JPH02152212A - Laminate-type capacitor provided with fuse function - Google Patents

Abstract

PURPOSE:To make a current-breaking operation sure by a method wherein a fuse part is formed in such a way that at least one part is exposed at the external surface of a dielectric laminate structure. CONSTITUTION:A dielectric laminate structure 4 is formed by alternately laminating the desired number of dielectric layers 2 and 3. Internal electrodes 5 and 6 are formed individually on the dielectric layers 2 and 3. One part at each internal electrode 5 is formed so as to be slender; a fuse part 7 is constituted here. The fuse part 7 is formed along one long side of each dielectric layer 2. The fuse part 7 is formed in such a way that it is exposed on the external surface, i.e. one side face, of the laminate structure 4. The fuse part 7 is fused surely; reliability of a current-breaking operation can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a multilayer capacitor with a fuse function. The present invention relates to multilayer capacitors.

[Prior Art] A multilayer capacitor generally includes a plurality of laminated dielectric layers made of, for example, ceramic, and a plurality of internal electrodes are opposed to each other via each dielectric layer to form a capacitance. It is formed like this.

In such multilayer capacitors, in order to provide a fuse function, fuse wires are attached to the outside of the capacitor (see U.S. Pat. No. 4,107,759 or U.S. Pat. Similar to electrodes, a fuse part is placed between dielectric layers (for example, see Utility Model Application Publication No. 63-87819), or a part of the internal electrode is made thinner so that this thinner part functions as a fuse (especially (Refer to No. 62-141923)
and so on. The present invention is particularly directed to the latter prior art or related art, in which the fuse portion is disposed between dielectric layers.

[Problems to be Solved by the Invention] In the above-described prior art or related technology that is of interest to the present invention, when a current exceeding a predetermined value flows through a capacitor, a fuse section melts and cuts off the current. However, since the fuse part is formed between dielectric layers, in other words, it is formed in a closed space, it may not be severed even if it melts, ensuring reliable current interruption. It may not be possible to accomplish the action.

SUMMARY OF THE INVENTION Therefore, the present invention aims to provide an improvement in a multilayer capacitor with a fuse function in order to ensure a reliable current interrupting operation.

[Means for Solving the Problems] The present invention includes a dielectric laminate structure consisting of a plurality of laminated dielectric layers, and a plurality of internal electrodes are connected to each of the dielectric layers to form a capacitance. A fuse section is formed between at least one set of adjacent dielectric layers, and has a fuse section that is blown by Joule heat generated when a current of a predetermined amount or more flows. The present invention is directed toward multilayer capacitors, and is characterized by the adoption of the following configuration in order to solve the above-mentioned technical problems.

That is, the fuse portion is formed such that at least a portion thereof is exposed on the outer surface of the dielectric laminate structure.

[Function] In the multilayer capacitor with a fuse function according to the present invention, when a current of a predetermined value or more flows, a fuse occurs in the fuse portion. At least a portion of the molten metal generated by such blowing of the fuse portion flows out to the outer surface of the dielectric laminated structure.

[Effects of the Invention] As described above, according to the present invention, an escape route for the metal contained in the melted fuse portion is actively formed, so that when the fuse blows, metal deficiency immediately occurs in the fuse portion. Therefore, a quick and reliable current interrupting operation can be achieved.

Further, according to the present invention, since the fuse portion is exposed on the outer surface of the dielectric laminated structure, it is possible to visually check from the outside whether the fuse portion is blown.

In addition, in order to form a fuse part, which is a feature of the present invention, when a part of an internal electrode constitutes a fuse part, it is only necessary to change the pattern of such an internal electrode, and it is also possible to form a fuse part that is a feature of the present invention. In the case of forming individual fuse parts without using a fuse, it is only necessary to design the pattern of the fuse part itself as desired. No special equipment is required. Therefore, the cost does not increase in order to obtain the multilayer capacitor with a fuse function according to the present invention.

[Embodiment] In the embodiment described below with reference to the drawings, a part of the internal electrode is formed thin and has a fuse function.

FIG. 1 shows a perspective view of the external appearance of a multilayer capacitor 1 with a fuse function as an embodiment of the present invention.

FIG. 2 shows a perspective view of two typical types of dielectric layers 2 and 3 among the plurality of dielectric layers used to obtain the multilayer capacitor 1 shown in FIG.

The dielectric laminated structure 4 shown in FIG. 1 is constructed by alternately laminating a desired number of dielectric layers 2 and 3 shown in FIG. ) are obtained by laminating a predetermined number of dielectric layers above and below the above-described alternately laminated dielectric layers 2 and 3.

Internal electrodes 5 and 6 are formed in dielectric layers 2 and 3, respectively. The internal electrode 5 is formed thin at the negative part, and the fuse part 7 is formed here. It should be noted that the fuse portion 7 is formed along one long side of the dielectric layer 2. The internal electrode 5 is also formed along one short side of the dielectric layer 2 . On the other hand, the internal electrode 6 is formed along the short side of the dielectric layer 3, which is opposite to the short side from which the internal electrode 5 is drawn out.

When the dielectric layers 2 and 3 are alternately stacked, the internal electrodes 5 and 6 face each other with the corresponding dielectric layer 2 or 3 interposed therebetween, thereby forming a capacitance. In order to extract such capacitance to the outside, external electrodes 8 and 9 are formed at both longitudinal ends of the laminated structure 4, respectively, as shown in FIG. One external electrode 8 is electrically connected to the internal electrode 5 , and the other external electrode 9 is electrically connected to the internal electrode 6 .

