JP7714481B2 - Metallized Film - Google Patents

Description

The present invention relates to a metallized film used in a resin-molded film capacitor, in which a vapor-deposited metal electrode formed on the surface of a dielectric film is divided into a large-area divided electrode and a small-area divided electrode, and multiple small-area divided electrodes are arranged in parallel and adjacent to each other with an insulating slit between them, and multiple adjacent small-area divided electrodes are electrically connected in common to each large-area divided electrode via fuses (micro-deposited metal regions) made of a vapor-deposited metal film.

Metalized films used in resin-molded film capacitors have traditionally been equipped with safety mechanisms consisting of split electrodes and fuses. When split electrodes are formed on a metalized film, even if a breakdown occurs that exceeds the metalized film's self-healing function, current flows from the surrounding split electrodes to the split electrode with the breakdown via the fuse. This fuse action evaporates and dissipates the vapor-deposited metal film on the fuse, separating the split electrode with the breakdown from the other split electrodes and restoring the insulation, ensuring a high level of safety.

Japanese Patent Application Publication No. 5-326322 JP 2017-50436 A Japanese Patent Application Laid-Open No. 2019-192689

In actual use, this type of film capacitor generates gas due to evaporation and scattering of the metal vapor-deposited film of the fuse, which accumulates within the molding resin. Over time, the amount of accumulated gas gradually increases, and when it reaches a limit, it induces cracks and damage to the molding resin, shortening the lifespan of the capacitor (see, for example, Patent Documents 1, 2, and 3).

This invention was created in light of these circumstances, and its purpose is to minimize the amount of gas generated in metallized films used in resin-molded film capacitors that are equipped with safety mechanisms consisting of split electrodes and fuses, thereby preventing cracks, breakage, etc., and improving the life of the capacitor.

The metallized film according to the present invention comprises:
The metal vapor deposition electrode formed on the film surface of the dielectric film is divided into a large-area divided electrode having a relatively large electrode area and a small-area divided electrode having a relatively small electrode area,
a plurality of the small area divided electrodes are arranged adjacent to each other in parallel with an insulating slit therebetween,
In a metallized film, each of the adjacent small-area divided electrodes is electrically connected to each of the large-area divided electrodes via a fuse made of a vapor-deposited metal film,
The value obtained by dividing the area of one of the large-area divided electrodes by the width of one of the fuses is 1.5×10 ² or less.

In a film capacitor having the above-mentioned metallized film pattern structure, if a breakdown occurs in a small-area divided electrode and the current density flowing from the adjacent large-area divided electrode to the small-area divided electrode via the fuse becomes excessive and exceeds a predetermined value, the vapor-deposited metal film forming the fuse will evaporate and disperse. This fuse action separates the small-area divided electrode that has experienced the breakdown from the other divided electrodes, stopping further breakdown (insulation recovery) and ensuring safety (safety function due to fuse action).

In the safety function based on this fuse operation, gas may be generated when the evaporated metal film evaporates and disperses, but the inventors have found through various experiments that, as in the above-described configuration of the present invention, the amount of gas generated due to the evaporation and dispersal of the evaporated metal film during fuse operation can be suppressed to a low level appropriate for safety by setting the value obtained by dividing the area of the large-area divided electrode by the width of one fuse (hereinafter referred to as the "divided value") to ^{1.5 x 102} or less. Here, the width of the fuse is the distance between the tip ends of a pair of insulating slits that face each other and sandwich the fuse between the longitudinal ends.

In the above division value "1.5 x 10 ² or less,""1.5" indicates two significant figures, and the specific range is "145≦p<155."

The amount of gas generated is proportional to the energy flowing from the large-area divided electrode to the small-area divided electrode via the fuse. This inflow energy is proportional to the product of the area S of the large-area divided electrode from which the energy flows and the square of the applied voltage. If the applied voltage is constant, the smaller the area S of the large-area divided electrode, the smaller the inflow energy, and the more suppressed the amount of gas generated. Looking at this from another perspective, the inflow energy is proportional to the width W of the fuse formed in the insulating slit that separates the large-area divided electrode from the small-area divided electrode. In other words, the smaller the fuse width W, the more suppressed the amount of gas generated.

