JP2009010265A - Metalized film capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metalized film capacitor which can suppress the deterioration of characteristics of a vehicle-mounting capacitor in harsh environments of temperatures and humidity required for the capacitor. <P>SOLUTION: The metalized film capacitor comprises capacitor elements 6 formed by winding or a metalized film or stacking metalized films, a case 9 in which the capacitor elements 6 are accommodated, and a resin 10 filled in the case 9. The case 9 is obtained by mixing 50-85 wt.% of glass fiber in a PPS resin and molding the obtained mixture, the resin 10 is prepared by mixing 50-80 wt.% of silica in an epoxy resin having a glass transition point not lower than 115°C in such a manner that the obtained mixture has a viscosity of 1,500-3,000 mPa s at 60°C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a capacitor used in industrial equipment and automobiles, and more particularly to a metallized film capacitor used in an inverter circuit for driving a motor of a hybrid automobile or the like.

  Conventionally, a metallized film capacitor has a metal electrode deposited on at least one surface of a dielectric film to form a deposited electrode, and a metallicon is formed on an end surface of a wound body formed by winding the film to form a capacitor element. A plurality of capacitor elements are housed in a case, and then the case is filled with resin and cured.

  As the resin filled around the capacitor element, epoxy resin, or epoxy resin and urethane resin are usually used, thereby suppressing deterioration of the capacitor characteristics due to humidity or temperature change outside the case ( For example, see Patent Document 1).

JP 2003-338423 A

  In recent years, metallized film capacitors used as smoothing capacitors in inverter circuits for driving motors of hybrid vehicles and the like have a high temperature of 90 ° C.-90% RH, a high humidity environment, and a temperature change of −40 ° C. to + 120 ° C. However, it is required that the characteristics do not deteriorate.

Therefore, in the metallized film capacitor described in Patent Document 1, urethane resin is used as the resin filled in the case. The urethane resin has a smaller elastic modulus than the epoxy resin, and can suppress the occurrence of cracks in the temperature cycle test to some extent.
However, even in the metallized film capacitor according to Patent Document 1, the case and the resin filled in the case are peeled off (case-resin peeling) or cracks are formed on the resin surface in the above severe temperature and humidity environment. There was a problem of occurrence (resin cracking).
The metalized film capacitor in which such a problem has occurred easily absorbs moisture outside the case, and it has been difficult to maintain the characteristics over a long period of time.

  In view of the above problems, an object of the present invention is to provide a metallized film capacitor capable of suppressing deterioration of characteristics under severe temperature and humidity environments required for a vehicle-mounted capacitor.

  The present invention is a metallized film capacitor comprising a capacitor element formed by winding or laminating a metallized film, a case in which the capacitor element is accommodated, and a resin filled in the case. A polyphenylene sulfide resin is molded by mixing 50 to 85 wt% glass fiber, and the filled resin is an epoxy resin having a glass transition point of 115 ° C. or higher and an inorganic filler mixed therein. This is a metallized film capacitor.

  In addition, examples of the inorganic filler include silica, alumina, titanium oxide, white carbon, mica, talc, clay, glass fiber, and the like, but 50 to 80 wt% silica is preferable.

  Further, in a method of manufacturing a metallized film capacitor in which a capacitor element formed by winding or laminating a metallized film is housed in a case, and the case is filled with a resin, the case is made of polyphenylene sulfide resin. A resin formed by mixing 50 to 85 wt% glass fiber is used, and the resin to be filled is such that the glass transition point is 115 ° C. or higher and the viscosity at 60 ° C. is 1500 to 3000 mPa · s. An epoxy resin mixed with an inorganic filler is used.

  Examples of the inorganic filler include silica, alumina, titanium oxide, white carbon, mica, talc, clay, glass fiber, and the like, but 50 to 80 wt% silica is preferable.

  Unless otherwise specified, the ratio of the mixture in this specification is represented by “wt% (wt%)”. For example, the ratio of the substance A in the substance C obtained by mixing 25 g of the substance A and 100 g of the substance B is 25 / (25 + 100) × 100 = 20 wt%.

