JP2008277671A - Metallized film capacitor and PEN film used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve high heat resistance and high withstand voltage at the same time regarding a metallized film capacitor used for a motor vehicle or the like. <P>SOLUTION: The capacitor comprises an element whereon a pair of metallized films are wound so that a metal vapor deposition electrode 2 is disposed opposed via a dielectric film 1 and a metallicon electrode 4 formed in both ends of the element. A PEN film which does not contain a filler is used as the dielectric film 1 and thermal contraction rate of the PEN film in a longitudinal direction at 150°C is 1.5 to 4.0%. According to this constitution, unevenness of a film surface is reduced as filler is not incorporated, and the film does not bite air when the dielectric film 1 is wound in lamination. Furthermore, since thermal contraction rate in a longitudinal direction is large, an element of higher winding fastening force can be obtained by carrying out thermal aging, thus achieving high heat resistance and high withstand voltage at the same time. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY The present invention is used in various electronic equipment, electrical equipment, industrial equipment, automobiles, etc., and in particular, a metallized film capacitor that is optimal for smoothing, filtering, and snubbing of motor drive inverter circuits of hybrid automobiles and PEN used therefor It relates to film.

  In recent years, from the viewpoint of environmental protection, all electric devices are controlled by inverter circuits, and energy saving and high efficiency are being promoted. In particular, in the automobile industry, hybrid vehicles (hereinafter referred to as HEVs) that run on electric motors and engines have been introduced into the market, and the development of technologies relating to energy saving and high efficiency has been activated, which is friendly to the global environment.

  Since such a HEV electric motor has a high operating voltage range of several hundred volts, a metallized film capacitor having high withstand voltage and low loss electric characteristics as a capacitor used in connection with such an electric motor. In addition, the trend of adopting metalized film capacitors with a very long life is conspicuous due to the demand for maintenance-free in the market.

  And since this kind of metallized film capacitor is mounted on automobiles, high heat resistance and high voltage resistance are required, and various developments and proposals for high heat resistance and high voltage resistance have been made. Met.

  4 (a) and 4 (b) are a developed perspective view and a sectional view of a dielectric film showing the structure of a conventional metalized film capacitor of this type. In FIG. 4, 20 is a dielectric film made of polypropylene, 21 is a metal vapor deposition electrode formed on one side of the dielectric film 20, 22 is a non-metal which is an exposed portion of the dielectric film 20 provided continuously in the longitudinal direction on one end side in the width direction of the dielectric film 20. It is a vapor deposition part, and thereby a metallized film is formed. Using this metallized film as a pair, the metal vapor-deposited electrodes 21 are wound so as to face each other with the dielectric film 20 therebetween, and zinc is sprayed on both end surfaces. The metallicon electrode 23 is formed.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
Japanese Patent Laid-Open No. 4-163042

  However, the above conventional metallized film capacitor generally uses a polypropylene film (hereinafter referred to as a PP film) as a dielectric film material, and therefore has low heat resistance (about 110 ° C.) and is required for automobiles. There is a problem that the severe heat resistance temperature (150 ° C.) cannot be satisfied.

  For this purpose, inorganic fillers such as polyethylene-2,6-naphthalate (hereinafter referred to as PEN), polyphenylene sulfite (hereinafter referred to as PPS), polyethylene terephthalate (hereinafter referred to as PET) are used as dielectric film materials. Although it is conceivable to improve the heat resistance by using a dielectric film containing benzene, among these materials, for example, when a PEN film having excellent heat resistance is used, sufficient heat resistance is obtained. However, there is a problem that the withstand voltage is low, and the withstand voltage performance cannot be sufficiently satisfied even if the electrode pattern formed by metal vapor deposition cultivated in the conventional PP film is used as it is.

  Furthermore, since the conventional PEN film contains an inorganic filler, the unevenness (surface roughness) of the film surface increases, so it is desirable to bite air when such films are stacked and wound. In addition, there is a problem that the inorganic filler is detached by handling such a film and the withstand voltage is lowered.

  An object of the present invention is to solve such a conventional problem and to provide a metallized film capacitor capable of simultaneously achieving high heat resistance and high voltage resistance and a dielectric film used therefor. .