To summarize the above correlations, the amount of gas generated is proportional to the area S of the large-area divided electrode, and also proportional to the width W of the fuse. Therefore, in order to control the amount of gas generated due to the evaporation and scattering of the metal vapor-deposited film caused by fuse operation to a low, safe level, it is necessary that the value [S/W] obtained by dividing the area S of the large-area divided electrode by the width W of the fuse be within a specified range.

Based on this knowledge, the present invention has clarified the appropriate value for the division value [S/W], and as a result of various experiments, the value of the division value [S/W] has been determined to be "1.5 x ¹⁰² or less" to two significant digits.

The metallized film of the present invention, configured as described above, has the following preferred embodiments and variations.

[1] Large-area divided electrodes and small-area divided electrodes are arranged alternately in the width direction of the film.

[2] Furthermore, there are at least two sets of large-area electrode array regions in which the large-area divided electrodes are arranged in parallel along the longitudinal direction of the film and small-area electrode array regions in which the small-area divided electrodes are arranged in parallel along the longitudinal direction of the film, in the film width direction.

This is because the basic characteristic configuration of the present invention is repeated in two sets, occupying a large portion of the total area of the metallized film, making it possible to effectively suppress gas generation caused by evaporation and scattering of the metal vapor-deposited film due to fuse operation.

[3] Furthermore, the insulating slit between the pair of adjacent small-area divided electrodes has a cut in its middle, and a path-extension fuse made of a metal vapor-deposited film is formed in the cut, electrically connecting the pair of small-area divided electrodes. With this configuration, more paths can be secured for current flowing from a large-area divided electrode to a small-area divided electrode to flow from the small-area divided electrode to another large-area divided electrode, further extending the life of the capacitor.

According to the present invention, by setting the value obtained by dividing the area of the large-area divided electrode by the width of one fuse to 1.5 × ¹⁰ or less, the amount of gas generated due to evaporation and scattering of the metal vapor-deposited film during fuse operation can be suppressed to a low level that is safe. As a result, the amount of gas generated inside the resin-molded film capacitor can be suppressed within an appropriate range, preventing cracks and damage to the capacitor and extending its lifespan.

FIG. 1 is a plan view showing a pattern structure of a metallized film in a first embodiment of the present invention; FIG. 1 is an enlarged plan view showing a portion of a pattern structure of a metallized film according to a first embodiment of the present invention. FIG. 1 is an explanatory diagram of the width of a fuse according to a first embodiment of the present invention; FIG. 1 is a plan view showing two overlapping sheets of metallized film according to a first embodiment of the present invention; 1 is a perspective view of a capacitor element using a metallized film according to a first embodiment of the present invention; FIG. 10 is a plan view showing a pattern structure of a metallized film in a second embodiment of the present invention. 1 is a diagram illustrating the operation of dielectric breakdown and clearing of a metallized film according to an embodiment of the present invention. 1 is a diagram illustrating the operation of dielectric breakdown and clearing of a metallized film according to an embodiment of the present invention.

The following describes in detail, using specific examples, the metallized film used in the resin-molded film capacitor of the present invention having the above-described configuration.

[First Example]
In the figure, reference numeral 1 denotes a metallized film, 2 denotes a dielectric film (FIG. 1 shows a state in which part of the vapor-deposited metal electrode has been peeled off), 3 denotes a vapor-deposited metal electrode made of a metal such as aluminum, zinc, or an alloy thereof, A1, A2, and A3 denote large-area electrode array regions constituting part of vapor-deposited metal electrode 3, B1, B2, and B3 denote small-area electrode array regions constituting the remaining part of vapor-deposited metal electrode 3, z1 to z9 denote insulating slits, α1, α2, and α3 denote large-area divided electrodes with relatively large electrode areas, β1, β2, and β3 denote small-area divided electrodes with relatively small electrode areas, f1, f2, and f3 denote fuses made of vapor-deposited metal film, 4 denotes electrode lead connections, and 5 denotes an insulating margin.

