JPH05243100A - Manufacture of solid-state electrolytic capacitor - Google Patents

Abstract

PURPOSE:To enhance pressure resistance, reduce leakage current variability and improve reliability. CONSTITUTION:In a solid-state electrolytic capacitor which connects a capacitor element 1 having an anode lead wire 2 to a metal frame 3 and forms an armor, a solid-state electrolytic capacitor is manufactured under the following manufacturing process comprising a step for interconnecting the anode lead wire 2 and the metal frame 3 and bringing a soldering material into contact with at least either the anode lead wire 2 or the metal frame 3, and a step for heating, melting and solidifying the soldering material 4 without the application of pressure and then connecting the lead wire 2 to the metal frame 3. This solid-state electrolytic capacitor is manufactured by heating, melting and solidfying the metal frame 3 and connecting the metal frame to the anode wire 2 after having placed the anode lead wire 2 into mutual contact with the metal frame 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solid electrolytic capacitor.

[0002]

2. Description of the Related Art A chip type solid electrolytic capacitor such as tantalum is manufactured, for example, as follows. That is, first,
A sintered body made of fine powder of tantalum or the like is formed by drawing out an anode lead wire of tantalum or the like. Next, this sintered body is anodized to form an oxide film, and then a manganese dioxide layer and a cathode layer are sequentially formed to form a capacitor element. Then, as shown in FIG. 4A, the anode lead wire 21 is placed on the plane of the metal frame 22. Thereafter, as shown in FIG. 4B, the anode lead wire 21 is resistance-welded to the metal frame 22. The cathode layer is connected to the metal frame 22 with a conductive adhesive. The capacitor element 23 is attached to the metal frame 2
After connecting to 2, transfer molding is performed to form an exterior.

[0003]

However, in order to connect the anode lead wire 21 to the metal frame 22 by resistance welding, it is necessary to apply pressure to the contact point between the anode lead wire 21 and the metal frame 22. Therefore, this pressure applies stress to the portion of the anode lead wire 21 in the sintered body. And, due to this stress, the oxide film is deteriorated or damaged. As a result, the capacitor element 23
There is a drawback that the withstand voltage is lowered and the variation of the leakage current is increased to lower the reliability.

An object of the present invention is to provide a method for manufacturing a solid electrolytic capacitor which has improved reliability, improved breakdown voltage, reduced leakage current variation, and high reliability.

[0005]

In order to achieve the above-mentioned object, the invention of claim 1 is a method of manufacturing a solid electrolytic capacitor in which a capacitor element from which an anode lead wire is drawn out is connected to a metal frame to form an exterior. In the step of contacting the anode lead wire and the metal frame with each other, and contacting the brazing material with at least one of the anode lead wire and the metal frame, and heating and melting the brazing material without applying pressure after this step. The present invention provides a method for manufacturing a solid electrolytic capacitor, which comprises performing a step of solidifying and connecting the anode lead wire and the metal frame.

In the invention of claim 2, the step of contacting the anode lead wire and the metal frame with each other, and after this step, the metal frame is heated and melted and solidified to connect the anode lead wire and the metal frame. The present invention provides a method for manufacturing a solid electrolytic capacitor, characterized in that

A laser or an arc discharge method is used to heat and melt the brazing material and the metal frame.

[0008]

Since the anode lead wire is connected to the metal frame by heating, melting and solidifying the brazing material and the metal frame, stress is not applied to the anode lead wire at the time of connection. Therefore, the anode lead wire does not deteriorate or damage the oxide film of the capacitor element.

[0009]

EXAMPLES The present invention will be described below based on examples. Example 1: First, an anode lead wire made of a 0.24φ tantalum wire is pulled out to form a sintered body made of fine tantalum powder. Next, this sintered body is anodized to form an oxide film. After forming the oxide film, it is impregnated with a manganese nitrate solution and thermally decomposed to form a manganese dioxide layer.
Thereafter, colloidal carbon is attached to form a carbon layer, the cathode is pulled out, and silver paste is applied to the surface of the carbon layer to form a cathode layer. After forming the cathode layer,
As shown in (a), the anode lead wire 2 of the capacitor element 1
Are placed on the flat surface portion of the metal frame 3 and brought into contact therewith. After the contact, as shown in FIG. 1B, the Ag-Ti foil-like brazing material with a thickness of 0.05 mm cut into 0.5 mm × 2.0 mm squares on the anode lead wire 2 and the metal frame 3. Place 4 and make contact. Next, 18 W of YAG laser is applied to the brazing material 4.
Irradiate for 1 second and heat to melt. Then, the brazing material 4 is solidified and the anode lead wire 2 is connected to the metal frame 3. The cathode layer of the capacitor element 1 is connected to the metal frame 3 with a conductive adhesive. After connection, transfer molding is performed with an epoxy resin to form an exterior. After forming the outer package, aging is performed to form terminals to obtain a chip type tantalum solid electrolytic capacitor.

