JP2014093505A - Film capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film capacitor in which a metal case hardly coming off from a content mainly comprising a resin, in a film capacitor including: a capacitor element using a film as a dielectric; a tubular metal case with a bottom having an opening on an upper end face where the capacitor element is housed; a lead tab connected to the capacitor element and led out to the outside of the metal case; and a filling resin for filling the inside of the metal case.SOLUTION: There is provided a film capacitor provided with protrusions formed of an insulating resin adhesive on the inner side surface of a metal case.

Description

  The present invention relates to a film capacitor.

Conventionally, as shown in FIG. 6, a film capacitor is formed by depositing aluminum (Al) or zinc (Zn) on a resin film such as polypropylene (PP), polyethylene terephthalate (PET), or polystyrene (PS). The capacitor element 1 is formed by forming and stacking or winding it, or the capacitor element 1 is configured by stacking or winding Al foil electrodes together with a film. In the case of vapor-deposited metal, a metallicon end face electrode 4 is applied to the capacitor element 1 thus formed, and a lead tab 5 is welded or soldered to the end face electrode 4 and accommodated in a bottomed cylindrical resin case 11. Is drawn out of the resin case 9, filled with a filled resin 3 into the bottomed cylindrical resin case 11, and filled with the filled resin 3 in the capacitor element 1 and the drawing tab 5 portion.
By the way, when a metal case is used instead of a resin case as the material of the case, the metal case is separated from the resin-based content because the linear expansion coefficient of the metal case is significantly different from the resin-based content. It tends to occur. For this reason, Patent Document 1 discloses a method in which a concave portion is provided on the inner wall surface of a metal case, and the wedge-shaped shape is filled with a filling resin.
Patent Document 2 discloses a configuration in which a plurality of concave and convex portions or groove portions are arranged by deforming the side of the case so that the contents in the bottomed cylindrical case can be locked in the case. Has been.

JP 2007-19136 A Japanese Utility Model Publication No. 5-43521

As in Patent Document 1, a method of providing a recess on the inner wall surface of a metal case and filling the wedge-shaped shape with a filling resin is different from a method of forming a metal case to form the recess. Processing equipment is required, and in order to obtain a wedge-like function, the metal case itself needs to be thickened accordingly. Therefore, the metal case tends to be heavy and the storage capacity tends to decrease. .
In addition, in the configuration in which the case side surface itself is deformed as in Patent Document 2, when the case is made of metal, it is easy to come into contact with the capacitor element housed inside or the drawer tab drawn out from the capacitor element. It tends to be difficult.

  Therefore, the present invention provides a film capacitor that is lightweight even when a metal case is used, and that the metal case is not easily detached from the resin-based contents while ensuring insulation between the capacitor element and the metal case. Is an issue.

In order to solve the above problems, the present invention provides the following film capacitor.
(1) 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, and a drawer connected to the capacitor element and drawn out of the metal case A film capacitor comprising a tab and a filling resin filling the inside of the metal case, wherein an insulating protrusion is provided on the inner surface of the side surface of the metal case.
(2) The film capacitor according to (1), wherein the insulating protrusion is an epoxy resin.
(3) The film capacitor according to (1) or (2), wherein the insulating protrusion has a base.

  Even when a metal case is used, it is possible to provide a film capacitor in which the metal case is less likely to be detached from the resin-based contents while ensuring insulation between the capacitor element 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 perspective view of a film capacitor showing an embodiment of the present invention. The sectional view of the film capacitor in which another embodiment of the present invention is shown is shown. The partially expanded perspective view of the film capacitor which shows another embodiment of this invention is shown. 6 shows a method of making an insulating protrusion of a film capacitor showing another embodiment of the present invention. The schematic sectional drawing of the conventional film capacitor is shown.

  The capacitor element described in the present invention forms electrodes by depositing aluminum (Al) or zinc (Zn) on a resin film such as polypropylene (PP), polyethylene terephthalate (PET), or polystyrene (PS). A capacitor element is formed by stacking or winding, or a capacitor element is formed by stacking or winding an Al foil electrode together with a film, and a conventional capacitor element for a film capacitor can be used. In the case of vapor-deposited metal, a metallicon end face electrode is applied to the capacitor element thus formed, and a lead tab is welded or soldered to the end face electrode.