As shown in Figures 1 and 2, metallized film 1 has vapor-deposited metal electrodes 3 patterned on the surface of dielectric film 2. These vapor-deposited metal electrodes 3 are composed of three sets of large-area electrode array regions and small-area electrode array regions: (A1, B1), (A2, B2), and (A3, B3). A1 is the first large-area electrode array region, and B1 is the first small-area electrode array region; these form the first large-area electrode array region and small-area electrode array region set (A1, B1). A2 is the second large-area electrode array region, and B2 is the second small-area electrode array region; these form the second large-area electrode array region and small-area electrode array region set (A2, B2). A3 is the third large-area electrode array region, and B3 is the third small-area electrode array region; these form the third large-area electrode array region and small-area electrode array region set (A3, B3). In this example, there are three sets (three columns) of repeated large-area electrode array regions and small-area electrode array regions.

The large-area electrode array region Ai (i = 1, 2, 3) is a region having, as its basic constituent elements, a plurality of large-area divided electrodes α1, α2, α3 formed by first insulating slits z1, z4, z7 arranged at predetermined intervals in the longitudinal direction X of the film. The small-area electrode array region Bi (i = 1, 2, 3) is a region having, as its basic constituent elements, a plurality of small-area divided electrodes β1, β2, β3 formed by insulating slits (z2, z3), (z5, z6), (z8, z9) arranged at predetermined intervals in the longitudinal direction X of the film. Three sets of large-area electrode array region and small-area electrode array region (Ai, Bi) are repeatedly arranged along the width direction Y of the film. In other words, large-area electrode array regions consisting of large-area divided electrodes and small-area electrode array regions consisting of small-area divided electrodes are alternately arranged in the width direction Y of the film. The metallized film 1 is constructed by forming vapor-deposited metal electrodes 3, each consisting of three sets of large-area electrode array regions and small-area electrode array regions, on at least one side of the dielectric film 2.

In the above, the first insulating slit z1 is shorter than the second and third insulating slits z2 and z3, and also shorter than the fourth and seventh insulating slits z4 and z7. The fourth insulating slit z4 is approximately the same length as the seventh insulating slit z7. The fifth and sixth insulating slits z5 and z6 are approximately the same length as the second and third insulating slits z2 and z3. The eighth and ninth insulating slits z8 and z9 are approximately the same length as the first insulating slit z1.

The large-area divided electrode α1 in the first row has a horizontally long rectangular shape, while the large-area divided electrodes α2 and α3 in the second and third rows have a vertically long rectangular shape. Here, the horizontal direction is the longitudinal direction X of the film, and the vertical direction is the width direction Y of the film. Although their shapes are different as described above, the areas of the large-area divided electrodes α2 and α3 in the second and third rows are approximately the same size as the area of the large-area divided electrode α1 in the first row. The area of the large-area divided electrode α2 in the second row is approximately the same size as the area of the large-area divided electrode α3 in the third row. Note that these area relationships may be the same.

The lengths of the fifth and sixth insulating slits z5, z6 are approximately the same as the lengths of the second and third insulating slits z2, z3. The lengths of the first, eighth, and ninth insulating slits z1, z8, z9 are approximately half the lengths of the second, third, fifth, and sixth insulating slits z2, z3, z5, z6. The length of the fourth insulating slit z4 is approximately the same as the length of the seventh insulating slit z7, and approximately twice the lengths of the first, eighth, and ninth insulating slits z1, z8, z9.

The pattern structure of the metallized film is explained in more detail below.

The first row of large-area electrode array regions A1 includes an electrode lead connection portion 4 for connecting a sprayed metal electrode (metallikon) at one edge of the metallized film 1 in the film width direction Y. This electrode lead connection portion 4 is a region that extends continuously along the film longitudinal direction X at one edge of the film width direction Y (a narrow, horizontally elongated conductive region outside the dashed line in Figure 1) and is integrally connected to the first row of large-area electrode array regions A1. The electrode lead connection portion 4 has a thicker electrode thickness than other regions of the vapor-deposited metal electrode 3 (heavy edge). This results in high connection reliability between the electrode lead connection portion 4 and the electrode lead portion (metallikon) 9.