In this way, the multilayer capacitor 1 shown in FIG. 1 is obtained. As can be seen from FIG. 1, the above-mentioned fuse portion 7 is formed so as to be exposed on the outer surface, that is, one side surface, of the laminated structure 4.

Therefore, when a current of more than a predetermined value flows through the multilayer capacitor 1, the metal that constitutes the fuse part 7 is melted by the generated Joule heat, but the melted metal immediately melts into the multilayer structure. It flows out to the outer surface of 4. Therefore, the fuse portion 7 is reliably blown, and the reliability of the current interrupting operation is increased.

Note that the increase in the equivalent series resistance and equivalent series inductance of the multilayer capacitor 1 due to the presence of the fuse part 7 is as follows.
By increasing the number of dielectric layers 2 and 3,
It can be suppressed.

A dielectric laminate structure can also be obtained by laminating dielectric layers shown in FIG. 3 or 4.

In FIG. 3, dielectric layers 10, 11, 12, 13 are shown. Internal electrodes 14 and 16 are formed on the dielectric layers 10 and 12, respectively, and are drawn out to the left short side. Dielectric layers 11 and 13 are substantially similar;
Internal electrodes 15 and 17 are formed, respectively, which are drawn out on the right short side.

A fuse portion 18 is formed in the internal electrode 14 and extends along the lower long side. A fuse portion 19 is formed in the internal electrode 16 and extends along the upper long side.

To obtain a dielectric laminated structure, the dielectric layer 10°11.1
2.13 are repeated and laminated in this order a desired number of times. The laminated structure thus obtained has the fuse portion 18 exposed on one side and the fuse portion 19 exposed on the other side.

In FIG. 4, dielectric layers 20, 2], 22, 23 are shown. Internal electrodes 24 and 26 are formed in the dielectric layers 20 and 22, respectively, and extend to the left short side. Furthermore, internal electrodes 25 and 27 are formed on the dielectric layers 21 and 23, respectively, and extend to the right short side.

Fuse portions 28 and 29 are formed in the internal electrodes 24 and 26, respectively, and extend along the lower long sides.

The positions of these fuse parts 28 and 29 are shifted from each other in the left-right direction.

As in the case described above, the dielectric layer 20. 21°22.
2B, this order is repeated an appropriate number of times to obtain a dielectric laminated structure.

The embodiments shown in FIGS. 3 and 4 are superior to the embodiments shown in FIGS. 1 and 2 in the following points.

That is, as shown in FIG. 1, when a plurality of fuse parts 7 are vertically aligned on the outer surface of the laminated structure 4, if the dielectric layers 2 and 3 are thin, the adjacent fuse parts If part 7 is too close to each other, due to humidity, etc.
There is a possibility of short circuit. Although there is no problem with the function of the capacitor even if the circuit is short-circuited in this way, the fuse function may be lost. However, according to the embodiment shown in FIGS. Since one fuse section or one fuse section 28 and one fuse section 29 can be separated in distance, the possibility of short circuit as described above is reduced.

Although the invention has been described above in connection with the illustrated embodiments, various other modifications are possible within the scope of the invention.

For example, the pattern of the internal electrodes formed on the dielectric layer is arbitrary as long as the fuse portion is at least partially exposed on the outer surface of the dielectric laminate structure.

In addition, the fuse part formed as part of the internal electrode is
It may be formed of the same metal material as the other parts of the internal electrode, or may be formed of a different metal material.

For example, only the metal forming the fuse portion may be a metal with a lower melting point.

Furthermore, instead of forming the fuse part as a part of the internal electrode, the fuse part may be formed separately from the internal electrode, as described in the above-mentioned Japanese Utility Model Application Laid-open No. 63-87819. In this case, the layer forming the fuse portion does not necessarily have to be a dielectric layer in the narrow sense; in this invention, an insulator is also included in the dielectric layer in the broad sense.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the appearance of a multilayer capacitor 1 with a fuse function as an embodiment of the present invention. FIG. 2 is a perspective view showing dielectric layers 2 and 3 constituting the dielectric laminate structure 4 of the multilayer capacitor 1 shown in FIG. FIGS. 3 and 4 are plan views showing dielectric layers 10-13 and 20-23, respectively, used in other embodiments of the invention. In the figure, 1 is a multilayer capacitor with a fuse function, 2
, 3.10 to 13. 20 to 23 are dielectric layers, 4 is a dielectric laminated structure, 5, 6. 14 to 17 degrees, 24 to 27 are internal electrodes, 7. 18, 19, 28 degrees are fuse parts. It is. (2 others) Figure 3 Figure 4

Claims (1)

[Claims] A dielectric laminated structure consisting of a plurality of laminated dielectric layers is provided, and a plurality of internal electrodes are arranged to face each other with each of the dielectric layers interposed therebetween to form a capacitance. In the laminated capacitor with a fuse function, a fuse portion is formed between at least one set of adjacent dielectric layers and is blown by Joule heat generated when a current of a predetermined amount or more flows. A multilayer capacitor with a fuse function, wherein at least a portion of the multilayer capacitor is formed such that at least a portion thereof is exposed on the outer surface of the dielectric multilayer structure.