JPH0837126A - Multilayer capacitor - Google Patents

Abstract

PURPOSE:To provide a compact multilayer capacitor with excellent withstand voltage performance and a large capacity. CONSTITUTION:The title capacitor is provided on the same plane with a first internal electrode group 2 where a first interal electrode 2a connecting with one external terminal 4a, a second interal electrode 2b connecting with the other external terminal 4b and a floating internal electrode 2c between the electrodes 2a and 2b are prepared, and a second internal group 12 consisting of a plurality of floating internal electrodes 12a that is prepared on one surface opposing to the group 2 with a dielectric 1 in between and excludes the internal electrodes connecting with the terminals 4a and 4b, and the groups 2 and 12 are alternatively prepared therein. Therefore, at least serially connected four capacitor parts 5 can be formed between the electrodes 2c and 12a in the groups 2 and 12 between the electrodes 2a and 2b connecting respectively with different external terminals (4a or 4b).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer capacitor, and more particularly to a high voltage and high capacity multilayer capacitor.

[0002]

2. Description of the Related Art In a multilayer capacitor, for example, as shown in FIG. 5, an element (chip) 53 in which a dielectric (layer) 51 and internal electrodes 52a and 52b are alternately laminated is provided. 6 has a structure (normal structure) in which external terminals 54a and 54b, which are electrically connected to the internal electrodes 52a and 52b, which are drawn out to the opposite end face every other layer, are arranged on both end sides of the layer, as shown in FIG. , Two capacitor parts connected in series between internal electrodes 52a and 52b connected to different external terminals 54a and 54b, which are arranged so as to face each other with a dielectric 51 forming an element (chip) 53 interposed therebetween. External terminals 54a,
Some have a structure in which the floating internal electrodes 62 that are not connected to 54b are arranged (two-series structure).

By the way, generally, the thickness (element thickness) t of the dielectric material sandwiched by the internal electrodes and the breakdown voltage value (BDV).
The relation of is not linear but a curve approximated by the following equation. Breakdown voltage ^{(BDV) = A · t n} ( where, A, n represents, at constant determined by the material, n represents normal around 0.5)

Taking a high dielectric material having a dielectric constant of about 1 × 10 ⁴ as an example, the relationship between the element thickness and the breakdown voltage value is as shown in FIG. 7, and the element thickness and its unit thickness The relationship of the breakdown voltage value per hit is as shown in FIG.

That is, as shown in FIGS. 7 and 8, the smaller the element thickness, the higher the breakdown voltage value per unit thickness tends to be.

Therefore, when designing a high breakdown voltage multilayer capacitor using a material having such a tendency, as shown in FIG.
In the structure as shown in FIG. 6, it is necessary to greatly increase the element thickness. That is, referring to FIG. 7, for example, if the breakdown voltage value is 1 kV, the required element thickness is 75 μm, but if the breakdown voltage value is 2 kV, the required element thickness is 250 μm.

As described above, in the case of the multilayer capacitor having the structure shown in FIGS. 5 and 6, it is necessary to significantly increase the element thickness when designing a high breakdown voltage capacitor. Not only the breakdown voltage value per unit thickness becomes lower, but also the capacitance that can be acquired becomes smaller as the element thickness becomes thicker, and the problem that the performance of the dielectric cannot be fully exhibited. There is a point.

An object of the present invention is to solve the above problems, and to provide a small-sized and large-capacity multilayer capacitor having excellent withstand voltage performance.

[0009]

In order to achieve the above object, the inventors have made it possible to utilize a region having the smallest possible element thickness, which is advantageous in both the breakdown voltage value and the obtainable capacitance. In order to do so, various experiments and studies were conducted, and on the same plane, an internal electrode connected to one external terminal, an internal electrode connected to the other external terminal, and a floating internal electrode arranged between them were provided. An internal electrode group and a plurality of floating internal electrodes, which do not include an internal electrode connected to an external terminal, are disposed alternately on one surface facing the internal electrode group via a dielectric. , If a desired capacitance is obtained by forming a large number of series-connected capacitor sections between internal electrodes connected to different external terminals (that is, a multiple series structure), the withstand voltage performance is improved. Excellent, small size and large capacity We know that the layer capacitor obtained, further experiments, the present invention has been completed by extensive studies.