The first large-area electrode row region A1 is a collection of numerous large-area divided electrodes α1... arranged in parallel along the film's longitudinal direction X. Adjacent large-area divided electrodes α1, α1... in the film's longitudinal direction X are separated from each other by first insulating slits z1... extending in the film's width direction Y.

The first small-area electrode row region B1 is a collection of many small-area divided electrodes β1... arranged in parallel along the film longitudinal direction X. The number of small-area divided electrodes β1... is eight times the number of large-area divided electrodes α1... (as shown in the example). Adjacent small-area divided electrodes β1, β1... in the film longitudinal direction X are separated by second and third insulating slits z2, z3... extending in the film width direction Y. The second insulating slit z2 has a linear, continuous shape over the entire length of the small-area divided electrode β1 in the long-side direction. The third insulating slit z3 has notches in two locations along the long-side direction. The small-area divided electrodes β1... are electrically connected at both ends along the long side to the large-area divided electrodes α1, α2 in the first and second large-area electrode row regions A1, A2, respectively, via fuses f1, f1 made of evaporated metal films. Path extension fuses f ₁₂ and f ₁₃ made of a metal vapor deposition film are formed in the cut portions of the third insulating slits z3 located every other between adjacent small area divided electrodes β1, β1, ... in the longitudinal direction X of the film.

The second and third insulating slits z2, z3 are both formed in a Muller-Lyer shape (a shape with inward-pointing arrowheads at both ends of a line segment of a predetermined length). The array regions of the arrowhead groups, which are aligned in an orderly fashion adjacent to and facing each other in the longitudinal direction X of the film, define the boundary between the first large-area electrode array region A1 and the first small-area electrode array region B1, and form a regular arrangement of fuses f1 between adjacent arrowheads. The first row of large-area divided electrodes α1 are electrically connected to the numerous small-area divided electrodes β1 via the upper row of fuses f1. Furthermore, the numerous small-area divided electrodes β1 are electrically connected to the second row of large-area divided electrodes α2 via the lower row of fuses f1.

The second large-area electrode row region A2 is a collection of numerous large-area divided electrodes α2 arranged in parallel along the film's longitudinal direction X. Adjacent large-area divided electrodes α2, α2 in the film's longitudinal direction X are separated by insulating slits z4 extending in the film's width direction Y.

The second small-area electrode array region B2 is a collection of many small-area divided electrodes β2... arranged in parallel along the film longitudinal direction X. The number of small-area divided electrodes β2... is four times the number of large-area divided electrodes α2... in the second row (in the illustrated example). Adjacent small-area divided electrodes β2, β2... in the film longitudinal direction X are separated by fifth and sixth insulating slits z5, z6... extending in the film width direction Y. The fifth insulating slit z5 has a linear, continuous shape along the entire length of the small-area divided electrode β2 in the long-side direction. The sixth insulating slit z6 has notches in two locations along the long side. The small-area divided electrodes β2... are electrically connected at both ends along the long side to the large-area divided electrodes α2, α3 in the second and third large-area electrode array regions A2, A3 via fuses f2, f2 made of evaporated metal films. Path expansion fuses f ₂₂ and f ₂₃ made of a metal vapor deposition film are formed in the cut portions of the sixth insulating slits z6 located every other between adjacent small area divided electrodes β2, β2, ... in the longitudinal direction X of the film.

The third large-area electrode row region A3 is a collection of numerous large-area divided electrodes α3... arranged in parallel along the film longitudinal direction X. Adjacent large-area divided electrodes α3, α3... in the film longitudinal direction X are separated from each other by seventh insulating slits z7... extending in the film width direction Y.

In the third small-area electrode row region B3, its eighth and ninth insulating slits z8, z9 are connected to the insulating margin 5 at the other edge of the metallized film 1 in the film width direction Y. This insulating margin 5 is a horizontally elongated insulating region that extends continuously in the film longitudinal direction X at the other edge of the dielectric film 2 in the film width direction Y.

