JP2014157961A - Metallized film capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve capacitor characteristics of a metalized film capacitor.SOLUTION: In the present invention, a metallized film capacitor 1 is configured such that a terminal 6 is connected to an extraction electrode 5 so as to be perpendicular to a linear projecting part 7 floated on the extraction electrode 5 by a winding core 3, at least one junction between the terminal 6 and the extraction electrode 5 is provided at the upper part and the lower part of the projecting part 7, respectively, and the projecting part 7 is not joined to the terminal 6. By the configuration of the present invention, the terminal 6 and the extraction electrode 5 can be firmly connected with a sufficient area. Accordingly, the dielectric tangent of the metallized film capacitor 1 is decreased, so that capacitor characteristics thereof can be improved.

Description

  The present invention relates to a metallized film capacitor mounted on, for example, various electronic devices, electric devices, and electronic and electric circuits of industrial devices.

  Generally, metallized film capacitors are roughly classified into those using a metal foil as an electrode and those using a deposited metal provided on a dielectric film as an electrode. Among these, metallized film capacitors using evaporated metal as an electrode (hereinafter referred to as “deposited electrode”) have a smaller volume occupied by the electrode than those using metal foil and can be reduced in size and weight. In the case where a short circuit occurs in an insulation defect part, the deposition electrode around the defect part is evaporated and scattered by the short circuit energy to insulate and insulate it, and the function of the capacitor is restored). Widely used.

  The structure of this type of metallized film capacitor will be described with reference to FIG. 6 using the metallized film capacitor 100 described in Patent Document 1 as an example. FIG. 6 is a perspective view of the metallized film capacitor 100.

  As shown in FIG. 6, the metallized film capacitor 100 includes a metal winding shaft in which a metal electrode film is formed by depositing a metal such as aluminum or zinc on the surface of a dielectric film such as polypropylene. The lead electrode 102 is formed by hot-pressing after being wound around 101 and thermally spraying a metal such as zinc on both end faces thereof. The metallized film capacitor 100 is used by further connecting the lead electrode 102 to a terminal (not shown) such as a lead wire or a bus bar by resistance welding or soldering.

  In the metallized film capacitor 100 of Patent Document 1, a metal winding shaft 101 is used, and the winding shaft 101 is divided into two parts to prevent short-circuiting between the extraction electrodes 102 on both end faces.

JP 2008-21128 A

  In a metallized film capacitor, in order to improve the capacitor characteristics, it is desirable to reduce the power loss and thus the dielectric loss tangent (tan δ) as much as possible.

  This dielectric loss tangent varies depending on various factors such as the material of the dielectric film and the connection state between the wound body and the extraction electrode, but among these, it depends greatly on the connection state between the extraction electrode and the terminal.

  Therefore, in order to obtain a metallized film capacitor having high capacitor characteristics, it is important for the metallized film capacitor to find an optimal connection state between the extraction electrode and the terminal.

  As a result of intensive studies by the present inventors to achieve the above object, the terminal is connected to the extraction electrode so as to be perpendicular to the linear convex portion that is raised on the extraction electrode by the winding core, and the terminal and It has been found that a metallized film capacitor having a small dielectric loss tangent can be realized by providing at least one lead electrode joining portion above and below the projecting portion, and having the projecting portion not joined to the terminal.

  By setting it as the above structures, the metallized film capacitor of this invention can connect a terminal and an extraction electrode firmly with sufficient area. As a result, it is possible to suppress the occurrence of terminal connection failure and the like, and it is possible to provide a metallized film capacitor having a small dielectric loss tangent and excellent capacitor characteristics.

