JPH02106027A - Molded chip tantalum solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To improve workability of production of solid electrolytic capacitors while preventing defective connection by winding a fuse on a capacitor element so that the fuse is connected to a fuse connecting part of the surface of the capacitor element and to a cathode terminal. CONSTITUTION:A fuse 15 is wound on a capacitor element 11, so that the fuse 15 is connected to the surface of the capacitor element 11 and to a cathode terminal 19 on the opposite surfaces of the capacitor element 11, respectively. Thus, the fuse 15 is wound on the capacitor element 11 so that it is connected to a fuse connecting part 18 provided on the surface of the capacitor element and to the cathode terminal 10 on the opposite surfaces of the capacitor element 11. In this manner, the fuse 15 is not deformed when it is connected and the connecting operation can be performed with desirable workability. Further, defective connection of the fuse 15 also can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a molded buttantal solid electrolytic capacitor in which a capacitor element and a cathode terminal are connected via a fuse and covered with a molded resin.

[Conventional technology]

Conventionally, Kuntal solid electrolytic capacitors have been used, which are tantalum metal used as an anodic body, an oxide film formed on the surface by anodic oxidation to serve as a dielectric, and a solid electrolyte placed in close contact with this oxide film to form a cathode. There is. Such a tantalum solid electrolytic capacitor may be coated with a molded resin, have a terminal structure suitable for face bonding, and be configured as a chip capacitor to be incorporated into a hybrid IC circuit.

In such a molded buttantal solid electrolytic capacitor, the capacitor element and the cathode terminal led out to the outside are connected via a fuse, so that if a short circuit occurs due to reverse insertion into the set or overvoltage, the surrounding Products have been proposed that prevent the circuit from burning out and improve safety. The inventors of the present invention have made several proposals regarding such molded buttantal solid electrolytic capacitors.

FIG. 3 shows the basic configuration of a molded chimbutantalum solid electrolytic capacitor (hereinafter referred to as "chip capacitor") that was previously proposed by the inventor of the present invention.

This chip capacitor includes a capacitor element, an anode lead wire 2 led out from the capacitor element 1, an anode terminal 3 connected to the anode lead wire 2, and a conductive bonding material 4 on the surface of the cathode layer of the capacitor element 1. A fuse 5 connected to the fuse 5 and a cathode terminal 7 connected to the fuse 5 by a conductive bonding material 6 similar to the conductive bonding material 4 are molded so that the cathode terminal 3 and the cathode terminal 7 are led out to the outside. It is constructed by being packaged and housed in a molded resin 8. In the vicinity of the lead-out portion of the anode lead-out wire 2 of the capacitor element 1, an insulating plate 9 made of Teflon or the like is provided.

The capacitor element 1 is made by molding tantalum powder and firing it in vacuum, forming an oxide film on it and using it as a dielectric.
It is constructed by forming an electrolyte such as manganese dioxide on the surface of this oxide film, and further laminating a carbon layer and a cathode layer, and the anode lead wire 2 led out from this capacitor element 1 is made of Kunthal metal. . The anode terminal 3 is made of nickel nickel silver, 42 alloy, stainless steel, or the like with solder plating on steel. Further, the fuse 5 is made of a plate-shaped or linear low-melting point alloy material, and the mold resin 8 is made of epoxy resin, silicone resin, or the like. Further, the conductive bonding material 4.6 is, for example, a conductive adhesive or solder (including cream solder).

In the cathode layer on the surface of the capacitor element 1, an insulating coating N10 is formed on at least the portion facing the fuse 5 by dipping, coating, or pasting a sheet.

For example, when this chip capacitor breaks down due to a short circuit occurring in the capacitor element 1, the fuse 5
A large current flows through the fuse 5, and the fuse 5 is blown out. This prevents damage to other circuit components, such as when a short circuit occurs in the capacitor element 1. Further, when the temperature of the capacitor element 1 rises to an undesirable degree, the amount of heat from the capacitor element 1 is conducted to the fuse 5, thereby causing the fuse 5 to be blown.

In this way, the fuse 5 also serves as a so-called temperature fuse, and prevents the capacitor element 1 from burning out.

The above-mentioned insulating coating layer 10 covers a portion of the fuse 5 other than the end connected to the capacitor element 1 and the capacitor element 1.
It is provided to insulate between the fuse 5 and the surface and to ensure the length of the effective portion of the fuse 5 necessary to obtain the desired fusing characteristics. That is, when the fuse 5 comes into contact with the surface of the capacitor element 1, a current flows through this contact portion, causing changes in the characteristics of the chip capacitor such as changes in capacitance and the fusing characteristics of the fuse 5. Therefore, when the insulation coating [10] is not provided, the characteristics of the chip capacitor and the blowing characteristics of the fuse 5 become unstable.

