JPH05166682A - Capacitor - Google Patents

Abstract

PURPOSE:To provide a capacitor which has materialized high breakdown strength as well as miniaturization. CONSTITUTION:A dielectric film 8 is made and also a constant voltage element 14 is installed on one side of an electrode plate 2, and besides a conductive polymer layer 10 is overlaid on the dielectric oxide film 8, thus capacitor elements 21 and 22 to be stacked are made, and two or more capacitor elements are stacked through conductive binders 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor using a conductive polymer layer.

[0002]

2. Description of the Related Art Conventionally, solid electrolytic capacitors have been miniaturized by using an anode body on a chip and have been developed for mounting on a hybrid integrated circuit. In this solid electrolytic capacitor, for example, an aluminum plate is used as an anode body, and its surface is subjected to surface widening treatment by etching, a dielectric layer is formed on the surface by chemical conversion treatment, and an organic semiconductor is formed on the upper surface of the dielectric layer. A solid electrolyte layer is formed by growing layers, and a cathode terminal is formed by stacking a conductor layer that substantially forms a cathode on the solid electrolyte layer.

[0003]

By the way, in this solid electrolytic capacitor, quality control is troublesome, such as high degree of hermetic sealing is required to prevent deterioration of the solid electrolyte layer.
In addition, the withstand voltage is generally about 16 WV, which is not suitable for the 24 V power source, which is in the highest demand.

Therefore, it is an object of the present invention to provide a capacitor which is miniaturized and has a high breakdown voltage.

[0005]

The capacitor of the present invention comprises:
A dielectric oxide film (8) is formed on one surface of the electrode plate (2), constant voltage elements (14, D ₁ , D ₂ ) are installed, and conductivity is provided on the dielectric oxide film. A capacitor element (2) to be laminated with a polymer layer (10) applied
1, 22), and two or more capacitor elements are laminated with a conductive adhesive (16) interposed.

The capacitor of the present invention is characterized in that a conductive polymer layer (20) is interposed between the laminated capacitor elements.

Further, the capacitor of the present invention is characterized in that the conductive polymer layer is composed of any one of polypyrrole, polyaniline and polythiophene.

[0008]

In the capacitor of the present invention, a dielectric oxide film is formed on one surface of the electrode plate, a constant voltage element is installed, and a conductive polymer layer is deposited on the dielectric oxide film. It is used as a capacitor element to be stacked. In this capacitor element, the portion of the dielectric oxide film and the conductive polymer layer formed on one surface of the electrode plate contributes to the capacity formation. However, the dielectric oxide film and the conductive polymer layer formed for each capacitor element have a slightly different insulation resistance for each capacitor element, and it is difficult to form each insulation resistance (leakage resistance) uniformly. However, it is impossible to balance the stacked capacitor elements. As a result, the voltage division value differs for each capacitor element, causing dielectric breakdown in each capacitor element. In order to prevent such inconvenience, a constant voltage element is added in parallel for each capacitor element, and the individually connected constant voltage elements can effectively prevent the dielectric breakdown of the capacitor element, Higher breakdown voltage is realized by stacking capacitor elements.

Further, in the capacitor of the present invention, a dielectric oxide film is formed on an etched electrode plate, and a conductive polymer layer is deposited on the dielectric oxide film to form a capacitor element. It is laminated on. When a plurality of capacitor elements are laminated in this way, the conductive adhesive constitutes a substantial cathode layer, and at the same time forms a connection conductor for each capacitor element, and each capacitor element is connected in series. Compose one capacitor. Therefore, the withstand voltage of the capacitor including a plurality of capacitor elements is a value obtained by adding the withstand voltage of each capacitor element, and the withstand voltage can be increased according to the number of stacked layers.

If the conductive polymer layer is made of polypyrrole, polyaniline or polythiophene, a capacitor element having the required characteristics can be obtained.

[0011]

The capacitor of the present invention will be described in detail below with reference to the embodiments shown in the drawings.

