JPH02298013A - Solid electrolyte capacitor - Google Patents

Abstract

PURPOSE:To prevent a voltage drop and to restore a dielectric layer surely by a method wherein an anode foil on which the dielectric layer is formed by an anodic oxidation operation is provided on the surface of a valve metal and a valve metal layer is formed at a part coming into contact with the anode foil and on the surface of an anode extraction lead near the part. CONSTITUTION:A part coming into contact with an anode foil 13 and the surface of an anode extraction lead 11 near the part are coated with a conductive paint constituted of a powder of a valve metal, e.g. aluminum; a valve metal layer 12 is formed; the anode extraction lead 11 is welded to the anode foil 13 at a part of the valve metal layer 12. Then, a dielectric layer 14 on the surface of the anode foil 13 is restored in a chemical formation liquid. In addition to aluminum, tantalum, titanium or niobium is used for the valve metal Iayer 12.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a solid electrolytic capacitor suitable for reducing impedance in a high frequency region.0 Prior Art In recent years, as power supplies have become smaller, electrolytic capacitors have become more and more compatible with high frequencies. is required. In order to cope with higher frequencies, it is necessary to reduce the equivalent series resistance of electrolytic capacitors as much as possible. However, as the frequency becomes higher, it is required to reduce the inductance as much as possible.

A conventional solid electrolytic capacitor will be explained below.

FIG. 4 shows the structure of a capacitor element constituting a functional polymer electrolytic capacitor which is a conventional solid electrolytic capacitor and is made to handle high frequencies. Figure 4a shows a strip-shaped capacitor element foil with a plurality of projections formed at predetermined intervals on one side, Figure 4S is a partially enlarged view of Figure 4, and Figure 4C is a A sectional view taken along the line B-B in the figure is shown.

In Fig. 4, 1 is an anode foil made by roughening aluminum foil and further provided with a dielectric layer 2, 3 is a conductive polymer layer, and 4 is a conductive polymer layer.
6 is a carbon layer, and 6 is a silver paint layer. The carbon layer 4 and the silver paint layer 6 are provided for drawing out the cathode, and in this case, the conductive polymer layer 3
is the true cathode.

A method for drawing out the electrodes of the capacitor element constituting the functional polymer electrolytic capacitor constructed as described above will be described below.

First, attach the anode lead e to the part C-a in Figure 4.
to weld. Next, the anode foil 1 is cut at a portion that contacts the silver paint layer 6 on the opposite side. Thereafter, or at the same time, the cathode lead 7 was attached by soldering or the like to form a functional polymer electrolytic capacitor.

Fig. 6 shows a diagram in which both electrodes are drawn out from the capacitor element, Fig. 5 a is a plan view thereof, and Fig. 5 or D-D of Fig. 5 a.
A line cross-sectional view is shown. In FIG. 5, 6 is an anode lead, and 7 is a cathode lead.

In addition to the above, instead of using the strip-shaped anode foil 1 as shown in FIG. polymer layer 3,
Conventionally, a method of forming a carbon layer 4 and a silver paint layer 6 has been used.

FIG. 6 shows a functional polymer electrolytic capacitor manufactured by this method, and FIG. 6a shows a plan view thereof, and FIG.

In FIG. 6, 8 is a valve metal anode lead whose periphery in contact with the anode foil 1 is replaced with valve metal.

In this method, when repairing the dielectric layer 2 by dipping the anode foil 1 in a chemical solution, the chemical solution creeps up to the anode lead 6. Since voltage cannot be applied when using
Dielectric layer 2 cannot be repaired. In order to avoid this, a valve metal anode lead 8 is used.

FIG. 3 shows how the dielectric layer 2 of the anode foil 1 to which the anode lead lead 6 is attached is repaired in a chemical solution.

Problems to be Solved by the Invention However, in the conventional configuration described above, the band-shaped anode foil 1 is widely used to fix the capacitor element foil which is band-shaped and has a plurality of protrusions at predetermined intervals on one side. The problem was that the effective utilization rate of 1 was less than half.

