Film capacitor

A capacitor element used in Example 1 includes, as shown in FIG. 2 , electrode segments 16 A forming four columns Y 11 -Y 14 each of which is constituted by electrode segments 16 A arranged in second direction 13 B, and electrode segments 16 B forming four columns Y 21 -Y 24 each of which is constituted by electrode segments 16 B arranged in second direction 13 B.

In Example 1, second fuses 18 A are provided in each of four columns Y 11 -Y 14 , and second fuses 18 B are provided in each of four columns Y 21 -Y 24 . Second fuses 18 A and 18 B dispersedly arranged in the columns as above are prevented from overlapping each other on in wound metalized films 10 A and 10 B. In Example 1, the number of second fuses 18 A provided in each of four columns Y 11 -Y 14 is substantially equal to the number of second fuses 18 B provided in respective one of four columns Y 21 -Y 24 . In Example 1, widths of second fuses 18 A and 18 B in first direction 13 A are smaller than widths of first fuses 17 A and 17 B in second direction 13 B. In a column (column Y 12 ) out of four columns Y 11 -Y 14 which includes plural second fuses 18 A, second fuses 18 A are located on straight line LA parallel to second direction 13 B. Similarly, a column (column Y 22 ) out of four columns Y 21 -Y 24 which includes plural second fuses 18 B, fuses 18 B are located placed on straight line LB parallel to second direction 13 B. In Example 1, the total number of second fuses 18 A is about 30% of the total number of electrode segments 16 A while the total number of second fuses 18 B is about 30% of the total number of electrode segments 16 B. In each of columns Y 11 -Y 14 , there are electrode segments 16 A which are adjacent to each other in second direction 13 B but are not connected to each other with second fuse 18 A. Similarly, in each of columns Y 21 -Y 24 , there are electrode segments 16 B which are adjacent to each other in second direction 13 B but are not connected to each other with second fuse 18 B.

In Example 1, electrode films 12 A and 12 B are made by vapor-depositing aluminum mainly, and external electrodes 15 A and 15 B are formed by spraying zinc. Alloy of aluminum and zinc is vapor-deposited on electrode films 12 A and 12 B at ends 310 A, 310 B, 311 A, and 311 B to form low-resistance portions 22 A and 22 B. Low-resistance portions 22 A and 22 B connect electrode films 12 A and 12 B to external electrodes 15 A and 15 B in a preferable condition, respectively, hence providing capacitor element 14 with a low resistance.

FIG. 3 is a plan view of metalized films 10 A and 10 B included in Example 2 of film capacitor 13 in accordance with the embodiment. Metalized films 10 A and 10 B used in Example 2 is different from those used in Example 1 only in the positions of second fuses 18 A and 18 B. Second fuses 18 A adjacent to each other in second direction 13 B deviate from each other in first direction 13 A while second fuses 18 B adjacent to each other in second direction 13 B deviate from each other in first direction 13 A. To be more specific, in a column (column Y 12 ) including plural second fuses 18 A, second fuses 18 A are not located on one straight line parallel to second direction 13 B while, in a column (column Y 22 ) including plural second fuses 18 B, second fuses 18 B are not located on one straight line parallel to second direction 18 B.

FIG. 4 is a plan view of metalized film 110 of Comparative Example 1 of a film capacitor. Metalized film 110 is different from metallized films 10 A and 10 B of Example 1 only in the positions of second fuses 118 . A pair of metalized films 110 are stacked on each other and wound together, thereby producing Comparative Example 1 of the film capacitor similarly to Example 1 of the film capacitor. In Comparative Example 1, second fuses 118 are provided only in columns Y 14 and Y 24 . In other words, second fuses 118 are not dispersed in columns Y 11 -Y 14 and Y 21 -Y 24 , but are provided in columns Y 14 and Y 24 . To be more specific, second fuses 118 are located on center axis LP of each of columns Y 14 and Y 24 , so that second fuses 118 do not deviate in first direction 13 A but are arranged on one straight line.

