JP2888922B2 - Method for manufacturing solid electrolytic capacitor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a solid electrolytic capacitor using a capacitor element wound with an electrode foil.

[Conventional technology]

2. Description of the Related Art Conventionally, in a solid electrolytic capacitor, as shown in FIG. 2A, for example, terminal leads 4, 6 are provided on an anode-side and cathode-side electrode foil 2 formed of a valve metal foil such as a high-purity aluminum foil. Is connected, a heat-resistant separator 8 such as glass fiber paper is sandwiched between the electrode foils 2 and wound into a cylindrical shape to form the capacitor element 10. A locking tape 12 is wound around the peripheral surface of the capacitor element 10. Next, manganese nitrate to the capacitor element _{10 {Mn (NO 3) 2} }
After the impregnation with the aqueous solution, a baking treatment is performed at a temperature of about 250 ° C. to transform manganese nitrate, whereby a solid electrolyte layer made of manganese dioxide is formed on the surface of the electrode foil 2 of the capacitor element 10.

[Problems to be solved by the invention]

Incidentally, as the locking tape 12 wound around the capacitor element 10, for example, a polyphenylene sulfide resin (PPS) tape is used. When this PPS tape is used for the locking tape 12, the PPS tape is melted by a baking treatment for denaturing manganese nitrate,
As shown in (B) of the figure, it contracts and adheres to the center of the peripheral surface of the capacitor element 10. For this reason, the shrinked PPS tape increases the outer diameter of the capacitor element 10, and therefore, a step of removing the shrink-fixing tape 12 adhered by shrinking is required for storage in the outer case.

For this reason, as the locking tape 12, a polyimide tape having heat resistance to such an extent that it is not melted and shrunk in the baking treatment is used. This polyimide tape does not thermally deform by heat treatment at about 500 ° C., but since the adhesive strength is reduced, before the solidification of the capacitor element 10 with manganese dioxide, for example, as shown in FIG. It spreads and separates from the capacitor element 10. As described above, when the capacitor element 10 is exposed from the locking tape 12, manganese dioxide adheres to that portion, the diameter of the capacitor element 10 increases, and the shape of the capacitor element 10 becomes uneven. Since the diameter of capacitor element 10 is set in relation to the outer case, if the diameter is increased due to adhesion of manganese dioxide or loosening of capacitor element 10, it may not be able to be stored in the outer case. In addition, since the distance between the electrodes is widened, electric characteristics such as loss may be deteriorated.

Accordingly, an object of the present invention is to provide a method for manufacturing a solid electrolytic capacitor that prevents inconvenience due to a decrease in the adhesive force of a locking tape and simplifies the process by omitting a removing step of the locking tape. .

[Means for solving the problem]

That is, the method for manufacturing a solid electrolytic capacitor of the present invention comprises:
Winding the electrode foil (2) to form a capacitor element (10),
A polyporavanic acid tape (1
3), the capacitor element is loosened and impregnated with manganese nitrate, and then a solid electrolyte layer made of manganese dioxide is formed on the electrode foil inside the capacitor element by a baking treatment. It is characterized in that the acid tape is removed by thermal decomposition.

[Action]

The polyporavanic acid tape can stabilize the capacitor element at room temperature, and is thermally decomposed at an increase in the number of firings or at the firing processing temperature together with the formation of the solid electrolyte layer of the capacitor element. In other words, when a polyporabanic acid tape is used as the locking tape, when the number of firings is small, the tape functions as a locking for the capacitor element, and when the number of firings is increased, the solid electrolyte layer is thermally decomposed and disappears at the same time. With the formation of the electrolyte layer, the outer peripheral surface of the capacitor element can be exposed. Therefore, unlike the conventional PPS tape and polyimide tape, a removing step is not required, and the manufacturing process is simplified.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

FIG. 1 shows an embodiment of a method for manufacturing a solid electrolytic capacitor according to the present invention.

