JPH0158646B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to metallized film capacitors.

In recent years, polyester film (hereinafter referred to as PET film) and polypropylene film (hereinafter referred to as PP film)
Capacitors with Zn metal or Al metal deposited on a film (also called film) began to be used. For PET films, those with Zn metal vapor-deposited are generally used, but in capacitors using this PET film, when the temperature exceeds 75 to 80 degrees Celsius, the dielectric loss tangent increases rapidly and thermal runaway occurs. It has the disadvantage of being unusable for capacitors, which have become increasingly harsher in operating temperature and voltage has become higher year by year.
Naturally, there are limits to ambient temperature and potential gradient.
On the other hand, PP film has a very stable dielectric loss tangent as long as it is below the melting point of the film itself, and there is a tendency to use PP film especially when used at high temperatures and high voltages. However, as shown in Figure 1
In a capacitor using a metallized film (hereinafter referred to as MPP film) 1 in which Al metal is vapor-deposited on a PP film, when the applied voltage increases, the Al metal vapor-deposited on the electrode margin 2 side is caused by corona generated from the end face of the capacitor. is scattered, and
MPP film itself has a blocking effect and has very poor impregnability with insulating oil, making it very easy for air and other voids to get mixed in. For this reason, corona is likely to occur, and as mentioned above, the Al metal deposited on that part will scatter, resulting in a drawback that the capacitance change rate significantly exceeds ±4% in the capacitor durability test specified by JISC4908. It was hot. Approximately 60% of the reason for the decrease in capacity is due to an increase in the margin width due to corona generated at the end face.

The present invention seeks to overcome the above-mentioned drawbacks and provide a highly reliable metallized film capacitor that reduces the occurrence of corona.

That is, metals such as Al and Zn are vapor-deposited, and a capacitor element is formed by arranging opposing electrode margin parts of a metallized film having an undeposited electrode margin part at one end in opposite directions and winding the film. This is a metallized film capacitor characterized in that a metallicon metal is welded to the end face of the element, a synthetic resin is fixed onto the metallicon metal, and the capacitor is housed in an exterior case.

The present invention will be described below with reference to embodiments shown in FIGS. 2 to 4.

Figure 2 is a cross-sectional view of the main parts of a capacitor element.
A non-vaporized electrode margin portion 5 is provided at one end of a metallized film (MPP film) 1 in which Al metal 4 is vapor-deposited on a film 3, and a capacitor element 6 is formed by winding the opposing electrode margin portions 5 in opposite directions. A metallicon metal 7 is welded to the end face of the capacitor element 6, and a paraffin-based, polyethylene-based, or aggressive polypropylene-based wax is impregnated therein. Next, the metallcon metal 7 and the lead wire 8 are connected by soldering, welding, or the like, and a synthetic resin 9 such as epoxy, polyurethane, polypropylene, or polyethylene is coated on the metallicon metal 7 and fixed. Then, the terminals 11 mounted on the terminal board 10 and the lead wires 8 are connected, and the terminals 11 are inserted into the outer case 12 and sealed to complete the metallized film capacitor. In this case, wax or the like may be filled between the exterior case 12 and the capacitor element 6 to improve heat radiation.

The metallized film capacitor of the present invention is constructed as described above.

Therefore, when a corona occurs between the metallicon metal 7 of the electrode margin part 5 shown in FIG.
Gases such as CO ₂ and H ₂ are generated, but since both end faces of the capacitor element 6 are fixed with synthetic resin 9, the generated gas increases the internal pressure at the end faces of the capacitor element 6, which prevents the generation of corona. suppress. The synthetic resin 9 is inside the outer case 12 and is not affected by the outside air and does not crack. Therefore, the scattering of the metal vapor deposited film at the boundary of the electrode margin portion 5 was reduced, and the capacity reduction rate was significantly improved. Particularly in flat capacitors with a narrow dielectric film width, the welding area of the metallicon metal is relatively large, so the improvement effect is large. The synthetic resin 9 applied to the bottom surface of the case 12 of the capacitor element 6 may also be used as an element fixing agent.

Next, MPP film is laminated and wound to form a capacitor element, and then molten metal is sprayed onto this to form a metallicon to form an electrode lead-out part, paraffin wax is impregnated, and an epoxy resin is applied on the metallicon metal. The resin is fixed and stored in an external case.
We created a metallized film capacitor with a rating of 400WVAC and 12μF. The above metallized film capacitor was subjected to a 1000-hour continuous current test in accordance with JISC4908, and the capacitance was measured. Figure 4 shows the results compared with a conventional product in which no resin is applied to both end surfaces of the capacitor element.

As is clear from FIG. 4, the product of the present invention suppressed corona generation, significantly improved the rate of change in capacity, and was demonstrated to be highly reliable.

In addition, although the above-mentioned embodiment described the case where the vapor-deposited metal is Al metal, it is also possible to use a metallized film capacitor with Zn metal vapor-deposited, or a metal film capacitor with a laminated plastic film with Zn metal vapor-deposited and a plastic film with Al metal vapor-deposited. Similar effects were obtained with chemical film capacitors.

In addition, the impregnating agent is not limited to paraffin wax, but also polyethylene wax, attacking polypropylene wax, etc. with a melting point of 70~
Similar results were obtained with solid insulation in the 120°C range or without impregnation.

As mentioned above, the metallized film capacitor of the present invention suppresses the generation of corona in the capacitor, significantly improves the electrical characteristics, and has great industrial and practical value.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of the main parts of a conventional metallized film capacitor element, FIG. 2 is a cross-sectional view of the main parts of a metallized film capacitor element according to an embodiment of the present invention, and FIG. 3 is a metallized film capacitor element of the present invention. FIG. 4 is a cross-sectional view of a capacitor, and is a capacitance change rate vs. energization time characteristic diagram of a metallized film capacitor comparing a product of the present invention and a conventional product. 1: metallized film, 5: electrode margin part,
6: Capacitor element, 7: Metallicon metal, 9:
Synthetic resin, 12: Exterior case.

Claims (1)

[Claims] 1 A capacitor element is formed by depositing a metal such as Al or Zn and winding a metallized film having a non-deposited electrode margin at one end with opposing electrode margins arranged in opposite directions. A metallized film capacitor characterized in that a metallicon metal is welded to the end face of the element, a synthetic resin is fixed onto the metallicon metal, and the metallized film capacitor is housed in an exterior case.