Samples of film capacitors employing metalized films 10 A and 10 B of Examples 1 and 2 and metalized film 110 employed in Comparative Example 1 are produced, and subjected to a withstanding voltage test. In this test, a predetermined voltage is applied between external electrodes 15 A and 15 B in atmosphere of 100° C., and then, it is determined visually whether fine though-holes are formed in dielectric films 11 A and 11 B or not (fine through-hole break occurs or not). Electrode films 12 A and 12 B having various thicknesses are produced for the samples of Examples 1 and 2 and Comparative Example 1. The sheet resistance of each of electrode films 12 A and 12 B of these samples is set at 11Ω/□, 13Ω/□, and 15Ω/□.

Table 1 shows presence of the through-holes in the samples of Examples 1 and 2 and Comparative Example 1 after the withstanding voltage test. The test is preformed three times to each sample. In Table 1, a letter “A” represents samples with no fine through-hole therein, a letter “C” represents samples with fine through-holes found in twice or more in the three-time tests.

As shown in Table 1, in Example 1, when electrode films 12 A and 12 B are rather thin (the sheet resistance is not smaller than 13Ω/□), no fine through-hole break is found, and thus, the samples of Example 1 exhibit more preferable withstanding voltage performance than the samples of Comparative Example 1. In Example 2, electrode films 12 A and 12 B are thick (low sheet resistance) and prevent the fuses from being fused easily, but have no fine through-hole break found, and the samples of Example 2 exhibit more preferable withstanding voltage performance than the samples of example 1.

The reason of the test result is that in wound metalized films 10 A and 10 B of Example 2, only a few of second fuses 18 A and 18 B overlap each other. To be more specific, in Examples 1 and 2, second fuses 18 A and 18 B are dispersedly arranged in columns Y 11 -Y 14 and Y 21 -Y 24 . Particularly in Example 2, second fuses 18 A and 18 B deviate from each other in each of columns Y 11 -Y 14 and Y 21 -Y 24 in first direction 13 A. This arrangement prevents second fuses 18 A and 18 B from overlapping each other while metalized films 10 A and 10 B are wound. Second fuses 18 A and 18 B employed in Examples 1 and 2 has small widths, so that second fuses 18 A and 18 B may be fused easily. However, if one of second fuses 18 A and 18 B is fused, other second fuses 18 A and 18 B continue to work stably, hence increasing the withstanding voltage.

Samples of Comparative Example 1, on the other hand, have all of second fuses 118 provided in one column Y 14 and one column Y 24 , and more specifically, are located on center axes LP of columns Y 14 and Y 24 . While metalized film 110 is wound, a lot of second fuses 118 overlap each other. When a certain second fuse out of second fuses 118 is fused, other second fuses 118 overlapping the certain second fuse are affected in performance, and are hardly fused, so that the fine through-hole break occurs.

Film capacitors 13 of Examples 1 and 2 allow few of second fuses 18 A and 18 B to overlap each other while metalized films 10 A and 10 B are wound, hence increasing the withstanding voltage of film capacitors 13 . The sample of Example 2 allows electrode films 12 A and 12 B to be thin, accordingly improving the self-healing property.

In conventional film capacitor 1 shown in FIG. 7 , fuses 8 and 9 may not increase the withstanding voltage stably. In capacitor element 5 , some second fuses 9 overlap another second fuse 9 via dielectric film 2 .

When certain second fuse 9 is fused first, dielectric film 2 may change its properties due to the heat by the fusing, or other second fuses 9 may be prevented from being fused due to a gas pressure generated at the fusing. In such a state, if a defect occurs in the electrode films due to an electric current over the rated current flowing thereto, since the other second fuses 9 are hardly fused, electrode segments 7 including the defect cannot be separated, and may generate fine through-hole break, namely insulation breakdown.

Particularly in the case that a lot of second fuses 9 are arranged on one straight line, the fuses tend to overlap each other via a dielectric film when metalized films are stacked and wound together, so that the other second fuses 9 can be affected easily. A small width of fuse 9 enhances the function as a fuse; however, the other fuses 9 tend to be affected more easily. As a result, film capacitor 1 cannot increase the withstanding voltage stably.

Film capacitor 13 in accordance with the embodiment allows second fuses 18 A and 18 B to hardly overlap each other while metalized films 10 A and 10 B are wound together, so that the withstanding voltage can be increased. Particularly in Example 2, thinner electrode films 12 A and 12 B can improve the healing property.