The third small-area electrode array region B3 is a collection of many small-area divided electrodes β3... arranged in parallel along the film longitudinal direction X. The number of small-area divided electrodes β3... is four times the number of large-area divided electrodes α3... in the third row (in the illustrated example). Adjacent small-area divided electrodes β3, β3... in the film longitudinal direction X are separated by eighth and ninth insulating slits z8, z9... extending in the film width direction Y. The eighth insulating slit z8 has a linear, continuous shape over the entire length of the small-area divided electrode β3 in the long-side direction. The ninth insulating slit z9 has a cut in one location along the long side. The small-area divided electrodes β3... are electrically connected at one end along the long side to the large-area divided electrodes α3 in the third large-area electrode array region A3 via fuses f3 made of evaporated metal film. A path expansion fuse f ₃₂ made of a metal vapor deposition film is formed in the cut portion of the insulating slit z9 located every other between adjacent small area divided electrodes β3, β3, . . . in the longitudinal direction X of the film.

In the metallized film of this embodiment, the vapor-deposited metal electrode 3 formed on the film surface of the dielectric film 2 is divided into large-area divided electrodes (α1, α2, α3) and small-area divided electrodes (β1, β2, β3). A plurality of the small-area divided electrodes (β1, β2, β3) are arranged in parallel, adjacent to each other with insulating slits (z2, z3), (z5, z6), and (z8, z9) sandwiched between them. Adjacent small-area divided electrodes (β1, β2, β3) are electrically connected in common to each large-area divided electrode (α1, α2, α3) via fuses (f1, f2, f3) made of vapor-deposited metal.

In addition, the small-area divided electrode β1 in the first small-area electrode row region B1 is connected to the large-area divided electrode α1 in the first large-area electrode row region A1 and the large-area divided electrode α2 in the second large-area electrode row region A2 via fuses f1, f1 at both ends in the film width direction Y, respectively. The small-area divided electrode β2 in the second small-area electrode row region B2 is connected to the large-area divided electrode α2 in the second large-area electrode row region A2 and the large-area divided electrode α3 in the third large-area electrode row region A3 via fuses f2, f2 at both ends in the film width direction Y, respectively. The small-area divided electrode β3 in the third small-area electrode row region B3 is connected to the large-area divided electrode α3 in the third large-area electrode row region A3 via fuse f3 at one end in the film width direction Y. The other end of the small-area divided electrode β3 in the film width direction Y is electrically closed by an insulating margin 5.

The first insulating slit z1 in the first large-area electrode row region A1, which separates adjacent large-area divided electrodes α1, α1, is linearly connected to the linearly connected second insulating slit z2 in the first small-area electrode row region B1. The fourth insulating slit z4 in the second large-area electrode row region A2, which separates adjacent large-area divided electrodes α2, α2, is linearly connected to the linearly connected second insulating slit z2 in the first small-area electrode row region B1 and the linearly connected fifth insulating slit z5 in the second small-area electrode row region B2. The seventh insulating slit z7 in the third large-area electrode row region A3, which separates adjacent large-area divided electrodes α3, α3, is linearly connected to the linearly connected fifth insulating slit z5 in the second small-area electrode row region B2 and the linearly connected eighth insulating slit z8 in the third small-area electrode row region B3.

Insulating slit z1 is located in the same position as insulating slits z5, z7, and z8 in the longitudinal direction X of the film. Insulating slit z4 is located in the same position as insulating slits z2, z5, and z8 in the longitudinal direction X of the film. Insulating slits z3, z6, and z9 are located in the same position as each other in the longitudinal direction X of the film. The pitch of the first insulating slit z1 is four times the pitch of the second insulating slit z2 and the pitch of the third insulating slit z3. The pitch of the fourth and seventh insulating slits z4 and z7 is twice the pitch of the insulating slits z2, z5, and z8.