  According to the present invention, as a case in which a capacitor element is accommodated, the heat resistance and humidity resistance of the case are improved by using a polyphenylene sulfide resin mixed with a glass fiber of 50 to 85 wt%, The bondability between the resin filled in the case and the case is improved, and an epoxy resin having a glass transition point of 115 ° C. or higher and a viscosity adjusted by mixing an inorganic filler is used as the filled resin. Provides improved metal strength, heat resistance, moisture resistance, and moldability, and provides a metalized film capacitor that can suppress deterioration of characteristics under severe temperature and humidity conditions required for in-vehicle capacitors. can do.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS.

[Examples 1-1 to 4, Comparative Examples 1-1 and 2] Comparison of Glass Fiber Mixing Amounts in Case In FIG. 1, 1 is a metallized polypropylene film (hereinafter referred to as a metallized film), and 2 is a metallized film. A vapor deposition electrode region 3 μm thick in which aluminum is vapor-deposited on one side, 1 is a margin portion where no electrode is formed. The vapor deposition electrode region 2 is divided into a plurality of vapor deposition electrodes 4, which are connected in parallel via a fuse portion 5.

FIG. 2 shows a capacitor element according to the present invention. Capacitor element 6 is formed by stacking and winding metallized film 1 shown in FIG. 1 and metallized film 1 ′ on which electrodes are vapor-deposited upside down, pressing the wound body into a flat shape, Metallicon portions 7 and 7 'are formed on both end faces.
Since the metallized films 1 and 1 ′ are provided with margin portions 3 and 3 ′, respectively, the metallicon portion 7 is connected only to the vapor deposition electrode region 2 ′, and the metallicon portion 7 ′ is connected only to the vapor deposition electrode region 2 Is done.

FIG. 3 is a cross-sectional view of a metallized film capacitor in which ten capacitor elements 6 produced as described above are stored in a case 9 and then filled and cured with a resin 10.
The metallicon parts 7 of the capacitor elements 6 are connected in parallel by an electrode plate 8, and the electrode plate 8 is drawn out of the case by a lead terminal 11.
Further, the other metallicon part 7 ′ not shown in FIG. 3 is similarly connected in parallel by the electrode plate, and is drawn to the outside by the lead terminal.

  In Examples 1-1 to 1-4 and Comparative Examples 1-1 and 2, 65 wt% of silica was mixed with an epoxy resin having a glass transition point of 115 ° C., and the viscosity at 60 ° C. was adjusted to 2000 mPa · s. A metallized film capacitor having a rated voltage of 500 V and a capacitance of 2000 μF was produced using a case in which 40 to 95 wt% glass fiber was mixed with resin and polyphenylene sulfide resin (hereinafter referred to as PPS resin) and molded. .

(Conventional example 1)
FIG. 4 shows a cross-sectional view of a metallized film capacitor according to Conventional Example 1.
This metallized film capacitor used two types of resins 10 and 10 ′ in the same manner as the metallized film capacitor described in Patent Document 1. Resin 10 was prepared by mixing 65 wt% of silica with an epoxy resin having a glass transition point of 105 ° C. so that the viscosity at 60 ° C. was 2000 mPa · s, and resin 10 ′ was a urethane resin.
The case 9 is formed by mixing 85 wt% glass fiber with PPS resin.
In addition, for the capacitor element 6, the electrode plate 8, and the lead terminal 10, a metallized film capacitor having a rated voltage of 500 V and a capacitance of 2000 μF was produced in the same manner as in Examples 1-1 to 4.

For each of the five metallized film capacitors according to Examples 1-1 to 1-4, Comparative Examples 1-1, and 2 and Conventional Example 1, a temperature cycle test of −40 ° C. to + 120 ° C. was performed, and case-resin peeling, etc. The presence or absence of abnormal appearance was confirmed.
Thereafter, each capacitor was subjected to a moisture resistance load test in which a voltage of 500 V was applied at 90 ° C. to 90% RH for 1000 hours, and the capacitance change rate (average value) before and after the test was measured. These test results are shown in Table 1.
In the temperature cycle test, the temperature was raised from −40 ° C. to + 120 ° C. in 2 hours and then the temperature was lowered from + 120 ° C. to −40 ° C. in 2 hours as one cycle, and this was repeated 2000 times.

  Further, in the test according to Table 1, it was also evaluated whether or not the case material made of PPS resin and glass fiber was distributed to every corner of the mold during case molding (case moldability).

