JPH0770440B2 - Chip solid electrolytic capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Application Field Tantalum solid electrolytic capacitors are characterized by their small size and large capacity, and are very suitable for the recent trend toward miniaturization of electronic devices. In particular, there is a strong demand for chip-type products, and not only consumer equipment but also automobiles,
Demand for computers is expanding. The present invention relates to a small chip-shaped solid electrolytic capacitor used for consumer and industrial electronic devices.

2. Description of the Related Art As shown in FIG. 4, the conventional tantalum chip solid electrolytic capacitor has a porous metal electrode body 2 and a valve action metal such as tantalum aluminum having a circular cross section. No processing was applied to the wire 1, and the dielectric oxide film 3 was formed on the surface of the electrode body 2 including the anode lead wire 1.
And an electrolyte layer 4 of manganese dioxide or the like is further formed on the surface thereof to form a carbon layer 5, a cathode layer 6 and the like to form a capacitor element, and the cathode lead wire 1 of the capacitor element is welded to the capacitor element by means such as welding. A plate-shaped cathode terminal 7 having a shape as shown in FIG. 4 is connected, and then a cathode terminal 9 having a shape as shown in FIG. Then, both terminals are pulled out in opposite directions, and the terminals are bent inward toward the lower side of the capacitor body along the end face and the bottom face to form a chip solid electrolytic capacitor.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in such a conventional configuration, when the anode lead wire is connected to the anode terminal by welding, the capacitor element shakes its head up and down and is not necessarily parallel to the anode terminal. Often tilts upwards or downwards, that is, the anode,
Since the horizontal surfaces of both terminals of the cathode are not accurately projected on the same horizontal surface, when setting both terminals by sandwiching them in the mold and applying resin molding by the transfer molding method, the lead-out root of the capacitor element anode lead wire There was a problem that mechanical stress was applied to the capacitor, the leakage current of the capacitor was increased, and the manufacturing yield was deteriorated.

The present invention solves such a problem, and an object of the present invention is to provide a chip-shaped solid electrolytic capacitor having a structure that prevents stress from being applied to a capacitor element and having a high manufacturing yield.

Means for Solving the Problem In order to solve this problem, the present invention provides a recess in a part of an anode lead wire between a capacitor element and an anode terminal to form a weak portion having a small thickness and a small tensile strength. It is formed in parallel with the vertical surface of the capacitor body. Then, the thickness of the recess is set to be 1/2 or less of the wire diameter.

Operation With such a structure, when the anode lead wire is connected to the anode terminal by welding, even if the capacitor element and the anode terminal are not parallel to each other and may tilt upward or downward, that is, Even if the horizontal planes of both terminals do not appear accurately on the same horizontal plane, the concave portion with small tensile strength that bends easily in the vertical direction absorbs physical strain applied from the vertical direction and prevents stress applied to the root of the anode lead wire. Therefore, damage to the capacitor element can be prevented.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings of FIGS. In addition, in FIG. 1 to FIG.
The same parts as those shown in the figure are designated by the same reference numerals.

As shown in FIG. 1, a tantalum wire having a circular cross section with a diameter of 0.3 mm is embedded in 100 mg of tantalum metal powder, pressed, and then sintered by a general method to obtain a tantalum anode lead wire 1.
A porous electrode body 2 for 6V 47uF having 6V is obtained, and at the upper and lower positions of about 1.0 mm from the lead-out base portion 11 of the anode lead-out wire 1, press-shaped recesses of substantially the same shape are formed. A rolling part 12 having a rolling width of 0.3 mm and a rolling thickness of 0.1 mm was formed. After that, the electrode body 2 including the rolling part 12 is anodized.
A dielectric oxide film 3 is formed on the surface of the capacitor by a general method, an electrolyte layer 4 of manganese dioxide or the like is further formed on the upper surface thereof, and a carbon layer 5, a cathode layer 6 and the like are sequentially formed to form a capacitor element. And Next, between the welded portion 13 of the anode terminal 7 and the capacitor element, the rolled portion 12 of the anode lead wire 1 is provided.
The anode terminal 7 and the anode lead-out wire 1 so that the recess is located in parallel with the upper and lower surfaces of the capacitor body, and then the cathode portion of the capacitor element is connected to the cathode terminal 9 with solder or conductive adhesive 8 Etc., and then set them in a transfer mold so that both terminals are pulled out at opposite ends, and mold-encapsulate with the exterior resin 10. Was bent inward to obtain a chip solid electrolytic capacitor.