  In order to solve the above-described problems, the present invention comprises an element in which a pair of metallized films are wound so that metal vapor-deposited electrodes face each other through a dielectric film, and metallicon electrodes formed on both end faces of the element. In the metallized film capacitor, a PEN (polyethylene-2,6-naphthalate) film containing no filler is used as the dielectric film, and the thermal contraction rate in the longitudinal direction (winding direction) of this PEN film at 150 ° C. It is set as the structure which is 1.5 to 4.0%.

  Moreover, as a dielectric film, the thermal contraction rate in the longitudinal direction (winding direction) at 150 ° C. is 1.5 to 4.0%, the surface roughness Ra of at least one surface is 10 to 50 nm, and the static friction coefficient of at least one surface is 0. A PEN (polyethylene-2,6-naphthalate) film containing 25 to 0.5 and containing no filler is used.

  As described above, the metallized film capacitor according to the present invention uses a PEN film that does not contain a filler as a dielectric film, and the PEN film has a thermal contraction rate in the longitudinal direction (winding direction) at 150 ° C. of 1.5. By having a composition of ˜4.0%, since there is no filler, unevenness (surface roughness) on the film surface is reduced, so that air can be bitten when such films are overlapped and wound. In addition, since the thermal shrinkage rate in the longitudinal direction is large, it becomes possible to obtain an element with higher winding force by thermal aging, thereby achieving high heat resistance and high voltage resistance at the same time. The effect that it can be obtained.

(Embodiment 1)
Hereinafter, the first to fourth aspects of the present invention will be described with reference to the first embodiment.

  1A and 1B are a developed perspective view and a sectional view of a dielectric film showing a configuration of a metallized film capacitor according to Embodiment 1 of the present invention. In FIG. 1, 1 is a dielectric film, 2 is a metal vapor deposition electrode formed on one side of the dielectric film 1, 3 is a non-metal which is an exposed portion of the dielectric film 1 provided continuously on one end side in the width direction of the dielectric film 1 in the longitudinal direction. It is a vapor deposition part, and thereby a metallized film is formed. Using this metallized film as a pair, the metal vapor-deposited electrodes 2 are wound so as to face each other with the dielectric film 1 therebetween, and zinc is sprayed on both end faces. A pair of metallicon electrodes 4 is formed.

  In the present embodiment, a PEN (polyethylene-2,6-naphthalate) film (thickness: 3 μm) containing no filler is used as the dielectric film 1. This is because the unevenness (surface roughness) of the film surface is reduced by not containing the filler, so that air is not chewed when such films are overlapped and wound, thereby ensuring close contact between the films. The purpose is to improve the state and increase the capacity.

  In addition, the longitudinal direction (winding) of the dielectric film 1 at 150 ° C. for the purpose of further improving the contact state between the films after winding to obtain an element having a high winding force. (Table 1) shows the results of evaluating the capacitor characteristics after producing a metallized film capacitor using a dielectric film having a changed direction of thermal shrinkage and heat aging it. In addition, the heat shrinkage rate in the width direction (direction intersecting with the longitudinal direction) was in the range of 0.1 to 0.5%.

  In Table 1, the capacity appearance rate is the ratio of the capacity value as a product to the theoretical calculation value, and the capacity change rate is the capacity change rate when DC750V is applied for 10 minutes at room temperature. .

  As apparent from (Table 1), in the range where the heat shrinkage rate in the longitudinal direction (winding direction) at 150 ° C. of the dielectric film 1 is in the range of 1.5 to 4.0%, the capacity appearance rate and the capacity change rate. It can be seen that the characteristics are stable. When the heat shrinkage rate is less than 1.5%, the improvement in the adhesion state between the films is small, so the capacity does not increase, and when the heat shrinkage rate exceeds 4.0%, it is unnecessary due to excessive restriction. It can be seen that stress is generated, the withstand voltage is lowered, and the capacity change rate is increased, which is not preferable.