Example 3 is different from Example 1 in the number of second fuses 18 A and 18 B. In Example 3, the ratio Rn of the total number of second fuses 18 A to the total number of electrode segments 16 A is 5% while the ratio Rn of the total number of second fuses 18 B to the total number of electrode segments 16 B is 5%. Second fuses 18 A are dispersedly arranged in plural columns Y 11 -Y 14 , similarly to Example 1. In each of columns Y 11 -Y 14 , second fuses 18 A adjacent to each other deviate from each other in first direction 13 A. Second fuses 18 B are dispersedly arranged in plural columns Y 21 -Y 24 , and second fuses 18 B adjacent to each other deviate from each other in first direction 13 A.

Example 4 is different from Example 1 in the number of second fuses 18 A and 18 B. In Example 4, the ratio Rn of the total number of second fuses 18 A to the total number of electrode segments 16 A is 10% while the ratio Rn of the total number of second fuses 18 B to the total number of electrode segments 16 B is 10%. Second fuses 18 A are dispersedly arranged in plural columns Y 11 -Y 14 . In each of columns Y 11 -Y 14 , second fuses 18 A adjacent to each other deviate from each other in first direction 13 A. Second fuses 18 B are dispersedly arranged in plural columns Y 21 -Y 24 , and second fuses 18 B adjacent to each other deviate from each other in first direction 13 A.

Example 5 is different from Example 1 in the number of second fuses 18 A and 18 B. In Example 5, the ratio Rn of the total number of second fuses 18 A to the total number of electrode segments 16 A is 20% while the ratio Rn of the total number of second fuses 18 B to the total number of electrode segments 16 B is 20%. Second fuses 18 A are dispersedly arranged in plural columns Y 11 -Y 14 . In each of columns Y 11 -Y 14 , second fuses 18 A adjacent to each other deviate from each other in first direction 13 A. Second fuses 18 B are dispersedly arranged in plural columns Y 21 -Y 24 , and second fuses 18 B adjacent to each other deviate from each other in first direction 13 A.

Example 6 is different from Example 1 in the number of second fuses 18 A and 18 B. In Example 6, the ratio Rn of the total number of second fuses 18 A to the total number of electrode segments 16 A is 35% while the ration Rn of the total number of second fuses 18 B to the total number of electrode segments 16 B is 35%. Second fuses 18 A are dispersedly arranged in plural columns Y 11 -Y 14 . In each of columns Y 11 -Y 14 , second fuses 18 A adjacent to each other deviate from each other in first direction 13 A. Second fuses 18 B are dispersedly arranged in plural columns Y 21 -Y 24 , and second fuses 18 B adjacent to each other deviate from each other in first direction 13 A.

Example 7 is different from Example 1 in the number of second fuses 18 A and 18 B. In Example 7, the ratio Rn of the total number of second fuses 18 A to the total number of electrode segments 16 A is 40% while the ratio Rn of the total number of second fuses 18 B to the total number of electrode segments 16 B is 40%. Second fuses 18 A are dispersedly arranged in plural columns Y 11 -Y 14 . In each of columns Y 11 -Y 14 , second fuses 18 A adjacent to each other deviate from each other in first direction 13 A. Second fuses 18 B are dispersedly arranged in plural columns Y 21 -Y 24 , and second fuses 18 B adjacent to each other deviate from each other in first direction 13 A.

Table 2 shows presence or absence of the fine through-hole break after the withstanding voltage test performed for Examples 3 to 7. Each sample is subjected to the test three times. In Table 2, a letter “A” represents a sample having no fine through-hole formed therein at the test of three times, and a letter “B” represents a sample having fine through-holes formed therein at the tent once out of three times.

As shown in Table 2, the ratio Rn of the total number of second fuses 18 A ( 18 B) to the total number of electrode segments 16 A ( 16 B) not larger than 35% can increase the withstanding voltage. Since a larger number of electrode segments 16 A and 16 B requires a larger number of second fuses 18 A and 18 B connected thereto, when an excessively large current flows, some of second fuses 18 A and 18 B may not be fused. As a result, electrode segments 16 A and 16 B with defects can be neither insulated nor isolated, thereby producing the fine through-hole break.

