JPS6356692B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a multilayer capacitor in which a capacitor element is formed by cutting a capacitor base formed by winding a metallized film, and electrode contact layers are formed on both end faces of the capacitor element. It is something. Generally, this type of multilayer capacitor has a structure in which a plurality of microcapacitors are connected in parallel through an electrode contact layer formed by metal spraying, and due to this structure, the capacitor itself has a protective function. This protection function means that when a voltage is applied to a capacitor for a long time or when it is used harshly, the dielectric material deteriorates and partial breakdown occurs, causing excessive current to flow through the vapor deposited electrode that connects the microcapacitor. A self-healing action occurs between the electrode contact layer and the electrode contact layer, quickly disconnecting a microcapacitor with an insulation defect from other microcapacitors, and at the same time preventing the growth of the insulation defect, thereby preventing smoke and ignition. This is to prevent abnormal situations. That is, the vapor deposition electrode itself becomes a fuse. However, the performance of this protective function is greatly influenced by the manufacturing conditions and shape of the capacitor, and depending on the conditions, it may not function at all, and the manufacturing conditions may be extremely complicated or The area that was said to have a protective function was also thought to have a small capacity. In view of the current situation, the present invention has made it possible to simplify the manufacturing conditions and to greatly expand the applicable capacity. Conventionally, it was thought that the range in which the protective function could be exerted was limited to small cutting widths. In other words, in cases where the contact area between the vapor deposited electrode and the electrode contact layer is large, when current flows through the contact portion at the time of partial breakdown, the vapor deposited electrode cannot be sufficiently scattered, resulting in a continuous flow of excessive current. This eventually leads to smoke and ignition, and is therefore limited by the contact area, that is, the width of the electrode contact layer. The present invention improves the performance of the protective function by cutting diagonally so that the cutting width of one electrode contact layer and the cutting width of the other electrode contact layer are different. Hereinafter, the content of the present invention will be explained based on specific examples. As shown in FIG. 1, a capacitor element 3 is constructed by stacking a double-sided metallized film 1, which is a polyethylene terephthalate film with a thickness of 5μ and vapor-deposited electrodes formed on both sides, and a polypropylene film 2 with a thickness of 5μ. 2nd on end face
As shown in the figure, an electrode contact layer 4a formed by metal spraying,
4b to make a multilayer capacitor. In addition, in the present invention, as shown in FIG. 3, the capacitor element 3 is cut diagonally so that the width A of one electrode contact layer 4a is smaller than the width B of the other electrode contact layer 4b. And so. In addition, when manufacturing the multilayer capacitors shown in FIGS. 2 and 3, in order to investigate the protective function, the opposing width W of the vapor-deposited electrodes was set to a constant 26 mm, and the electrode contact layer 4
Capacitor elements were made by varying the widths L of a and 4b, and the exterior was filled with epoxy resin. The following table shows the conventional and present invention capacitors manufactured as described above, with AC300V applied in a constant temperature bath at a temperature of 120°C, and the protection function activated when the melt amount suddenly decreased. This shows the results of an external appearance inspection and confirmation of remaining capacity.

[Table] As is clear from this table, in conventional capacitors, when the L dimension is varied from 10 to 100 mm and the operation of the protective function is investigated, the effective width of the opposing electrodes is
It did not work at 2.0x 60mm or more, leading to smoke and fire. On the other hand, in the capacitor of the present invention, even when the A dimension was fixed at 20 mm and the B dimension was varied from 40 to 180 mm, the protection function worked perfectly, no smoke or fire occurred, and the capacitance became zero. When this capacitor was disassembled, it was found that the vapor-deposited electrode was scattered at the contact area between the vapor-deposited electrode and the electrode contact layer at the A dimension part and completely recovered by itself. In other words, the broken microcapacitor was completely disconnected. In addition, the experimental results revealed that if the cutting width of either electrode contact layer is 2.0 times or less the effective width of the opposing electrode, the protective function works more reliably than the shorter one. Here, unlike the capacitor according to the invention,
In order to make the widths of the opposing electrode contact layers different, it is possible to use a mask during metal spraying, but this would create a shadow from the mask, and the mask itself would also be sprayed with metal, making cleaning difficult and impractical. Furthermore, since parts that are not sprayed with metal are also cut during cutting, cutting conditions such as rotational speed and feed rate tend to become unstable. On the other hand, in the present invention, there is no such problem,
It is also possible to produce it rationally. Further, in the present invention, it is not necessary to completely cut the capacitor element 3, but by providing a cut groove 5 in a diagonal direction along one electrode contact layer 4b as shown in FIGS. 4a and 4b. A composite capacitor with protection function can be obtained. At this time, the widths of the cut and divided electrode contact layers 4a' and 4a'' are different.As described above, according to the present invention, it is possible to easily obtain a multilayer capacitor with a highly reliable protection function. It can be done.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing the main parts of a multilayer capacitor.
FIG. 2 is a perspective view showing a conventional multilayer capacitor, FIG. 3 is a perspective view showing a multilayer capacitor according to an embodiment of the present invention, and FIG. 4 is a perspective view showing a multilayer capacitor according to another embodiment of the present invention. It is an equivalent circuit diagram. 1... Double-sided metalized film, 2... Polypropylene film, 3... Capacitor element, 4a, 4
b, 4a', 4a''... Electrode contact layer, 5... Cut groove.

Claims (1)

[Claims] 1. In a multilayer capacitor in which a capacitor element is formed by cutting a capacitor base formed by winding a metallized film, and electrode contact layers are formed on both end surfaces of the capacitor element, one electrode contact layer is formed on both end surfaces of the capacitor element. A multilayer capacitor characterized in that a capacitor element is cut diagonally so that the width of one layer is smaller than the width of the other electrode contact layer. 2. The multilayer capacitor according to claim 1, wherein the width of either electrode contact layer is 2.0 times or less the effective electrode width of the vapor-deposited metallized film electrode. 3. In a multilayer capacitor in which a capacitor element is formed by cutting a capacitor base formed by winding a metallized film, and electrode contact layers are formed on both end faces of the capacitor element, the effective electrode portion of the vapor-deposited electrode of the metallized film 1. A multilayer capacitor characterized in that the electrode contact layer is completely cut, and one electrode contact layer is provided with grooves diagonally so as to be divided into different widths.