JP5766511B2 - Film capacitor - Google Patents

Description

  The present invention relates to a film capacitor.

Conventionally, as shown in FIG. 6, film capacitors are formed by depositing aluminum (Al) or zinc (Zn) on a film of polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), or the like. Then, the capacitor element 1 is configured by laminating or winding this, or the capacitor element 1 is configured by laminating or winding the Al foil electrode together with the film. In the case of vapor-deposited metal, the end face electrode 8 of the metallicon is applied to the capacitor element 1 formed in this way, and a lead tab 10 is welded or soldered to the end face electrode 8 and stored in the case 17, and the lead tab 10 is pulled out of the case 17. The filling resin 4 is injected into the case 17 and the capacitor resin 1 and the pull-out tab 10 are filled and cured.
By the way, since the above-mentioned drawer tab is fixed only by the filling resin, the fixing tends to be unstable. Therefore, Patent Document 1 discloses a method in which the drawer tab is connected and fixed to an external terminal of a sealing resin cap provided at the open end of the metal case, and the metal case is filled with resin.

JP2011-711179A

In Patent Document 1, if a metal case is filled with a resin, if it is performed in a vacuum, the gas contained in the resin may be fired, and a sealing resin cap may be lifted from the metal case.
In addition, in the method in which a resin cap for sealing is provided at the open end of the metal case and the inside of the metal case is filled with resin, the adhesion between the metal in the metal case and the resin to be filled is weak, so the open end of the metal case From the sealing resin cap, the metal case and the sealing portion provided in the capacitor, moisture easily enters the capacitor.

Therefore, in the present invention, the sealing resin cap is filled with the resin without being lifted from the metal case and is cured, and moisture enters the capacitor from the gap between the sealing resin cap and the metal case. It is an object of the present invention to provide a film capacitor with improved moisture resistance.

In order to solve the above problems, the present invention provides the following film capacitor.
(1) a capacitor element using a film as a dielectric, a bottomed cylindrical metal case having an opening on the upper end surface for housing the capacitor element, a resin cap for sealing the opening of the metal case, A film capacitor including a filling resin for filling the inside of the metal case, and a cylindrical projecting portion integrally projecting from a peripheral portion of the resin cap in a bottom direction of the metal case along a side surface of the metal case. The overhanging portion has a fitting portion fitted into the opening of the metal case, and either the fitting portion or the opposite surface around the opening of the metal case that is in contact with the fitting portion. and that the gap between the opening periphery of the fitting portion and the metal case is provided with a protrusion pushing within the elastic limit of the resin cap, the protrusion Or on the side in contact with the protrusion, the film capacitor, wherein the resin cap is fixed to the metal casing, providing a catch portion.
(2) As the hooking portion, an annular concave portion that is inserted corresponding to the protruding portion is provided on the side in contact with the protruding portion, or an annular convex portion on the inner side of the protruding portion on the side in contact with the protruding portion. Or at least one of the surface of the projecting portion or the surface of the portion in contact with the projecting portion is an annular concavo-convex surface.

  With the configuration of the present invention in which a protruding portion or a hooking portion is provided on the side in contact with this protruding portion, the resin cap for sealing is filled and cured without lifting the resin cap from the metal case by adjusting the protruding degree of the protruding portion In addition, it is possible to provide a film capacitor having improved moisture resistance by suppressing the intrusion of moisture into the capacitor from the contact portion between the sealing resin cap and the metal case.

1 is a cross-sectional view of a film capacitor showing an embodiment of the present invention. 1 is a partially enlarged cross-sectional view of a film capacitor showing an embodiment of the present invention. The partially expanded sectional view of the film capacitor manufacturing method which shows embodiment of this invention is shown. The other partially expanded sectional view of the film capacitor manufacturing method which shows embodiment of this invention is shown. The other partially expanded sectional view of the film capacitor manufacturing method which shows embodiment of this invention is shown. The schematic sectional drawing of the conventional film capacitor is shown.

The metal case described in the present invention is a bottomed cylindrical metal container having an opening on the upper end surface, and aluminum, magnesium, iron, stainless steel, copper, or an alloy thereof can be used as the metal.
In particular, aluminum can be preferably used because it is excellent in light weight, workability, and cost. As the aluminum material, pure aluminum (A1000 series) and Al—Zn and Al—Mg as aluminum alloy series (A3000 series and A5000 series) can also be used.
As a method for producing the metal case, an impact molding method or the like can be used, and the case thickness is 0.3 to 2 mm. Preferably, the case thickness is 0.5 to 1.5 mm.