Samples of film capacitor are produced. In these samples, a metalized film including second fuses 18 A disposed in only one of columns Y 11 -Y 14 and another metalized film including second fuses 18 B disposed in only one of columns Y 21 -Y 24 stacked and wound together. In each sample, second fuses 18 A connect all the electrode segments 16 A adjacent to each other in second direction 13 B in respective one of columns Y 11 -Y 14 , and second fuses 18 B connect all electrode segments 16 B adjacent to each other in second direction 13 B disposed in respective one of columns Y 21 -Y 24 . These samples are subject to a voltage step-up test. In the step-up test, a voltage applied between external electrodes 15 A and 15 B of each sample in atmosphere of 100° C., and the voltage is increased by a predetermined voltage every predetermined time. A capacitance change ratio of the capacitance of each sample before increasing the voltage to the capacitance of each sample after increasing the voltage is obtained. Then, voltage Vf at which the capacitance change ratio becomes 15% is measured. Table 3 shows voltage Vf of each sample.

As shown in Table 3, second fuses 18 A and 18 B disposed in columns Y 14 and Y 24 closest to ends 410 A and 410 B ( 411 A and 411 B) opposite to ends 310 A and 310 B ( 311 A and 311 B) to be connected to external electrodes 15 A and 15 B provide the capacitors with higher voltage Vf and smaller capacitance change ratio than second fuses 18 A and 18 B disposed in columns Y 11 and Y 21 closest to ends 310 A and 310 B ( 311 A and 311 B) to be connected to external electrodes 15 A and 15 B, respectively. A reason for the above result is that, when first fuses 17 A and 17 B or second fuses 18 A and 18 B are fused and isolate certain electrode segments 16 A and 16 B, other electrode segments 16 A and 16 B affected by these isolated certain fuses can no more form the capacitance of film capacitor 13 . In the case that second fuses 18 A and 18 B are disposed in columns Y 11 and Y 21 closest to ends 310 A and 31 B ( 311 A and 311 B) to be connected to external electrodes 15 A and 15 B, respectively, isolation of certain electrode segments 16 A and 16 B disable electrode segments 16 A and 16 B connected to the isolated electrode segments to form the capacitance. On the other hand, in the case that second fuses 18 A and 18 B are disposed in columns Y 14 and Y 24 closest to ends 410 A and 410 B ( 411 A and 411 B), namely, closest to insulation margins 20 A and 20 B, respectively, even if being fused, the number of electrode segments 16 A and 16 B that cannot form the capacitance due to the fusing of second fuses 18 A and 18 B is decreased, and prevents the capacitance from decreasing. Thus, second fuses 18 A and 18 B disposed in columns Y 14 and Y 24 closest to insulation margins 20 A and 20 B, namely, ends 410 A and 410 B ( 411 A and 411 B), respectively, decreases the capacitance change ratio.

As described above, second fuses 18 A and 18 B are preferably arranged in columns Y 11 -Y 14 and Y 21 -Y 24 dispersedly, and the number of second fuses 18 A and 18 B is preferably larger in the columns closer to ends 410 A and 410 B ( 411 A and 411 B) opposite to ends 310 A and 310 B ( 311 A and 311 B) to be connected to external electrodes 15 A and 15 B than the number of second fuses 18 A and 18 B in the columns closer to ends 310 A and 310 B ( 311 A and 311 B), respectively.

A preferable structure of film capacitor 13 in actual use will be described below.

Samples of film capacitor 13 Comparative Examples 2 and 3 and Example 8 are produced. Second fuses 18 A and 18 B of these samples have smaller widths in first direction 13 A than the samples of Examples 1-7, and dielectric films 11 A and 11 B of these samples have larger thicknesses than Examples 1-7. To be more specific, dielectric films 11 A and 11 B of film capacitors 13 employed in Examples 1-7 have thicknesses of 2.5 μm while dielectric films 11 A and 11 B employed in Comparative Examples 2 and 3 and Examples 8 have thicknesses of 4.0 μm, so that second fuses 18 A and 18 B of the samples for Comparative Examples 2 and 3 and Example 8 tend to be fused more easily than those of samples of Examples 1-7. The fusing of the second fuses and the larger thicknesses of dielectric films 11 A and 11 B allow the samples of Comparative Examples 2 and 3 and Example 8 to more hardly have the fine through-hole break than the samples of Examples 1-7.

