JP3129033B2 - Chip-shaped solid electrolytic capacitor - Google Patents

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 solid electrolytic capacitor having good solderability.

[0002]

2. Description of the Related Art Conventional chip-shaped solid electrolytic capacitors are:
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 in which the capacitor is sealed with resin, and is used for practical use. On the other hand, when the use environment is severe, a chip including external terminals having a configuration as shown in FIG. 3 is used as a solid electrolytic capacitor requiring higher reliability in order to prevent moisture from entering through the external terminals and entering. Solid electrolytic capacitors have been proposed.

[0003] That is, FIG. 3 shows a state in which a cutout portion 3 is present at a lead-out position of a side surface of a capacitor of a lead frame 2 led out from a side surface of a capacitor 1, and an external terminal is connected by the presence of the cutout portion. It is configured to reduce the amount of transmitted moisture.

[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 a chip-shaped solid electrolytic capacitor is mounted on a substrate by solder cream, The external terminals are distorted due to the hardening force of the solder, and a predetermined position of the substrate of the chip-shaped solid electrolytic capacitor may be shifted.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the gist of the present invention is that a notch is provided at a lead-out position of a side surface of a capacitor of a lead frame. This is a chip-shaped solid electrolytic capacitor in which resin corresponding to the thickness of the lead frame is embedded so as to protrude from the side surface of the capacitor.

Hereinafter, the present invention will be described in more detail. FIG.
FIG. 1 is a schematic view showing an example for explaining a chip-shaped solid electrolytic capacitor of the present invention. FIG. 1 shows that an external electrode composed of a pair of lead frames 2 is led out from a side surface of a capacitor 1, and a cutout portion is provided at a lead-out position on a side surface of the capacitor, and a resin 4 having a thickness of the lead frame 2 is provided in the cutout portion. This shows a state where the capacitor 1 is buried protruding from the side surface of the capacitor 1. 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.

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

The solid electrolytic capacitor element of the present invention uses a conventionally known aluminum solid electrolytic capacitor element or a tantalum solid electrolytic capacitor element formed from a substrate such as aluminum and tantalum, and the negative electrode of each capacitor element has a pair of leads. Each is electrically connected to the frame. The above-described capacitor element is sealed with a resin or the like, and the pair of lead frames is led out from the side surface of the capacitor, and is bent in an L shape along the capacitor body.

The pair of lead frames has a notch at the lead-out position on the side surface of the capacitor, and may have any shape such as a square or a pentagon. It is important to increase the size of the cut-out portion directly derived from the capacitor so that moisture does not enter the capacitor through the frame. Also, the size of the notch of the lead frame provided on the side of the capacitor, when mounting the manufactured chip-shaped solid electrolytic capacitor on the board with solder,
It is determined by a preliminary experiment or the like so as not to cause a solder defect.

Further, in the present invention, it is necessary that a resin corresponding to the thickness of the lead frame is embedded in the cutout portion of the lead frame so as to protrude 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 employed. As described above, as a method of embedding such a resin in a cutout portion of a lead frame, a lead frame is processed into an L-shape along a capacitor body as described above, and then a resin is introduced from the outside and cured, and a capacitor element is prepared in advance. The sealing resin itself is designed to include the protruding part in anticipation of the cutout part of the lead frame, and there is a method of manufacturing simultaneously with the sealing.However, the method described later is used in order not to increase the number of manufacturing steps of the capacitor. preferable. In the case of the method described later, the cutout portion of the lead frame fits into the protrusion at the time of sealing.

[0012]

Since the resin corresponding to the thickness of the lead frame protrudes from the side of the capacitor and is buried in the notch of the lead frame, there is no reduction in strength due to the notch in the lead frame.

[0013]

The present invention will be described below with reference to examples and comparative examples.

[0014] pieces 5 mm × 3 mm aluminum etched foil of Examples 1 to 3 and Comparative Examples 1~3 45μF / cm ² of forming a dielectric oxide layer on the chemical conversion treatment to the surface by phosphoric acid and phosphate in the acid aqueous solution of ammonium Was immersed in a mixture of an aqueous solution of lead acetate trihydrate (2.4 mol / l) and an aqueous solution of ammonium persulfate (4.0 mol / l) such that 3 mm x 3 mm of small pieces were immersed in the mixture and allowed to stand at 60 ° C for 20 minutes. A semiconductor layer made of lead and lead sulfate was formed.

After these operations were performed 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, width of protrusions 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 by silver paste. Then, except for a part of the lead frame, it was sealed by transfer molding with epoxy resin, and the length was 7.3 mm, the width was 4.3 mm, and the height was 2.8 mm.
Was obtained.

Further, a lead frame led out from the middle of the side surface of the capacitor was bent in an L shape along the capacitor body to obtain a chip-shaped solid electrolytic capacitor. In Examples 1 to 3 and Comparative Examples 1 and 2 using the above-described capacitors,
Notches shown in Table 1 were provided at lead-out positions on the side surfaces of the capacitors.

In the first to third embodiments, the notch of the lead frame is protruded from the side of the capacitor by epoxy molding by transfer molding with a mold designed to fill the notch with a sealing resin. buried.

[0019]

[Table 1]

The chip-shaped solid electrolytic capacitors obtained in the above Examples and Comparative Examples were each 100 points each having a land area of 3.5 m.
The number of misalignments when a substrate is mounted in a reflow furnace at 230 ° C. for 10 seconds using solder on a substrate of mx 2 mm, and the capacitor when the substrate is left in a humidity of 60 ° C. and 90% RH for 500 hours after the substrate is mounted. Table 2 shows the rate of change in capacity.

[0021]

[Table 2]

[0022]

According to the chip-shaped solid electrolytic capacitor of the present invention, the lead frame has a notch at the lead-out position on the side of the capacitor, and the resin corresponding to the thickness of the lead frame protrudes from the side of the capacitor at the notch. Since the chip-shaped solid electrolytic capacitor is buried, there is no displacement of the manufactured chip-shaped solid electrolytic capacitor at the time of attaching the substrate, and the moisture resistance is also good.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a state in which a cutout portion is provided at a lead-out position of a lead frame led out from a side surface of a capacitor, and the cutout portion is filled with resin protruding from a side surface of the capacitor.

FIG. 2 is a front view showing the shape of external terminals of a conventional chip-shaped solid electrolytic capacitor.

FIG. 3 is a schematic view showing a conventional chip-shaped solid electrolytic capacitor having a cutout portion in a lead frame.
In addition, in order to make it easy to understand, the inside which cannot be seen from the outside is partially shown by a dotted line.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capacitor 2 Lead frame 3 Notch of lead frame 4 Resin

Continuation of the front page (56) References JP-A-3-89508 (JP, A) JP-A-59-131143 (JP, U) JP-A-61-76954 (JP, U) JP-A-55-77840 (JP) , U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01G 9/004 H01G 9/08

Claims (1)

(57) [Claims] 1. An external terminal comprising a pair of lead frames is led out from a side surface of a capacitor, and is extended along a capacitor body.
In the chip-shaped solid electrolytic capacitor bent in the shape of a letter, there is a cutout portion at the lead-out position of the capacitor side surface of the lead frame, and the cutout portion is filled with resin corresponding to the thickness of the lead frame from the capacitor side surface. A chip-shaped solid electrolytic capacitor characterized by the following: