JP2007324272A - Capacitor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems in the prior art capacitor that a corona discharge start voltage is low and an amount of corona discharge is great, that is, when the capacitor is used under a condition of a high potential gradient, generated corona discharge causes discharge degradation in a dielectric film, and this causes the life characteristic of the capacitor to be remarkably adversely influenced. <P>SOLUTION: In a capacitor; a capacitor element obtained by winding a plurality of metallized films having metal deposited thereon is thermally sprayed for electrode lead out to provide external leading connection lines to the capacitor element, the capacitor element is placed in a capacitor case, the case is filled with a resin, and then the resin is set. The plurality of metallized films are not thermally bonded. Upon molding the capacitor element, a cold-curing polyurethane resin is used as the filling resin. A maximum of temperatures used in all steps of manufacturing the capacitor is not higher than 60°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power capacitor used for power factor improvement, a metallized film capacitor (hereinafter simply referred to as a capacitor) for use in various electric circuits, and a method for manufacturing the same.

  Conventionally, many proposals have been made on improvement of various characteristics of power capacitors and capacitors for electric devices used in various electric circuits. For example, in the dry capacitor manufacturing method described in Patent Document 1, corona discharge is started. The proposal for increasing the voltage (referred to as partial discharge start voltage in Patent Document 1), and the dry metallized film capacitor described in Patent Document 2 is provided with a self-protection mechanism to enhance safety and further to dielectric loss tangent Proposals have been made to prevent the deterioration of the material.

  The configuration of those proposals will be described below for conventional techniques.

  As a conventional general dry capacitor in Patent Document 1, a capacitor element in which a metallized film on which a metal such as Al or Zn is vapor-deposited is placed on the surface of a dielectric film made of polypropylene is filled with an insulating gas. Or those molded with an epoxy resin or the like are known.

  The method for manufacturing a dry capacitor of Patent Document 1 has been proposed for the purpose of improving the corona discharge characteristics of a dry capacitor, and the structure thereof is a metallized film obtained by performing metal vapor deposition on the surface of a polypropylene film having a smoother surface compared to the conventional one. A capacitor element is produced by winding, heated at a temperature of 80 ° C. or higher, subjected to heat blocking treatment, and then subjected to metallicon treatment and lead drawing treatment on both sides of the capacitor element. The peel strength between the metallized film layers increased, and the start voltage of corona discharge, which is generated due to the concentration of electrolysis in the gaps between the metallized film layers and causes deterioration of the metallized film, is 45 to 50 V / It is improved from μm to about 100 V / μm.

  There is also a dry metallized film capacitor as in Patent Document 2. 18 and 19, the metallization having the vapor deposition electrode 19 provided with the insulating margin portion 17 at the width direction end portion of the dielectric film 16 having a low dielectric constant and further provided with the insulating groove 18 in the width direction. A film and a metallized film made of a dielectric film 20 having a high dielectric constant are wound and heat-treated within a temperature range of 80 to 120 ° C., and when the dielectric film is partially broken, its insulation margin portion 17 In the vicinity, the vapor deposition electrode 19 having the insulating groove 18 is scattered in the length direction, has a simple structure, has a self-safety mechanism, and the temperature of the heat treatment is in a temperature range of 80 to 120 ° C. This prevents the loss tangent from deteriorating.

  Further, a general capacitor and a manufacturing method thereof will be described with reference to FIGS. 20 and 21A to 21D.

  20 and 21 (a) to 21 (d) are schematic diagrams of the internal structure of a capacitor and assembly process diagrams of the capacitor. A plurality of metallized films 107 formed by vapor-depositing metal 109 on a dielectric film 108 are wound. The capacitor element 101 is provided with an electrode extraction metallicon 102, the external lead-out connection line 104 is connected to the capacitor element 101 with solder 103 or the like, placed in a resin case 105, and a capacitor is formed by filling and curing the filling resin 106. is doing.

