JPH0564848B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a metallized film capacitor used for electrical equipment, low voltage phase advancement, etc., and particularly relates to the structure of its metal thin film layer (electrode). BACKGROUND TECHNOLOGY Conventionally, in order to suppress partial discharge that occurs between the layers of metallized film in a metallized film capacitor, or to suppress moisture that enters between the layers of metallized film, so-called It is known to use a dielectric film that is thermally bonded. This thermally bonded dielectric film is
Attempts have been made to coat the surface of an ordinary dielectric film with a thermoplastic resin having a low melting point. Furthermore, attempts have been made to use a dielectric film whose surface is provided with an activated layer through corona discharge treatment or the like. Additionally, attempts have already been made to use thin metal film layers to increase the adhesion of dielectric films. However, all of these methods have had to rely on adhesion between a dielectric film and a metal thin film layer, rather than adhesion between dielectric films. Problems to be Solved by the Invention In bonding such a dielectric film and a metal thin film layer, in particular, the mechanical strength of the metal thin film layer itself and the surface of the dielectric film on which the metal thin film layer is provided are important. The problem is the adhesion strength of the metal thin film layer itself, but this mechanical strength and adhesion strength were not sufficient. For this reason, when a metallized film capacitor is subjected to thermal shock tests at low temperatures (e.g. -30°C) and high temperatures (e.g. 100°C), the film layers easily peel off, resulting in an increase in the amount of charge in the partial discharge that occurs. However, there was a problem that reliability was compromised. The present invention aims to solve these problems. Means for Solving the Problems In order to solve the above-mentioned problems, the present invention is characterized in that holes are formed partially in the metal thin film layer, and the dielectric films are bonded together at the holes. It is. If we increase the area of the pores and increase the density,
The adhesive strength can be increased depending on the area. Effect The adhesive strength between dielectric films is 1 to 10% higher than the adhesive strength between dielectric films and metal thin film layers.
Since it is two orders of magnitude higher, even if the adhesion is limited to a partial hole, it can sufficiently resist the force that tends to separate the film layers. Furthermore, by increasing the density of the pores, even if the metal thin film layer and the dielectric film come off in areas other than the pores, there will be a large gap between the film layers because they are still bonded in the pores. It has the effect of not causing This suppresses the occurrence of large partial discharges, thereby increasing the reliability of the metallized film capacitor. Examples Examples will be described below with reference to the drawings. FIG. 1 is a diagram illustrating holes in a metal thin film layer according to the present invention. A metal thin film layer 1 is provided on a dielectric film, and holes 2 of pitch A and diameter B are provided in this metal thin film layer 1. It shows that The structure is such that the surface of the underlying dielectric film is exposed at the hole 2 portion. The method for forming the holes 2 in the metal thin film layer 1 is to apply paraffin oil, etc., which is used for forming a normal vapor deposition margin, to the areas where the holes 2 are desired to be formed by transferring, etc., before forming the metal thin film layer 1 by vacuum evaporation. If this is done, the metal thin film layer 1 with holes 2 as shown in FIG. 1 can be obtained since the holes 2 are removed and the metal thin film layer 1 is vacuum evaporated. Another method is to form a metal thin film layer 1 without holes 2 during vacuum evaporation, and then apply an electrode to the holes 2 and apply current to the metal layer 1 in the holes 2 using Joule heat. There is also a method of evaporating and scattering the thin film layer 1. When the dielectric film is polyolefin, the influence of residual paraffin can be reduced by corona discharge treatment on both surfaces. The smaller both the pitch A and the hole diameter B, the more uniform the bonding will be as a whole, and the reduction in the electrode area due to the holes 2, that is, the reduction in the capacitance of the metallized film capacitor, can be reduced. Taking the method of transferring paraffin oil to a dielectric film before vacuum deposition as an example, it can be thought of in the same way as gravure printing, so the pitch A is 0.1 to 1 mm, and the hole diameter B is 0.02 to 0.1 mm. If so, it can be fully implemented using existing technology. In addition, the capacitance lost due to the holes is, for example, about 2% when the pitch is 1 mm and the hole diameter is 0.1 mmφ, and at this level, the benefit from improved reliability is much greater. FIG. 2 is a cross-sectional view of a main part showing the film interlayers of the metallized film capacitor according to the present invention.
A metal thin film layer 1 is provided on a dielectric film 3, and holes 2 are provided in the metal thin film layer 1. The thickness of the metal thin film layer 1 is generally 100 to 400 mm.
The thickness is approximately .ANG., and compared to the dielectric film 3, the thickness is actually negligible. At the hole 2, the dielectric films will be glued together, so
Peeling between film layers is less likely to occur. Note that the hole diameter and hole pitch are drawn much larger than they actually are to make the diagram easier to understand. More specific examples will be described below. One surface of a polypropylene film with a thickness of 8 μm was subjected to a corona discharge treatment, and paraffin oil (manufactured by Etsuso Co., Ltd., CRYSTOL-145) was applied thereon by transfer with a pitch of 1 mm and a diameter of 0.1 mm. Aluminum was deposited on this corona discharge treated surface by vacuum deposition to a deposited film resistance of 3.5Ω/thickness. At this time, the areas where the paraffin oil has been transferred become holes without being vapor deposited. Thereafter, a metallized film capacitor was produced using the same process as conventional metallized film capacitors. Paraffin oil was transferred onto both surfaces of a 6 μm thick double-sided corona discharge treated polypropylene film (YK-41 manufactured by Toray Industries, Inc.) with a pitch of 0.5 mm and a diameter of 0.04 mm, using a roller transfer method. After evaporating zinc as a core metal, vacuum evaporation was performed so that the resistance value of the deposited film was 20 Ω/hole at the electrode facing part and 4 Ω/hole at the edge where the end electrode was provided, thereby creating a double-sided metallized film.
This double-sided metallized film and a 5 μm thick double-sided corona discharge treated polypropylene film are overlapped and wound as a laminated film.
It was made into a metallized film capacitor. To evaluate the metallized film capacitor, we conducted a continuous thermal shock electrification test at -30°C and 100°C. The temperature repeat cycle is -30℃,
One cycle is 6 hours at 100°C. The applied voltage is 480V AC for the metallized film capacitor, and 400V AC for the metallized film capacitor. For comparison of each metallized film capacitor, a conventional metallized film capacitor without holes in the metal thin film layer was prototyped and evaluated. The results are shown in the table below. The capacitance is 20 μF each, and the quantity is 6 each.

[Table] Effects of the invention As is clear from the examples, according to the present invention, the metallized film capacitor in which holes are provided in the metal thin film layer has stable adhesion between the film layers even after repeated thermal shock tests, and has a large gap. As a result of not occurring,
Large partial discharges do not occur, and a significant effect is obtained in terms of the average number of cycles until breakdown. This was confirmed by measuring the amount of partial discharge of the metallized film capacitor before destruction and by disassembling it.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the structure of a metal thin film layer according to an embodiment of the present invention, and FIG. 2 is a sectional view of a main part of a metallized film capacitor according to an embodiment of the present invention. 1... Metal thin film layer, 2... Hole, 3... Dielectric film.

Claims (1)

[Scope of Claims] 1. A metallized film capacitor formed by winding or laminating a metallized film provided with a metal thin film layer on the surface of a dielectric film that generates adhesive force by applying pressure and heating. A metallized film capacitor, characterized in that the metal thin film layer is partially provided with holes, and the dielectric films are bonded together at the holes. 2. The metallized film capacitor according to claim 1, wherein the dielectric film is a polyolefin film with activation layers provided on both surfaces by corona discharge treatment.