As can be seen from the test results in Table 1, the metalized film capacitors according to Examples 1-1 to 4 using a case in which 50 to 85 wt% of glass fiber is mixed improve the adhesion between the resin and the case. There was no case-resin peeling, and the capacitance hardly changed even in the moisture resistance load test conducted after the temperature cycle test.
However, in Comparative Example 1-2 in which the glass fiber mixing amount was 95 wt%, the case moldability was deteriorated because the viscosity of the case material was high. In Comparative Example 1-1 in which the mixing amount of the glass fiber is 40 wt%, the case-resin adhesion is poor, and the heat resistance and moisture resistance of the case are lowered, so that the capacitance is reduced. .

On the other hand, since the metallized film capacitor according to Conventional Example 1 uses a case in which glass fiber is mixed with 85 wt%, no case-resin peeling was observed, but 90 ° C.-90% RH. In the moisture resistance load test, the capacitance was greatly reduced by absorbing external moisture as compared with other good ones.
This seems to be because the glass transition point (105 ° C.) of the epoxy resin according to Conventional Example 1 is lower than the glass transition point (115 ° C.) of the epoxy resin according to Examples 1-1 to 4, and the heat resistance is inferior. It is.

  From the above, a resin prepared so that the viscosity is 2000 mPa · s by mixing 65 wt% of silica with an epoxy resin having a glass transition point of 115 ° C., and a glass fiber of 50 to 85 wt% is mixed with the PPS resin. In the case of the metallized film capacitors according to Examples 1-1 to 4 using the case, no appearance abnormality occurred in the temperature cycle test of −40 to + 120 ° C., and in the moisture resistance load test at 90 ° C. to 90% RH. However, it was found that the capacitance hardly changed and the case moldability was also good.

[Examples 2-1 to 3 and Comparative Examples 2-1 and 2] Comparison of amount of silica in filled resin Next, as Examples 2-1 to 3 and Comparative Examples 2-1 and 2, the glass transition point is 115 ° C. 20 wt% to 90 wt% silica as an inorganic filler was mixed with the epoxy resin, and a resin prepared so that the viscosity at 60 ° C. was 1000 to 4000 mPa · s, and 85 wt% glass fiber was mixed with the PPS resin. A case was used, and the other steps were the same as in Examples 1-1 to 1-4, and a metallized film capacitor having a rated voltage of 500 V and a capacitance of 2000 μF was produced.

(Conventional example 2)
Conventional Example 2 is a resin prepared by mixing 80 wt% silica with an epoxy resin having a glass transition point of 105 ° C., and a viscosity of 3000 mPa · s at 60 ° C., and 85 wt% glass fiber in PPS resin. A metallized film capacitor having a rated voltage of 500 V and a capacitance of 2000 μF was prepared in the same manner as in Examples 1-1 to 4 except for the above-described case.

For each of the five metallized film capacitors according to Examples 2-1 to 2-3, Comparative Examples 2-1 and 2, and Conventional Example 2, a temperature cycle test of −40 ° C. to + 120 ° C. was performed, and case-resin peeling, etc. The presence or absence of abnormal appearance was confirmed.
Thereafter, each capacitor was subjected to a moisture resistance load test in which a voltage of 500 V was applied at 90 ° C. to 90% RH for 1000 hours, and the capacitance change rate (average value) before and after the test was measured. These test results are shown in Table 2.

The metallized film capacitors according to Examples 2-1 to 2-3 using a resin prepared by mixing 50 to 80 wt% of silica with an epoxy resin and having a viscosity at 60 ° C. of 1500 to 3000 mPa · s, There was no case-resin peeling and resin cracking, and the capacitance hardly changed in the moisture resistance load test conducted after the temperature cycle test.
However, in Comparative Example 2-1, in which the viscosity of the resin is 1000 mPa · s, since the resin shrinks when cured, the resin easily cracks in the temperature cycle test, and the capacitance is low in the moisture resistance load test. Declined.
Further, in Comparative Example 2-2 prepared so that the viscosity of the resin is 4000 mPa · s, since the viscosity of the resin is too high, it takes time for the resin filling operation, and between the case and the filled resin. Due to the generation of bubbles, case-resin peeling occurred in the temperature cycle test, and the capacitance decreased.

