JP2005150186A - Method for manufacturing solid state electrolytic capacitor and manufacturing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a dielectric oxide film on a peripheral surface of an anode body almost uniformly. <P>SOLUTION: The solid state electrolytic capacitor 1 is manufactured through a process for forming the anode body 20 which is constituted of valve metal and protrudes an anode lead 22 from one end portion; a process for fixing the anode lead 22 to a conductive bar 30, a process for arranging an electrode 4 provided with a current feeding part 40 to be disposed opposite to a side surface of the anode body 20 in a tank 3, and put in formation liquid 31 inside the tank 3; a process for arranging the bar 30 on the tank 3 to which bar the anode lead 22 is fixed, immersing the anode body 20 in the formation liquid 31, and disposing the current feeding part 40 of the electrode 4 opposite to a side surface of the anode body 20; and a process for applying a current to the electrode 4 from the bar 30, and forming the dielectric oxide film 21 on the anode body 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a manufacturing method and a manufacturing apparatus for a chip-type solid electrolytic capacitor.

The applicant has previously proposed a chip-type solid electrolytic capacitor shown in FIG.
As shown in FIG. 9, the solid electrolytic capacitor (1) includes a capacitor element (2) to which lead frames (9) and (90) are attached. The capacitor element (2) is a housing (7) made of synthetic resin. Covered with. The lead frames (9) and (90) are bent along the peripheral surface of the housing (7).
The capacitor element (2) has an anode lead (22) protruding from one end of an anode body (20) made of a valve metal, and a dielectric oxide film (21) containing phosphorus is formed on the peripheral surface of the anode body (20). Forming. A cathode layer (5) is formed on the dielectric oxide film (21). The cathode layer (5) includes a solid electrolyte layer (50), a carbon layer (6), and a silver paste layer (60). The lead frames (9) and (90) are attached to the silver paste layer (60) and the anode lead (22), respectively. Here, the valve metal refers to a metal on which an extremely dense and durable dielectric oxide film is formed by electrolytic oxidation treatment. Al (aluminum), Ta (tantalum), Ti (titanium), Nb (niobium) Etc. The solid electrolyte includes polythiophene-based and polypyrrole-based conductive polymers.

The dielectric oxide film (21) is formed by the following method (see, for example, Patent Document 1).
First, as shown in FIG. 10, the tip of the anode lead (22) is attached to a metal bar (30), and the anode body (20) is placed in the chemical conversion liquid (31) in the tank (3), specifically. Soak in an aqueous phosphoric acid solution. A plate-like electrode (4) as a cathode is provided on the inner lower surface of the tank (3). When a direct current is passed from the bar (30) toward the electrode (4), a dielectric oxide film (21) is formed on the anode body (20). This is called chemical conversion treatment.
JP 2003-86466 A

In the conventional method, as shown in an enlarged view in FIG. 11, a current flows from the anode lead (22) through the lower surface of the anode body (20) to the electrode (4). Therefore, a dielectric oxide film (21) is likely to be formed on the lower surface of the anode body (20) facing the electrode (4) as indicated by a cross. However, on the upper surface and side surface of the anode body (20) located farther from the electrode (4) than the lower surface of the anode body (20), a portion where the dielectric oxide film (21) is formed thin is formed.
That is, the thickness of the coating (21) formed on the peripheral surface of the anode body (20) can vary. Therefore, LC (leakage current) increased in the thin part of the film (21), and ESR (equivalent series resistance) increased in the part of the thick film (21), which deteriorated the characteristics of the solid electrolytic capacitor (1). .
An object of the present invention is to form the dielectric oxide film (21) substantially uniformly on the peripheral surface of the anode body (20).

The solid electrolytic capacitor (1) includes a step of forming an anode body (20) composed of a valve metal and projecting an anode lead (22) from one end portion;
Attaching the anode lead (22) to the conductive bar (30);
In the tank (3), an electrode (4) provided with a current-carrying portion (40) to be opposed to the side surface of the anode body (20) is disposed, and the chemical conversion liquid (31) is placed in the tank (3);
The bar (30) with the anode lead (22) attached is placed on the tank (3), the anode body (20) is immersed in the chemical conversion liquid (31), and the current-carrying part (40) of the electrode (4) is the anode body. A step of facing the side surface of (20);
The electrode (4) is energized from the bar (30) to produce a dielectric oxide film (21) on the anode body (20).