  FIG. 21A is a process diagram for winding up the capacitor element, in which a plurality of metallized films 107 formed by depositing a metal 109 on a dielectric film 108 are wound to form the capacitor element 101. FIG. 2B is a process diagram for forming an electrode takeout metallicon on the capacitor element 101. The electrode takeout metallicon 102 is formed by melting and spraying a zinc wire 115 on the end face of the capacitor element 101. . FIG. 21C is a process diagram for attaching the external lead-out connection line to the capacitor element. The external lead-out connection line 104 is connected to the capacitor element 101 by the solder 103. FIG. 21D is a process diagram for accommodating the capacitor element 101 in the resin case 105. The capacitor element 101 provided with the external lead-out connection line 104 is inserted into the resin case 105, and the filling resin 106 is cast. is there. More generally, there is a step of curing the cast filling resin 106. Generally, the filling resin is cured by applying a temperature of 80 ° C to 100 ° C.

Further, generally, there is a step of performing heat treatment (within a temperature range of 80 ° C. to 120 ° C.) after forming the electrode extraction metallicon 102 on the capacitor element 1. In the conventional method of manufacturing a dry capacitor disclosed in Patent Document 1, this step is performed before the metallicon 102 for electrode extraction is applied.
JP-A-4-249309 Japanese Utility Model Publication No.59-91719

  The problem of the capacitor obtained by Patent Document 1, Patent Document 2, and a conventional general capacitor manufacturing method as described above will be described with reference to FIGS. 3 to 7 and FIG.

  FIG. 3 is a state diagram of the metallized film 7 before performing the heat treatment (within a temperature range of 80 ° C. to 120 ° C.) in the capacitor manufacturing process described above. According to this state, a plurality of metallized films 7 are overlapped. Since the winding is performed, the metallized film 7 and the metallized film 7 are in a uniformly arranged state, and there is a slight space between the metallized film 7 and the metallized film 7.

  When the element in this state is heat-treated, the state shown in FIG. 4 is obtained. That is, FIG. 4 is a view showing the metallized film after the heat treatment in the conventional method for producing a capacitor. By performing the heat treatment, there is no space between the metallized film 7 and the metallized film 7 described above. The adhesive film 7 and the metallized film 7 are bonded together to form an adhesive portion 10. This state is generally called a blocking state. 4 can be said to be an ideal state when heat treatment is performed.

  However, in the general process, the following state may occur.

  FIG. 5 is a diagram of the metallized film before heat treatment of the capacitor, and shows a case where a large air pocket 11 exists between the metallized film 7 and the metallized film 7 before the heat treatment. When heat treatment is performed in this state, an air pocket 11 remains between the metallized film 7 and the metallized film 7, as shown in FIG. In general, in order to eliminate the air reservoir 11, heat treatment is performed in a vacuum, but it cannot be completely eliminated. In the state where the air reservoir 11 remains, the portion where the air reservoir 11 is present is not in an adhesive state between the metallized film 7 and the metallized film 7, and the metallized film 7 and the metallized portion where no air reservoir 11 is present. Between the films 7, an adhesive state 10 is obtained. After the heat treatment, the pressure in the air reservoir 11 is in a negative pressure state than the pressure outside the capacitor element 1. When a voltage is applied to the capacitor in such a state, the following state is obtained.

  FIG. 7 shows an explanatory diagram thereof. FIG. 7 is an electric field explanatory diagram of the metallized film after heat treatment of the capacitor in the conventional example. Since a voltage is applied between the metallized films 7 facing each other, there is no air reservoir 11 as shown in FIG. However, the electric field tends to concentrate on the air reservoir 11 in the state shown in FIG. When a high charge concentrates around the air reservoir 11, corona discharge occurs, and only the surrounding dielectric film is damaged, and there is a possibility that it will eventually be destroyed. In other words, when it is used under a high potential gradient where the voltage applied per unit thickness of the dielectric film is high, the corona discharge will cause discharge deterioration in the dielectric film, which will have a significant adverse effect on the life characteristics of the capacitor. Is affected.

  The presence or absence of such air pockets can be determined by looking at the corona discharge start voltage of corona discharge characteristics and the amount of corona discharge. In the state as shown in FIG. 7, the corona discharge start voltage is low and the corona discharge amount is large.

