JPH065474A - Solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain a solid electrolytic capacitor which can be simply manufactured at a low cost and has a terminal structure for external connection capable of preventing defective packaging. CONSTITUTION:A terminal 40 for external connection is constituted of a metal foil layer 44 previously coated with an adhesive agent layer 42 composed of epoxy based resin or the like having large adhesion to sealing resin 16 and a resin case 14, and a weld part 24 of the metal foil 44 and an inner electrode 20 are welded by using laser welding or the like. In this case, the adhesive agent layer 42 of the weld part 24 may be omitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leadless type solid electrolytic capacitor suitable for surface mounting on a printed circuit board or the like used in small electronic equipment, and more particularly to improvement of a terminal structure for external connection thereof. .

[0002]

2. Description of the Related Art Generally, in response to a demand for miniaturization and portability of electronic equipment, solid electrolytic capacitors used in these equipment are required to be compact and easy to be surface-mounted. For this reason, at present, the conventional lead terminal type is changed to the leadless type.

A brief description of this type of leadless solid electrolytic capacitor will now be given with reference to FIG.
The solid electrolytic capacitor 10 includes a capacitor element 12 (see FIG.
Is also housed in a resin case 14 and sealed with a potting resin 16 for sealing, such as an epoxy resin, the sealing side is cut, and the cut surface 18 (FIG. 5) is provided with an internal electrode 20 of the capacitor element 12. , 20 exposed and then connected to the internal electrodes 20, 20 for external connection terminals 22, 22
Is bent and attached so as to straddle the cut surface 18 and one side surface 14a of the resin case 14. The internal electrode 20 and the bent piece 22a on the side of the cut surface 18 of the external connection terminal 22 are usually bonded by laser welding 24 (FIG. 5). In this solid electrolytic capacitor 10, as shown in FIGS. 4 and 5, the bent piece 22b on the resin case 14 side of the external connection terminal 22 is soldered 28 to the printed circuit board 26 so as to be in contact with the printed circuit board 26. Surface mounted.

In the conventional solid electrolytic capacitor 10, however, the external connection terminal 22 has the cut surface side bent piece 2.
Only the internal electrode 20 of 2a is bonded, and the resin case side bent portion 22b is free. Therefore, when mounting by soldering 28, the external connection terminal 2
When a force in the expanding direction acts on 2, the solid electrolytic capacitor 1
0 is not only lifted in the direction of the arrow 29 (tombstone phenomenon or Manhattan phenomenon), but in some cases, the laser welding 24 at the internal electrode 20 portion peels off (hereinafter referred to as mounting failure).

Therefore, the present applicant previously developed a new technique for preventing such a mounting defect and filed a patent application (Japanese Patent Application No. 3-347269 and Japanese Utility Model Application No. 3-50).
928). Hereinafter, these techniques will be briefly described. In the former case, as shown in FIG.
The resin case side bent piece 22b end portion 22c is configured to be embedded and fixed in the resin case side surface 14a (hereinafter, referred to as bent piece fixing means). In the latter, as shown in FIG. 7, basically, the cut surface side bent piece 22a and / or the resin case side bent piece 22b of the external connection terminal 22 are covered and held by the heat resistant insulating tape 30. (Hereinafter, referred to as a holding tape means). Therefore, according to this technique, when soldering and mounting, even if a force in the expanding direction acts on the external connection terminal 22, the mounting failure does not occur.

[0006]

However, the above-mentioned conventional techniques still have drawbacks to be improved. That is, first, the former bent piece fixing means is to embed and fix the end of the bent piece by applying ultrasonic waves or heat while pressing the end of the bent piece against the side surface of the resin case. The latter holding tape means heat-presses the heat-resistant resin tape to the cut surface (sealing resin) and the side surface of the resin case, thereby thermocompressing the tape to the cut surface and the side surface of the resin case.
However, all of these operations are complicated and require many steps, which causes a problem of increasing the product cost.

Therefore, an object of the present invention is to provide a solid electrolytic capacitor which can be manufactured easily and inexpensively and which can surely prevent mounting failure.

[0008]

In order to achieve the above object, a solid electrolytic capacitor according to the present invention is constructed such that a capacitor element is housed in a resin case and sealed with resin, and then the sealing side is cut. A solid electrolytic capacitor in which an internal electrode of the capacitor element is exposed, and then an external connection terminal connected to the internal electrode is bent and attached so as to straddle the cut surface and one side surface of the resin case. In the above, the external connection terminal is constituted by a metal foil layer which is previously coated with an adhesive layer having strong adhesiveness to a sealing resin and a resin case, and a contact portion between the metal foil and the internal electrode is welded. It is characterized in that it is configured to.