(A) Perspective perspective view before flattening of the element in Embodiment 1, (b) Perspective perspective view after flattening of the element Front sectional view of metallized film capacitor of Embodiment 1 (A) Front sectional view of the metalized film capacitor of Comparative Example 1, (b) Front sectional view of the metalized film capacitor of Comparative Example 2 (A) Graph showing dielectric tangent measurement result of metallized film capacitor of Embodiment 1, (b) Graph showing dielectric tangent measurement result of metalized film capacitor of Comparative Example 1, (c) Metallization of Comparative Example 2 Graph showing the dielectric loss tangent measurement results of film capacitors Front sectional view of metallized film capacitor of Embodiment 2 A perspective view of a conventional metallized film capacitor

(Embodiment 1)
Hereinafter, the configuration of the metallized film capacitor 1 of the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1A is a perspective view of the element 2 of the metallized film capacitor 1 of the present embodiment before flattening, and FIG. 1B is the process of flattening the element 2 of the metalized film capacitor 1 of the present embodiment. FIG. 2 is a front perspective view of the metallized film capacitor 1 of the present embodiment.

  First, the element 2 used for the metallized film capacitor 1 of the present embodiment will be described. As shown in FIG. 1A, the element 2 of the metallized film capacitor 1 of the present embodiment is composed of a core 3 and a metallized film 4 wound around the core 3. The element 2 is flattened as shown in FIG. 1B by being pressed as described later, but before pressing, it has a cylindrical shape as shown in FIG. 1A.

  The metallized film 4 is formed by depositing metal in a predetermined pattern on a dielectric film. Then, the two metallized films 4 are made into a positive and negative pair, and wound around the core 3 so that the metal electrode films formed by vapor deposition face each other through the dielectric film.

  In the metallized film capacitor 1 of the present embodiment, a polypropylene film having a width of 30 mm and a thickness of 3.0 μm was used as the dielectric film, but other than this, polyethylene terephthalate, polyethylene naphthalate, poly Resin films such as phenyl sulfide and polystyrene may be used. Further, in the metallized film capacitor 1 of the present embodiment, the metal electrode film is formed by vapor-depositing aluminum, but in addition to this, a metal electrode such as zinc, tin, magnesium, or an alloy thereof is used. A film may be formed.

  The core 3 is made of a polypropylene film as in the case of the dielectric film of the metallized film capacitor 1. The core 3 is formed by winding a polypropylene film having a thickness of about 10 μm and a width equal to or slightly longer than the dielectric film on the shaft of the winding device for about 5 turns. Note that the winding of the metallized film 4 on the core 3 is performed as it is after the core 3 is formed on the shaft of the winding device. Then, after the winding of the metallized film 4 around the core 3 is completed, the metallized film 4 and the core 3 are extracted together from the shaft of the winding device, and the element as shown in FIG. 2 is produced.

  The element 2 shown in FIG. 1 (a) is pressed from above by a cold press to have a flat shape as shown in FIG. 1 (b). Here, as shown in FIG. 1A, the winding core 3 has a hollow cylindrical shape, and the winding core 3 is formed of a polypropylene film and has a mechanical strength that is not so high. Is easy to do. Thus, by processing the element 2 into a flat shape, an increase in size of the metallized film capacitor 1 as a product can be suppressed.

  The core 3 is crushed from a cylindrical shape to a flat shape by the above flattening process, and both end surfaces thereof are linear as shown in FIG. Further, since the core 3 is made of a polypropylene film whose width is slightly longer than that of the dielectric film as described above, both linear ends of the core 3 crushed into the flat shape are the ends of the metallized film 4. It will be in the state which protruded slightly outward from the surface. In the element 2 of the present embodiment, one end face protrudes by about 0.5 mm, but the amount of the protrusion varies somewhat.

  Then, as shown in FIG. 2, after metal is sprayed on both end faces of the element 2 to form the extraction electrode 5, the terminal 6 is connected to complete the metallized film capacitor 1.

  In the metallized film capacitor 1 of the present embodiment, zinc is used as the metal sprayed on both end faces of the element 2, and the extraction electrode 5 having a thickness of about 0.8 mm is formed. In addition to zinc, a metal such as aluminum may be used. Here, since the extraction electrode 5 is formed to be very thin, as shown in FIG. 2, the linear end portions of the core 3 slightly protruding from both end surfaces of the element 2 are raised on the extraction electrode 5. In the surface of the extraction electrode 5, the portions corresponding to both ends of the core 3 are convex portions 7 protruding linearly in the same manner as the shapes of both ends of the core 3. The convex portion 7 is formed on both the extraction electrodes 5 of the element 2 and is raised from the surface of the extraction electrode 5 by about 0.5 mm.