That is, the multilayer capacitor of the present invention is a multilayer capacitor in which an internal electrode connected to an external terminal and an internal electrode not connected are arranged in a dielectric, and the dielectric and the internal electrode form a multilayer structure. Between the first connection internal electrode connected to one external terminal, the second connection internal electrode connected to the other external terminal, and the first and second connection internal electrodes on the same plane. A first internal electrode group having a floating internal electrode located therein, and an internal connected to an external terminal provided on one surface facing the first internal electrode group via a dielectric. Second internal electrode groups each including a plurality of floating internal electrodes not including electrodes are alternately arranged, and the floating internal electrodes in the first and second internal electrode groups are connected to different external terminals. A series connection between the first and second connection inner electrodes Capacitor unit is characterized by being configured so as to form four or more.

Further, it is characterized in that the thickness of the dielectric (element thickness) interposed between the internal electrodes is 100 μm or less.

[0012]

[Function] By adopting the multi-series structure, the breakdown voltage value per element thickness (unit thickness) becomes large, and it becomes possible to use a dielectric material having a small element thickness and also a dielectric material having a small element thickness. Because it will be possible
It is possible to increase the number of layers. Therefore,
It is possible to obtain a multilayer capacitor that is small in size, has excellent withstand voltage performance, and has a large capacity.

When the thickness of the dielectric (element thickness) interposed between the internal electrodes is 100 μm or less, the breakdown voltage value often becomes a problem, but according to the present invention,
Even in such a case (for example, when the element thickness is in the range of 10 to 100 μm), it is possible to obtain sufficient withstand voltage performance, which is particularly significant.

[0014]

EXAMPLES Examples of the present invention will be shown below to describe the features of the present invention in more detail.

[Embodiment 1] FIGS. 1 and 2 are sectional views showing a multilayer capacitor according to an embodiment of the present invention.

First, the multilayer capacitor 10 shown in FIG. 1 will be described. The multilayer capacitor 10 is a multilayer capacitor having a four-series series structure, and one external terminal 4 on the same plane.
a, a first connection internal electrode 2a connected to a, a second connection internal electrode 2b connected to the other external terminal 4b, and a floating internal electrode 2c located between the first and second connection internal electrodes 2a, 2b. Is connected to a first internal electrode group 2 formed by disposing the first internal electrode group 2 and external terminals 4a and 4b arranged on a surface facing the first internal electrode group 2 via a dielectric (layer) 1. It is formed by alternately arranging a second internal electrode group 12 including a plurality of (two in this case) floating internal electrodes 12a that do not include internal electrodes.

Further, as shown in FIG. 1, the first internal electrode group 2 and the second internal electrode group 12 have their respective floating internal electrodes (2c and 12a) forming a dielectric 1 therebetween. For example, the first internal electrode group 2 and the second internal electrode group 12 in the uppermost layer in FIG. 1 are different from each other in the external terminal 4a. , 4b connected between the first and second connection internal electrodes 2a, 2b, the capacitor section 5 connected in series.
Are formed (four). The dimension (size) of the multilayer capacitor 10 of this example is such that the length L = 5.7.
mm, width W = 5.0 mm, and thickness T = 2.0 mm.

The multilayer capacitor 20 shown in FIG.
It is a monolithic capacitor having a serial series structure, and its basic structure is the monolithic capacitor 10 having a 4-series structure shown in FIG.
Is the same as That is, this multilayer capacitor 2
0 is the first on the same plane, which is connected to one of the external terminals 4a.
Connection internal electrode 2a, second connection internal electrode 2b connected to the other external terminal 4b, and floating internal electrode 2c (here four) located between the first and second connection internal electrodes 2a and 2b. A first internal electrode group 2 formed by disposing the internal electrodes and an internal electrode connected to the external terminals 4a and 4b on the surface facing the first internal electrode group 2 via the dielectric 1. It is formed by alternately arranging a plurality of (five in this case) floating internal electrodes 12a not included in the second internal electrode groups 12.

