JPH0722280A - Chip solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To prevent positional shift at the time of mounting a chip capacitor on a board by filling a notch, made in the side face of the capacitor at the lead out position of a lead frame, with a resin as thick as the lead frame while projecting from the side face of the capacitor. CONSTITUTION:An outer electrode comprising a pair of lead frames 2 is lead out from the side face of a capacitor 1 provided with a notch at the lead out position. The notch is filled with a resin 4 as thick as the lead frame 2 while projecting from the side face of the capacitor 1. Since the lead frame 2 is flush with the resin 4 on the side face of the capacitor, the strength is not lowered by the notch in the lead frame and positional shift is prevented at the time of mounting the chip capacitor on a board resulting in a chip solid electrolytic capacitor excellent in moisture resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor, and more particularly to a chip solid electrolytic capacitor having good solderability.

[0002]

2. Description of the Related Art A conventional chip-shaped solid electrolytic capacitor is
As shown in FIG. 2, an external terminal composed of a pair of lead frames 2 is led out from the side surface of the capacitor, and the capacitor element is bent into an L-shape along the capacitor 1 sealed with resin for practical use. On the other hand, in a harsh environment, a solid electrolytic capacitor, which requires higher reliability, has a structure as shown in FIG. 3 for the purpose of preventing moisture from invading through the external terminal. Solid electrolytic capacitors have been proposed.

That is, FIG. 3 shows a state in which the cutout portion 3 exists at the lead-out position on the side surface of the capacitor of the lead frame 2 which is led out from the side surface of the capacitor 1, and the presence of the cutout portion serves to connect the external terminal. It is designed to reduce the amount of moisture transmitted.

[0004]

However, when the notch is provided in the external terminal as described above, the strength of the external terminal is reduced. For example, when the chip solid electrolytic capacitor is mounted on the substrate by solder cream, The external terminals may be distorted due to the curing force of the solder, causing a displacement of the chip-shaped solid electrolytic capacitor at a predetermined position on the substrate.

[0005]

The present invention has been made in order to solve the above-mentioned problems, and the gist thereof is that there is a notch at the lead-out position on the side surface of the capacitor of the lead frame, and the notch is provided in the notch. This is a chip solid electrolytic capacitor in which the resin corresponding to the thickness of the lead frame is projected and embedded from the side surface of the capacitor.

The present invention will be described in more detail below. Figure 1
FIG. 3 is a schematic view showing an example for explaining the chip solid electrolytic capacitor of the present invention. In FIG. 1, an external electrode composed of a pair of lead frames 2 is led out from a side surface of a capacitor 1, a cutout portion is provided at a lead-out position on the side surface of the capacitor, and the resin 4 for the thickness of the leadframe 2 is provided in the cutout portion. The state where the capacitor 1 is projected and embedded from the side surface of the capacitor 1 is shown. That is, in FIG. 1, the lead frame 2 and the resin 4 are flush with each other on the lead frame lead-out side surface of the capacitor.

It should be noted that in FIG. 1, the resin surface other than 2 and 4 on the lead frame lead-out side of the capacitor is shown lower than the resin surfaces 2 and 4 by the thickness of the lead frame.
It goes without saying that it may be on the same plane as.

As the solid electrolytic capacitor element of the present invention, a conventionally known aluminum solid electrolytic capacitor element or tantalum solid electrolytic capacitor element formed of a substrate such as aluminum and tantalum is used, and the negative and positive electrodes of each capacitor element form a pair of leads. Each is electrically connected to the frame. The above-mentioned capacitor element is sealed with a resin or the like, and the pair of lead frames are led out to the outside from the side surfaces of the capacitor and are bent into an L shape along the capacitor body.

Further, the pair of lead frames has a notch at the lead-out position on the side surface of the capacitor, and the shape thereof may be any shape such as a quadrangle and a pentagon, but when the capacitor is left under high humidity, the lead frame may be lead. In order to prevent moisture from entering the inside of the condenser through the frame, it is important to make the cutout portion of the portion directly led out from the condenser large. In addition, the size of the cutout portion of the lead frame provided on the side surface of the capacitor is determined by mounting the manufactured chip-shaped solid electrolytic capacitor on the substrate by soldering.
It is determined by preliminary experiments etc. so that solder failure does not occur.

Further, according to the present invention, it is necessary that the above-mentioned cutout portion of the lead frame is filled with the resin for the thickness of the lead frame so as to project from the side surface of the capacitor.