  Further, in the same manner as described above, the surface roughness of the dielectric film 1 for the purpose of further improving the contact state between the respective films after winding and obtaining an element having a high winding force. Table 2 shows the results of producing metallized film capacitors using dielectric films with varying Ra and evaluating the capacitor characteristics.

  The workability in (Table 2) represents whether or not the dielectric film slipped or slipped in the metal vapor deposition electrode formation or element winding process. The symbol “X” means that no slippage or slippage occurred.

  As apparent from Table 2, it can be seen that the capacitance appearance rate and the capacitance change rate characteristics are stable when the surface roughness Ra of the dielectric film 1 is in the range of 10 to 50 nm. When the surface roughness Ra is less than 10 nm, the handling is affected and the withstand voltage is lowered to increase the capacity change rate. When the surface roughness Ra exceeds 50 nm, the capacity appearance rate is decreased. It turns out that it is not preferable.

  Further, in the same manner as described above, the static friction coefficient of the dielectric film 1 is set for the purpose of further improving the contact state between the respective films after winding and obtaining an element having a high winding force. Table 3 shows the results of producing a metallized film capacitor using the changed dielectric film and evaluating the capacitor characteristics.

  As apparent from Table 3, it can be seen that the capacity appearance rate and capacity change rate characteristics are stable when the static friction coefficient of the dielectric film 1 is in the range of 0.25 to 0.5. When the static friction coefficient is less than 0.25, slipping is too good, and unnecessary stress is generated due to excessive tightening, and the withstand voltage is lowered, so that the capacity change rate increases, and the static friction coefficient is 0.5. It can be seen that exceeding this is not preferable because it affects handling.

  Thus, as a dielectric film used for the metallized film capacitor according to the present invention, a PEN film containing no filler is used, and the thermal shrinkage ratio in the longitudinal direction (winding direction) at 150 ° C. of this PEN film is 1.5. -4.0%, the surface roughness Ra of at least one surface is 10 to 50 nm, and the static friction coefficient of at least one surface is 0.25 to 0.5. This makes it possible to obtain an element having a high tightening force, thereby achieving a special effect that high heat resistance and high withstand voltage can be achieved at the same time.

  In addition, in this Embodiment, although demonstrated in the example using the PEN film which does not contain a filler as a dielectric film, this invention is not limited to this, The PEN film which does not contain the said filler, By including an inorganic filler having a particle size of 0.001 to 1.0 μm in an amount of 1 part by weight or less, only handling properties are improved without adversely affecting the excellent performance as the metallized film capacitor. Is possible. However, when the particle size of the inorganic filler is increased or the content is increased, care must be taken because the performance as a metallized film capacitor is adversely affected.

  In addition, the PEN film that does not contain the above fillers may have other properties such as additives such as antioxidants and plasticizers, polyester resins such as PET, and syndiotactic polystyrene resins, as long as the electrical properties are not impaired. May be added.

(Embodiment 2)
Hereinafter, the second and second embodiments of the present invention will be described.

  In this embodiment, the configuration of the dielectric film used in the metallized film capacitor described in the first embodiment is partially different, and the other configurations are the same as those in the first embodiment. For this reason, the same parts are denoted by the same reference numerals and detailed description thereof is omitted, and only different parts will be described below with reference to the drawings.

  FIG. 2 is a sectional view showing a configuration of a dielectric film used in the metallized film capacitor according to the second embodiment of the present invention. In FIG. 2, 5 is a dielectric film, and this dielectric film 5 is Similar to the dielectric film 1 according to the first embodiment, a PEN film containing no filler is used, and the heat shrinkage ratio in the longitudinal direction (winding direction) at 150 ° C. of this PEN film is 1.5 to 4.0%. The surface roughness Ra of at least one surface is 10 to 50 nm, and the static friction coefficient of at least one surface is 0.25 to 0.5.

  It should be noted that the PEN film not containing the filler is not limited to the electrical properties of the PEN film, but includes additives such as antioxidants and plasticizers, polyester resins such as PET, and other resins such as syndiotactic polystyrene resins. May be added.

  6 is a coating layer formed on one surface of the dielectric film 5. The coating layer 6 is made of a binder resin containing an inorganic filler 6a such as silicon oxide, and has a thickness of 0.01 to 1 μm. The roughness Ra is 35 nm, and as the binder resin, resins such as polyester, polyolefin, polyurethane, polyimide, and polyamide can be used.