  And the lead wire as the terminal 6 is connected to the extraction electrode 5 at both ends of the element 2 by resistance welding. This lead wire is a tin-plated annealed copper wire having a diameter of 0.8 mm.

  In resistance welding in the metallized film capacitor 1 of the present embodiment, a current of 1.2 kA is passed, the terminal 6 is melted by the generated resistance heat, and at the same time, the terminal 6 is pressed in the direction of the element 2 with a pressure of about 19.6 N. By doing so, the terminal 6 and the extraction electrode 5 are welded.

  Here, the terminal 6 is disposed so as to be perpendicular to the linear convex portion 7, and the terminal 6 is partially in contact with the convex portion 7. Although not shown in FIG. 2, the terminal 6 overlaps vertically at the center of the straight portion of the convex portion 7. Since the terminal 6 was pressed in the direction of the element 2 during resistance welding, the terminal 6 is deformed into a shape along the surface of the extraction electrode 5 and is slightly bent at the position of the convex portion 7 as shown in FIG. It has become.

  In particular, in the metallized film capacitor 1 of this embodiment, two resistance welding joints are provided per one end face of the element 2 across the convex part 7, and the convex part 7 is not joined to the terminal 6. It is characterized by. That is, as shown in FIG. 2, on one end face of the element 2, a joint 8 is provided above the convex portion 7, and one joint 9 is provided below the convex portion 7. No joint is provided at a position corresponding to 7.

  As described above, in the metallized film capacitor 1 of the present embodiment, the joints 8 and 9 of resistance welding are provided across the convex portion 7, so that the dielectric loss tangent is small and the capacitor characteristics are excellent. .

  This effect will be described in comparison with Comparative Examples 1 and 2 shown in FIGS. These metallized film capacitors 201 and 301 of Comparative Examples 1 and 2 are obtained by changing only the arrangement of the joints with the metallized film capacitor 1 of the present embodiment, and other configurations are the metallized films of the present embodiment. The same as the film capacitor 1.

  First, as shown in FIG. 3A, the metallized film capacitor 201 of Comparative Example 1 has a joint portion 208 on the convex portion 207 and a joint portion 209 below the convex portion 207 on both end faces of the element 202. Provided.

  Next, as shown in FIG. 3B, the metalized film capacitor 301 of Comparative Example 2 is provided with joint portions 308 and 309 adjacent to each other below the convex portion 307 on both end faces of the element 302. .

  FIG. 4 shows the results of verifying the quality of dielectric loss tangent for these metallized film capacitors of the present embodiment, Comparative Example 1 and Comparative Example 2. In this measurement, 20 samples were prepared for each metallized film capacitor (N = 20), and the dispersion of dielectric loss tangent was evaluated. The dielectric loss tangent was measured at room temperature with a measurement voltage of 1 VAC and a frequency of 1 kHz. In the graph of FIG. 4, the vertical axis represents the dielectric loss tangent (%), the horizontal axis represents the number of metallized film capacitors (pieces), and the graphs of FIGS. 4 (a), (b), and (c) are the present embodiment, respectively. These results are for metallized film capacitor 1, metallized film capacitor 201 of comparative example 1, and metallized film capacitor 301 of comparative example 2.