The formation of the portion of the anode lead wire having a small tensile strength must be performed by rolling or the like before anodizing. After forming a dielectric oxide film by anodic oxidation,
This is because when rolling is performed after forming the electrolyte layer of manganese dioxide or the like, that is, after forming the capacitor element, impact and stress at the time of working are applied to the root portion to increase the leakage current.

It is desirable that the thickness of the rolled portion 12 is as thin as possible in each manufacturing process so as not to hinder the tensile strength in the vertical direction. However, from the drawing root 11 of the anode lead wire 1 to the welding point of the anode terminal 7. When the rolling distance is within 4 mm and the rolling width is in the range of 0.15 to 1.0 mm, the strain applied in the vertical direction can be sufficiently absorbed if the thickness of the rolled portion 12 is 1/2 or less of the diameter of the anode lead wire 1.
About this, the result confirmed experimentally is shown in FIG. This is a measurement of the change in leakage current when the anode lead wire between the 6V 47uF capacitor element and the weld is bent 90 degrees.As you can see from the figure, the leakage current decreases as the rolled part becomes thinner. Increase of 0.15mm
From [1/2 of wire diameter] or less, there is no increase in leakage current. That is, this rolling part absorbs the mechanical stress applied from the outside in the vertical direction and prevents the force applied to the root part of the capacitor element.

In addition, the 6V 47uF capacitor element with the 0.1 mm rolled part molded with epoxy resin has a defective rate of 1.2% compared to the conventional structure with a defective rate of 10%. I was able to improve.

EFFECTS OF THE INVENTION As described above, according to the present invention, the following effects can be obtained.

1 At the same time as absorbing the stress applied in the manufacturing process, the mechanical stress applied in the vertical direction during transfer molding can be absorbed, and the yield can be greatly improved.

2 It is possible to obtain a stable chip capacitor that is resistant to thermal shock.

[Brief description of drawings]

FIG. 1 is a sectional view of a chip solid electrolytic capacitor according to an embodiment of the present invention, FIG. 2 is an enlarged perspective view of a main part of the capacitor, and FIG. 3 is a characteristic diagram for explaining the effect of the capacitor. FIG. 4 is a sectional view of a conventional chip solid electrolytic capacitor. 1 ... Anode lead wire, 2 ... Electrode body, 3 ... Oxide film, 4
...... Electrolyte layer, 5 ...... Carbon layer, 6 ...... Conductor layer, 7
…… Anode terminal, 9 …… Cathode terminal, 10 …… Exterior resin, 11…
… Root part, 12 …… Rolling part, 13 …… Welding part.

Claims (1)

[Claims] Claim: What is claimed is: 1. A dielectric oxide film is formed on the surface of an electrode body having an anode lead wire, and an electrolyte layer and a cathode layer are formed on the oxide film to form a capacitor element. And molded into a capacitor main body by means of, and the anode lead wire and the cathode terminal connected to the cathode layer and the cathode terminal are drawn out from the exterior resin and bent along the outer surface of the capacitor main body, and A recess is formed at a position within 4.0 mm from the root of the anode lead wire so that the thickness thereof is approximately 1/2 or less of the diameter of the anode lead wire, and a dielectric is formed on the surface of the electrode body including the recess. A positive oxide wire is formed, and the anode lead wire is provided with an anode terminal, and a concave portion of the anode lead wire is arranged between the welded portion and the capacitor element, and the concave portion forms an upper surface or a lower surface of the capacitor body. Chip solid electrolytic capacitor connected by welding so as to be positioned in line relationship.