Example 2: The procedure of Example 1 was repeated except that the anode lead wire was connected to the metal frame as follows. That is, as shown in FIG. 2A, the bent portion 6 is formed on the metal frame 5. Then, the anode lead wire 8 of the capacitor element 7 is placed on the end face of the bent portion 6 and brought into contact therewith. Next, the brazing material 9 is placed on and contacted with the anode lead wire 8 and the end surface of the bent portion 6. Then, the brazing material 9 is irradiated with the YAG laser under the same conditions as in Example 1, and the brazing material 9 is melted and solidified, and the anode lead wire 8 is connected to the metal frame 5 as shown in FIG.

Example 3: The procedure of Example 1 is repeated except that the anode lead wire is connected to the metal frame as follows. That is, as shown in FIG. 3A, the bent portion 12 having the recess 11 is formed in the metal frame 10. Then, the anode lead wire 14 of the capacitor element 13 is formed in the recess 11.
Place and contact. After the contact, Example 1 is provided on the upper portion of the bent portion 12.
The YAG laser is irradiated under the same conditions as above to heat, melt, and solidify, and the anode lead wire 14 is connected as shown in FIG.

Next, with respect to Examples 1 to 3 and the conventional example, the breakdown voltage failure and the variation of the initial leakage current were measured. Each sample shall be rated at 16V and 2.2μF.

The manufacturing conditions of the conventional example are as follows. Conventional example: In Example 1, the anode lead wire is manufactured under the same conditions except that it is connected to a metal frame as follows. That is, as shown in FIG. 4A, the anode lead wire 21 of the capacitor element 23 is placed on the flat surface portion of the metal frame 22.
Then, resistance welding is performed by applying a pressure of 3 kg / mm ² to the anode lead wire 21.

The withstand voltage defect is represented by the number of short-circuited by applying a voltage of 20 V to the sample. The number of samples is 100 each.
It is 0. As a result of the measurement, the number of Examples 1 to 3 was 0, whereas the number of Conventional Example was 2.

The initial leakage current is a value one minute after the rated voltage is applied, and the results are shown in FIG. As is apparent from FIG. 5, Examples 1 to 3 showed almost the same variation. However, in the conventional example, the maximum value is 0.1 μA or more,
It increased by an order of magnitude and the variation was very large.

Further, in the capacitor of Example 3, the metal frame 1 which covers the anode lead wire 14 after the connection.
The change in tan δ when the thickness t of 0 was changed was measured, and
It was shown to. The thickness t is expressed as a ratio to the diameter of the anode lead wire 14. Then, tan δ was measured at a frequency of 120 Hz. As is clear from FIG. 6, the thickness t is the anode lead wire 1.
When the diameter of 4 is 2/5 or more, tan δ has less variation and is stable at a low value. Therefore, the metal frame 10
It is understood that the coating thickness t of is preferably 2/5 or more.

[0017]

As described above, according to the manufacturing method of the invention of claim 1, since the anode lead wire is connected to the metal frame by heating and melting and solidifying the brazing material without pressurizing, the pressure resistance is increased. A highly reliable solid electrolytic capacitor capable of reducing defects and reducing variations in leakage current can be obtained.
Also, according to the manufacturing method of the second aspect of the invention, since the metal frame is heated and melted and solidified to connect the anode lead wire, a solid electrolytic capacitor having the same effect can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view before and after connecting a capacitor element according to an embodiment of the present invention to a metal frame.

FIG. 2 is a perspective view before and after connecting a capacitor element of another embodiment of the invention of claim 1 to a metal frame.

FIG. 3 shows perspective views before and after connecting the capacitor element of the embodiment of the invention of claim 2 to a metal frame.

FIG. 4 shows perspective views before and after a conventional capacitor element is connected to a metal frame.

FIG. 5 shows a graph of leakage current.

FIG. 6 shows a graph of tan δ.

[Explanation of symbols]

1, 7, 13 ... Capacitor element, 2, 8, 14 ... Anode lead wire, 3, 5, 10 ... Metal frame, 4, 9, 3
... wax material.

Claims (2)

[Claims] 1. A method of manufacturing a solid electrolytic capacitor, wherein a capacitor element from which an anode lead wire is drawn out is connected to a metal frame to form an outer package, the anode lead wire and the metal frame are in contact with each other, and the anode lead wire and Performing a step of contacting at least one of the metal frames with a brazing material, and a step of connecting the anode lead wire and the metal frame after this step by heating, melting and solidifying the brazing material without applying pressure. And a method for manufacturing a solid electrolytic capacitor. 2. A method of manufacturing a solid electrolytic capacitor in which a capacitor element from which an anode lead wire is drawn out is connected to a metal frame to form an outer package, a step of bringing the anode lead wire and the metal frame into contact with each other, and after this step, And a step of connecting the anode lead wire to the metal frame by heating, melting and solidifying the metal frame.