JPH04359416A - Metal vapor deposited film capacitor - Google Patents

Abstract

PURPOSE:To satisfy both of the current resistance and the safty mechanism operating characteristic in a capacitor in which a pair of metal vapor deposited film with a partial electrode and a non-partial electrode and which comprises a safty mechanism. CONSTITUTION:A part at the side end of an anti-margin part 2a in the width direction of a first metal vapor deposited film 1 is a heavy edge 3a of which the film resistance is lower than the other parts.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a capacitor using a metallized film having a safety mechanism.

0002

[Prior Art and Problems to be Solved by the Invention] Capacitors are often used which are constructed by winding a metal vapor-deposited film made by vapor-depositing a metal such as aluminum around a dielectric film. By providing a slit section, the electrode is divided into multiple pieces in the length direction,
Products equipped with a safety mechanism that prevents the progress of dielectric breakdown that occurs internally have been developed.

Among these, for example, the one disclosed in Japanese Utility Model Application Publication No. 1-21544 has a pair of metal-deposited films in the form of the above-mentioned split electrodes, and although it exhibits a self-safety function, it has the following problems. There was a problem. That is,
First, it is necessary to form many slits in a split electrode type metallized film. There are several ways to form this slit, such as forming it during vapor deposition and removing it with a laser after vapor deposition, but in either case, in the case of this split electrode, the structural process of the vapor-deposited film becomes complicated. The cost increases accordingly. Furthermore, since the area of the electrode is reduced by the provision of the slit portion, the dimensions required to secure the capacitance required as a capacitor are increased. Since the electrode peripheral length increases due to the presence of the slit portion, there is a greater tendency for capacitance to decrease due to electrode retraction due to overload, etc., and for capacitor loss to increase due to increase in film resistance loss.

[0004] Furthermore, for example, the one disclosed in Japanese Utility Model Application Publication No. 2-27553 is one in which only one of a pair of metal-deposited films is of a split electrode type, and in this case, the above-mentioned double electrode type is used. The cost will be reduced compared to However, it lacks durability against inrush currents that occur especially when opening and closing capacitors. In other words, since the electrode on the non-divided side, especially its lead extraction part, does not have a safety function to localize the destructive part, the deterioration caused by the above-mentioned overcurrent progresses, resulting in a large increase in loss, a significant decrease in capacity, etc. adverse effects may occur. As a countermeasure to this problem, it is conceivable to make the non-divided electrode thicker to strengthen the contact with the extraction lead, but in this case, the self-safety function determined by cooperation with the divided electrode will deteriorate.

[0005] This invention was made to solve the problems of the conventional ones as described above, and the self-safety function is impaired in a capacitor that combines metal vapor deposited films of split electrode type and non-split electrode type. The aim is to significantly improve durability against overcurrent without causing any damage.

[0006]

[Means and Effects for Solving the Problems] The metal vapor deposited film capacitor according to the present invention has a coating resistance value of the first metal vapor deposited film having no slit portion at the end portion on the side opposite to the margin portion in the width direction. The heavy edge is lower than that of the other parts. The current from the lead-out lead is evenly distributed at the heavy edge portion where the film resistance is low, which alleviates the unbalanced current distribution, thereby suppressing the occurrence of local breakage and local heating.

[0007] Furthermore, the degree to which the film resistance value of the heavy edge part is lowered is 1/3 to 2/3 of the resistance value of other parts.
It is appropriate to double it. Furthermore, the specific value of the film resistance value is 1.0 to 5.0 Ω/□ for the heavy edge part,
It is appropriate to set the other parts to 2.5 to 10 Ω/□. Further, the second metallized film having the slit portion may contain at least 50% by weight of zinc as the vapor-deposited metal. In this case, due to the presence of zinc, the electrode wear is small and the capacity decrease is alleviated.

[0008]

[Embodiment] Fig. 1 shows a metallized film capacitor according to an embodiment of the present invention. Fig. 1 (1) is an exploded perspective view thereof, and Fig. 1 (2) is a cross-sectional view of a pair of metallized films. . In the figure, 1 is the first metallized film,
An electrode coating 3 is formed on the surface of a first dielectric film 2 such as a polypropylene film by metal vapor deposition. 2
A is a margin portion, and the electrode coating 3 is not formed in this portion. A heavy edge portion 3a is formed at the end opposite to the margin portion 2a, and is made thicker than other portions of the electrode coating 3 so that the coating resistance value is lowered. Reference numeral 4 denotes a second metal-deposited film, in which an electrode coating 6 is formed on the surface of the second dielectric film 5, and this electrode coating 6 is provided with a slit portion 6b in addition to a margin portion 6a. . The electrode coating 6 is divided into a plurality of pieces in the length direction by the slit portion 6b, and exhibits a self-security function. 7 is a lead pull-out part, in which the first pair of wound leads are drawn out.
It is formed by spraying molten metal such as solder onto the end surfaces of the second metal vapor deposited films 1 and 4. Therefore, the lead lead-out portion 7 is welded and connected to the upper end of the electrode coating 3 of the first metallized film 1, that is, the end surface of the heavy edge portion 3a. A lead lead-out portion 8 is similarly formed on the other side of the wound film, and is welded and connected to the end surface of the lower end portion of the electrode coating 6 of the second metallized film 4 .