  First, as a result of comparing FIG. 4A and FIG. 4B, the metallized film capacitor 1 of the present embodiment has a lower overall dielectric loss tangent than the metallized film capacitor 201 of Comparative Example 1. became. The average dielectric loss tangent of the metallized film capacitor 1 of the present embodiment was 0.126%, whereas the average dielectric loss tangent of the metallized film capacitor 201 of Comparative Example 1 was 0.156%. This is considered because the joint portion 208 of the metalized film capacitor 201 of Comparative Example 1 is formed on the convex portion 207, and the terminal 206 and the extraction electrode 205 are not joined with a sufficient contact area and adhesive force. It is done. 4 (a) and 4 (b), the metallized film capacitor 201 of Comparative Example 1 has a large variation in dielectric loss tangent compared to the metallized film capacitor 1 of the present embodiment, and a constant quality is maintained. I understand that there is no. This is because, in the metallized film capacitor 201 of Comparative Example 1, since the joint portion 208 is formed on the convex portion 207, it is difficult to weld the terminal 206 and the extraction electrode 205, and the terminal 206 and the extraction electrode 205 are sufficiently adhered to each other. This is considered to be caused by the fact that it is difficult to position the terminal 206 at a predetermined position of the extraction electrode 205.

  Thus, the metallized film capacitor 1 of the present embodiment has superior capacitor characteristics as compared to the metallized film capacitor 201 of Comparative Example 1. In addition, it can be seen that it is desirable not to provide a joint on the convex portion 207 for the reason described above in order to keep the quality of the metalized film capacitor as constant as possible.

  Furthermore, comparing FIG. 4A and FIG. 4C, it can be seen that the metallized film capacitor 1 of the present embodiment has a slightly lower dielectric loss tangent as a whole than the metallized film capacitor 301 of Comparative Example 2. . Specifically, the average of the dielectric loss tangent was 0.1126% for the metallized film capacitor 1 of the present embodiment and 0.136% for the metallized film capacitor 301 of Comparative Example 2. Thus, the metallized film capacitor 1 of the present embodiment has a lower dielectric loss tangent than the metallized film capacitor 301 of Comparative Example 2. This is because the joints 8 and 9 of the metallized film capacitor 1 of the present embodiment are provided at positions spaced apart from each other, whereas in the metallized film capacitor 301 of Comparative Example 2, the joints 308 and 308 are provided. It is presumed that this is caused by the fact that 309 is provided adjacently. That is, as illustrated in FIG. 3B, in the metallized film capacitor 301 of Comparative Example 2, no joint is provided above the convex portion 307, and the upper portion of the terminal 306 is higher than the convex portion 307. It is conceivable that the portion tends to float outward from the extraction electrode 305. Therefore, it is presumed that the terminal 306 cannot sufficiently adhere to the extraction electrode 305, and therefore the metallized film capacitor 1 of the present embodiment has a lower dielectric loss tangent.

  As described above, as shown in the verification results, the metallized film capacitor 1 of the present embodiment has a low dielectric loss tangent compared to the metallized film capacitors of other configurations, and has excellent capacitor characteristics.

  Further, according to the metallized film capacitor 1 of the present embodiment, the lead wire as the terminal 6 is not tilted or displaced, and the dimensional accuracy between the two terminals 6 is excellent. It has become.

  In particular, the metallized film capacitor 1 of the present embodiment may use joining means such as soldering in addition to resistance welding, but resistance welding is desirable among various joining means. This is to prevent the end face of the metallized film 4 from being heat-shrinked due to the heat effect during soldering and the deterioration of the dielectric loss tangent. Further, in the case of the metallized film capacitor 1 of the present embodiment in which the area of the extraction electrode 5 originally welded is small, the solder spreads and the solder may protrude from the extraction electrode 5.

  Moreover, in order to improve the joining strength of the terminal 6 and the extraction electrode 5, an alloy wire may be used as the thermal spray metal material for forming the extraction electrode 5, but from the viewpoint of cost, the metallized film capacitor 1 of the present embodiment. Thus, it is desirable to use only a wire formed of a single metal such as zinc. Of course, the wire formed of such a single metal is inferior in bonding strength to the alloy wire, but in the metallized film capacitor 1 of the present embodiment, the lead electrode 5 is formed of a wire formed of a single metal. Even when formed, sufficient bonding strength can be ensured. Therefore, the metallized film capacitor 1 of the present embodiment can achieve both sufficient bonding strength and cost reduction.

(Embodiment 2)
In the metallized film capacitor 21 of the present embodiment, the terminal configuration is different from that of the metallized film capacitor of the first embodiment shown in FIG. The configuration of the terminal 26 of this embodiment will be described in detail, and the description of the other configurations will be omitted.

