JPS6127166Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to an improved structure of a multilayer capacitor. In general, a multilayer capacitor is made by laminating multiple layers of a pair of metallized dielectrics 2, each of which has a metal electrode 1 formed by vapor deposition or coating, leaving a margin on one end of one side of a dielectric such as insulating paper or an organic film. A protective film layer 4 is provided on both outer sides of the element 3, a metallicon electrode 5 is formed on a portion of the metal electrode 1 protruding from both sides, and a lead wire 6 is attached to the metallicon electrode 5. However, since the multilayer capacitor with such a configuration obtains the required capacitance from a single capacitor element 3, it is especially difficult to deal with dielectric breakdown at a certain point in the metallized dielectric 2 that constitutes the capacitor element 3. When connected to a high-power power source or when AC is applied, the shot's joule heat melts the adjacent metallized dielectric, causing dielectric breakdown to occur continuously, rapidly losing its function as a capacitor, and causing breakdown at the same time. Since it is continuous and rapid, it generates a lot of heat, which has the disadvantage of causing fire. Conventional multilayer capacitors have a structure in which a plastic insulating sheet made of polyethylene terephthalate, polypropylene, polyester, etc. is inserted between one or more laminated layers of a multilayer film, as disclosed in Japanese Patent Application Laid-open No. 54-106855. has also been proposed. However, although the presence of these insulating sheets can slow down the continuous melting of the laminated film due to the dule heat of the shot, the heat resistance effect of these plastic insulating sheets alone against the dule heat is small, and eventually the insulating sheet will also melt. As a result, not only did it lose its function as a capacitor, but it also had the problem that it could not be an effective measure to eliminate ignition. The present invention was developed in view of the above points, and by dividing the multilayer capacitor element into multiple parts with a heat-resistant layer, it is possible to create a multilayer capacitor that can maintain its function as a capacitor for a long period of time without the risk of catching fire in the event of dielectric breakdown. The purpose is to provide An embodiment of the present invention will be described below with reference to the drawings. That is, as shown in FIG. 2, a metal electrode 1 is formed by vapor deposition or coating, leaving a margin on one side of a dielectric material such as insulating paper or an organic film.
1, a plurality of pairs of metallized dielectrics 12 are laminated, heat-resistant layers 13 are interposed between arbitrary laminated layers of the metallized dielectrics 12, and at the same time heat-resistant layers 13 similar to those described above are provided on both outer sides. A capacitor element 14, which is sandwiched between heat-resistant layers 13 and divided into a plurality of regions, is formed.
Then, metallicon electrodes 15 are formed on the metal electrodes 11 that protrude from both sides of the capacitor element 14,
Thereafter, a lead wire 16 is attached to the metallikon electrode 15. The heat-resistant layer 13 may be made of organic materials such as polyamide, polyimide, polyamide-imide, nylon, Teflon, phenol, polyvinylidene fluoride and other fluorinated or chlorinated hydrocarbons, polyester, polyethylene terephthalate, polypropylene, polycarbonate, polysulfone, or glass fiber. , silica, alumina, or other inorganic fillers mixed therein and molded into a film or sheet shape, or glass fiber, silica, alumina, or the like molded into a sheet or plate shape may be used as appropriate. Even if dielectric breakdown occurs in the multilayer capacitor constructed as described above and the metallized dielectric material in a certain portion melts, the interruption is prevented by the presence of the heat-resistant layer 13, so that the capacitor element 14 is made of melted metallization. Only the region formed by the dielectric material is destroyed; the other regions are completely intact, and although the capacitance of the destroyed region is reduced, it can still function satisfactorily as a capacitor. Furthermore, since the destruction does not spread to other areas, there is little heat generation, and the drawbacks that could lead to fire can be eliminated. Next, the effects of the present invention will be clarified through experimental examples. That is, a plurality of metallized polyester films made by depositing aluminum on one side of a 6μ polyester film leaving a margin at one end were laminated to investigate dielectric breakdown in a 6 μF multilayer capacitor. The present invention (A) divides the space between the laminated layers into four using a heat-resistant layer made of a 50μ polyester sheet containing 30% glass fiber, while the conventional example (B) uses a 50μ polyester sheet between the laminated layers and divides the space into four. This is what I did. Figure 3 shows the present invention (A) and the conventional example (B).
The time-capacitance change rate when a voltage of 420V.AC is applied to is shown. As is clear from Figure 3, the capacity of the conventional example (B) decreases at an accelerating rate after 500 hours, whereas the capacity of the present invention (A) decreases slightly after 500 hours, but after that. The results showed that a constant capacity was maintained for a long time. However, after testing, we disassembled both the present invention (A) and the conventional example (B) and found that most of the metallized polyester film in the conventional example (B) had melted, including the insulating sheet, whereas the present invention
(A) The metallized polyester film in one region between the heat-resistant layers was melted, while the other metalized polyester films were completely intact, demonstrating the excellent effect of the heat-resistant layers. Next, we conducted a destructive test to investigate the effect on ignition, and the results are shown in the table below. The table shows the presence or absence of a heat-resistant layer or insulating sheet and the number of divided regions of a 60V multilayer capacitor made of a 6μ aluminum-deposited polyester film.
The graph shows the ignition rate at the time when the voltage was maintained at 50V for 3 minutes at the start and the voltage was stepped up to failure, and 100 samples were used for each voltage.

[Table] From the above, conventional examples (a) to (e) showed a high ignition rate, while the present inventions (f) to (l) did not ignite at all and showed high safety. In the above embodiments, one side of the metallized dielectric is metallized, but the same effect can be obtained with a metallized dielectric on both sides. As described above, according to the present invention, a heat-resistant layer is interposed between any laminated layers of metallized dielectric material to form a capacitor element divided into a plurality of regions, so that when dielectric breakdown occurs in one part, the breakdown part occurs in another part. It is possible to obtain a multilayer capacitor that can maintain its function as a capacitor for a long period of time without spreading over the area, and at the same time there is no risk of fire.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a multilayer capacitor according to a conventional reference example, FIG. 2 is a perspective view showing a multilayer capacitor according to an embodiment of the present invention, and FIG.
FIG. 3 is a characteristic curve diagram showing a rate of change in capacitance. 12...metalized dielectric, 13...heat resistant layer, 14
... Capacitor element, 15 ... Metallicon electrode,
16... Lead wire.

Claims (1)

[Scope of utility model registration request] A multilayer capacitor in which a pair of metallized dielectrics are laminated and lead wires are attached to metallized electrodes formed on both end faces, and the capacitor is divided into multiple regions with a heat-resistant layer interposed between arbitrary laminations of the metallized dielectrics. A multilayer capacitor characterized by the fact that it is an element.