Next, in order to determine the optimum conditions for forming the heavy edge portion 3a, test results for sample capacitors manufactured under various conditions will be described. Specifications of the test capacitor Metal-deposited film Type Zinc-deposited polypropylene film Dimensions Width 50mm, thickness 8μm Capacitor rating Voltage 400VAC Capacity 15μF Exterior Epoxy resin potting structure in plastic case Number of samples 10 types 10 pieces each

[0010] The test results are shown in Table 1.

[Table 1] However, in Table 1, sample type NO. 1~NO. 5 adopts the shape shown by the electrode coating 6 in FIG. 1 (1) as a divided electrode (second metal vapor deposited film 4 in FIG. 1), and N
O. 6~NO. Reference numeral 10 has a fuse portion formed at the lower end of the electrode coating 6 shown in the figure by narrowing the current-carrying portion. In addition, the rate of occurrence of non-split electrode deterioration refers to the rate at which the lead connection of the non-split electrode 3 occurs when a withstand current test is performed in which short-circuiting of a charged test capacitor is repeated by increasing the charging voltage in steps. Indicates the percentage of items that have deteriorated. Moreover, the safety mechanism operation rate indicates the result based on the safety test set in JISC4908 "Capacitors for electrical equipment" and JISC4901 "Low voltage phase advancing capacitors".

The above test results revealed the following. That is, when the film resistance value of the heavy edge portion is within the range of 1/3 to 2/3 times that of the other portions, both current resistance and safety mechanism operability are satisfied. In addition, when expressed in film resistance value, the heavy edge part is 1.0 to 5.0Ω/□,
The other parts correspond to a range of 2.5 to 10 Ω/□. Therefore, by forming a heavy edge part that satisfies the conditions obtained above, the deterioration phenomenon during operation will definitely occur at the split electrode 6 of the second metal vapor deposited film, so by setting the pattern appropriately, Desired safety mechanism operating characteristics can be obtained.

Although polypropylene film was used as the dielectric film in the above embodiments, other types of films such as polyethylene terephthalate film may be used. Furthermore, in the above embodiment, the case where zinc was used as the vapor-deposited metal was explained, but this is expected to reduce the amount of electrode consumption, and the material used is not limited to zinc in the application of this invention. . Therefore, reduction in electrode wear is observed when the zinc content is 50% by weight or more, so 50% by weight of zinc is applied only to the second metallized film 4 where the peripheral length of the electrode increases due to the presence of slits. The above vapor-deposited metals may also be used.

[0013]

According to the present invention, as described above, since a predetermined heavy edge portion is formed, satisfactory results can be obtained in both current resistance and safety mechanism operability. Also, at least 50% by weight of the deposited metal of the second metal deposited film.
By containing zinc, a decrease in capacity caused by an increase in the amount of electrode consumption due to the presence of the slit portion is suppressed.

[Brief explanation of drawings]

FIG. 1 shows a metallized film capacitor according to an embodiment of the present invention, and FIG. 1 (1) is an exploded perspective view of the capacitor;
Figure (2) is a cross-sectional view of a pair of metal-deposited films.

[Explanation of symbols]

1 is the first metallized film, 2 is the first dielectric film, 2a is the margin part, 3 is the electrode coating forming the non-divided electrode, 3a is the heavy edge part, 4 is the second metallized film, 5 6 is a second dielectric film, 6 is an electrode coating forming a divided electrode, 6a is a margin portion, 6b is a slit portion,
7 and 8 are lead extraction parts.

Claims (4)

[Claims] 1. A first metal-deposited film in which an electrode coating is formed by metal vapor deposition on the first dielectric film except for a margin provided at one end in the width direction; and a second dielectric film. A second metal vapor deposition method in which an electrode coating is formed by metal vapor deposition on the film except for the margin portion provided at the other end in the width direction and the slit portions provided in the width direction at predetermined intervals in the length direction. In a metallized film capacitor configured by overlapping and winding a film, the end portion of the first metallized film on the side opposite to the margin in the width direction is formed into a heavy edge whose film resistance value is lower than that of the other portions. A metal vapor deposited film capacitor characterized by the following. 2. The film resistance value of the heavy edge portion of the first metallized film is set to 1/ of that of the non-heavy edge portion of the first metallized film and the second metallized film.
2. The metal-deposited film capacitor according to claim 1, wherein the capacitor is 3 to 2/3 times as large. 3. The coating resistance value of the heavy edge portion of the first metallized film is 1.0 to 5.0Ω/□, and the coating of the non-heavy edge portion of the first metallized film and the second metallized film is 3. The metallized film capacitor according to claim 1, wherein the metallized film capacitor has a resistance value of 2.5 to 10 Ω/□. 4. The metallized film capacitor according to claim 1, wherein the second metallized film contains at least 50% by weight of zinc as the metallized metal.