COMPARATIVE EXAMPLE 2

FIG. 5A is a plan view of metalized film 10 A ( 10 B) of film capacitor 13 employed in Comparative Example 2. In metalized film 10 A ( 10 B), electrode segments 16 A ( 16 B) are disposed in three columns Y 11 -Y 3 (Y 21 -Y 23 ) arranged in second direction 13 B. Electrode segments 16 A ( 16 B) in column Y 11 (Y 12 ) are connected to electrode portions 21 A ( 21 B) with first fuses 17 A ( 17 B). In column Y 13 (Y 23 ) farthest from external electrodes 15 A ( 15 B), all electrode segments 16 A ( 16 B) disposed in second direction 13 B are connected to each other with second fuses 18 A ( 18 B). In columns Y 11 and Y 12 (Y 21 and 22 ), no second fuses 18 A ( 18 B) are disposed, so that electrode segments 16 A ( 16 B) are not connected to each other with second fuses 18 A ( 18 B).

COMPARATIVE EXAMPLE 3

FIG. 5B is a plan view of metalized film 10 A ( 10 B) of film capacitor 13 employed in Comparative Example 3. In metalized film 10 A ( 10 B), similarly to Comparative Example 2, electrode segments 16 A ( 16 B) are disposed in three columns Y 11 -Y 13 (Y 21 -Y 23 ) arranged in second direction 13 B. Electrode segments 16 A ( 16 B) in column Y 11 (Y 12 ) are connected to electrode portions 21 A ( 21 B) with first fuses 17 A ( 17 B). In column Y 13 (Y 23 ), all electrode segments 16 A ( 16 B) disposed in second direction 13 B are connected to each other with second fuses 18 A ( 18 B).

In columns Y 11 and Y 12 (Y 21 and Y 22 ) of Comparative Example 3, similarly to column Y 13 (Y 23 ), all electrode segments 16 A ( 16 B) are connected to each other with second fuses 18 A ( 18 B). In other words, metalized film 10 A ( 10 B) employed in Comparative Example 3 includes certain electrode segments 16 A ( 16 B) connected to other electrode segments 16 A ( 16 B) surrounding certain electrode segments 16 A ( 16 B) with second fuses 18 A ( 18 B) and first fuses 17 A ( 17 B).

FIG. 5C is a plan view of metalized film 10 A ( 10 B) of film capacitor 13 employed in Example 8. In metalized film 10 A ( 10 B), similar to those employed in Comparative Examples 2 and 3, electrode segments 16 A ( 16 B) are disposed in three columns Y 11 -Y 13 (Y 21 -Y 23 ) arranged in second direction 13 B. Electrode segments 16 A ( 16 B) in column Y 11 (Y 12 ) are connected to electrode portions 21 A ( 21 B) with first fuses 17 A ( 17 B). In column Y 13 (Y 23 ), all electrode segments 16 A ( 16 B) arranged in second direction 13 B are connected to each other with second fuses 18 A ( 18 B). Similarly to Comparative Example 2 and 3, all electrode segments 16 A ( 16 B) disposed in column Y 13 (Y 23 ) farthest from external electrodes 15 A ( 15 B) along second direction 13 B are connected to each other with second fuses 18 A ( 18 B). However, in metalized film 10 A ( 10 B) employed in Example 8, second fuses 18 A ( 18 B) are arranged dispersedly in columns Y 11 and Y 12 (Y 21 and Y 22 ) except column Y 13 (Y 23 ).

To be more specific, second fuses 18 A disposed in columns Y 11 (Y 21 ) are arranged in second direction 13 B while skipping electrode segments at predetermined intervals, namely, one fuse for two electrode segments 16 A ( 16 B), so that second fuses 18 A. In column Y 12 (Y 22 ), similar to in column Y 11 (Y 12 ), second fuses 18 A ( 18 B) are arranged in the second direction while skipping the electrode segments at given intervals. Each second fuse 18 A disposed in column Y 11 (Y 21 ) is not adjacent in first direction 13 A to each second fuse 18 A disposed in column Y 12 (Y 22 ), so that in columns Y 11 and Y 12 (Y 21 and Y 22 ), second fuses 18 A ( 18 B) disposed in column Y 11 and second fuses 18 A ( 18 B) disposed in column Y 12 are alternately arranged along first direction 13 A.