The resin cap in the present invention seals the opening of the metal case, and is provided with a cylindrical projecting portion integrally projecting from the peripheral portion in the side surface direction of the metal case. An inset portion is provided around the opening of the case.
As a material of the resin cap, a molded product such as PET (polyethylene terephthalate), PPS (polyphenylene sulfide), PPE (polyphenylene ether), PBT (polybutylene terephthalate), POM (polyoxymethylene), PPO (polyphenylene oxide), or the like Vacuum molded products such as polyvinyl chloride and polycarbonate can be used. It may be reinforced with glass fiber. Preferably, a heat-resistant crystalline resin such as PPS, PBT, or PPE that does not undergo plastic deformation even at the curing temperature of the filled resin is preferable.

The filling resin in the present invention is an insulating filler for capacitors, and those generally used for filling film capacitors can be used. For example, a resin such as an epoxy resin or a urethane resin mixed with a filler can be used. As the filler, hydroxides such as silicon, titanium, aluminum, calcium, zirconium, and magnesium, oxides, carbides, nitrides, and composites thereof can be used. If necessary, a flame retardant and an antioxidant may be added.
This filling resin is injected into the metal case in a liquid form through a through hole or the like provided in the resin cap, and is solidified by heating or polymerization with a curing agent after filling. The filling resin that protrudes from the inside of the metal case is blocked by a dam-shaped circulating body or a blocking groove provided on the outer surface of the sealing body. The one integrated with the sealing body is preferable, but another part may be used. For example, when the adhesive tape is circulated in a dam shape, or when the heat shrinkable tube is provided on the outer periphery of the side surface of the metal case, the protruding filling resin may be blocked by protruding to the external terminal side.
The filling resin may be a single layer material, or may be the same material or a plurality of layers with different physical property values, and the type or amount of the resin or filler can be selected separately. By selecting them separately, it is possible to optimize the hardness of the resin around the filled resin, the coefficient of thermal expansion, the adhesion with the constituent materials, and the like.
For example, a relatively flexible urethane-based resin can be selected on the capacitor element side, and an epoxy-based resin having relatively high strength and adhesion to the external terminal can be selected on the sealing body side. It is also possible to select such that the amount of filler is small on the capacitor element side and large on the sealing body side.

The protruding portion in the present invention is provided on the opposite surface of the portion where the cylindrical overhang portion of the resin cap is fitted into the metal case and the metal case in contact with the fitted portion, and pushes the gap between the fitting portions. It needs to be large enough to spread. The metal case around the fitting, the resin cap, or both are pushed out. The size of the expansion is preferably within the elastic limit of the metal case or the resin cap, and it is not preferable that both are plastically deformed. The size of the spread is increased according to the outer shape of the capacitor, but it is about 0.5 mm to 2 mm, preferably about 0.7 mm to 1.5 mm. If it is small, it is difficult to obtain the effect of moisture resistance. The elastic limit of the cap or metal case is easily exceeded.
The shape of the protrusion may be thick or may be deformed from the back to a convex shape by rotating sesame or the like.
In addition, it is preferable to form the protrusions in an annular shape on the side surface of the metal case in a direction parallel to the bottom surface of the case because the degree of expansion is preferable, but the protrusions may be intermittently formed in an annular shape.
Further, the contact between the metal case and the resin cap at the protruding portion is preferably surface contact in terms of moisture resistance, and the contact width is about 0.5 mm to 3 mm, preferably about 0.7 mm to 2.5 mm. If it is small, the effect of moisture resistance is difficult to obtain, and if it is large, processing may be difficult. As the shape of the protruding portion, a shape closer to a trapezoid than a semi-elliptical shape is preferable because the contact width can be easily obtained.