A pair of adjacent small-area divided electrodes β1, β1 across the second insulating slit z2 are not directly connected to each other, but are connected via the upper fuse f1 and large-area divided electrode α1, and via the lower fuse f1 and large-area divided electrode α2. The same is true for a pair of adjacent small-area divided electrodes β2, β2 across the fifth insulating slit z5. A pair of adjacent small-area divided electrodes β3, β3 across the eighth insulating slit z8 (excluding the insulating slit continuous with the seventh insulating slit z7) are not directly connected to each other, but are connected via the upper fuse f3 and large-area divided electrode α3.

A pair of adjacent small area divided electrodes β1, β1 across the third insulating slit z3 are directly connected to each other via path extension fuses _f12 , _f13 . A pair of adjacent small area divided electrodes β2, β2 across the sixth insulating slit z6 are directly connected to each other via path extension fuses _f22 , _f23 . A pair of adjacent small area divided electrodes β3, β3 across the ninth insulating slit z9 are directly connected to each other via path extension fuse _f32 .

Next, using Figure 3, we will explain the width W of the fuse f1 (f2, f3) that connects the large-area divided electrode α1 (α2, α3) and the small-area divided electrode β1 (β2, β3).

Fuse f1 is formed by a vapor-deposited metal film between the tip of insulating slit z2 (more precisely, tip z2' of the arrowhead) and the tip of the adjacent insulating slit z3 (z3'). The width W of fuse f1, sandwiched between these two tips, is the minimum distance between tip z2' of insulating slit z2 and tip z3' of insulating slit z3.

Two sheets of metallized film 1, each having a dielectric film 2 and a vapor-deposited metal electrode 3 formed thereon, are prepared as described above. As shown in Figure 4, the metallized films 1 are flipped 180 degrees and stacked in two layers, slightly offset in the film width direction Y so that the electrode lead connection portion 4 of one metallized film 1 does not overlap the vapor-deposited metal electrode of the other metallized film 1. The first large-area electrode array region A1 along the side edge of the upper metallized film 1 faces the third small-area electrode array region B3 of the lower metallized film 1 directly below it. The electrode lead connection portion 4 faces the insulating margin 5. The second large-area electrode array region A2 of the upper metallized film 1 faces the second small-area electrode array region B2 of the lower metallized film 1. The third large-area electrode array region A3 of the upper metallized film 1 faces the first small-area electrode array region B1 of the lower metallized film 1. Furthermore, the first small-area electrode array region B1 in the upper metallized film 1 faces the third large-area electrode array region A3 in the lower metallized film 1. The second small-area electrode array region B2 in the upper metallized film 1 faces the second large-area electrode array region A2 in the lower metallized film 1. The first large-area electrode array region A1 on the side edge of the lower metallized film 1 faces directly below the third small-area electrode array region B3 in the upper metallized film 1. The insulating margin 5 faces the electrode lead connection portion 4. In short, the small-area electrode array region in one metallized film faces the large-area electrode array region in the other metallized film.

Since there is a risk of short-circuit breakdown if the large-area electrode array region of one metallized film faces the large-area electrode array region of the other metallized film, it is preferable that all of the large-area electrode array regions of one metallized film face the small-area electrode array regions of the other metallized film.

As described above, the upper and lower metallized films 1 are stacked and wound around the outer periphery of a winding core 6 in multiple layers as shown in FIG. 5. An outer packaging film 7 is then wrapped around the outermost layer, and the resulting structure is flattened into an elongated oval shape by pressing, yielding a metallized multilayer film 8. Furthermore, electrode lead portions (metallikon) 9, 9 are formed by metal spraying at both axial ends of the metallized multilayer film 8, yielding a highly flat metallized film capacitor element C. The electrode lead portions 9, 9 are electrically connected to the electrode lead connection portions 4, 4 on both axial sides. The metallized film capacitor element C configured in this manner is housed in, for example, a resin case and sealed with a resin filling the resin case, except for the electrode lead terminal portions that connect to external terminals.

In addition, instead of winding two long layers of metallized film 1,1 as described above, there is also a type of capacitor element in which two short layers of metallized film 1,1 are stacked.

