JPH0130284B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a capacitor whose electrodes are taken out by metallization (metal spraying) treatment. More specifically, there are intermittent blank areas (removed areas) of the deposited film along the electrode end where metallization is applied to limit the current.
This invention relates to a capacitor with a split electrode structure that has a self-safety function by providing a self-protection function. Conventionally, as shown in Fig. 1, a capacitor in which metal is vapor-deposited on a dielectric sheet 1 such as a plastic film or insulating paper and used as a vapor-deposited electrode 2 has an approximate shape as shown in Fig. 2. Electrodes are taken out from both sides through processing. However,
When such capacitors were used at high temperatures or high voltages, the dielectric sheet suffered dielectric breakdown, which could cause the capacitors to break down or catch fire. In addition, in the figure, 3 is the margin part, 4
is the metallized part (metal sprayed part), 5 is the lead wire,
A is the metallic spraying direction. As one solution to this problem, a capacitor with a split electrode structure has been proposed and is known as a capacitor with a safety function. However, even with this method,
There were some problems with the reliability of the security functions. In view of these circumstances, the present invention aims to provide a capacitor with a more reliable safety function. The reason for the self-safety function according to the present invention is as shown in Figure 3. If a part of the dielectric sheet breaks down, current is supplied from the metallic contact portion as shown in Figure 3A. , a current flows between the blank parts 6 of the vapor deposited film 2 as shown by arrows, and a current flows through the broken part 7 to the other electrode. In this case, as shown in FIG. (disconnection part), cuts off the supply of current from the metallicon side, and as a result prevents the damage from expanding. This is the main principle of the self-security function in the present invention, but unless the size of the blank part 6 and the distance between the blank parts 6 and the other blank parts 6 are not sufficiently considered, the self-security function will not work. It is necessary to consider this carefully, as the capacitance may easily decrease or the capacitor may have a large tan δ. As shown in FIG. 4, blank portions 6 of the vapor deposited film of various sizes and shapes are provided along the edge of the film on the side of the vapor deposited film 2 to be subjected to the metallicon treatment. Here, the length of the electrode 2 is L, and the shortest distances between adjacent blank parts 6 are named a ₁ , a ₂ , a _{3 .} . . , a _o as shown in the figure. Next, the current pass rate P is defined by the following equation. According to the results of detailed studies by the present inventors, it has been found that by setting 1≦P≦40 in the split electrode structure, a self-protection function is activated, and a capacitor with reduced capacitance and small tan δ can be realized. Next, a concrete explanation will be given using examples. Example 1 A uniform rectangular vapor deposited film blank part 6 as shown in FIG. 6 was provided on one side of a PET film with a thickness of 7.5 μm.
Further, as shown in this figure, vapor deposited film removal portions or lines 9 for dividing the electrode in the longitudinal direction are provided at intervals g to constitute a divided vapor deposition electrode 2', and the other surface is a conventionally used vapor deposited electrode 2'. There is no blank area for the vapor deposited film, but only a margin area is provided (see Figure 5).A PP film with a thickness of 6 μm is wrapped and rolled to match the double-sided vapor deposited PET film, and treated with metallicon. I got a capacitor. The dimensions and values at this time are as shown in sample No. 13 in Table 1 below. The obtained capacitor was packaged with epoxy resin, and the capacitance and tan δ were confirmed, as shown in sample No. 13 in Table 1, showing excellent characteristics. When the capacitor was destroyed, there was almost no ignition, smoke, or cracking, and it was confirmed that the capacitor had a sufficient self-safety function. Here, a reliability of 98% or higher was judged as ○, and was expressed as "no ignition, no smoke, no cracks." The resistance of the deposited film used here was 3.2 to 3.8 Ω/sq.

[Table] ○...No ignition, smoke, or cracks ×...Ignition, smoke, or cracks Example 2 With the same dielectric configuration as Example 1, the current pass rate P
We fabricated capacitors with various division intervals g of the separately deposited electrodes, and evaluated the results for samples from sample No. 14 to
Shown in No.19. In all cases, excellent results were obtained in terms of capacity, tan δ, and self-security function. When we created sample No. 20 and sample No. 21 with the same dielectric composition and extremely low current pass rates, we found that although the self-protection function was extremely excellent,
It was found that the tan δ was about one order of magnitude larger, making it unsuitable as a capacitor. On the other hand, the current pass rates P of Sample No. 22, Sample No. 23, and Sample No. 24 are 67%, 71%, and 50%, but the self-protection function of these samples was poor. . Note that the vapor-deposited film used here had a vapor-deposited film resistance of 3.2 to 3.8 Ω/sq. In the above example, an example was shown in which a double-sided vapor-deposited PET film and a PP laminated film were used, but the same results can be obtained with a capacitor using a single-sided vapor-deposited PET film and a single-sided PP film. ,or
Even capacitors using only PET film have PP
It can also be obtained with a capacitor using only film. Furthermore, although the above embodiments show an example of a wound type capacitor, it goes without saying that the same effect can be obtained with a so-called multilayer type capacitor.
Furthermore, in each of the above embodiments, a vapor deposited film blank part is provided on only one side, and the other side has a structure of a vapor deposition electrode without a vapor deposited film blank part, which is conventionally used. , the same effect can be obtained even if similar vapor deposited film blank areas are provided on both sides. Furthermore, although the above example shows an example in which a uniform rectangular vapor deposited film blank area is provided, this does not necessarily have to be uniform, and as shown in FIG. The same effect can also be obtained by providing a section. As described above, according to the present invention, it is possible to provide a safe capacitor with a self-protection function, and its industrial efficiency is great.

[Brief explanation of drawings]

Figure 1 is a perspective view of a conventional metallized film, Figure 2 is a perspective view of a conventional metallized film.
The figure is a perspective view of a general capacitor, Figures 3A and 3B are plan views of the metallized film showing the state when the self-protection function is activated, and Figure 4 is a metallized film used in the capacitor of the present invention. FIG. 5 is a cross-sectional view of the vapor-deposited film, and FIG. 6 is a plan view of still another example of the metallized film used in the capacitor of the present invention. 1...Dielectric sheet (plastic film,
(insulating paper, etc.), 2...deposited electrode (deposited film), 2'...
Segmented vapor deposition electrode, 3...margin part, 4...metallicon part (sprayed metal part), 5...lead wire, 6...
Blank part of the vapor deposited electrode (blank part of the vapor deposited film), 7... Destruction part, 8... Disconnection part, 9... Vapor deposited electrode removed part or line.

Claims (1)

[Claims] 1 At least one of the two opposing electrodes is a vapor deposition electrode, and the vapor deposition electrode has a plurality of divided electrode structures, and the current pass rate is 1 to 40 along the electrode edge of the divided electrode. A capacitor characterized in that an intermittent vapor deposited film blank part of 10% is provided, and the vapor deposited electrode blank part is located at a position overlapping a margin part on a counter electrode side.