cells are stacked may be used to increase the capacity.

Furthermore, the shape of the reduction-reoxidation type semiconductor ceramic unit and the shape of the electrodes may be changed arbitrarily.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention. FIG. 2 is a plan view showing an experimental example of the present invention. FIG. 3 is a sectional view showing a modification of the embodiment of FIG. 1. FIG. 4 is a sectional view showing still another modification of the embodiment of FIG. 1. FIG. 5 is a sectional view showing a conventional reduction and reoxidation type semiconductor ceramic capacitor. FIG. 6 is an equivalent circuit diagram of the conventional example shown in FIG. In the figure, 10 is a reduction and reoxidation type semiconductor ceramic capacitor, 12 is a reduction and reoxidation type semiconductor ceramic unit, 12a is a semiconductor portion, 12b is a reoxidation layer, 14 is a first electrode, 16
indicates a second electrode, and 18 indicates an internal electrode. Patent applicant Murata Manufacturing Co., Ltd. Representative Patent attorney Oka 1) Zen Kei (1 idiot)

Claims (1)

[Scope of Claims] A reduced and reoxidized semiconductor magnetic capacitor comprising a reduced and reoxidized semiconductor ceramic unit having a semiconductor portion and a reoxidized layer exposed on the surface, and at least two electrodes formed on the surface of the semiconductor portion. comprising an internal electrode formed on an internal semiconductor part of the unit and connected to one of the electrodes,
Reduction-reoxidation type semiconductor porcelain capacitor.