  20 and 21 (a) to 21 (d), generally, there is a step of casting the filled resin and then curing the cast filled resin 106, and after filling, 80 ° C to 100 ° C. Heat to ℃ to cure the filled resin. Also at this time, partial adhesion between the metallized films 7 occurs, and an air reservoir layer 12 as shown in FIG. 7 may be generated.

  FIG. 12 is a view showing a state in which a conventional heat-treated capacitor is disassembled and the metallized film is slowly peeled off, and a plurality of metallized films 7 formed by depositing metal 9 on dielectric film 8 are wound. Since each of the metallized films of the capacitor element has a bonding portion 10 between the metallized films as shown in FIG. 6, it is originally deposited with the metal 9 bonded to the opposing dielectric film 8. It will peel off from the dielectric film 8 surface. When a part that is bonded and a part that is not bonded exist, the air reservoir layer 12 is generated.

  The present invention solves such a conventional problem and provides a dry-type capacitor excellent in corona discharge characteristics that does not generate an air reservoir layer.

  In order to solve the above problems, the capacitor of the present invention is provided with a metallicon for extracting an electrode on a capacitor element formed by winding a plurality of metallized films obtained by vapor-depositing a metal on a dielectric film, and providing an external lead connection line. In a capacitor that is provided and placed in a capacitor case and filled and cured with a filling resin, the capacitor is characterized in that a plurality of metallized films are not adhered by heat, and the filling resin that molds the capacitor element is cured at room temperature. This is a capacitor and a method for manufacturing a capacitor, in which a polyurethane resin of a mold is used, and the temperature applied in all capacitor manufacturing processes is 60 ° C. or lower.

  According to the configuration of the present invention as described above, a metallized film obtained by vapor-depositing a metal on a dielectric film, an electrode extraction metallicon is applied to a capacitor element obtained by winding a plurality of windings, and an external lead connection line is provided on the capacitor element. In a capacitor that is placed in a capacitor case and filled and cured with a filled resin, since multiple metallized films are not bonded by heat, the occurrence of air pockets remaining between the metallized films is prevented. It is possible to prevent corona discharge that occurs from the starting point and to obtain a high corona starting voltage. In addition, even after corona discharge has occurred, the amount of discharge can be kept significantly lower than before, and as a result, there is a great effect in stabilizing the life characteristics of the capacitor under a high potential gradient. By these methods, the performance and safety of the capacitor are further improved, and the capacitor can be reduced in size and weight.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic diagram of the internal structure of a capacitor according to Embodiment 1 of the present invention, and FIGS. 2A to 2D are assembly process diagrams of the capacitor according to Embodiment 1 of the present invention.

  In FIG. 1, a capacitor element 1 formed by winding a plurality of metallized films obtained by vapor-depositing metal on a dielectric film is provided with an electrode extraction metallicon 2, and an external lead-out connection line 4 is connected to the solder element 3. Are connected to each other, placed in the resin case 5, and the filled resin 6 is filled and cured to form a capacitor.

  The manufacturing process will be described in more detail.

  As shown in FIG. 2A, a capacitor element 1 is formed by winding and winding two metallized films 7 formed by vapor-depositing aluminum on a 6 μm thick polypropylene film. As shown in FIG. 2 (b), the zinc wire 15 was melted and sprayed to form the metallicon 2 for taking out the electrode, followed by heat treatment. Further, as shown in FIG. 2 (c), the external lead-out connection line 4 is connected to the capacitor element 1 by solder 3, and as shown in FIG. 2 (d), the capacitor element 1 is stored in the resin case 5 and filled. Resin 6 was injected and cured to produce a dry capacitor. The temperature applied to the capacitor element was set to 60 ° C. or lower during all the manufacturing steps of the capacitor in the first embodiment, including the temperature of the heat treatment and the ambient temperature at the time of curing the filled resin. Moreover, it confirmed that the capacitor | condenser element 1 at this time was the state which the several metallized film 7 has not adhere | attached with the heat | fever.