On the other hand, in the metallized film capacitor according to Conventional Example 2, the case-resin peeling occurred in the temperature cycle test, the external moisture was absorbed in the moisture resistance load test at 90 ° C.-90% RH, and the capacitance was It was greatly reduced.
This is probably because the epoxy resin used in the metallized film capacitor according to Conventional Example 2 has a low glass transition point and poor heat resistance.

  From the test results shown in Table 2, a resin prepared by mixing 50-80 wt% silica with an epoxy resin having a glass transition point of 115 ° C., and having a viscosity at 60 ° C. of 1500-3000 mPa · s, In the metallized film capacitors according to Examples 2-1 to 2-3 using a case in which 85 wt% glass fiber was mixed with PPS resin, no appearance abnormality occurred in a temperature cycle test of −40 to + 120 ° C., and 90 It was found that the capacitance hardly changed in the moisture resistance load test at a temperature of -90% RH.

  As described above, when the test results shown in Tables 1 and 2 are summarized, as a case, a PPS resin mixed with 50 to 85 wt% glass fiber is used, and the resin has a glass transition point. The harshness required for in-vehicle capacitors by using an epoxy resin prepared by mixing 50-80 wt% silica with an epoxy resin of 115 ° C. or higher and having a viscosity at 60 ° C. of 1500-3000 mPa · s. It was possible to obtain a metallized film capacitor that can withstand a temperature cycle test (-40 ° C. to + 120 ° C.) and a moisture resistance load test (90 ° C.-90% RH).

  In each example, the viscosity of the epoxy resin was adjusted by mixing silica as an inorganic filler, but instead of this, alumina, titanium oxide, white carbon, mica, talc, clay, glass fiber or the like may be used. Similar effects can be obtained. Moreover, if the glass transition point of an epoxy resin is 115 degreeC or more, the same effect can be acquired.

In addition, various capacitor elements other than the capacitor elements used in the embodiments can be applied to the present invention.
For example, the vapor deposition electrode region 2 may be formed on both surfaces of the metallized film 1 shown in FIG. 1, and the entire vapor deposition electrode region 2 excluding the margin portion 3 may be used as one large vapor deposition electrode 4.
In FIG. 2, the capacitor element 6 is formed by winding the metallized film 1, but a necessary number of metallized films 1 may be laminated and formed. Further, the capacitor element 6 may be formed by winding or laminating two kinds of metallized films 1 having different shapes of the vapor deposition electrode 4.
Moreover, in order to improve the pressure resistance of a capacitor, it can replace with the metallized film 1 and the type of film which does not form an electrode can also be used.

It is a top view of a metallized polypropylene film. It is a perspective view of a capacitor element. It is sectional drawing of the metallized film capacitor which concerns on an Example and a comparative example. It is sectional drawing of the metallized film capacitor which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1 'Metallized polypropylene film 2, 2' Evaporation electrode area | region 3, 3 'Margin part 4, 4' Evaporation electrode 5, 5 'Fuse part 6 Capacitor element 7, 7' Metallicon part 8 Electrode plate 9 Case 10 Resin ( Epoxy resin)
10 'resin (urethane resin)
11 Lead terminal

Claims (4)

In a metallized film capacitor comprising a capacitor element formed by winding or laminating a metallized film, a case in which the capacitor element is accommodated, and a resin filled in the case,
The case is formed by mixing polyphenylene sulfide resin with 50 to 85 wt% glass fiber, and the resin to be filled is an epoxy resin having a glass transition point of 115 ° C. or higher and an inorganic filler mixed therein. A metallized film capacitor characterized in that   The metallized film capacitor according to claim 1, wherein the inorganic filler is silica, and the amount of the inorganic filler mixed is 50 to 80 wt%. In a method of manufacturing a metallized film capacitor manufactured by winding a capacitor element formed by winding or laminating a metallized film in a case and filling the case with a resin,
As the case, a polyphenylene sulfide resin mixed with 50 to 85 wt% glass fiber is used,
A metallized film capacitor comprising an epoxy resin mixed with an inorganic filler so that the glass transition point is 115 ° C. or higher and the viscosity at 60 ° C. is 1500 to 3000 mPa · s as the resin to be filled. Manufacturing method.   The method for producing a metalized film capacitor according to claim 3, wherein 50 to 80 wt% of silica is used as the inorganic filler.

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