JPH06275478A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a solid electrolytic capacitor wherein variation of welding strength at an external connection terminal is suppressed. CONSTITUTION:In capacitor element formation step (A), with a manganese dioxide layer, for example, use as an electrolyte layer, respective aluminum foils as an anode body and cathode body are, with a separator in between, wound up, for a capacitor element to be formed. In capacitor element sealing step (B), an element is inserted into a resin case, to be sealed up with an epoxy resin. In resin cutting step (C), the metal terminal side of the element in the resin case is, together with the epoxy resin and metal terminal, cut to a specified length. In chemical grinding step (C*), processing is performed as NaOH (aq) washing HNO3 (aq) washing ethanol washing drying, for the cut cross section to be cleaned. In terminal welding step (D), to the metal terminal, exposing itself after cutting of element, an external connection terminal is, by supersonic welding or laser welding, welded.

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 suitable for surface mounting on a printed circuit board or the like used in small electronic equipment.

[0002]

2. Description of the Related Art Electronic components such as resistors and ceramic capacitors are becoming
The size is reduced to a size of 1005 parts of 1.0 mm x 0.5 mm, which enables high-density mounting on a printed circuit board or the like. While miniaturization of electronic parts is desired, an electrolytic capacitor having a relatively large capacity characteristic is required to be further miniaturized from the conventional one having a cylindrical lead terminal. Therefore, the applicant first
A leadless rectangular solid electrolytic capacitor suitable for surface mounting as shown in FIG. 2 has been proposed (JP-A-4-1168).
No. 15).

FIGS. 3A to 3D are schematic perspective views of main steps for explaining the method of manufacturing the solid electrolytic capacitor shown in FIG. The conventional manufacturing method will be briefly described below. 2 and 3, the same components are designated by the same reference numerals.

In FIG. 3A, reference numeral 10 is a capacitor element, which is formed by winding each metal foil as an anode body and a cathode body through a separator. In this case, a description will be given by taking an example of a capacitor element in which an aluminum foil is used as each metal foil and a manganese dioxide layer is used as an electrolyte layer.
In this case, each aluminum foil may be subjected to a surface roughening treatment by etching, and when the aluminum foil is wound, a metal terminal (for example, an aluminum round bar) to be a terminal outlet of the capacitor element 10 in advance is wound. ) Attach 12 and 14 to each aluminum foil.

FIG. 3B shows the capacitor element 10 described above.
Is impregnated with manganese nitrate and baked to form a manganese dioxide layer, which is then inserted into the rectangular resin case 24 and sealed with the epoxy resin 22.

FIG. 3C shows a state in which the side surface of the rectangular resin case 24 on the side of the metal terminals 12 and 14 is cut into a predetermined length together with the epoxy resin 22 and the metal terminals 12 and 14.

In FIG. 3D, after the cutting step and after drying, the metal plate pieces 26 and 28 of the external connection terminals are exposed to the exposed metal terminals 12 and 14 by ultrasonic welding or laser welding. Attach by welding 30. Finally, as shown in FIG. 2, by printing the rating of the solid electrolytic capacitor, the polarity of the electrodes and the like on the resin case 24, a small solid electrolytic capacitor for surface mounting is completed.

FIG. 4 is a flow chart showing the main steps of the conventional method for manufacturing a solid electrolytic capacitor. That is, (A) capacitor element forming step,
(B) Capacitor element sealing step with resin such as epoxy resin after inserting the capacitor element into the resin case, (C)
It is manufactured in the order of a resin cutting step of cutting the resin case together with the metal terminal, and (D) a terminal welding step of attaching the external connection terminal.

[0009]

However, according to the method for manufacturing a solid electrolytic capacitor described above, in the terminal welding step (D) of attaching the external connection terminal to the metal terminal of the capacitor element after the resin is cut and dried. However, there is a problem in that the variation in the terminal welding strength is large and a low terminal welding strength is produced, which lowers the manufacturing yield.

Therefore, an object of the present invention is to suppress variations in the terminal welding strength and improve the terminal welding strength when welding the external connection terminals to the exposed metal terminals of the capacitor element after the resin cutting step. It is to provide a method for manufacturing a solid electrolytic capacitor that can increase the temperature.

[0011]

A method for manufacturing a solid electrolytic capacitor according to the present invention comprises a capacitor element forming step of forming a capacitor element to which metal terminals for a positive electrode and a negative electrode are attached, and the capacitor element forming step. Capacitor element sealing step of inserting into a resin case and sealing the inside of the resin case with a sealing resin in a state where the metal terminal projects outside, and the metal terminal of the capacitor element sealed in the resin case projects outside The resin cutting step of cutting the cut side together with the resin case to a predetermined length, the chemical polishing step of chemically polishing the cut surface exposed in the resin cutting step, cleaning and drying after cleaning, and the metal terminals of the exposed cut surface. And a terminal welding step of welding the external connection terminals to each other.

Further, in the above-mentioned manufacturing method, in the chemical polishing step, chemical polishing using an aqueous solution of sodium hydroxide is carried out, after polishing, washed with water, further immersed in an aqueous solution of nitric acid, washed again with water, then washed with ethanol, and then dried. It is suitable if it does.

[0013]

According to the method of manufacturing a solid electrolytic capacitor of the present invention, after the capacitor element forming step and the capacitor element sealing step, the cut surface exposed in the resin cutting step in the chemical polishing step is chemically polished, washed and dried. . With the addition of this chemical polishing step, the exposed metal terminal cut portion eliminates the roughness of the surface caused by scratches due to cutting, and removes the impurities adhering to the cut surface and the oxide film of the metal terminal to clean the metal terminal. Since the surface becomes a surface, defects on the surface of the welded portion in the next terminal welding step are reduced and the welding strength is improved.