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, Al-Zn and Al-Mg can also be used as the aluminum alloy system (A3000 system, A5000 system).
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 filling resin in the present invention is a resin that fills the gap in the metal case, and since it is necessary to mitigate the difference in thermal expansion between the resin-based capacitor element and the metal case, it is more difficult than a hard resin such as an epoxy resin. A soft resin having rubber elasticity such as urethane resin and silicone resin is preferably used. Further, if necessary, a filler is mixed in the resin so as to approach the linear expansion coefficient of the metal case. For example, a solvent-free 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, an antioxidant, an ion scavenger, and a stress relaxation agent may be added.
This filling resin is injected into the inside from the opening of the metal case in a liquid state, and is solidified by heating after filling, polymerization by a curing agent, or the like. 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 strong strength and adhesion to the external terminal can be selected on the opening side. It is also possible to select such that the amount of filler is small on the capacitor element side and large on the opening side.

Insulating protrusions in the present invention are insulative protruding structures that are provided on the inner surface of the side surface of the metal case, and are bonded to the inner surface side of the side surface of the metal case. The height from the case is about 0.5 mm to 5 mm. The shape is not particularly limited, such as a cone, an elliptical cone, an angular guess, a cylinder, an elliptical column, and a rectangular column. A belt-like body projecting along the inner circumferential direction of the inner side surface is also preferable in that respect because the contents can be easily locked in the case. A shape having a wide skirt on the bottom side or a shape having a brim on the hat is also preferable in terms of improving the adhesion to the metal case or the adhesion to the filling resin.
The material of the insulating protrusions is preferably an insulating material that has high adhesion to the metal case.
Specifically, among adhesives such as inorganic adhesives and organic adhesives, those that can maintain the protrusion shape even after being laminated and fixed on the metal case surface are preferable. The higher the viscosity before solidification, the easier it is to maintain the height of the protrusion shape after solidification. An organic adhesive is preferable from the viewpoint of adhesion between the metal of the metal case and the filling resin and handling.
As the type of the organic adhesive, a resin system such as urethane resin and epoxy resin, a rubber system such as styrene butadiene rubber, chloroprene rubber, and silicone, or a modified or mixed material thereof can be used. In particular, an epoxy resin is preferable in terms of good adhesion of the metal case to the metal.
The epoxy resin adhesive is an adhesive mainly composed of an epoxy resin, and there are a one-component type and a two-component type depending on the curing method. In the two-pack type, when a curing agent such as amine is added to an epoxy resin prepolymer obtained by condensation reaction of bisphenol A and epichlorohydrin, graft polymerization occurs, and the three-dimensional polymer cures and adheres over time and thermosetting. In order to achieve room temperature curing, it is necessary to use a two-part solution using polyamide, aromatic sulfonic acid, or the like as a curing agent. When blended with polymers such as nylon and isocyanate, the peel resistance and impact resistance are improved.

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. FIG. 2 shows a partially enlarged perspective view of the insulating protrusion of the film capacitor showing the 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 a filling resin 3 filling the metal case 2. The end face of the capacitor element 1 is provided with a metallicon end face electrode 4, and a lead tab 5 is welded or soldered to the end face electrode 4. The lead tab 5 is drawn out of the metal case 2. It has a structure.
The drawer tab 5 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 the case of FIGS. 1 and 2, the insulating projections 6 are provided to be scattered on the inner surface of the side surface of the metal case 2. The shape of the insulating projection 6 in the case of FIG. 2 is three strips protruding along the inner peripheral direction of the inner surface of the metal case 2, and is perpendicular to the length direction of the metal case 2. The cross section of is a semicircle.
In this case, the insulating projection 6 is created by, for example, using a discharge device or the like, and discharging the fixed amount at a constant speed, for example, to set the height of the insulating projection 6. The insulating protrusions 6 may make one turn or several turns spirally along the inner peripheral direction of the inner surface of the metal case 2, but it is preferable to omit the portion in contact with the drawer tab 5 in terms of space. . From the viewpoint of easy filling of the filling resin 3, it is preferable to be intermittent.