(Embodiment 2)
The same material and conditions as in the first embodiment except that the capacitor element 1 provided with the external lead-out connection line 4 is inserted into the resin case 5 and a room temperature curing type polyurethane resin is used as the filling resin in the second embodiment. A dry capacitor was produced.

  The description of the capacitors obtained in the first and second embodiments will be described with reference to FIGS.

  FIG. 8 is a diagram of the metallized film of the capacitor in the first and second embodiments. In the state of the process diagram, a plurality of metallized films 7 formed by depositing the metal layer 9 on the dielectric film 8 are superposed. FIG. 3 is a diagram illustrating a state where the winding described in FIG. 2A and the electrode extraction metallicon illustrated in FIG. In this state, there is some space between the metallized film 7 and the metallized film 7. The element in this state is heat-treated so that a plurality of metallized films are not bonded by heat, and the state shown in FIG. 9 is obtained. That is, FIG. 9 shows the metallized film after heat treatment of the capacitor in the first embodiment, and there is no space between the metallized film 7 and the metallized film 7. They are very close to each other but are not in an adhesive state.

  Further, as shown in FIG. 10, even when a large air reservoir 11 exists between the metallized film 7 and the metallized film 7 before the heat treatment, the heat treatment is performed in a state in which the plurality of metallized films are not bonded by heat. Therefore, as shown in FIG. 11, the air reservoir 11 does not remain between the metallized film 7 and the metallized film 7, and the same pressure as the outside of the capacitor element 1 is maintained. That is, a negative pressure state does not occur between the metallized film 7 and the metallized film 7.

  When a capacitor is formed in this state to become a product and a voltage is applied, there is no air accumulation between the metallized film 7 and the metallized film 7 of the capacitor element, and no negative pressure is applied. Even when a voltage is applied between the electrodes 7, the electric field is not uniformly distributed between the electrodes and the electric field is not concentrated, and the original insulation performance of the film can be brought out.

  That is, even when looking at the corona discharge start voltage of the corona discharge characteristics and the characteristics of the corona discharge amount, the corona discharge start voltage is high and the corona discharge amount is small in the state shown in FIG. That is, since there is little corona discharge generated even when used under a high potential gradient, it is difficult for the dielectric film 8 to undergo discharge deterioration and the like, and as a result, the life characteristics of the capacitor can be improved satisfactorily.

  In order to verify the significance of the specific characteristics, a verification sample was prepared under the following conditions, and the verification results are shown in FIGS.

  FIG. 13 is a transition diagram of the corona discharge amount by the heat treatment at each temperature in the first embodiment. FIG. 14 is a capacity change diagram of the charge test for each heat treatment temperature.

  Capacitor samples were produced in the same procedure as the capacitor of the first embodiment, and for comparison, several conventional capacitors were produced and compared as Conventional Example 1.

  As the capacitor of the first embodiment, samples having heat treatment temperatures of 20 ° C., 30 ° C., 40 ° C., 50 ° C., and 60 ° C. correspond. Further, the capacitors in Conventional Example 1 correspond to samples of 70 ° C., 80 ° C., 90 ° C., 100 ° C., 110 ° C., and 120 ° C. In the graph of FIG. 13, the vertical axis represents the corona discharge amount when a high voltage corresponding to twice the rated voltage of the capacitor is applied.

  As can be clearly seen from FIG. 13, the discharge amount of the capacitors at 20 ° C., 30 ° C., 40 ° C., and 50 ° C. of the first embodiment is as follows, although a high voltage corresponding to twice the rated voltage is applied. The corona discharge amount is 2000 PC or less, and even a 60 ° C. capacitor has a corona discharge amount of 4000 PC or less. Compared with this, in the capacitor in the conventional example, the corona discharge of 10000 PC or more is generated in the capacitor of 8500 PC at 80 ° C., 80 ° C., 90 ° C., 100 ° C., 110 ° C., and 120 ° C.