The catching part in the present invention is a function for preventing the resin cap and the metal case from being lifted so that the resin cap does not float from the metal case. A method of providing a corresponding annular recess, a method of providing an annular projection on the center side of the film capacitor inside the projection on the side in contact with the projection, or the surface of the projection or this projection Is obtained by a method in which at least one of the surfaces in contact with the surface is formed into an annular uneven surface.
The annular recess as the catching portion is a concave portion in which the top portion of the protruding portion provided at the sealing portion of the resin cap or metal case is in contact with the protruding portion, and at least a part of the protruding portion is in the annular recessed portion. The resin cap is caught on the metal case by entering.
In addition, the annular convex portion as the catching portion is a convex shape provided at the tip portion of the fitting portion on the side in contact with the projecting portion, and the sealing resin cap is lifted from the metal case by being caught by the projecting portion. To prevent it. The annular protrusion may be annular or intermittent.
The annular uneven surface as the catching portion is a fine uneven surface such as a matte surface, a hairline surface, a grid surface of the hairline, and is provided on at least one of the surface of the protruding portion or the surface of the inset portion in contact with the protruding portion. Provide. Preferably it is provided on both sides. In this case, the shape of the protruding portion is preferably a shape close to a trapezoid rather than a semi-elliptical shape because the contact width can be easily obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view of a film capacitor showing an embodiment of the present invention.
In FIG. 1, a capacitor element 1 using a film as a dielectric, a bottomed cylindrical metal case 2 having an opening on the upper end surface for storing the capacitor element 1, and an opening of the metal case 2 are sealed. In a film capacitor having a resin cap 3 and a filling resin 4 filling the inside of the metal case 2, a cylindrical protrusion that integrally protrudes from the peripheral portion of the resin cap 3 in the inner surface direction of the metal case 2. The protruding portion 5 has a fitting portion 6 fitted into the opening of the metal case 2, and the fitting portion 6 and the metal are formed on the opposing surface around the opening of the metal case 2 in contact with the fitting portion 6. It shows that the protruding portion 7 is provided to widen the gap between the case 2 and the periphery of the opening.

  In the case of FIG. 1, an annular recess 13 corresponding to the protruding portion 7 to be inserted is then provided in the fitting portion 6 of the resin cap 3 by rotating sesame or the like. Thereafter, the resin cap 3 is sealed, and a projecting portion 7 is provided to spread the gap between the fitting portion 6 and the periphery of the opening of the metal case 2 by rotating sesame or the like from the outer surface of the metal case 2 in contact with the fitting portion 6. It shows that. The protrusion 7 may be provided before the resin cap 3 is sealed, and is provided before the filling resin 4 is filled from the through hole 11 of the resin cap.

Further, end face electrodes 8 are formed on both end faces of the capacitor element 1 by a method such as thermal spraying of a metal such as zinc metal, and this is connected to the external terminals 9 provided on the resin cap 3 for connection to the outside. Connect by tab 10.
As the material of the main body of the external terminal 9, for example, a material made of a metal or an alloy such as copper, aluminum, iron, nickel, stainless steel, phosphor bronze or the like may be plated with tin, solder, or the like. The shape is a conical shape with a diameter of about 1 mm to 30 mm, and its size is determined by the amount of electricity flowing. The outside is connected by providing a processed portion such as a screw that can be connected by a bolt or the like.

  The drawer tab 10 can be deformed, such as a metal foil, thin plate, or wire, and can be used without limitation as long as it can be soldered, welded, or pressed. In particular, copper or a copper alloy is preferable as an electrical good conductor. In addition, a portion other than the connection portion may be covered with an insulator. In some cases, the drawer tab 10 may be integrated with the external terminal 9.

  In addition, although the example which used the metallized polypropylene film was shown in this Embodiment, it is not limited to this, Using other metallized films, such as a metallized polyester film and a metallized phenylene sulfide film Also good.

  In addition, an example of a capacitor element in which two metallized films each having a metallized vapor deposition electrode formed on one side of a dielectric are wound and wound is shown, but the present invention is not limited to this, and metal vapor deposition electrodes are formed on both sides. A capacitor element produced by stacking and winding the metallized film and a dielectric film on which no metal vapor-deposited electrode is formed may be used.