[Problem to be solved by the invention]

However, in the above-mentioned chip capacitor, due to the deformation of the fuse 5 and the bending of the cathode terminal 7, when connecting the fuse 5 to the capacitor element and the cathode terminal 7, both ends of the fuse 5 are connected to the capacitor 61. It is relatively difficult to locate the element 1 and the cathode terminal 7 at the connection target part, and the end of one example of the capacitor element of the cathode terminal 7 is lifted from the surface of the capacitor element 1, so that it is difficult to make a sufficient connection at this part. Area may not be obtained. For this reason, it is not possible to improve the workability during the manufacture of chip capacitors, and it is not possible to connect the fuse 5 to the capacitor element 1 and the cathode terminal 7 reliably and firmly, which may result in connection failures. there were.

Furthermore, when the connection area between the fuse 5 and the capacitor element l is small, the heat transfer efficiency from the capacitor element 1 to the fuse 5 is poor, so that the fuse 5 must reliably fulfill its role as the temperature fuse described above. I couldn't.

An object of the present invention is to provide a molded chimbutantalum solid electrolytic capacitor that can solve the above-mentioned technical problems, improve workability during manufacturing, and prevent poor connection of fuses. It is to be.

Means for Solving Problem C] In the molded chip tantalum solid electrolytic capacitor of the present invention, a fuse is wound around a capacitor element, and the fuse is connected to the fuse on the surface of the capacitor element on opposite sides of the capacitor element. It is characterized in that each connection is made between the fuse and the cathode terminal and between the fuse and the cathode terminal.

The connections between the fuse and the fuse connection portion on the surface of the capacitor element and between the fuse and the cathode terminal may be made before the fuse is wound around the capacitor element, and either one of the connections may be made before the fuse is wound around the capacitor element. The connection may also be made after the winding of the fuse to the capacitor element (-=J).

[Effect]

According to the configuration of the present invention, the fuse is wound around the capacitor element and connected to the fuse connection portion provided on the surface of the capacitor element and the cathode terminal on the surface of the capacitor element. Therefore, the fuses are not deformed when each connection is made, and the connection work is performed with good workability, and no faulty connections of the fuses occur.

Further, the fuse is usually made of a material that can be easily deformed, and therefore the fuse can be wound around the capacitor element with good workability.

In addition, since the fuse is wound around the capacitor element, the connection area between the fuse and the fuse connection part on the surface of the capacitor element can be increased, and as a result, the heat generated in the capacitor element is efficiently transferred to the fuse. be done.

Therefore, the fuse is reliably blown not only when a large current flows through the fuse due to a short circuit in the capacitor element, but also when the capacitor element generates abnormal heat.

Furthermore, between the fuse and the fuse connection part,
and each connection between the fuse and the cathode terminal is
This is done on mutually opposite capacitor element surfaces with respect to the capacitor element, thus ensuring sufficient length to obtain the desired fusing characteristics of the fuse.

〔Example〕

FIG. 1 is an exploded perspective view showing the basic structure of a molded chip tantalum solid electrolytic capacitor (hereinafter referred to as "chip capacitor") according to an embodiment of the present invention, and FIG. 2 is a sectional view thereof. However, FIG. 1 shows the state before the mold exterior is applied. This chip capacitor is
Tantalum powder is molded and fired in a vacuum to form an oxide film, which is used as a dielectric. An electrolyte such as manganese dioxide is formed on the surface of this oxide film, and then a carbon layer and a cathode layer are laminated. The capacitor element 11 configured as shown in FIG. An anode lead wire 12 made of tantalum metal is led out from this capacitor element 11, and an anode terminal 13 is welded to this anode lead wire 12. This anode terminal 13 is made of nickel.

It is made of nickel silver, 4270I, or stainless steel with solder plating applied to the steel. An insulating plate 14 made of Teflon or the like is provided near the lead-out portion of the anode lead-out wire 12 of the capacitor element 11.

The cathode layer on the surface of the capacitor element 11 is provided with a central portion 15 m of a fuse 15 made of a low melting point alloy material in the form of a plate, for example.
The vicinity is connected by a conductive bonding material 16. After this connection, the fuse 15 is wound around the surface of the capacitor element 11, and its both ends 15a, 15b are arranged on the opposite side of the capacitor element 11 from the center part 15m.

The conductive bonding material 16 is a conductive adhesive, solder (including cream solder), or the like.

An insulating coating layer 17 is formed on the surface of the capacitor element 11 except for a part by dipping, coating, pasting a sheet, or the like. This insulating coating layer 17 is made of, for example, an epoxy or silicone resin material. A part of the surface of the capacitor element 11 where the insulating coating layer 17 is not formed is a fuse connection part 18, and the vicinity of the center part 15m of the fuse 15 is connected to this fuse connection part 18. The insulating coating layer 17 is formed at least on the remaining surface of the capacitor element 11 other than the fuse connection part 18, and is formed in a portion facing the fuse 15, and therefore faces the surface of the capacitor element 11 other than the fuse connection part 18. Each part of the fuse 15 is insulated from the capacitor element 11. Both ends 15a and 15b of the fuse 15 are also located on the surface of the insulating coating layer 17, and are insulated from the surface of the capacitor element 11.

Both ends 15a and 15b of the fuse 15 have the following in common:
A cathode terminal 19 similar to the anode terminal 13 is connected by a conductive bonding material 20 similar to the conductive bonding material 16 .