As the resin used in the present invention, known resins such as epoxy resin, phenol resin, melamine resin and arylate resin can be adopted. As a method of embedding such a resin in the notch portion of the lead frame, as described above, the lead frame is processed into an L shape along the capacitor body, and then the resin is introduced from the outside to be hardened and the capacitor element is preliminarily set. There is a method in which the resin to be sealed itself is designed including the protruding portion in anticipation of the cutout portion of the lead frame, and it is manufactured at the same time as the sealing.However, the method described below is used in order not to increase the manufacturing time of the capacitor. preferable. In the case of the method described below, the notch portion of the lead frame fits into the protruding portion at the time of sealing.

[0012]

Since the resin corresponding to the thickness of the lead frame is embedded in the notch portion of the lead frame so as to project from the side surface of the capacitor, there is no reduction in strength due to the notch of the lead frame.

[0013]

EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples.

Examples 1 to 3 and Comparative Examples 1 to 3 Small pieces of aluminum etching foil of 45 μF / cm ² having a dielectric oxide film layer formed on the surface by chemical conversion treatment in an aqueous solution of phosphoric acid and ammonium phosphate 5 mm × 3 mm Is soaked in a mixed solution of an aqueous solution of lead acetate trihydrate (2.4 mol / liter) and ammonium persulfate (4.0 mol / liter) so that the small pieces (3 mm × 3 mm) are immersed, and the mixture is allowed to stand at 60 ° C. for 20 minutes, and then dioxide is added. A semiconductor layer made of lead and lead sulfate was formed.

After performing such an operation three times, a carbon paste and a silver paste were sequentially laminated on the semiconductor layer to form a conductor layer.

On the other hand, a lead frame having a pair of separately prepared protrusions (thickness 0.1 mm, protrusion width 3.2 mm)
The anode part of the capacitor element and a part of the conductor layer forming part were placed on the respective convex parts, and the former was connected by welding and the latter was connected by silver paste. Subsequently, the lead frame was partially removed by transfer molding using epoxy resin, and the length was 7.3 mm, width was 4.3 mm, and height was 2.8 mm.
A molded body of was obtained.

Further, the lead frame led out from the middle of the side surface of the capacitor was bent into an L shape along the capacitor body to obtain a chip solid electrolytic capacitor. In addition, in Examples 1 to 3 and Comparative Examples 1 and 2 using the above-mentioned capacitors,
The notch shown in Table 1 was provided at the lead-out position on the side surface of the capacitor of the lead frame.

Further, in Examples 1 to 3, the cutout portion of the lead frame is projected from the side surface of the capacitor by transfer molding with a mold designed to fill the cutout portion with the sealing resin, and the cutout portion is made of epoxy resin. buried.

[0019]

[Table 1]

100 points of each of the chip-shaped solid electrolytic capacitors obtained in the above-mentioned Examples and Comparative Examples were replaced with a land area of 3.5 m.
The number of misaligned parts when soldering to a m × 2 mm substrate at 230 ° C. for 10 seconds in a reflow furnace, and the capacitor when left to stand at 60 ° C. and 90% RH in humidity for 500 hours. The rate of change in capacity is shown in Table 2.

[0021]

[Table 2]

[0022]

According to the chip solid electrolytic capacitor of the present invention, there is a notch at the lead-out position on the side surface of the capacitor of the lead frame, and the resin corresponding to the thickness of the lead frame protrudes from the side surface of the capacitor in the notch. Since the chip-shaped solid electrolytic capacitor thus manufactured is embedded in the substrate, there is no displacement when mounted on the substrate, and the moisture resistance performance is good.

[Brief description of drawings]

FIG. 1 is a schematic view showing a state in which a lead-out portion led out from a side surface of a capacitor has a cutout portion at a lead-out position, and a resin is projected and embedded in the cutout portion from a side surface of the capacitor.

FIG. 2 is a front view showing the shape of an external terminal of a conventional chip solid electrolytic capacitor.

FIG. 3 is a schematic view showing a conventional chip-shaped solid electrolytic capacitor having a notch portion on a lead frame.
Incidentally, in order to facilitate understanding, the inside which cannot be seen from the outside is partially shown by a dotted line.

[Explanation of symbols]

 1 Capacitor 2 Lead frame 3 Notch part of lead frame 4 Resin

Claims (1)

[Claims] 1. An external terminal composed of a pair of lead frames is led out from the side surface of the capacitor and L is provided along the capacitor body.
In the chip-shaped solid electrolytic capacitor bent into a letter shape, there is a notch at the lead-out position on the capacitor side face of the lead frame, and the notch is filled with resin for the thickness of the lead frame protruding from the capacitor side face. The chip-shaped solid electrolytic capacitor characterized in that