  7 is a metal vapor deposition electrode, and this metal vapor deposition electrode 7 is provided on a surface different from the surface on which the coating layer 6 is provided.

  The dielectric film according to the present embodiment configured as described above can adjust the surface roughness by the coating layer 6 due to the configuration in which the coating layer 6 is provided on one surface of the dielectric film 5. Therefore, it is possible to achieve a special effect that it is possible to control the tightening force when the handling property is improved and the wound element is thermally aged.

  Further, the surface of the dielectric film 5 is more than the surface of the coating layer 6 because of the configuration in which the metal vapor deposition electrode 7 is provided on the surface different from the surface on which the coating layer 6 is provided, that is, the surface of the dielectric film 5. Since the surface roughness is small, the metal vapor-deposited electrode 7 is stably formed, and an extraordinary effect is achieved in that more stable performance can be exhibited.

(Embodiment 3)
The third aspect of the present invention will be described below with reference to the seventh embodiment.

  In this embodiment, the configuration of the dielectric film used in the metallized film capacitor described in the first embodiment is partially different, and the other configurations are the same as those in the first embodiment. For this reason, the same parts are denoted by the same reference numerals and detailed description thereof is omitted, and only different parts will be described below with reference to the drawings.

  FIG. 3 is a plan view of the main part showing the configuration of the metallized film used in the metallized film capacitor according to Embodiment 3 of the present invention. In FIG. Uses a PEN film with a thickness of 2.0 μm and a width of 30 mm (containing 0.6 part by weight of an inorganic filler with a particle diameter of 0.8 μm) as a dielectric film, and the surface of the PEN film is nonmetallic. A plurality of divided electrode portions 10 are formed by providing a slit portion 9 serving as a vapor deposition portion to form a metal vapor deposition electrode, and the divided electrode portions 10 are connected in parallel by a fuse portion 11. .

  Then, the metallized film 8 thus configured is paired, and an element is manufactured by winding the metal vapor deposition electrode so as to face each other through the dielectric film, and metallized electrodes are formed on both end faces of the element by metal spraying. The metallized film capacitor according to the present embodiment is configured by forming.

  A / b indicated by a ratio when the width of the fuse portion 11 formed in the metallized film 8 thus configured is a and the length of the divided electrode portion 10 in the longitudinal direction of the metallized film 8 is b. Table 4 shows the results of confirming the withstand voltage characteristics of the capacitor when the pass rate of the deposition pattern is defined and the pass rate a / b is changed.

  The capacity of each metallized film capacitor produced is 100 μF, the initial withstand voltage yield is performed in the state of the metallized film, and the voltage step-up test is performed by increasing the applied voltage every predetermined time in an atmosphere of 120 ° C. The voltage when the capacity became -5% and -97% was obtained. Sample No. 4 shows the pass rate of a metal deposition pattern formed mainly in the case of a conventional product using a PP film as a dielectric film.

  As is clear from Table 4, the metalized film capacitor according to the present embodiment has a pass ratio a / b of the metal vapor deposition electrode formed on the metallized film 8 using the PEN film as a dielectric film, 4.0. By making the following, the initial breakdown voltage yield is excellent, and in the voltage step-up test, it shows a withstand voltage characteristic equal to or higher than that of a conventional product using a PP film as a dielectric film. By setting b to 1.0 or less, a more remarkable effect can be exhibited. However, when the pass rate a / b becomes 0.3, the withstand voltage characteristic also reaches its peak, so the pass rate a / b is 4.0 or less, preferably 1.0 to 0.4.

  Subsequently, with respect to the specifications of sample Nos. 6 to 9 in which the pass ratio a / b is in the range of 1.0 to 0.4, the withstand voltage characteristics of the capacitor when the resistance value of the metal deposition electrode is changed. The results of confirming are shown in (Table 5) and (Table 6).