  On the electrode (4), an energization section (40) that should face the side surface of the anode body (20) is provided. The current flowing from the bar (30) to the anode body (20) passes through the side surface of the anode body (20) and reaches the energization section (40) of the electrode (4). A dielectric oxide film (21) is formed on the upper surface and side surfaces of the anode body (20). Compared with the conventional manufacturing method, the distance between the side surface of the anode body (20) and the electrode (4) is shortened, so the thickness of the dielectric oxide film (21) formed on the peripheral surface of the anode body (20) The unevenness is reduced. As a result, the LC and ESR of the solid electrolytic capacitor (1) can be improved, and the thickness of the dielectric oxide film (21) is substantially uniform, so that the capacitance of the solid electrolytic capacitor (1) varies. Can be reduced. In addition, by making the distance between the side surface of the anode body (20) and the electrode (4) closer to each other, the current value flowing through the bar (30) can be reduced when the dielectric oxide film (21) is formed. It leads to reduction of.

(First embodiment)
Hereinafter, an example of the present invention will be described with reference to the drawings.
The solid electrolytic capacitor (1) manufactured by the method of this example is the same as the conventional one shown in FIG. This example is characterized by the method and apparatus for producing the solid electrolytic capacitor (1).
FIG. 1 is a perspective view of the electrode (4), and FIG. 2 is an enlarged view of the anode body (20) when chemical conversion treatment is performed using the electrode (4) of FIG. The electrode (4) is a metal plate having a thickness of 1 mm and has a large number of through holes (41). The anode body (20) is fitted in each through hole (41) with a margin. The through hole (41) is opened by etching, but may be punched out.
During the chemical conversion treatment, the anode lead (22) is attached to the bar (30), and the anode body (20) is immersed in the chemical conversion liquid (31), specifically, the phosphoric acid aqueous solution. The anode body (20) is fitted into the through hole (41), and the periphery of the through hole (41) faces the side surface of the anode body (20). That is, the periphery of the through hole (41) is the energization part (40) facing the side surface of the anode body (20).

When the bar (30) is energized, current flows through the anode body (20) and reaches the periphery of the through hole (41) from the side surface of the anode body (20). Part of the current exits from the lower surface of the anode body (20) and reaches the electrode (4). A dielectric oxide film (21) is formed on the side surface and the lower surface of the anode body (20).
In this example, since the distance between the side surface of the anode body (20) and the electrode (4) is shorter than that of the conventional manufacturing method, the dielectric formed on the peripheral surface of the anode body (20). The thickness of the oxide film (21) is less uneven. As a result, the LC and ESR of the solid electrolytic capacitor can be improved and the thickness of the dielectric oxide film (21) is substantially uniform, so that the variation in the capacitance of the solid electrolytic capacitor (1) can be reduced. . In addition, by making the distance between the side surface of the anode body (20) and the electrode (4) closer to each other, the current value flowing through the bar (30) can be reduced when the dielectric oxide film (21) is formed. It leads to reduction of.

(Second embodiment)
As shown in FIG. 3, a chemical conversion treatment may be performed by providing a conductive wall piece (42) covering the side surface of the anode body (20) on the electrode (4). In this case, as shown in FIG. 4, the current from the bar (30) flows through the anode body (20) to the wall piece (42), and the dielectric oxide film (21) is formed on the side surface of the anode body (20). Is formed.
Part of the current exits from the lower surface of the anode body (20) and reaches the electrode (4). A dielectric oxide film (21) is formed on the lower surface of the anode body (20).
Further, as shown in FIG. 5, two electrodes (4) and (4) are provided substantially in parallel, and the anode body (20) is fitted into the through holes (41) of both electrodes (4) and (4), so that the anode A dielectric oxide film (21) may be formed on the peripheral surface of the body (20). Both electrodes (4) and (4) may be overlapped.
As shown in FIG. 6, the anode body 20 has a width W of 3.2 mm, a height H of 3.5 mm, and a depth B of 2.5 mm. Therefore, even when two electrodes (4) and (4) having a thickness of 1 mm are stacked, the periphery of the through hole (41) faces the side surface of the anode body (20). The dimensions of the anode body (20) are not limited to the above dimensions.

表１乃至表３の結果から、本例に於ける電極(４)を用いて形成した固体電解コンデンサ(１)の方が、静電容量の最大値と最小値の差が小さくなり、ＥＳＲが悪化することなく、ＬＣを改善できた。 In the actual chemical conversion treatment, as shown in FIG. 7, about 50 bars (30) are hung side by side on the tank (3). Each bar (30) is provided with approximately 50 anode bodies (20) and (20) at substantially equal intervals.
The applicant made a capacitor element (2) by subjecting the anode body (20) to chemical conversion treatment using the conventional electrode (4) and the electrode (4) of this example. A solid electrolytic capacitor (1) was produced from the capacitor element (2), and the capacitance of the solid electrolytic capacitor (1) was measured.
Tables 1, 2 and 3 show the average values of capacitance (unit: μF) and withstand voltage of the solid electrolytic capacitor (1) formed using the conventional electrode (4) and the electrode (4) of this example. It is a table | surface which shows the average value, maximum value, and minimum value of (unit: V), ESR (unit: Ω), and LC (unit: μA).
Here, the withstand voltage is an allowable voltage that can be applied to the lead frames (9) and (90). That is, when a voltage of a certain voltage or higher is applied to the lead frame (9) (90), an overcurrent flows through the defective portion of the dielectric oxide film (21), the dielectric oxide film (21) is damaged, and the anode The body (20) and the cathode layer (5) are short-circuited. This constant voltage is called a withstand voltage. If the dielectric oxide film (21) is formed substantially uniformly, it is conceivable that the withstand voltage increases as compared with the conventional product in which the thickness of the film (21) varies.

From the results of Tables 1 to 3, the solid electrolytic capacitor (1) formed using the electrode (4) in this example has a smaller difference between the maximum value and the minimum value of the capacitance, and the ESR is smaller. LC could be improved without deteriorating.

  FIG. 8 is a graph showing the breakdown voltage distribution, where the horizontal axis indicates the breakdown voltage and the vertical axis indicates the frequency (%). Here, “1 mm etching type cathode plate” refers to the electrode (4) shown in FIG. 2, “cup type cathode plate” refers to the electrode (4) shown in FIG. 4, and “2 mm etching type cathode plate”. "" Refers to the electrode (4) shown in FIG. Also from the graph of FIG. 8, it can be seen that the solid electrolytic capacitor (1) formed using the electrode (4) in this example has a higher breakdown voltage than the conventional product.

  The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. In addition, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

It is a perspective view of an electrode. It is an enlarged view of the anode body at the time of performing a chemical conversion treatment using the electrode of FIG. It is a perspective view of another electrode. It is an enlarged view of the anode body at the time of performing a chemical conversion treatment using the electrode of FIG. It is an enlarged view of the anode body at the time of performing a chemical conversion treatment using another electrode. It is a perspective view of an anode body. It is a top view of a tank. It is a graph which shows distribution of a proof pressure. It is sectional drawing of a solid electrolytic capacitor. It is sectional drawing of the manufacturing apparatus of the conventional solid electrolytic capacitor. It is an enlarged view of FIG.

Explanation of symbols

(1) Solid electrolytic capacitor
(2) Capacitor element
(3) Tank
(4) Electrode
(20) Anode body
(21) Dielectric oxide film
(22) Anode lead
(30) Bar
(40) Current-carrying part
(41) Through hole
(42) Wall piece

Claims (3)

Forming an anode body (20) made of a valve metal and projecting an anode lead (22) from one end; and
Attaching the anode lead (22) to the conductive bar (30);
In the tank (3), an electrode (4) provided with a current-carrying portion (40) to be opposed to the side surface of the anode body (20) is disposed, and the chemical conversion liquid (31) is placed in the tank (3);
The bar (30) with the anode lead (22) attached is placed on the tank (3), the anode body (20) is immersed in the chemical conversion liquid (31), and the current-carrying part (40) of the electrode (4) is the anode body. A step of facing the side surface of (20);
A method for producing a solid electrolytic capacitor comprising a step of energizing an electrode (4) from a bar (30) to form a dielectric oxide film (21) on an anode body (20). The current-carrying portion (40) is one of a peripheral edge of a through hole (41) provided in the electrode (4) and a conductive wall piece (42) provided on the electrode (4). Manufacturing method for solid electrolytic capacitor. A tank (3) containing a chemical conversion liquid (31) in which the anode body (20) is immersed, and an electrode (4) provided on the inner bottom surface of the tank (3) through which current flows through the anode body (20). In a solid electrolytic capacitor manufacturing apparatus,
An apparatus for manufacturing a solid electrolytic capacitor, wherein an energization section (40) to be opposed to the side surface of the anode body (20) is provided on the electrode (4).

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