JPH0669084A - Lamination type solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To improve yield when welding the anode part and the lead frame of a lamination type solid electrolytic capacitor and to achieve welding regardless of the number of lamination layers. CONSTITUTION:A metal plate 6 with a projection is provided between anode parts 1 and is connected to a lead frame 5, thus reducing the damage to a capacitor on connection as compared with a method for connecting the lead frame 5 directly to the anode parts and achieving connection regardless of the number of lamination layers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a laminated solid electrolytic capacitor.

[0002]

2. Description of the Related Art Conventional solid electrolytic capacitors, for example, aluminum solid electrolytic capacitors, etch the surface of aluminum foil to increase the surface area per unit area of the foil to form an oxide film, which is used as a dielectric. A conductive polymer or the like is formed on the aluminum foil to form an anode and the conductive polymer or the like as a cathode to form a capacitor.

Since such an aluminum solid electrolytic capacitor has a structure based on aluminum foil, the dimension in the thickness direction is extremely smaller than that in the length and width directions. Therefore, by laminating such an aluminum solid electrolytic capacitor in the thickness direction, a laminated solid electrolytic capacitor having a large capacity and good volume efficiency can be obtained.

FIG. 3 shows a vertical section of a conventional laminated solid electrolytic capacitor. The surface of the metal foil is etched to form a conductive polymer layer, a graphite layer, and a silver paste layer on a part of the surface of the anode part 1 on which an oxide film is formed to form a cathode part 2.
Configure the individual capacitors. Further, a plurality of these capacitors are laminated, and a conductive adhesive 3 is provided between the cathode parts 2,
A metal plate 4 for filling the difference in thickness between the anode part 1 and the cathode part 2 is inserted between the anode parts 1 and connected by resistance welding or laser welding. The cathode part 2 is connected to the lead frame 5 by a conductive adhesive 3 and the anode part 1 is connected by resistance welding.

[0005]

In this conventional laminated solid electrolytic capacitor, the lead frame 5 and the anode part 1 are connected by resistance welding. Therefore, the capacitor may be deformed due to the stress caused by the welding electrode and the characteristics may be deteriorated, or the welding current may flow into the capacitor side to destroy the capacitor, resulting in a problem that characteristic defects occur in this process.

Further, in such a structure, there is a problem that as the number of laminated capacitors increases, the distance between the welding electrodes becomes longer and welding becomes difficult.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a laminated solid electrolytic capacitor which eliminates characteristic defects that occur when a lead frame is welded to an anode part and which can be welded under stable welding conditions regardless of the number of laminated layers.

[0008]

The laminated solid electrolytic capacitor of the present invention is provided with a metal plate in the form of a protrusion for connecting to the lead frame at the anode part.

[0009]

The present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view and a perspective view of a laminated solid electrolytic capacitor according to an embodiment of the present invention.

A conductive polymer made of polypyrrole is formed on a part of the surface of the anode part 1 made of aluminum foil having a length of 4 mm, a width of 3 mm, and a thickness of 150 μm, which has an oxide film formed after the surface is etched by a known method. A graphite layer and a silver paste layer were sequentially formed, and as the cathode part 2, one capacitor element having a rated voltage of 16 V and a capacity of 1.5 μF was obtained.

Next, the metal plate 4 is resistance-welded to the anode portion 1. At this time, a metal plate 6 with a protrusion having a shape for attaching to the lead frame 5 in a later step is resistance-welded to the capacitor which is at an intermediate position during lamination.

Next, the cathode portion 2 is coated with a conductive adhesive and laminated, and then cured in a constant temperature bath at 150.degree. A laser beam is applied between the anode parts 1 from the side of the metal plate 6 with the protrusions having the protrusions.
The two ends of the are swept in the stacking direction and welded.

Next, the metal plate 6 with protrusions and the lead frame 5
Are resistance-welded, mold-molded, and aged to form a capacitor having a rated voltage of 16 V and a capacity of 4.7 μF.

Conventionally, when the anode part 1 and the lead frame 5 were directly resistance-welded, the characteristic defect was about 10% as shown in the table below, whereas in the present embodiment, the characteristic defect did not occur. Further, by adopting such a structure, there is no limitation on the number of layers that can be welded to the lead frame, and welding can be performed under constant welding conditions regardless of the number of layers.

FIG. 2 is a sectional view and a perspective view of another embodiment of the present invention. In this embodiment, the shape of the protruding metal plate 6 is shown in FIG.
It is assumed that there are two protrusions on both sides. As a result, at the time of laser welding the anode part 1, it is only necessary to sweep the laser once in the central part, and the laser welding time can be shortened. In addition, in the present embodiment as well, no characteristic failure occurred during welding of the anode part 1 and the lead frame 5, and the same effect as in the first embodiment was confirmed.

Table 1 shows the characteristic defect ratios at the time of lead frame welding of the first and second embodiments of the present invention and the conventional example. In both of the first and second embodiments, the leakage current defect and the capacity are large. Defects and tan δ defects were 0%.

Table 1

[0018]

As described above, according to the present invention, by providing a metal plate having a projection for connection with a lead frame on the anode part, the characteristic defect that occurs during welding with the lead frame is eliminated, and The effect is that welding can be performed under stable welding conditions regardless of the number of laminated layers.

[Brief description of drawings]

FIG. 1 is a vertical sectional view and a perspective view of an embodiment of the present invention.

FIG. 2 is a vertical sectional view and a perspective view of another embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view of an example of a conventional laminated solid electrolytic capacitor.

[Explanation of symbols]

 1 Anode part 2 Cathode part 3 Conductive adhesive 4 Metal plate 5 Lead frame 6 Metal plate with protrusions

Claims (1)

[Claims] 1. A plurality of metal foils having a valve action as an anode, a dielectric oxide film formed on the surface of the metal foil, and a conductive polymer or an inorganic semiconductor formed on the dielectric oxide film as a cathode. In a laminated solid electrolytic capacitor formed by stacking individual pieces, a metal plate is provided between the anodes of the laminated solid electrolytic capacitor, and one of them has a shape protruding from the anode and the metal plate. A laminated solid electrolytic capacitor having a lead frame connected to the protrusion.