  In order to further verify these comparative samples and confirm their significance, a capacitor life test at overvoltage was performed. A graph of the capacitance change of the capacitor sample is shown in FIG. That is, FIG. 14 is a capacity change diagram of the charge test for each heat treatment temperature. Since the graph becomes difficult to understand, only the result of the representative sample of the heat treatment temperature is described. The capacitor with the heat treatment temperature of 40 ° C. and 60 ° C. in the first embodiment has a capacitance change rate of −1% or less at an energization time of 2000 hours, indicating extremely stable capacitance change characteristics. This is because the amount of corona discharge is small as shown in FIG. 13 described above, so that even when used under a high potential gradient, it is difficult for the dielectric film to undergo discharge deterioration, etc. It is thought that there is. On the other hand, in the capacitors with the heat treatment temperatures of 70 ° C., 90 ° C., and 110 ° C. in Conventional Example 1, the capacity decreases significantly immediately after the start of the life test, and the capacity change rate tends to deteriorate after 1000 hours of energization time. . In the energization time of 2000 hours, the capacity change rate is -3% or more, and it is further deteriorated. This is because the corona discharge amount is as large as 10,000 PC or more as shown in FIG. 13 described above, so that the dielectric film is deteriorated by corona discharge, which has a significant adverse effect on the capacity life characteristics of the capacitor. When the test was further continued in this state, destruction sometimes occurred.

  As described above, when comparing the first embodiment with the first conventional example, the capacitor of the first embodiment clearly has good significance, and the temperature applied to the capacitor element is 60 in all the manufacturing processes of the capacitor. When the temperature is set to ℃ or less and the plurality of metallized films 7 are not adhered by heat, the corona discharge generated even when used under a high potential gradient is small, and the dielectric film is less likely to be deteriorated in discharge. As a result, it was confirmed that the life characteristics of the capacitor can be improved satisfactorily.

  A confirmation test sample of Embodiment 2 was produced with the following contents.

  The capacitor element having the heat treatment temperature of 60 ° C. shown in the first embodiment is provided with an external lead-out connection line 4 and inserted into the resin case 5 to cast urethane resin as a filling resin, and the atmosphere when the urethane resin is cured The temperature is about 60 ° C. or lower.

  Further, for comparison, the conventional example 2 was prepared by applying the external lead connection line 4 to the capacitor element having the heat treatment temperature of 60 ° C. shown in the first embodiment and inserting it into the resin case 5 as a filling resin. An epoxy resin is cast, and the atmosphere temperature at the time of curing of the epoxy resin is 80 ° C. to 100 ° C.

  FIG. 15 shows the state before curing after casting the filling resin in the second embodiment, FIG. 17 shows the state in which the epoxy resin is filled and cured at an ambient temperature of 80 ° C. to 100 ° C., and FIG. A state is shown in which a mold urethane resin is cast and the ambient temperature during curing is about 60 ° C. or lower.

  In other words, in the state in which the filling resin is cast, both the room temperature curable urethane resin and the epoxy resin are uniformly distributed between the capacitor element and the resin and on the surface of the resin as shown in FIG. In this state, when an epoxy resin is used as the filling resin, the air gap layer 13 is generated when the resin is cured as shown in FIG. The air gap layer 13 at the time of curing of the resin is generated when the curing reaction proceeds from the surface side of the capacitor where the temperature easily propagates in order to cure the filled resin at a high temperature. That is, since the resin is cured from the surface side and the inner side is finally cured, the curing shrinkage of the resin caused by the curing is all biased toward the capacitor element 1 side.

  The air gap layer 13 around the capacitor element when the resin is cured is generally in a negative pressure state, and similarly between the metallized films of the element is in a negative pressure state. For this reason, the above-described corona discharge start voltage of the corona discharge characteristics and the characteristics depending on the corona discharge amount tend to be further deteriorated.

