JPS6041725Y2 - Chip-shaped aluminum electrolytic capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chip-shaped aluminum electrolytic capacitor.

Recent advances in electronic circuits and systems have created a need for the development of chip capacitors that have maximum capacitance per unit volume by minimizing external lead wires, and have a shape that allows automatic mounting on circuit boards. .

Tantalum solid electrolytic capacitors and ceramic capacitors have conventionally been put into practical use as capacitors with the above-mentioned characteristics, but in the case of aluminum electrolytic capacitors in which a paste-like electrolyte is soaked into the capacitor element, the It is extremely difficult to mold with synthetic resin because the electrolyte is attached to the surface, and the molding temperature is 150~2.
Since high heat of 00° C. is directly applied to the element, it causes deterioration of the dielectric oxide film and loss of electrolyte, and the electrical characteristics of the capacitor become unstable.

For this reason, before molding, it is necessary to undercoat the element with an ultraviolet curing resin or the like before molding, but the undercoat resin must be one that does not dissolve in the paste electrolyte, which is particularly dangerous for aluminum electrolytic capacitors. It is required that the paste be neutral and harden before mixing with the paste electrolyte.

In addition, it is extremely difficult to provide an explosion-proof valve due to the structure of chip-shaped capacitors, which require small size, light weight, and dimensional accuracy. It is also extremely difficult to coat the resin to a constant thickness, resulting in variations in dimensions after molding, and in order to maintain a certain level of strength, the product must be molded to a slightly larger size, which goes against the trend of miniaturization and weight reduction. .

□On the other hand, chip-shaped aluminum electrolytic capacitors with electrodes in a laminated structure have been proposed, as in Utility Model Application Publication No. 54-5484, but because of the laminated structure, the capacitance is relatively small and it is difficult to obtain a large capacity capacitor. The manufacturing process is complicated, cannot be automated, is expensive, and this configuration has drawbacks such as the inability to provide an explosion-proof valve.

The present invention was developed in view of the above-mentioned circumstances.The capacitor element is impregnated with an electrolytic solution in advance and is housed in a square container made of synthetic resin with a hollow part. Attach a cap terminal formed of a cladding material whose outer side is made of a solderable metal, drill a hole in the solderable metal on the outer side of at least one of the cap terminals, and configure an explosion-proof valve with the inner valve action metal. By doing so, it is possible to avoid direct application of high heat to the elements during the process and prevent explosions, and to provide a chip-shaped aluminum electrolytic capacitor that has a large capacity, is easy to manufacture, and has stable electrical characteristics.

An embodiment of the present invention will be described below with reference to the drawings.

That is, as shown in FIGS. 1 and 2, a wound or laminated capacitor element 1 impregnated with a paste electrolyte in advance is coated with epoxy, polyimide, polyacetal, polyester, polyphenylene sulfide, polyethylene, polypropylene, polyphenylene oxide, or any of these. It is housed in a rectangular container 3 made of synthetic resin such as resin to which an inorganic substance is added and provided with a hollow portion 2.

The hollow portion 2 may have any shape as long as it accommodates the capacitor element 1 and has a truncated shape.

One end opening of the container 3 is provided with a cap terminal 4 that is attached integrally with the container 3 during molding or by crimping, fitting, welding, or the like after molding. 1 is connected to the cap terminal 4 by spot welding, ultrasonic welding, laser welding, or the like.

The inside of the cap terminal 4 is made of aluminum, tantalum,
It is made of a valve metal such as titanium, and the outside is made of a solderable metal, such as Al-Cu, Al.
-3n, made of a low-temperature solid phase bonded clad material such as Ti-Ni, a hole 6 is bored in the solderable metal on the outside, and an explosion-proof valve is constructed from the valve action metal on the inside.

Thereafter, the capacitor element 1 is housed in the hollow part 2 of the container 3, and the other electrode lead wire 8 is attached to the inside of the cap terminal 7 that covers the opening at the other end by spot welding, ultrasonic welding, laser welding, etc. Connecting.

Like the cap terminal 4, the cap terminal 7 is also made of a clad material whose inner side is made of a valve metal and whose outer side is made of a solderable metal.

After connecting the electrode lead wire 8 to the inside of the cap terminal 7, the cap terminal 7 is attached to the opening of the container 3 by crimping, fitting, welding, etc. to form a chip-shaped aluminum electrolytic capacitor as shown in FIG. This is what you get.

In this case, a rubber compound or instant curing adhesive may be applied to the inside of the cap terminal 7 in advance, a rubber packing may be interposed between the opening of the container 3 and the cap terminal 7, or a rubber ring may be placed around the outer periphery of the opening of the container 3. It is effective to attach by a method such as crimping, fitting, or welding with a sealing material 9 interposed therebetween to improve insulation and sealing properties.