Next, we will explain the division value, which is the greatest feature of this invention in this embodiment.

The division value, which is a characteristic element of the present invention, is the value obtained by dividing the area S of the large-area divided electrode αi (i = 1, 2, 3 in this embodiment) by the width W of the fuse fi (i = 1, 2, 3 in this embodiment), and in particular, the value obtained by dividing the area S of the large-area divided electrode α1 in the first large-area electrode row region A1 connected to the electrode lead connection portion 4 by the width W of the fuse f1 in the small-area divided electrode β1 in the first small-area electrode row region B1.

The value [S/W] obtained by dividing the area S of the large-area divided electrode α1 by the width W of the fuse f1 is set to approximately 150 in this embodiment ([S/W]=150). More specifically,
S = 24mm x 9.45mm = 226.8mm ²
W = 1.5 mm
S/W=226.8/1.5=151.2
It is.

As a result, in the example shown in Figure 1, cracks and breakage were prevented in the resin-molded film capacitor. This means that the amount of gas generated due to the evaporation and scattering of the metal vapor-deposited film caused by fuse operation was kept within a safe range, making it possible to extend the life of the film capacitor.

Second Example
In a second embodiment (not shown) formed in a pattern similar to that of FIG.
The division value [S/W] was set to approximately 120. Specifically,
S = 24mm x 9.45mm = 226.8mm ²
W = 1.9 mm
S/W=226.8/1.9≒119.4
As a result, cracks and breakages could be prevented in the resin-molded film capacitor, as in the example shown in Figure 1. This also means that the amount of gas generated due to evaporation and scattering of the metal vapor-deposited film caused by fuse operation could be suppressed within a safe range, making it possible to extend the life of the film capacitor.

[Third Example]
In the third embodiment shown in Fig. 6, vapor-deposited metal electrode 3 is composed of two sets of large-area electrode array regions and small-area electrode array regions, A1, B1 and A3, B3. The second intermediate set, A2, B2, shown in Fig. 1, is omitted. Although there are two sets, for convenience, the set A3, B3 is designated by the reference numeral for the second set. This is because the similarity in the pattern configuration is emphasized.

In this third embodiment, a first insulating slit z1 is added at the center of the pair of adjacent first insulating slits z1, z1 in the large-area divided electrode α1 of the first embodiment shown in Figure 1. The large-area divided electrode α1 is vertically long. In Figure 1, eight small-area divided electrodes β1 correspond to the large-area divided electrode α1, whereas in Figure 6, four small-area divided electrodes β1 correspond to the large-area divided electrode α1.

In the case of Fig. 6, the horizontal width (film longitudinal direction X) of the large-area divided electrode α1 is about half that of Fig. 1, while the vertical width (film width direction Y) of the large-area divided electrode α1 is about twice that of Fig. 1, so the area of the large-area divided electrode α1 is almost the same in Fig. 6 and Fig. 1. Since the width W of the fuse f1 is the same, the value [S/W] obtained by dividing the area S of the large-area divided electrode α1 by the width W of the fuse f1 is about 145. More specifically,
S = 12mm x 18mm = 216mm ²
W = 1.5 mm
S/W=216/1.5=144
It is.

As a result, in the case of the third embodiment, cracks, breakage, etc. were prevented in the resin-molded film capacitor. This means that the amount of gas generated due to the evaporation and scattering of the metal vapor-deposited film caused by fuse operation was suppressed within an appropriate range from a safety standpoint, making it possible to extend the life of the film capacitor.

Comparative Example
On the other hand, in metallized films in which the value [S/W] obtained by dividing the area S of the large-area divided electrode α1 by the width W of the fuse f1 exceeds 1.5 x ¹⁰² , gas generation caused by evaporation and scattering of the metal vapor-deposited film due to fuse operation cannot be sufficiently suppressed within a safe range. For example, in metallized film 1 having a pattern structure set at S/W = 200, clear cracks were observed in the resin-sealed case containing the metallized film capacitor element C due to gas generation caused by evaporation and scattering of the metal vapor-deposited film due to fuse operation.