As shown in FIG. 2, the first internal electrode group 2 and the second internal electrode group 12 have their respective floating internal electrodes (2c and 12a), respectively, via the dielectric 1. It is configured so as to face a part of two electrodes that face each other, and for example, the first and second uppermost layers in FIG.
Looking at the internal electrode groups 2 and 12, the first and second connection internal electrodes 2 connected to different external terminals 4a and 4b
10 series-connected capacitor portions 5 are formed between a and 2b. Incidentally, the multilayer capacitor 20 of this embodiment
Is the same as that of the multilayer capacitor 10 of FIG.
Length L = 5.7 mm, width W = 5.0 mm, thickness T = 2.0 mm
Is.

Then, the multilayer capacitor 10 (FIG. 1) and the multilayer capacitor 20 (FIG. 2) configured as described above are formed in the same manner. Of the different multilayer capacitors (the dimensions are the same as those of the multilayer capacitors 10 and 20), the magnitude of the acquired capacitance was measured. The breakdown voltage value of each multilayer capacitor was constant at AC 4 kV. Since the number of laminated layers is different for each multilayer capacitor, the element thickness is also different.
It is 0 μm to 80 μm. Also, the dielectric constant ε is about 1000.
0.

FIG. 3 shows the relationship between the number of series measured for each multilayer capacitor and the acquired capacitance.

As shown in FIG. 3, as the number of series stations increases, the electrostatic capacity greatly increases, and in the case of the multi-series series structure of four or more stations, it is larger than that in the normal structure or the two series series structure. It can be seen that the capacitance can be obtained.
For example, in the case of a normal structure multilayer capacitor, if the dimensions and the breakdown voltage value are the same, only a capacitance of about 3 nF can be obtained, whereas in the case of a multi-series capacitor structure of 4 to 20 series capacitors, It can be seen that can obtain a capacitance that is 6 to 40 times that.

This is because, by adopting the multiple series structure, the breakdown voltage value per element thickness (unit thickness) becomes large, it becomes possible to use a dielectric having a small element thickness, and the element thickness is small. It is possible to increase the number of stacked layers and obtain a large capacitance.

[Embodiment 2] A laminated capacitor having the same material and structure as the laminated capacitor of Embodiment 1 and having the same size (size) and acquired capacitance is prepared and destroyed by applying an AC voltage. The voltage value (BDV) was measured. In addition,
The dimensions of each multilayer capacitor are length L = 5.7 mm and width W =
5.0mm, thickness T = 2.0mm, capacitance is 10n
It was set to F. FIG. 4 shows the relationship between the series number of each multilayer capacitor and the breakdown voltage value (BDV).

As shown in FIG. 4, even with multilayer capacitors of the same size and the same capacity, the breakdown voltage value increases as the number of series in the series increases, and in the case of a multi-series series structure of four or more series. Indicates that the breakdown voltage value is significantly increased as compared with the case of the normal structure or the double series structure. That is, for example, in the case of a normal structure multilayer capacitor, the breakdown voltage value is about 2.8 kV, whereas
It can be seen that in the case of a multilayer capacitor having a multi-series series structure of 4 to 20 stations, a breakdown voltage value 1.7 to 2.9 times that is obtained.

As in the above-described embodiment, the multi-layer capacitor having the multiple series structure makes it possible to use a region having a large breakdown voltage value per unit thickness (unit thickness) and a small element thickness. Therefore, it is possible to obtain significantly better performance than the conventional multilayer capacitor in terms of both capacitance and breakdown voltage value. If the capacitance and breakdown voltage value are the same, the size of the capacitor will be significantly smaller. Can be converted.

Further, by selecting an appropriate series series number, it is possible to obtain a multilayer capacitor having desired characteristics with respect to the breakdown voltage value, the electrostatic capacitance, the element size, the number of stacked layers, and the like.