As described above, both ends 15a+5b of the fuse 15 are located on the opposite side with respect to the capacitor element 11 from the central part 15m, and the vicinity of the central part 15m and both ends 1
5a and 15b are insulated from the capacitor element 11 by the insulating coating layer 17, so that the fuse connection part 18 of the capacitor element 11
The fuse 15 has a sufficient effective length between it and the cathode terminal 19. This allows the fuse 15 to be stably blown.

After each connection related to the capacitor element 11 is made as described above, the anode terminal 13 and the cathode terminal 19 are led out to the outside, and a molding resin 2+ (secondary one) such as epoxy resin or silicone resin is used. A mold exterior is applied (see Figure 2).

In the above chip capacitor, when a short circuit occurs in the capacitor element 1, for example, a large current flows through the fuse 15, and the heat generated at this time causes the fuse 15 to melt. In this way, it is possible to prevent peripheral circuit components from being burned out.

When assembling the above chip capacitor, fuse 1
The connection of the central portion 15 m of the fuse connecting portion 1 of No. 5 to the fuse connecting portion 1 is made by pressing the central portion 15 m to the fuse connecting portion 1, thereby increasing the connection area and making the connection of this portion strong and reliable. can be done. Further, since the fuse 15 is wound around the capacitor element 11 after this connection, the fuse 15 is then wound around the capacitor element 11.
When connecting both ends 15a, 15b of 5 to the cathode terminal 19, the fuse 15 is not deformed to an undesirable degree, and therefore, this connection is also made firmly and reliably, and with good workability. Can be done.

Furthermore, as described above, since the connection area between the fuse connection portion 18 on the surface of the capacitor element 11 and the fuse 15 can be increased, the amount of heat from the capacitor element 11 can be efficiently transferred to the fuse 15. become. As a result, when the capacitor element 11 generates abnormal heat, the fuse 15 can be reliably fused to prevent the capacitor element 11 from burning out. In other words, in this chip capacitor, the fuse 15 can sufficiently fulfill the role of a so-called temperature fuse.

In the above-described embodiment, a plate-shaped fuse is used as the fuse 5, but the fuse may also be linear, and in this case as well, the linear fuse may be wound around the capacitor element 11. .

Further, in the above embodiment, when connecting the fuse 15, first the central portion 15m of the fuse 15 is connected to the fuse connection portion 18 of the capacitor element 11 using the conductive bonding material 16, and then the fuse 15 is wound around the capacitor element 11. However, after winding the fuse 15 around the capacitor element 11, a conductive bonding material is applied from the upper part of the center part 15m of the fuse 15.
m may be connected to the fuse connection portion I8.

[Effects of the Invention] According to the molded chip tantalum solid electrolytic capacitor of the present invention, since the fuse is wound around the capacitor element, each connection between the fuse, the fuse connection portion provided on the surface of the capacitor element, and the cathode terminal is There is no deformation of the fuse when this is carried out, and therefore this connection work can be carried out with good workability, and no faulty connection of the fuse will occur. Furthermore, the fuse is usually made of a material that can be easily deformed, so that winding the fuse around the aforementioned capacitor element is easy. In this way, this molded chip tantalum solid electrolytic capacitor can be manufactured with good workability, and the occurrence of faulty fuse connections can be reduced.

In addition, since the fuse is wound around the capacitor element, the connection area between the fuse and the fuse connection part on the surface of the capacitor element can be increased, and as a result, the heat generated in the capacitor element is efficiently transferred to the fuse. be done.

Therefore, not only when a large current flows through the fuse due to a short circuit in the capacitor element, but also when the capacitor element generates abnormal heat, it is possible to reliably blow out the fuse and prevent burnout of the capacitor element. become able to.

Furthermore, between the fuse and the fuse connection part,
and each connection between the fuse and the cathode terminal is
This is done on the surfaces of the capacitor elements on opposite sides of the capacitor element, thus ensuring a sufficient length of the fuse, thereby making it possible to stabilize its fusing characteristics.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing the basic structure of a molded buttantal solid electrolytic capacitor according to an embodiment of the present invention;
FIG. 2 is a cross-sectional view thereof, and FIG. 3 is a cross-sectional view showing the basic structure of the molded chip/butantal solid electrolytic capacitor previously proposed by the inventor of the present invention. 11... Capacitor element, 15... Fuse, 17
... Insulating coating layer, 18... Fuse connection part, 19.
...Cathode terminal, 21...Mold resin Fig. 3 Fig. 2

Claims (1)

[Scope of Claims] A molded chip tantalum solid electrolytic capacitor in which a capacitor element and a cathode terminal are connected via a fuse and provided with a molded exterior, wherein the fuse is wound around the capacitor element, and the fuse is wound on opposite sides with respect to the capacitor element. A molded chip tantalum solid electrolytic capacitor, characterized in that connections are made between the fuse and a fuse connection portion on the surface of the capacitor element, and between the fuse and a cathode terminal on the surface of the capacitor element.