  The configuration of the metallized film capacitor 21 according to the present embodiment will be described with reference to FIG. FIG. 5 is a front cross-sectional view showing the configuration of the metallized film capacitor 21.

  As shown in FIG. 5, in the metallized film capacitor 21, the terminal 26 is bent in the opposite direction to the metallized film capacitor 21 at the upper part and the lower part of the convex part 27. And between the upper part and the lower bent part of this convex part 27, it has been in the state which straddled the convex part 27 so that an arch might be drawn. For this reason, a gap exists between the convex portion 27 and the arch portion 30 of the terminal 26 arranged so as to face the convex portion 27, and the convex portion 27 and the terminal 26 are in a non-contact state. The joint portions 28 and 29 are provided in the upward and downward directions of the arch portion 30, respectively.

  Thus, if the shape of the terminal 26 is processed in advance so that the terminal 26 does not come into contact with the convex portion 27, a reaction force from the convex portion 27 is received when the terminal 26 is pressed against the extraction electrode 25 during welding. There is nothing. Therefore, the terminal 26 can be further closely adhered to the extraction electrode 25 and firmly welded, and the dielectric loss tangent can be further reduced.

  Further, the terminal 26 can be positioned with respect to the extraction electrode 25 with the arch portion 30 as a reference, and the positioning accuracy is excellent.

  Note that it is desirable that the bent portion at the base of the arch portion has a smoothly curved shape rather than a bent shape. By making it a curved shape, concentration of stress during welding can be prevented, and damage to the terminal 26 can be suppressed.

  As described above with reference to the first and second embodiments, the metallized film capacitor according to the present invention has a small dielectric loss tangent and excellent capacitor characteristics.

  In the description of the metallized film capacitor 1 according to the first embodiment and the metallized film capacitor 21 according to the second embodiment, terms indicating directions such as “upward” and “downward” are only relative to the relative positional relationship of the constituent members. It indicates a relative direction depending on the direction, and does not indicate an absolute direction such as a vertical direction or a horizontal direction. Therefore, when the metallized film capacitor 1 or the metallized film capacitor 21 is actually used, the terminals 6 and 26 are arranged so that the extending direction of the terminals 6 and 26 is upward in the vertical direction as shown in FIGS. For example, it may be arranged so as to face vertically downward or horizontally.

  Further, the present invention is not limited to the configuration of the metallized film capacitor 1 of the first embodiment and the metalized film capacitor 21 of the second embodiment, and can be implemented with various modifications within the scope of the invention. It is. That is, in the above description, the configuration in which the terminals 6 and 26 are lead wires is shown, but the present invention can be obtained in a configuration in which the terminals 6 and 26 are bus bars in addition to this configuration.

  The metallized film capacitor according to the present invention has a small dielectric loss tangent and excellent capacitor characteristics. Therefore, it is useful as a metallized film capacitor used in various fields such as various electronic devices, electric devices, electronic devices of industrial devices, and electric circuits.

DESCRIPTION OF SYMBOLS 1, 21 Metallized film capacitor 2 Element 3 Core 4 Metallized film 5, 25 Extraction electrode 6, 26 Terminal 7, 27 Convex part 8, 9, 28, 29 Joint part 30 Arch part

Claims (3)

A pair of metallized films having a metal electrode film on a dielectric film was wound around a core so that the metal electrode film faced through the dielectric film, and pressed to form a flat shape. Elements,
An extraction electrode provided by spraying metal on both end faces of the element;
A terminal connected to the extraction electrode;
The terminal is connected to the extraction electrode so as to be perpendicular to a linear convex portion that is raised on the extraction electrode by the winding core,
At least one junction between the terminal and the extraction electrode is provided above and below the projection, and the projection is not joined to the terminal. The metallized film capacitor according to claim 1, wherein the terminal and the extraction electrode are connected by resistance welding. The metallized film capacitor according to claim 1, wherein the terminal and the convex portion are in a non-contact state.

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