In the above embodiment, it was explained that the path expansion fuses f12, f13 made of a metal vapor deposition film are formed in the cut portions of the third insulating slits z3 located every other between adjacent small area divided electrodes _β1 , β1, _... in the longitudinal direction X of the film.

As shown in Figure 7, assume that breakdown occurs at point P in a small-area divided electrode β1. Because the resistance of the breakdown point P drops significantly, large currents _i1 , ⁱ² , _i3 , and _i4 suddenly flow in from the surrounding area, causing clearing by evaporation and scattering of the evaporated metal film. Current _i1 flows in from the upper fuse f1, current ⁱ² flows in from the lower fuse f1, current _i3 flows in from the upper fuse f1 and the upper path extension fuse _f12 , and current _i4 flows in from the lower fuse f1 and the lower path extension fuse _f13 .

When the clearing ends, the large current disappears and the state returns to a steady state. As shown in Figure 8, even if the large current flowing into the insulation breakdown point P becomes excessive, the excess current can be released to the large-area divided electrode _α1 or the large-area divided electrode α2 via the upper path extension fuse f12 or the lower path extension fuse _f13 .

In this way, the excess current is dispersed into small currents and flows out to the large-area divided electrodes α1 and α2. Therefore, clearing inside the small-area divided electrode β1 does not occur in the other five unit electrode regions _β1-2 , ^β1-3 , _β1-4 , _β1-5 , and _β1-6 except for the one unit electrode _{region β1-1} including the insulation breakdown point P.

In conclusion, in the small-area divided electrode β1 where breakdown occurred, the area proportion that lost its capacitance formation function was approximately one-sixth (the remaining approximately five-sixths remained as effective electrode area), which is a significant reduction.

In this way, by providing the path expansion fuses _f12 and _f13 in the middle of the insulating slit, it is possible to improve the voltage resistance performance while suppressing the reduction in the effective electrode area and thus the loss of the capacitance formation function, thereby improving the capacitor lifespan.

This invention is useful as a technology for preventing cracks and damage to the capacitor by suppressing the amount of gas generated by evaporation and scattering of the metal vapor-deposited film due to fuse operation within an appropriate range for metallized films used in film capacitors that are equipped with a safety mechanism consisting of split electrodes and fuse elements and are constructed as a resin molded type.

2 Dielectric film 3 Metal vapor deposition electrode A1, A2, A3 Large area electrode array region B1, B2, B3 Small area electrode array region α1, α2, α3 Large area divided electrode β1, β2, β3 Small area divided electrode f1, f2, f3 Fuses _f12 , _f13 Path expansion fuses _f22 , _f23 Path expansion fuses _f32 Path expansion fuse zi (i = 1, 2 ...) Insulation slit

Claims (4)

The metal vapor deposition electrode formed on the film surface of the dielectric film is divided into a large-area divided electrode having a relatively large electrode area and a small-area divided electrode having a relatively small electrode area,
a plurality of the small area divided electrodes are arranged adjacent to each other in parallel with an insulating slit therebetween,
In a metallized film, each of the adjacent small-area divided electrodes is electrically connected to each of the large-area divided electrodes via a fuse made of a vapor-deposited metal film,
A metallized film, characterized in that the value obtained by dividing the area of one of the large-area divided electrodes by the width of one of the fuses is 119.4 or more and 151.2 or less. The metallized film of claim 1, wherein the large-area divided electrodes and the small-area divided electrodes are arranged alternately in the width direction of the film. The metallized film of claim 2, wherein the film has at least two sets of large-area electrode array regions in which the large-area divided electrodes are arranged in parallel along the longitudinal direction of the film and small-area electrode array regions in which the small-area divided electrodes are arranged in parallel along the longitudinal direction of the film, in the width direction of the film. The metallized film described in any one of claims 1 to 3, wherein the insulating slit between the pair of adjacently arranged small-area divided electrodes has a cut in its middle, and a path-expansion fuse made of a vapor-deposited metal film is formed in the cut, electrically connecting the pair of small-area divided electrodes.