1, 2 and 3 show an embodiment of the capacitor of the present invention. This capacitor uses two or more chip-shaped electrode plates 2 formed of a film-forming metal such as aluminum. The electrode plate 2 has a capacitance forming surface 4 set on one side thereof. A notch 6 that is a flat surface is formed with a step from the capacitance forming surface 4. The capacitance forming surface 4 is subjected to surface expansion processing by etching. The surface of the notch 6 may also be etched. A dielectric oxide film 8 is formed on the capacitance forming surface 4 by chemical conversion treatment, and a conductive polymer layer 10 is formed on the dielectric oxide film 8. The conductive polymer layer 10 can be made of, for example, polypyrrole, polyaniline, or polythiophene.
Further, a constant voltage element 14 is installed in the notch 6 with a conductive adhesive 12. The constant voltage element 14 can be constituted by, for example, a Zener diode, and the cathode side thereof is connected to the electrode plate 2 side. With the electrode plate 2, the dielectric oxide film 8 and the conductive polymer layer 10 as described above, the constant voltage element 14 is used to form the capacitor elements 21 and 22 as a unit. In this case, the constant voltage element 14
An insulation gap 15 is set between the capacitor and the capacitance forming surface 4 for insulation.

Each of the capacitor elements 21 and 22 is adhered with a conductive adhesive 16, and in the case of this embodiment, a capacitor as a laminated body composed of two capacitor elements 21 and 22 is formed. In this embodiment, two capacitor elements 21 and 22 are laminated, but three or more capacitor elements 21, 22 ... 2n may be laminated to form one capacitor.

In this capacitor, as shown in FIG. 3, the anode terminal 32 and the cathode terminal 34 are used as external terminals.
Attached, each anode terminal 32 and cathode terminal 3
For convenience of surface mounting, 4 is devised so that the connection surface is flat. That is, the anode terminal 32 and the cathode terminal 34 are C-shaped so as to sandwich the capacitor from both end surfaces, but the projection 36 is formed on the connection surface side on the cathode terminal 34 side. The anode terminal 32 is connected to the capacitor element 2
1 is connected to the upper surface of the electrode plate 2 with a conductive adhesive 38, the cathode terminal 34 is connected to the conductive polymer layer 10 of the capacitor element 22 with a conductive adhesive 40, and the anode terminal 32 and the capacitor element 21 are connected. , 22 on the end face side and on the portion to be overlapped with the cathode terminal 34 with an insulating resin or the like.
Similarly, an insulating layer 42 made of an insulating resin or the like is provided on the end face on the side of the capacitor element 22 on the side of the cathode terminal 34 and on the side of the conductive polymer layer 10 in the same manner. And insulation between the cathode terminal 34 and the electrode plate 2 are ensured, and the connection surface for surface mounting is flattened.

According to this structure, the capacitor elements 21 and 22 are laminated and connected in series, and the constant voltage element 14 is connected in parallel to each of the capacitors 21 and 22. Therefore, the equivalent circuit of this capacitor is as shown in FIG.

In FIG. 4, C ₁ and C ₂ are capacitances of the capacitor elements 21 and 22, and R ₁ and R ₂ are insulation resistances of the capacitor elements 21 and 22. Therefore, the combined capacitance C is C = C ₁ · C ₂ / (C ₁ + C ₂ ) = Ci /
2 (where Ci = C ₁ = C ₂ ).

If the breakdown voltage of each capacitor element 21 and 22 is E ₁ and E ₂ , the breakdown voltage E of the capacitor is E = E
_{If 1} + E ₂ and E ₁ = E ₂ = Ei, then E = 2E
i (= 2E ₁ = 2E ₂ ), which is increased in proportion to the number n of laminated capacitor elements. Therefore, if the capacitor elements 21 and 22 have a multi-stage configuration in this way, a high breakdown voltage can be achieved according to the number of stacked layers of the capacitor elements 21, 22 ...