As shown in FIG. 5C , second fuses 18 A ( 18 B) are evenly arranged in column Y 11 (Y 21 ) and column Y 12 (Y 22 ) so that the number of second fuses 18 A in column Y 11 (Y 21 ) is equal to the number of second fuses 18 A in columns Y 12 (Y 22 ).

The samples of film capacitor 13 of Comparative Examples 2 and 3 and Example 8 are subjected to a voltage-time test for comparing the life of the samples of capacitors 13 . To be more specific, in the voltage-time test, a constant voltage of 1100V is applied between external electrodes 15 A and 15 B I atmosphere of 105° C. A change ratio of the capacitance of capacitor 13 before applying this voltage to the capacitance of capacitor 13 after applying this voltage is measured. The time when the capacitance change ratio becomes −10% is referred to as a high-temperature life, which is a criterion of the life. Three samples of each of Example 8 and Comparative Examples 2 and 3 are prepared, and thus nine samples in total are subject to the voltage-time test. Three samples of Example 8, for instance, exhibit different test results, and a middle one among the three results is determined as the high-temperature life of film capacitor 13 of Example 8. Similarly, the high-temperature life of film capacitors 13 of Comparative Examples 2 and 3 are determined.

FIGS. 6A, 6B, and 6C show the results of the voltage-time test performed to the samples of film capacitor 13 of Comparative Examples 2 and 3 and Example 8. In FIGS. 6A-6 B, the vertical axis represents a changing ratio of capacitance, and the horizontal axis represents time for which the voltage is applied.

The metalized film capacitor of Comparative Example 2 has a capacitance changing as shown in FIG. 6A , and has a high-temperature life of about 220 hours. The metalized film capacitor of Comparative Example 3 has a capacitance changing as shown in FIG. 6B , and has a high-temperature life of about 440 hours. The metalized film capacitor of Comparative Example 3 has a substantially longer high-temperature life than Comparative Example 2. This is because the metalized film capacitor of Comparative Example 3 allows first fuses 17 A ( 17 B) and second fuses 18 A ( 18 B) to be fused due to defects in electrode segment 16 A ( 16 B), thereby isolating the defective electrode segment 16 A ( 16 B) alone. In other words, in the metalized film capacitor of Comparative Example 2, an isolation of a defective electrode segment 16 A ( 16 B) isolates simultaneously other electrode segments 16 A ( 16 B) connected to the defective one from an electric-current route of the film capacitor, so that the capacitance decreases drastically. On the other hand, in the metalized film capacitor of Comparative Example 3 can isolate the defective electrode segment 16 A ( 16 B) alone, so that the capacitance decreases just a little. As a result, the high-temperature life of the metalized film capacitor of Comparative Example 3 is longer than that of the metalized film capacitor of Comparative Example 2.

The metalized film capacitor of Example 8 has a capacitance changing as shown in FIG. 6C , and has a high-temperature life of about 470 hours. In other words, the high-temperature life of film capacitor 13 of Example 8 is longer than that of film capacitor 13 of Comparative Example 3. This is because film capacitor 13 of Example 8 can isolate defective electrode segment 16 A ( 16 B) alone similarly to Comparative Example 3, and there are a fewer second fuses 18 A ( 18 B) overlap each other in wound metalized film 10 A ( 10 B) in Example 8 than in Comparative Example 3. To be more specific, Example 8 suppresses preventing fusing or possibility of malfunction of second fuses 18 A ( 18 B) due to smaller chances of overlapping of second fuses 18 A ( 18 B), so that second fuses 18 A ( 18 B) are appropriately fused for capacitor 13 to work properly.

According to the result of the voltage-time test, the film capacitor of Example 8 has the best property.

Film capacitors 13 of Comparative Example 3 and Example 8 are subjected to a withstanding voltage test to compare their capacitor performances. In the withstanding voltage test, a predetermined voltage is applied between metalized films 10 A and 10 B in atmosphere at 100° C., and it is determined visually whether the fine through-hole break occurs or not, similarly to the test performed for metalized films 10 A and 10 B of Examples 1 and 2. Electrode films 12 A and 12 B of metalized films 10 A and 10 B employed in Comparative Example 3 and Example 8 have resistance of 12Ω/□.