When using the valve metal anode lead 8, a certain length is required to connect the valve metal lead to a metal that can be soldered, and in this case, the lead part is highly functional. This has the problem of significantly increasing the inductance of the molecular electrolytic capacitor at high frequencies and making the shape of the capacitor more complicated.

The present invention solves the above-mentioned conventional problems, and aims to provide a solid electrolytic capacitor that is suitable for reducing impedance in a high frequency range by using a conductive polymer, and is also inexpensive and easy to manufacture. do.

Means for Solving the Problems In order to achieve the above object, the solid electrolytic capacitor of the present invention includes an anode foil in which a dielectric layer is provided on the surface of a valve metal by anodizing, and a portion in contact with the anode foil and its vicinity. A valve metal layer is provided on the surface of the anode lead.

Effect By having the above configuration, it is no longer necessary to form the anode foil into a strip with a plurality of protrusions at predetermined intervals on one side.
As a result, all the anode foil can be used effectively. In addition, when repairing the dielectric layer on the surface of the anode foil in a chemical solution, if the chemical solution creeps up onto the anode lead, υ, there is a valve on the surface of the lead in the area in contact with the anode foil and in the vicinity. Since the metal layer is provided, a voltage drop can be prevented, and as a result, the dielectric layer can be reliably repaired.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

Figure 1 shows that aluminum is coated by sputtering on the surface of the anode lead in the area in contact with the aluminum anode foil and in the vicinity of the aluminum anode foil used in an aluminum functional polymer/molecular electrolytic capacitor, which is a solid electrolytic capacitor according to an embodiment of the present invention. This figure shows the anode lead. In FIG. 1, 11 is an anode lead, and 12 is a valve metal layer, which in this embodiment is an aluminum layer.

FIG. 2 shows a state in which the capacitor element is connected to the cathode, and FIG. 2a shows a cross-sectional view thereof, and FIG.

In FIG. 2, 13 is an anode foil made by roughening aluminum foil and further providing a dielectric layer 14 by anodizing;
is a conductive polymer layer provided on the surface of the dielectric layer 14, 16 is a carbon layer provided on the surface of the conductive polymer layer 16, 17 is a silver paint layer provided on the surface of the carbon layer 16, and 18 is a silver paint. This is a cathode lead connected to a part of layer 17.

In addition, as a second embodiment, the anode drawer 11 in the portion in contact with the anode foil 13 made of aluminum and in the vicinity thereof is
An aluminum functional polymer electrolytic capacitor was prototyped using an anode lead whose surface was coated with a valve metal layer 12 made of aluminum by vapor deposition.

In addition, as a third embodiment, the anode lead 11 in the portion in contact with the anode foil 13 made of aluminum and in the vicinity thereof is
An aluminum functional polymer electrolytic capacitor was prototyped using a positive lead lead whose surface was coated with a valve metal layer 12 made of aluminum by thermal spraying.

In addition, as a fourth embodiment, the anode drawer 11 in the portion in contact with the anode foil 13 made of aluminum and in the vicinity thereof is
An aluminum functional polymer electrolytic capacitor was prototyped using an anode lead whose surface was coated with a conductive paint made of aluminum powder.

Regarding the solid electrolytic capacitor configured as above,
The method for drawing out the electrodes will be explained below.

First, a valve metal layer 12 is provided on the surface of the anode lead 11 in the area in contact with the anode foil 13 shown in FIG. Weld.

Then, as shown in FIGS. 3a, b, a, and cl, the dielectric layer 14 on the surface of the anode foil 13 is repaired in a chemical solution. Anode extraction when repairing this dielectric layer 14 -
To prevent chemical solution from creeping up to the electrode 11, the anode foil 13
Since the valve metal layer 12 is provided on the surface of the anode lead-out board 11 in the area in contact with and in the vicinity thereof, it is possible to prevent a voltage drop, and as a result, the dielectric layer 14 can be repaired reliably. It can be carried out. In addition, in this FIG. 3, 19 is a valve metal anode lead.