By the way, the insulation resistances R ₁ and R ₂ formed by the dielectric oxide film 8 and the conductive polymer layer 10 of the capacitor elements 21 and 22 are slightly different (R ₁ ≠ R ₂ ), and the insulation resistances are different. It is difficult to make R ₁ and R ₂ uniform as ideal values, and it is impossible to balance the stacked capacitor elements 21 and 22. When the insulation resistances R ₁ and R ₂ are different, the capacitor element 21,
The divided voltage values E ₁ and E _{2 for} each 22 are different, and when the difference between the two is large, the capacitor elements 21 and 22 cause inconvenience such as dielectric breakdown. In order to prevent such an inconvenience, a constant voltage element 14 is added in parallel for each capacitor element 21 and 22, and D ₁ and D ₂ are constant voltage elements added to each capacitor element 21 and 22. 14
Is shown. Thus, the constant voltage elements D ₁ and D ₂ that are individually connected to the capacitor elements 21 and 22 effectively prevent the dielectric breakdown of the capacitor elements 21 and 22, and increase the breakdown voltage by stacking the capacitor elements 21 and 22. Is realized.

Next, FIG. 5 shows another embodiment of the capacitor of the present invention. In this embodiment, the conductive polymer layer 20 is applied to the laminated surface side of the capacitor elements 21 and 22 to be laminated, that is, the back surface of the capacitance forming surface 4 of the capacitor element 21, and the conductive adhesive 16 is applied thereon. Is installed and the conductive polymer layer 10 side of the capacitor element 22 is laminated.

When the conductive polymer layer 20 is interposed between the capacitor elements 21 and 22 as described above, the equivalent circuit of the capacitor is as shown in FIG. That is, in this capacitor, the insulation resistance Ro due to the conductive polymer layer 20 is added, and a higher breakdown voltage is achieved. That is, assuming that the divided voltage value by the resistor Ro is Eo, the withstand voltage E of this capacitor is E = E ₁ + E ₂ + Eo, and E ₁ = E ₂
= Ei, E = 2Ei (= 2E ₁ = 2E ₂ ) + E
o, and the number of stacked capacitor elements 21, 22, ...
In addition, the withstand voltage is increased in accordance with the number of interpositions of the conductive polymer layer 20, and a higher breakdown voltage is achieved. In this case, the combined capacitance C of the capacitor elements 21 and 22 is C = C ₁ · C
₂ / (C ₁ + C ₂ ) = Ci / 2, which is the same as in the above embodiment.

[0021]

As described above, according to the present invention,
The following effects are obtained. a. The capacitor elements can be stacked in any number of stages to achieve high withstand voltage in proportion to the number of capacitor elements, and a small capacitor can be provided.A constant voltage element is provided in parallel with each stacked capacitor element. Therefore, it is possible to reliably prevent dielectric breakdown due to uneven insulation resistance of each capacitor element, and to provide a stable and highly reliable capacitor. b. If a conductive polymer layer is interposed between the laminated capacitor elements, the insulation resistance of the conductive polymer layer is added, and a higher breakdown voltage can be realized. c. If the conductive polymer layer is made of any one of polypyrrole, polyaniline, and polythiophene, a capacitor having necessary characteristics and high reliability can be realized.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a capacitor of the present invention.

FIG. 2 is a vertical cross-sectional view of the capacitor shown in FIG.

FIG. 3 is a vertical cross-sectional view in which external terminals are attached to the capacitor shown in FIG.

4 is a circuit diagram showing an equivalent circuit of the capacitor shown in FIG.

FIG. 5 is a vertical sectional view showing another embodiment of the capacitor of the present invention.

6 is a circuit diagram showing an equivalent circuit of the capacitor shown in FIG.

[Explanation of symbols]

 2 Electrode Plate 8 Dielectric Oxide Film 10 Conductive Polymer Layer 12 Conductive Adhesive 14 Constant Voltage Element 20 Conductive Polymer Layer 21, 22 Capacitor Element

Claims (3)

[Claims] 1. A dielectric oxide film is formed on one surface of an electrode plate, a constant voltage element is installed, and a conductive polymer layer is deposited on the dielectric oxide film and laminated. A capacitor, wherein the capacitor element is a power element, and two or more of the capacitor elements are laminated with a conductive adhesive interposed. 2. The capacitor according to claim 1, wherein a conductive polymer layer is interposed between the laminated capacitor elements. 3. The conductive polymer layer is polypyrrole,
The capacitor according to claim 1, wherein the capacitor is made of either polyaniline or polythiophene.