This test is performed repetitively three times to each sample. The fine through-hole break is visually confirmed in each test for Comparative Example 3 while no fine through-hole break is visually confirmed at all three tests for Example 8.

The fine through-hole break in actual use may degrade the capacitor performance, such as insulation resistance. Film capacitor 13 of Example 8 does not have the fine through-hole break in the withstanding voltage test, and is more reliable than film capacitor 13 of Comparative Example 3. Film capacitor 13 of Example 8 thus maintains a high withstanding voltage stably, and is suitable to be used in a high-voltage condition, such as in an HEV.

As discussed above and as shown in FIG. 5C , plural columns Y 11 -Y 13 (Y 21 -Y 23 ) includes a first column Y 11 or Y 12 (Y 12 or Y 22 ) and a second column Y 13 (Y 23 ) farther from external electrode 15 A ( 15 B) than the first column Y 11 or Y 12 . The number of one or more second fuses 18 A ( 18 B) out of the second fuses 18 A ( 18 B) located in the second column Y 13 (Y 23 ) may be larger than the number of one or more second fuses 18 A ( 18 B) out of second fuses 18 A ( 18 B) located in the first column Y 11 or Y 12 (Y 21 or Y 22 ).

As shown in FIG. 5C , second fuses 18 A ( 18 B) may connect all of electrode segments 16 A ( 16 B) out of plural electrode segments 16 A ( 16 B) disposed in the farthest column Y 13 (Y 23 ) to each other.

In each of the one or more other columns Y 11 and Y 12 ( 2 and Y 22 ), second fuses 18 A ( 18 B) are arranged in the second direction 13 B while skipping the electrode segments at predetermined intervals.

In each of other columns Y 11 and Y 12 (Y 21 and Y 22 ), second fuses 18 A ( 18 B) may be arranged in the second direction 13 B while skipping the second electrode segments at predetermined intervals. The number of one or more second fuses 18 A ( 18 B) out of second fuses 18 A 818 B) may be disposed in each other columns Y 11 and Y 12 (Y 21 and Y 22 ) may be identical to each other.

In two columns Y 11 and Y 12 (Y 21 and Y 22 ) out of other columns Y 11 and Y 12 (Y 21 and Y 22 ) adjacent to each other, second fuses 18 A ( 18 B) may be arranged alternately in the second direction 13 B.

In each of other multiple columns Y 11 and Y 12 (Y 21 and Y 22 ), second fuses 18 A ( 18 B) are arranged in second direction 13 B while skipping the second electrodes at predetermined intervals, and the number of one or more second fuses 18 A ( 18 B) out of second fuses 18 A ( 18 B) disposed in each of other columns Y 11 and Y 12 (Y 21 and Y 22 ) may be equal to each other.

In other columns Y 11 and Y 12 (Y 21 and Y 22 ) out of other columns Y 11 and Y 12 (Y 21 and Y 22 ) adjacent to each other, second fuses 18 A ( 18 B) can be alternately arranged in second direction 13 B.

Examples 1-8 are roll-type film capacitors 13 . A laminated-type film capacitor can also have similar advantages that second fuses 18 A ( 18 B) are disposed not to overlap each other to allow narrow second fuses 18 A to be fused stably, and increase a withstanding voltage. In laminated-type of film capacitors, a long metalized film 10 A ( 10 B) is cut at a predetermined width before being laminated, or the long metalized film is wound to have a large diameter before being cut. This configuration allows second fuses 18 A ( 18 B) to be arranged randomly similarly to Examples 1-8, and prevents the second fuses from overlapping each other.

In Examples 1-8, metalized films 10 A and 10 B functioning as positive and negative electrodes have the same structure; however, only one of metalized films 10 A and 10 B may include the electrode segments ( 16 A, 16 B), the first fuses ( 17 A, 17 B), and the second fuses ( 18 A, 18 B). Another metalized film can include no slits. Even in this case, film capacitor 13 has a high withstanding voltage.