FIG. 2 is a partially enlarged cross-sectional view of a film capacitor showing an embodiment of the present invention.
The enlarged portion shows the sealing portion between the resin cap 3 and the metal case 2. 2A shows a case where an annular concave portion 13 is provided in FIG. 2A, an annular convex portion 14 is provided in FIG. 2B, and an uneven surface 15 is provided in FIG. 2C. 2 shows the case where the protrusion is on the metal case, and the right figure of FIG. 2 shows the case where the protrusion is on the resin cap.
In the figure on the left side of FIG. 2A, the annular recess 13 is on the resin cap 3 side, and is projected into the annular recess 13 by the protrusion 7 provided on the metal case 2 to form a catching portion.
In the figure on the right side of FIG. 2A, the annular recess 13 is on the metal case 2 side, and is projected into the annular recess 13 by the protrusion 7 provided on the resin cap 3 to form a catching portion.
In FIG. 2B, the annular convex portion 14 is on the resin cap 3 side, and the protruding portion 7 provided on the metal case 2 is provided outside the annular convex portion 14, thereby forming a catching portion.
2C, the protruding portion 7 is on the metal case 2 side, and the surface of the protruding portion 7 and the surface of the portion of the resin cap 3 that contacts the protruding portion are the uneven surface 15, and the hooked portion. Is forming. When the resin cap 3 is soft and the unevenness of the uneven surface 15 on the surface of the projecting portion 7 is difficult to be recessed with the resin cap 3, the uneven surface 15 does not necessarily have to be provided on the resin cap 3 side.
In the right side of FIG. 2C, the protrusion 7 is on the resin cap 3 side, and the surface of the protrusion 7 and the surface of the portion in contact with the protrusion are irregular surfaces 15 to form a catching portion. Yes.

FIG. 3 is a partially enlarged cross-sectional view of the film capacitor manufacturing method showing the embodiment of the present invention. The enlarged portion is a sealing portion where the resin cap 3 and the periphery of the opening of the metal case 2 are fitted. FIG. 3A shows before fitting, and FIG. 3B shows after fitting.
First, as shown in FIG. 3A, a protrusion 7 is provided around the opening of the metal case 2, and an annular recess 13 is provided in the fitting portion 6 of the resin cap 3. Next, as shown in FIG. 3B, when the resin cap 3 is fitted around the opening of the metal case 2, the protruding portion 7 provided on the metal case 2 causes the fitting portion 6 of the resin cap 3 to be inward. It is deformed and the gap between the metal case 2 and the overhanging portion 5 is expanded.

FIG. 4 shows another partially enlarged cross-sectional view of the film capacitor manufacturing method showing the embodiment of the present invention. The enlarged portion is a sealing portion into which the resin cap 3 and the periphery of the opening of the metal case 2 are fitted. FIG. 4A shows a state before the protrusion 7 is provided, and FIG. FIG. 4C shows the state after the protrusion 7 is provided.
First, as shown in FIG. 4A, an annular recess 13 is provided in the fitting portion 6 of the resin cap 3, and it is shown that it is fitted around the opening of the metal case 2. Next, as shown in FIG. 4 (b), the protruding portion 7 is provided on the opening side surface of the metal case 2 so as to enter the annular recess 13 by the rotating sesame 16 as shown in FIG. 4 (c). In addition, it is shown that the projecting portion 7 has entered the annular recess 13 so that the fitting portion 6 of the resin cap 3 is deformed inward and the gap between the metal case 2 and the fitting portion 6 is widened.

FIG. 5 shows another partially enlarged cross-sectional view of the film capacitor manufacturing method showing the embodiment of the present invention. The enlarged portion is a sealing portion into which the resin cap 3 and the periphery of the opening of the metal case 2 are fitted. FIG. 5A shows a state before the protrusion 7 is provided, and FIG. FIG. 5C shows a state after the protrusion 7 is provided.
First, as shown in FIG. 5A, an uneven surface 15 is provided around the fitting portion 6 of the resin cap 3 and the periphery of the opening of the metal case 2, and the resin cap 3 is fitted around the opening of the metal case 2. It is shown that. Next, as shown in FIG. 5 (b), the rotating sesame 16 starts to provide the protruding portion 7 on the opening side surface of the metal case 2 at the uneven surface 15 portion, and as shown in FIG. 5 (c), the resin cap 3 is deformed inward, and the uneven surface 15 of the protruding portion 7 of the metal case 2 is formed on the uneven surface 15 of the embedded portion 6 of the resin cap 3 so that the gap between the metal case 2 and the embedded portion 6 is widened. It shows that it was in pressure contact.

Example 1
Capacitor elements consist of a single-sided metallized film in which a segment pattern is provided on the surface of a 5 μm-thick polypropylene film as a dielectric film, and a metallized film similar to this one in a staggered manner so that the metal surfaces do not overlap. The end electrodes were formed by the method of thermal spraying zinc metal on both ends wound up. In addition, a resin cap having a hooked portion provided with an annular concave portion that protrudes into a portion that comes into contact with a protruding portion that will be formed later by rotary sesame processing is provided corresponding to the protruding portion.
Next, the end face electrode of the capacitor element and the external terminal provided on the resin cap were connected to each other by soldering with a 200 μm thick foil-like lead tab.
Next, the capacitor element with a resin cap was accommodated in a metal case having a thickness of 0.8 mm.
Next, on the inner side of the periphery of the opening of the metal case, a protrusion was provided by rotating sesame so that the average clearance of 0.7 mm was wider than the clearance between the fitting portion of the resin cap and the periphery of the opening of the metal case. . The tip shape of the protruding portion on the side of contact with the resin cap was a shape close to a trapezoid, and the short dimension of the tip of the trapezoidal portion was 1.5 mm.
Next, a urethane-based filling resin was injected from a through hole provided in the resin cap, and after the foamed resin was degassed in a vacuum, it was thermally cured.