In the above description, the capacitor element 1 is housed in the container 3 with the cap terminal 4 attached to the opening at one end in advance. It may be attached.

Further, the explosion-proof valve may be provided on one cap terminal 7 or both cap terminals 4 and 7.

The chip-shaped aluminum electrolytic capacitor constructed in this way does not receive high heat directly from the capacitor element 1 during the packaging process, unlike those molded from synthetic resin, which prevents deterioration of the spacer paper or dielectric oxide film or loss of electrolyte. Because there is no such thing, the electrical characteristics of the capacitor are stable, and even if the gas pressure becomes high, the explosion-proof valve will work to prevent an explosion.Moreover, the capacitor element 1 used in ordinary aluminum electrolytic capacitors with lead wires. can be used as is, resulting in a large-capacity chip-shaped aluminum electrolytic capacitor.

In addition, the dimensional accuracy is excellent because there is no movement or deviation of the capacitor element 1 during molding, unlike when the capacitor element 1 is packaged by molding, and it also has better stability and workability when mounting on a circuit board than a cylindrical chip capacitor. .

Furthermore, the manufacturing process is extremely simple and can be automated, making it suitable for inexpensive mass production.

Next, Table 1 shows a comparison of characteristics between Example A of the present invention and conventional Reference Example B.

In Example A, the capacitor element is housed in a rectangular container made of polyphenylene sulfide resin, and a cap terminal made of Al-C;U clad material is used, and one cap terminal has a diameter of 1.8 mm.
In reference example B, the capacitor element is undercoated with ultraviolet curable resin, then transfer molded with epoxy resin, and a part of the capacitor element is made with a diameter of 2 mm. Orrrm
Both capacitors are chip-shaped aluminum electrolytic capacitors with a rating of 15WV and DC-10μF.

The leakage current, capacitance, and dielectric loss tangent show the average values for each m samples, and the valve operation test was conducted using 5 of the samples, and the variation width is shown.

Figure 4 shows the change in leakage current over time when the chip-shaped aluminum electrolytic capacitors of Example A and Reference Example B were left in a constant temperature bath at a temperature of 85°C while applying the rated voltage. Figure 5 shows the variation in time until valve operation.

As is clear from Table 1 and Figures 4 and 5, the valve operation of Example A of the present invention is more reliable and has less variation than the conventional reference example B, and it is extremely stable with little change over time as well as initial characteristics. It can be seen that it exhibits certain characteristics.

As detailed above, according to the present invention, a capacitor element impregnated with electrolyte is housed in a rectangular container with a hollow part, and the openings at both ends of the container have valve metal on the inside and solderable on the outside. A capacitor is manufactured by capping and attaching a cap terminal formed of a metal clad material, drilling a hole in the solderable metal on the outside of at least one of the cap terminals, and configuring an explosion-proof valve with the valve metal on the inside. The electrical characteristics of the capacitor are stable, and even if the gas pressure becomes high, the explosion-proof valve operates to reliably prevent an explosion, and a large-capacity chip capacitor can be obtained. Moreover, it can be automated and mass-produced at low cost. A suitable chip-shaped aluminum electrolytic capacitor can be provided.

[Brief explanation of the drawing]

1 and 2 show the state in the process of manufacturing a chip-shaped aluminum electrolytic capacitor according to an embodiment of the present invention. FIG. 1 is an exploded sectional view, FIG. 2 is an exploded perspective view, and FIG. The figure is a cross-sectional view showing the completed state of the chip-shaped aluminum electrolytic capacitor according to the present invention, Figure 4 is a characteristic curve diagram showing the change in leakage current over time, and Figure 5 is the variation in the time until valve operation in the valve operation test. FIG. DESCRIPTION OF SYMBOLS 1... Capacitor element, 2... Hollow part, 3... Container, 4, 7... Cap terminal, 6... Hole, 5゜8... Electrode lead wire, 9... Seal material.

Claims (3)

[Scope of utility model registration request] (1) A capacitor element impregnated with an electrolytic solution and having an electrode lead wire, a rectangular container made of a synthetic resin with a hollow part for accommodating the capacitor element, and an opening of the container to which the electrode lead wire is connected. The cap terminal is made of a cladding material with a valve-acting metal on the inside and a solderable metal on the outside. A chip-shaped aluminum electrolytic capacitor, characterized in that the explosion-proof valve is formed by drilling a hole in a metal that can be attached. (2) The container is made of epoxy, polyacetal, polyimide,
The chip-shaped aluminum electrolytic capacitor according to claim 1, which is a utility model, and is made of a synthetic resin such as polyester, polyphenylene sulfide, polyethylene, polypropylene, or polyphenylene oxide. (3) Cap terminal is Al-Cu, Al-3n,
A chip-shaped aluminum electrolytic capacitor according to claim 1 or 2, which is made of a low-temperature solid phase bonded cladding material such as Ti-Ni.