In the above solid electrolytic capacitor, the adhesive is composed of an epoxy adhesive, and the contact portion between the metal foil and the internal electrode is laser welded and the adhesive layer at the contact portion is absent. Can be configured to.

[0010]

According to the electrolytic capacitor of the present invention, the external connection terminal can be formed by bonding the metal foil layer having the strong adhesive layer. Therefore, the manufacturing process can be simplified, the manufacturing can be performed at low cost, and the adhesion to the sealing resin and the resin case can be strengthened to reliably prevent the mounting failure.

[0011]

Embodiments of the solid electrolytic capacitor according to the present invention will be described below in detail with reference to the accompanying drawings. For convenience of explanation, the same components as those of the conventional structure shown in FIGS. 3 to 7 are designated by the same reference numerals, and detailed description thereof will be omitted.

First, the structure of the solid electrolytic capacitor according to the present invention is basically the same as that of the conventional one described above. That is, although overlapping, it will be explained again. In FIG. 1 and FIG. 2, the solid electrolytic capacitor 10 stores the capacitor element 12 in the resin case 14, seals it with the potting resin 16 for sealing, and then cuts this sealing side. The internal electrode 20 of the capacitor element 12 on the cut surface 18 of the lever,
20 is exposed, and external connection terminals 40, 40 connected to the internal electrodes 20, 20 are formed so as to straddle the cut surface 18 and the side surface of the resin case 14.

However, in the external connection terminal 40 of this embodiment, an adhesive layer 42 having a strong adhesiveness to the sealing resin 16 and the resin case 14, preferably an adhesive layer made of an epoxy resin, is used. Pre-coated metal foil layer 44
It consists of. Then, the metal foil 44 and the internal electrode 2
The contact portion with 0 is welded 24 (FIG. 2) by laser welding or the like. In this case, the adhesive layer 4 at the contact portion
2 may be omitted.

As described above, according to the present invention, the external connection terminal can be formed by bonding the metal foil layer having the strong adhesive layer, so that the manufacturing process is simplified and the cost can be reduced. Also, the adhesion to the sealing resin and the resin case becomes firm, and the mounting failure can be surely prevented.

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

[0016]

As described above, in the solid electrolytic capacitor according to the present invention, the capacitor element is housed in the resin case and sealed with resin, and then the sealing side is cut to remove the internal electrode of the capacitor element. In a configuration in which the external connection terminal to be exposed and then connected to the internal electrode is bent and attached so as to straddle the cut surface and the side surface of the resin case, the external connection terminal is connected to the sealing member. An adhesive layer having a strong adhesiveness with respect to the resin and the resin case is constituted by a metal foil layer coated in advance, and the metal foil and the internal electrode are formed by welding the contacting portion.
The external connection terminal can be manufactured by adhering a metal foil layer having a strong adhesive layer, which simplifies the manufacturing process, can be manufactured at low cost, and strengthens the adhesion to the sealing resin and the resin case. It is possible to reliably prevent mounting defects.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a solid electrolytic capacitor according to the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a perspective view showing a structure of a terminal for external connection of a conventional solid electrolytic capacitor.

FIG. 4 is a perspective view showing a mounting state of the solid electrolytic capacitor shown in FIG. 3 on a printed board.

5 is a sectional view taken along line VV of FIG.

FIG. 6 is a perspective view showing another configuration example of a conventional external connection terminal structure of a solid electrolytic capacitor.

FIG. 7 is a perspective view showing still another configuration example of the external connection terminal structure of the conventional solid electrolytic capacitor.

[Explanation of symbols]

10 Solid Electrolytic Capacitor 12 Capacitor Element 14 Resin Case 14a Side 16 Sealing Resin 18 Cut Surface 20 Internal Electrode 24 Welding (Contact) 26 Printed Circuit Board 28 Soldering 30 Heat Resistant Insulation Tape 40 External Connection Terminal 42 Adhesive Layer 44 Metal Foil layer

Claims (2)

[Claims] 1. A capacitor element is housed in a resin case and sealed with a resin. Then, the sealing side is cut to expose an internal electrode of the capacitor element, and an external connection terminal for connecting to the internal electrode is then provided. In a solid electrolytic capacitor that is bent and attached so as to straddle the cut surface and one side surface of the resin case, the external connection terminal has strong adhesion to the sealing resin and the resin case. A solid electrolytic capacitor, characterized in that the adhesive layer is composed of a metal foil layer coated in advance, and a contact portion between the metal foil and the internal electrode is welded. 2. The solid electrolytic capacitor according to claim 1, wherein an adhesive layer is absent at a contact portion of the metal foil layer with the internal electrode.