(Example 2)
Before the capacitor element with the resin cap was housed in the metal case, it was produced in the same manner as in Example 1 except that the protrusion was processed into the metal case.

(Example 3)
It was produced in the same manner as in Example 1 except that the protrusion was provided on the resin cap side and the corresponding annular recess was provided in the metal case.

(Comparative Example 1-3)
Comparative Example 1-3 was produced in the same manner as Example 1-3, respectively, except that the catch portion was not provided. At this time, the protrusions of the protrusions were adjusted to be small so that the average clearance between the fitting part of the resin cap and the periphery of the opening of the metal case was the same.
(Comparative Example 4)
It was produced in the same manner as in Example 1 except that a hooked portion (annular recess) was not provided, a metal case without a protruding portion, and a resin cap without a protruding portion were used.

  Table 1 shows the number of resin caps for sealing that rise from the metal case during the defoaming of the filling resin in vacuum for each of the samples of Example 1-3 and Comparative Example 1-3. And the judgment result of the resin seepage of the metal case interface.

実施例は、比較例と比べて樹脂キャップが金属ケースからの浮き上がりが見られず良好であった。また、樹脂キャップと金属ケースとの界面の樹脂しみ出しについても、実施例は樹脂しみ出しが見られず良好であった。

In the examples, the resin caps were better than the comparative examples with no lifting from the metal case. Also, the resin exudation at the interface between the resin cap and the metal case was good because no resin exudation was observed in the examples.

Next, a rated voltage of 1100 V was applied to each of three samples of Example 1-3 and Comparative Example 4 at an ambient temperature of 85 ° C. and a relative humidity of 85% RH. As an intermediate measurement, the test was stopped every 250 h, the temperature of the capacitor was returned to room temperature, and the capacity change rate and the tan δ change rate were measured and evaluated at 1000 h. The measurement results of these samples are shown in Table 2.

  As shown in Table 2, in Example 1-3, both the capacity change rate and the tan δ change rate are remarkably improved as compared with Comparative Example 4. On the other hand, Comparative Example 4 has a large capacity change rate and tan δ change rate.

  DESCRIPTION OF SYMBOLS 1 ... Capacitor element, 2 ... Metal case, 3 ... Resin cap, 4 ... Filling resin, 5 ... Overhang | projection part, 6 ... Insertion part, 7 ... Projection part, 8 ... End surface electrode, 9 ... External terminal, 10 ... Drawer tab, DESCRIPTION OF SYMBOLS 11 ... Through-hole of resin cap, 12 ... Hook part, 13 ... Ring-shaped recessed part, 14 ... Ring-shaped convex part, 15 ... Uneven surface, 16 ... Rotating sesame, 17 ... Case

Claims (2)

A capacitor element using a film as a dielectric, a bottomed cylindrical metal case having an opening on the upper end surface for storing the capacitor element, a resin cap for sealing the opening of the metal case, and the inside of the metal case A cylindrically extending portion integrally projecting from the peripheral portion of the resin cap in the bottom direction of the metal case along the side surface of the metal case. The overhanging portion has a fitting portion fitted into the opening of the metal case, and the fitting is provided on either the fitting portion or the opposite surface around the opening of the metal case in contact with the fitting portion. the gap portion between the opening periphery of the metal case, and providing a protrusion pushing within the elastic limit of the resin cap, and this projecting portion On the side in contact with the protrusion, the film capacitor, wherein the resin cap is fixed to the metal casing, providing a catch portion.   Whether the hooked portion is provided with an annular concave portion that protrudes corresponding to the protruding portion on the side in contact with the protruding portion, or is provided with an annular convex portion on the inner side of the protruding portion on the side in contact with the protruding portion 2. The film capacitor according to claim 1, wherein at least one of the surface of the protruding portion or the surface of the portion in contact with the protruding portion is an annular uneven surface.

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