After repairing the dielectric layer 14, as shown in FIG.
, and a silver paint layer 17 is formed thereon. Finally, the cathode lead 18 is attached on top of the silver paint layer 17.

Regarding the solid electrolytic capacitor configured as above,
Table 1 shows the values of capacitance, loss angle tangent, and leakage current. Table 1 shows an example of the present invention having a rating of 1 ev, a rated capacity of 4.7 μF, a 70 V chemically formed foil, and a foil size of 5 mm x 12 mm, which exhibits satisfactory characteristics as a capacitor.

Table 1 (n=s) *Value of 120H2 **Value of 1eV2 Minute value Note that in the embodiment of the present invention, the anode foil 13 and the valve metal layer 12 are made of aluminum, but the anode foil 1゛3 or the valve metal layer 12 may be made of tantalum, titanium, or niobium in addition to aluminum.

Effects of the Invention As described above, according to the present invention, the anode foil is provided with a dielectric layer provided on the surface of the valve metal by anodizing, and the valve metal is provided on the surface of the anode lead in the area in contact with the anode foil and in the vicinity thereof. Because the layer is provided, it is possible to obtain a material suitable for lowering impedance in high frequency range using conductive polymer, and it is also possible to obtain an anode extraction when repairing the dielectric layer on the surface of the anode foil during the formation process. The existence of the valve metal prevents the voltage effect even when chemical liquid creeps up to the leads, and as a result, it is possible to realize a solid electrolytic capacitor that can reliably repair the dielectric layer. It is.

[Brief explanation of the drawing]

FIG. 1 is a partial perspective view of an anode lead with valve metal formed on the surface of the anode lead and the part in contact with the anode foil used in a solid electrolytic capacitor in an embodiment of the present invention, and FIG. It shows the state in which the capacitor element of a solid electrolytic capacitor in an embodiment of the invention is connected to the cathode, and FIG. 2a is a plan view thereof, FIG. Figure 3 a, b, c
, d shows how the dielectric layer of the anode foil with the anode lead attached is repaired during chemical conversion, and Figure 4 shows the configuration of the capacitor element of a conventional solid electrolytic capacitor. The turtle in Figure 4 is a front view of a strip-shaped capacitor element foil with a plurality of protrusions formed at predetermined intervals on one side. Figure 4 is an enlarged view of a portion of the turtle in Figure 4. Figure 6 is a sectional view taken along the line B-B in Figure 6. Figure 6 shows a conventional solid electrolytic capacitor with both electrodes drawn out to the capacitor element. Figure 6a is its plan view, and Figure 6 D in Figure 5 a
-D cross-sectional view, Figure 6 shows a conventional solid electrolytic capacitor connected to a capacitor element using a valve metal anode lead, up to the cathode; is a sectional view taken along the line - in FIG. 6a. 11... Anode extraction lead, 12...
・Valve metal layer, 13...Anode foil, 14...
・Dielectric layer, 16... Conductive polymer layer, 1e・
...Carbon layer, 17...Silver paint layer, 18...Cathode extraction lead. Name of agent: Patent attorney Shigetaka Awano and 1 other person11
--Ichiyo Nebhi? F1 ki dji lno sword 12- valve 4-7 hawk layer (2) (b) + I'll. To (to +
1 Figure 4 (Nose 2 (b) (
Q) Figure 5 (Yu 2(b) Straw 6

Claims (4)

[Claims] (1) A solid body characterized by comprising an anode foil in which a dielectric layer is provided on the surface of the valve metal by anodizing, and a valve metal layer is provided on the part in contact with the anode foil and the surface of the anode lead in the vicinity thereof. Electrolytic capacitor. (2) The solid electrolytic capacitor according to claim 1, wherein the valve metal layer is formed by vapor deposition, sputtering, or thermal spraying. (3) The solid electrolytic capacitor according to claim 1, wherein the valve metal layer is formed by applying a conductive paint made of valve metal powder. (4) The solid electrolytic capacitor according to claim 1, wherein the valve metal layer is made of aluminum, tantalum, titanium, or niobium.