The number of series stations needs to be four or more, but as shown in FIG. 3 and FIG.
When the number of series stations is close to 20, the effect of increasing the number of series stations becomes smaller, and in the case of a small multilayer capacitor, the element thickness becomes extremely small, and the internal electrode dimensions become extremely small. Manufacturing (processing)
Therefore, the number of series stations is preferably in the range of 4 to 20.

Further, the present invention is not limited to the above-mentioned embodiments, and various applications and modifications can be added within the scope of the gist of the invention.

[0030]

As described above, the multilayer capacitor of the present invention has the first connection internal electrode connected to one external terminal, the second connection internal electrode connected to the other external terminal, and the same on the same plane. A first internal electrode group having a floating internal electrode located between the first and second connection internal electrodes and a first internal electrode group disposed on one surface facing the first internal electrode group via a dielectric. A second internal electrode group including a plurality of floating internal electrodes that do not include an internal electrode connected to an external terminal is alternately arranged, and the floating internals in the first and second internal electrode groups are arranged. Since the electrodes are configured so that four or more capacitor parts connected in series are formed between the first and second connection internal electrodes connected to different external terminals, the element thickness (unit thickness) per It is possible to use a dielectric with a large breakdown voltage and a small element thickness. Together comprising, in the case of the same capacitor size, it is possible to increase the number of stacked layers.

Therefore, it is small in size and excellent in withstand voltage performance.
Moreover, a large-capacity multilayer capacitor can be obtained.

Further, by selecting an appropriate series number, it is possible to obtain a multilayer capacitor having desired characteristics with respect to the breakdown voltage value, the electrostatic capacitance, the element size, the number of stacked layers, and the like.

Further, when the thickness of the dielectric (element thickness) interposed between the internal electrodes is 100 μm or less, the breakdown voltage value often becomes a problem, but according to the present invention,
By making the element pressure thin to form a multiple structure, it is possible to obtain higher withstand voltage performance, which is particularly significant.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a structure of a multilayer capacitor according to an example of the present invention.

FIG. 3 is a diagram showing the relationship between the number of series stations and the acquired capacitance for a multilayer capacitor according to an example of the present invention.

FIG. 4 is a diagram showing a relationship between series series numbers and breakdown voltage values for a multilayer capacitor according to an example of the present invention.

FIG. 5 is a cross-sectional view showing a structure of a conventional multilayer capacitor having a normal structure.

FIG. 6 is a sectional view showing a structure of a conventional multilayer capacitor having a double series structure.

FIG. 7 is a diagram showing a relationship between an element thickness and a breakdown voltage value of a conventional multilayer capacitor.

FIG. 8 is a diagram showing a relationship between an element thickness of a conventional multilayer capacitor and a breakdown voltage value per unit thickness thereof.

[Explanation of symbols]

 1 Dielectric (Layer) 2 First Internal Electrode Group 2a First Connection Internal Electrode 2b Second Connection Internal Electrode 2c Floating Internal Electrode 4a, 4b External Terminal 5 Capacitor Section 10, 20 Multilayer Capacitor 12 Second Internal Electrode Group 12a Floating internal electrode

Claims (2)

[Claims] 1. A multilayer capacitor in which an internal electrode connected to an external terminal and an internal electrode not connected to the external terminal are arranged in a dielectric, and the dielectric and the internal electrode form a multilayer structure. A first connection internal electrode connected to one external terminal, a second connection internal electrode connected to the other external terminal,
And a first internal electrode group having a floating internal electrode located between the first and second connection internal electrodes, and a first internal electrode group facing the first internal electrode group via a dielectric. A second internal electrode group, which includes a plurality of floating internal electrodes not including internal electrodes connected to external terminals, disposed alternately on the surface, and in the first and second internal electrode groups. 2. The multilayer capacitor according to claim 4, wherein the floating internal electrode is configured such that four or more capacitor portions connected in series are formed between the first and second connection internal electrodes connected to different external terminals. 2. The multilayer capacitor according to claim 1, wherein the thickness of the dielectric (element thickness) interposed between the internal electrodes is 100 μm or less.