  On the other hand, as shown in FIG. 16, when the room temperature curing type urethane resin is filled and the ambient temperature at the time of curing is about 60 ° C. or less, the curing reaction proceeds more slowly than the region near the element, and finally the region around the resin case Therefore, the resin sink layer 14 when the filling resin is cured appears on the upper surface of the filling resin. The tendency also appears in the bottom part of the resin case (not shown). For this reason, the influence of shrinkage at the time of curing the filling resin around the capacitor element 1 is overwhelmingly less than when the epoxy resin of the conventional example is used, and no air gap layer is generated. In the conventional example, the negative pressure state is described around the capacitor element 1, but the pressure around the capacitor element 1 according to the second embodiment remains almost normal pressure because no air gap layer is generated. Therefore, it can be confirmed that the corona discharge starting voltage is increased, the amount of corona discharge is small, the dielectric film is less likely to be deteriorated by discharge, and the life characteristics of the capacitor can be improved as a result. is there.

  As described above, the corona discharge characteristics are improved by setting the ambient temperature during curing of the filled resin to 60 ° C. or lower. However, when the ambient temperature during curing with conventional epoxy resin is set to 60 ° C. or lower, It takes several tens of hours or more to cure, and the insulation and moisture resistance of the cured resin are not practical enough. Use a room temperature curable urethane resin as shown in the present invention. Thus, the ambient temperature during curing of the filled resin can be set to 60 ° C. or lower.

  In Embodiments 1 and 2, the capacitor element is an example of a single element. However, the embodiment of the present invention can be applied even if there are a plurality of capacitor elements, and the same effect can be obtained. In Embodiments 1 and 2, polypropylene is used for the dielectric film, but the present invention is not limited to this, and other dielectric films can also be used.

  INDUSTRIAL APPLICABILITY The present invention is useful for improving the corona discharge characteristics and life characteristics of electric devices such as capacitors, particularly power capacitors used for power factor improvement and capacitors for electric devices used in various electronic circuits. By these methods, the performance and safety of the capacitor are further improved, and the capacitor can be reduced in size and weight.

Schematic diagram of internal structure of capacitor according to this embodiment (A)-(d) Capacitor assembly process diagram according to this embodiment Metalized film before capacitor heat treatment in Conventional Example 1 Metalized film after heat treatment of capacitor in Conventional Example 1 Metalized film before capacitor heat treatment in Conventional Example 1 Metalized film after heat treatment of capacitor in Conventional Example 1 Electric field state diagram of metallized film before heat treatment of capacitor in Conventional Example 1 Metalized film diagram before heat treatment of capacitor in the first embodiment Metalized film diagram after heat treatment of capacitor in the first embodiment Metalized film diagram before heat treatment of capacitor in the second embodiment Metalized film diagram after heat treatment of capacitor in the second embodiment State diagram of turning the metalized film after heat treatment of the capacitor in Conventional Example 1 Graph of corona discharge amount by heat treatment at each temperature in the first embodiment Graph of change in capacity of charge test according to heat treatment temperature State diagram of filled resin before curing in Embodiment 2 and Conventional Example 2 The figure after urethane hardening in this Embodiment 2. Figure after epoxy curing in Conventional Example 2 Structure of conventional capacitor Cross-sectional view of a conventional capacitor Schematic diagram of the internal structure of a conventional capacitor Conventional capacitor assembly process diagram

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Metallicon for electrode extraction 3 Solder 4 External lead connection line 5 Resin case 6 Filling resin 7 Metallized film 8 Dielectric film 9 Metal 10 Film adhesion part

Claims (3)

A capacitor element formed by winding a plurality of metallized films obtained by vapor-depositing a metal on a film is provided with a metallicon for electrode extraction, and an external lead-out connection line is provided on the metallicon for electrode extraction, put in a capacitor case, and filled resin A capacitor formed by filling and curing, wherein the metallized films are not bonded to each other by heat. 2. The capacitor according to claim 1, wherein the filling resin is a room temperature curing type polyurethane resin. A capacitor element formed by winding a plurality of metallized films obtained by vapor-depositing a metal on a film is provided with a metallicon for electrode extraction, and an external lead-out connection line is provided on the metallicon for electrode extraction, put in a capacitor case, and filled resin In the capacitor formed by filling and curing, the temperature applied to the capacitor is 60 ° C. or lower in all steps for manufacturing the capacitor.

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