FIG. 3 shows a cross-sectional view of a film capacitor showing another embodiment of the present invention. FIG. 4 is a partially enlarged perspective view of a film capacitor showing another embodiment of the present invention.
The difference from FIG. 1 or FIG. 2 is that the insulating protrusion 6 has a skirt field 7. If the skirt field 7 is provided, the bonding area with the metal case 2 increases and the bonding strength is increased. Increase. In addition, when the insulating protrusion 6 is mainly made of resin, the insulating protrusion 6 often has better adhesion to the filling resin 3 than the metal case 2, and the insulating protrusion 6 is interposed through the insulating protrusion 6. The adhesion between the filling resin 3 and the metal case 2 is improved, which is preferable.

  Further, in the case of FIG. 3 or FIG. 4, in particular, the base 7 is combined with the adjacent insulating protrusion 6. As shown in FIG. 5, the adhesive 8 that becomes the insulating protrusion 6 is dropped on the inner surface of the side surface of the metal case 2, and the cylindrical squeegee 10 with the groove 9 is used to collect the adhesive. A plurality of insulating protrusions 6 or insulating protrusions 6 with skirts 7 can be formed simultaneously.

EXAMPLES The present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.
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.
Next, the end face electrodes of the capacitor elements were connected by soldering using a 200 μm thick foil-like lead tab.
Next, an insulating protrusion is applied to the inside of the side surface of a bottomed cylindrical metal case with a thickness of 0.8 mm by using an epoxy resin adhesive, and a cross-section with a width of 3 mm and a height of 3 mm is halved by a discharge device. The part which touched the drawer tab with a circle was omitted, and three rounds with a total length of 90 mm were made along the inner circumferential direction.
Next, the capacitor element was accommodated in this metal case.
Next, a urethane-based filling resin was injected, and after the defoaming of the filling resin in a vacuum, it was thermally cured.

(Example 2)
In order to create an insulating projection, an epoxy resin adhesive is dropped on the inside of the side surface of the metal case with a dispenser, and a cross-section with a width of 3 mm and a height of 3 mm is a semicircle by a grooved cylindrical squeegee, Other than having three ridges with a skirt (3 mm skirt length) on a pedestal with an average thickness of 100 μm and three protrusions with a length of 30 mm along the inner circumference and a distance of 3 mm between the protrusions Produced a capacitor in the same manner as in Example 1.

(Example 3)
A capacitor was prepared in the same manner as in Example 2 except that the insulating protrusion was formed in a shape having a skirt on the pedestal having an average thickness of 500 μm (the length of the skirt was 3 mm). .

(Comparative Example 1)
A capacitor was prepared in the same manner as in Example 1 except that no insulating protrusion was provided.

  In Table 1, about 20 samples of each of Examples 1 to 3 and Comparative Example 1 were subjected to a heat cycle of −20 ° C. and 80 ° C., and the metal case was tested to determine whether it was detached from the resin-based contents. The number is shown.

  In the example, the metal case was less likely to be detached from the resin-based content as compared with the comparative example. Also, it was better that the insulating protrusion had a base.

  DESCRIPTION OF SYMBOLS 1 ... Capacitor element, 2 ... Metal case, 3 ... Filling resin, 4 ... End surface electrode, 5 ... Draw-out tab, 6 ... Insulating protrusion, 7 ... Side field, 8 ... Adhesive, 9 ... Groove, 10 ... Squeegee, 11 ... Bottomed cylindrical resin case

Claims (3)

  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 drawer tab connected to the capacitor element and drawn out of the metal case, A film capacitor comprising a filling resin filling the inside of the metal case, wherein an insulating protrusion is provided on the inner surface of the side surface of the metal case.   The film capacitor according to claim 1, wherein the insulating protrusion is an epoxy resin.   The film capacitor according to claim 1, wherein the insulating protrusion has a base.

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