As shown in FIG. 1 (A), after connecting the terminal leads 4 and 6 to the anode and cathode electrode foils 2 formed of a valve metal foil such as a high-purity aluminum foil, each electrode foil 2 A capacitor element 10 is formed by sandwiching a heat-resistant separator 8 made of glass fiber paper or the like between them to form a capacitor element 10, and a polyporabanic acid tape 13 is wound around the peripheral surface of the capacitor element 10 as a loosening tape. This polyporavanic acid tape 13 is formed to have a width equal to the height of the capacitor element 10, and is wound around the peripheral surface of the capacitor element 10 by one or several turns.

Then, the capacitor element 10 Poriporaban acid tape 13 is wound manganese nitrate {Mn (NO _{3) 2}} was immersed in an aqueous solution,
The inside of the capacitor element 10 is impregnated with a manganese nitrate aqueous solution.

Next, the capacitor element 10 is housed in a firing furnace and subjected to a firing treatment at a temperature of about 250 ° C., whereby manganese dioxide is deposited inside the capacitor element 10 and a solid electrolyte layer is formed on the surface of the electrode foil 2 of the capacitor element 10. Is done. This firing step is repeated several times to several tens of times as necessary.

Then, in the firing step of the capacitor element 10, the polyporavanic acid tape 13 wound on the surface of the capacitor element 10 is decomposed and disappears through about four firing steps. That is, the capacitor element 10 is solidified by firing, and a solid electrolyte layer is formed therein. However, as shown in FIG. 1B, the polyporavanic acid tape 13 is thermally decomposed due to an increase in the number of firings. Then, the peripheral surface of the capacitor element 10 is exposed. In this case, when the number of firings is small, the polyporavanic acid tape 13 sufficiently fulfills the function of locking the capacitor element 10, and disappears due to thermal decomposition as the number of firings increases.

Therefore, if the polyporavanic acid tape 13 is used for securing the capacitor element 10, the polyporavanic acid tape 13 is used in the firing step for forming the solid electrolyte layer of the capacitor element 10.
Since the removal of 13 can be performed at the same time, it is possible to perform the locking for solidifying the capacitor element 10 and the formation of the solid electrolyte layer, and the step of removing the locking tape can be omitted.

〔Experimental result〕

In the experiment, the capacitor element 10 in which a polyporavanic acid tape 13 having the same width as the separator was wound on the peripheral surface was immersed in a manganese nitrate aqueous solution, and the inside of the capacitor element 10 impregnated with a manganese nitrate aqueous solution was heated at 250 ° C to 300 ° C. At the same temperature for 15 minutes.

Next, when the capacitor element 10 was placed at a temperature of 500 ° C. for 30 minutes, the polyporabanic acid tape 13 was thermally decomposed and disappeared, and the surface of the capacitor element 10 was exposed together with the formation of the solid electrolyte layer on the capacitor element 10. That is, the loosening tape made of the polyporabanic acid tape 13 was removed simultaneously with the formation of the solid electrolyte layer by the four firing treatments, but the capacitor element 10 was not loosened during the formation of the solid electrolyte layer. Therefore, it was confirmed that the polyporavanic acid tape had ideal characteristics as a locking tape.

〔The invention's effect〕

As described above, according to the present invention, the baking tape at the time of forming the solid electrolyte layer thermally decomposes and disappears, so that the outer peripheral surface of the capacitor element can be exposed together with the formation of the solid electrolyte layer. It is possible to prevent inconvenience due to a decrease in the adhesive force of the locking tape, and it is not necessary to separately set a removing step of the locking tape, so that the manufacturing process can be simplified and the manufacturing cost can be reduced. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a method for manufacturing a solid electrolytic capacitor of the present invention, and FIGS. 2 and 3 are perspective views showing a method for manufacturing a conventional solid electrolytic capacitor. 2 ... Electrode foil 10 ... Capacitor element 13 ... Polyporabanic acid tape

Claims (1)

(57) [Claims] 1. A capacitor element is formed by winding an electrode foil, and a polyporanic acid tape is wound around the periphery of the capacitor element to loosen the capacitor element and impregnate it with manganese nitrate. Forming a solid electrolyte layer made of manganese dioxide on the electrode foil inside the capacitor element, and removing the polyporavanic acid tape by thermal decomposition.