[0014]

Embodiments of the method for manufacturing a solid electrolytic capacitor according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a process flow chart of main processes in a method of manufacturing a solid electrolytic capacitor showing an embodiment of the present invention. The difference between the process flow diagram in FIG. 1 and the process flow diagram of the main process of the conventional solid electrolytic capacitor manufacturing method shown in FIG. 4 is that a conventional resin cutting process (C) and a terminal welding process (D) are performed. The chemical polishing step (C ^* ) is added between the two.

Thereafter, similarly to the conventional example, each metal foil as an anode body and a cathode body is wound via a separator, an aluminum foil is used as each metal foil, and a manganese dioxide layer is used as an electrolyte layer in a capacitor element. Will be explained as an example,
Oxide film treatment is applied to the anode body that has been roughened by etching, and when polypyrrole is used as the organic solid electrolyte layer to form a capacitor element by stacking the anode body and the cathode body (not shown), a separator is not required. You can 3A to 3D of a conventional example are external perspective views of respective steps shown in FIGS. 3A to 3D, and FIGS. 1A to 1C are process flow diagrams of the manufacturing method of FIG. 1 according to the present invention. Since it corresponds to (D) and (D), the same reference numerals are used for convenience of description, and detailed description will be omitted.

As described above, the resin cutting step (C) is conventionally used.
In the above, in the state where the capacitor element 10 is sealed in the resin case 24 with the epoxy resin 22 or the like, the resin case 24 is cut to a predetermined length together with the metal terminals 12 and 14 made of aluminum round bars, and after drying, the terminal welding step ( In D), the metal plate pieces 26 and 28 of the external connection terminals were welded. Therefore, the welding 30 is performed on the surfaces of the metal terminals 12 and 14 which are damaged in the resin cutting step (C) and which are in a roughened state and have impurities or an oxide film of aluminum. Therefore, the welding strength tends to vary.

Therefore, in the manufacturing process according to the present invention, the chemical polishing step (C ^* ) is additionally inserted before the terminal welding step (D) to expose the metal terminal 1 exposed by the resin cutting step (C).
The smoothing and cleaning of the surfaces of the welded parts 2 and 14 were attempted. An example of the content of this chemical polishing step (C ^* ) is as follows.

After the completion of the resin cutting step (C), first, the sodium hydroxide aqueous solution is used as an abrasive to chemically polish the cut surface. As a result, the cut surfaces of the resin case 24 and the metal terminals 12 and 14 become smooth and the metal terminal 1
The oxide film formed on the exposed aluminum surfaces 2 and 14 is dissolved and removed.

Next, the sodium hydroxide aqueous solution used at the time of chemical polishing is thoroughly washed with running water, and then immersed in a nitric acid aqueous solution for a short time to remove impurities such as fine metallic debris attached to the surface during cutting. Dissolve and remove.

The chemical polishing step is completed when the nitric acid aqueous solution is sufficiently removed by washing with running water again and the organic deposits are dissolved and removed by washing with ethanol, and then dried.

After the chemical polishing process (C ^* ) is performed on the cut surface, the metal plate piece 26 of the external connection terminal,
28 is connected to the exposed metal terminals 12 and 14 by welding 30 such as ultrasonic welding or laser welding.

[0023]

As is apparent from the above-described embodiments, according to the present invention, the cut surface exposed in the resin cutting step is chemically polished in the chemical polishing step, washed and dried. By adding this chemical polishing step, the exposed cut portion of the metal terminal smoothes the surface caused by the scratches caused by the cutting step, and the impurities adhering to the cut surface and the oxide film on the metal terminal are removed to clean the metal terminal. Since the surface becomes a surface, defects on the surface of the welded portion in the next terminal welding step are reduced and the welding strength is improved. As a result, variations in terminal welding strength are suppressed,
The terminal welding strength can be improved and the manufacturing yield can be increased.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the spirit of the present invention. Is.

[Brief description of drawings]

FIG. 1 is a process flow chart of main processes showing an embodiment of a method for manufacturing a solid electrolytic capacitor according to the present invention.

FIG. 2 is an external perspective view of a leadless rectangular solid electrolytic capacitor to which the method for manufacturing a solid electrolytic capacitor according to the present invention is applied.

3 is a schematic perspective view of main steps for explaining a conventional method for manufacturing the solid electrolytic capacitor shown in FIG.

FIG. 4 is a process flow chart of main processes showing an example of a conventional method for manufacturing a solid electrolytic capacitor.

[Explanation of symbols]

 10 Capacitor element 12 Metal terminal 14 Metal terminal 22 Epoxy resin 24 Rectangular resin case 26 Metal plate piece 28 Metal plate piece 30 Welding

Claims (2)

[Claims] 1. A capacitor element forming step of forming a capacitor element to which respective metal terminals for a plus electrode and a minus electrode are attached, and a step of inserting the capacitor element into a resin case and projecting the metal terminals to the outside. Capacitor element sealing step of sealing the inside of the resin case with a sealing resin, and resin cutting step of cutting the side of the capacitor element sealed in the resin case to the outside with the resin case to a predetermined length And a chemical polishing step of chemically polishing the cut surface exposed in the resin cutting step, followed by cleaning and drying, and a terminal welding step of welding the external connection terminal to each metal terminal of the exposed cut surface. A method of manufacturing a solid electrolytic capacitor, comprising: 2. The chemical polishing step comprises performing chemical polishing using an aqueous solution of sodium hydroxide, rinsing with water after polishing, further immersing in an aqueous solution of nitric acid, rinsing again with water, then rinsing with ethanol, and then drying. The method for manufacturing the solid electrolytic capacitor according to claim 1.