  (Table 5) shows a resistance value (25Ω / □) that is about twice the general resistance value (15Ω / □) of a conventional product using a PP film as a dielectric film, and (Table 6) shows the same value. The resistance value (45Ω / □) is approximately three times, and the test method is the same as the test in Table 4 above.

  As is clear from (Table 5) and (Table 6), the withstand voltage characteristics improve as the resistance value of the metal vapor deposition electrode is increased, and a higher withstand voltage can be achieved.

  As described above, when the metallized film capacitor according to the present invention forms a metal vapor-deposited electrode on a PEN film containing a small amount of inorganic filler, the width a of the fuse part and the divided electrode part in the longitudinal direction of the metallized film The pass rate a / b of the vapor deposition pattern indicated by the ratio of the length b is 4.0 or less, preferably 1.0 to 0.4, that is, the fuse portion is wide and the divided electrode portion is wide. By adopting a structure, the metal vapor deposition electrode evaporates with a small amount of energy and the area is separated, so that the operability of the self-protection function can be improved and the withstand voltage can be improved.・ High voltage resistance can be achieved at the same time.

  The metallized film capacitor according to the present invention and the PEN film used therefor have the effect of being able to achieve high heat resistance and high voltage resistance at the same time, and particularly as automobile capacitors that require particularly severe use conditions. Useful.

(A) The expansion | deployment perspective view which showed the structure of the metallized film capacitor by Embodiment 1 of this invention, (b) Sectional drawing of the dielectric film Sectional drawing which showed the structure of the dielectric film used for the metallized film capacitor by Embodiment 2 of this invention The principal part top view which showed the structure of the metallized film used for the metallized film capacitor by Embodiment 3 of this invention (A) An exploded perspective view showing a configuration of a conventional metallized film capacitor, (b) a sectional view of the dielectric film

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 5 Dielectric film 2, 7 Metal vapor deposition electrode 3 Non-metal vapor deposition part 4 Metallicon electrode 6 Coating layer 6a Inorganic filler 8 Metallized film 9 Slit part 10 Divided electrode part 11 Fuse part

Claims (9)

An element in which a pair of metallized films having a metal vapor deposition electrode formed on a dielectric film is wound so that the metal vapor deposition electrode faces through the dielectric film, and both ends of the element are formed by metal spraying. In a metallized film capacitor comprising a pair of metallicon electrodes, a PEN (polyethylene-2,6-naphthalate) film containing no filler is used as the dielectric film, and the longitudinal direction (winding direction) of the PEN film at 150 ° C. ) Is a metallized film capacitor having a heat shrinkage ratio of 1.5 to 4.0%. The metallized film capacitor according to claim 1, wherein the surface roughness Ra of at least one side of the PEN film is 10 to 50 nm. The metallized film capacitor according to claim 1, wherein the static friction coefficient of at least one surface of the PEN film is 0.25 to 0.5. The metallized film capacitor according to claim 1, wherein an inorganic filler having a particle size of 0.001 to 1.0 μm is contained in the PEN film in an amount of 1 part by weight or less. The metallized film capacitor according to claim 1, wherein a coating layer comprising an inorganic filler and a binder resin is provided on one side of the PEN film. The metallized film capacitor according to claim 5, wherein a metal-deposited electrode is formed on the surface of the PEN film on which the coating layer is not provided. The metal vapor deposition electrode formed on the dielectric film is provided with a divided electrode portion, and has a self-security function configured by connecting the divided electrode portion with a fuse portion, and the width (a) of the fuse portion. The metallized film capacitor according to claim 1, wherein the pass rate (a / b) of the vapor deposition pattern represented by the ratio of the length (b) of the divided electrode portions in the longitudinal direction of the metallized film is 4.0 or less. . A dielectric film for a wound metallized film capacitor having a heat shrinkage ratio in the longitudinal direction (winding direction) at 150 ° C. of 1.5 to 4.0% and a surface roughness Ra of at least one surface of 10 A PEN (polyethylene-2,6-naphthalate) film containing no filler and having a static friction coefficient of 0.25 to 0.5 nm at least on one side of ˜50 nm. The PEN film according to claim 8, wherein an inorganic filler having a particle size of 0.001 to 1.0 µm is contained in an amount of 1 part by weight or less.

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