JPS6027111A - Metallized film capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to metallized film capacitors, and more particularly to their evaporated electrode structures.

Conventional configurations and their problems Conventional ↓Metalized film capacitors are used for the purpose of downsizing capacitors and increasing their voltage resistance due to their self-healing feature. However, in order to achieve even higher voltage resistance, it is necessary to improve self-healing properties. This can be achieved by reducing the thickness of the metal thin film, but the aluminum zinc conventionally used for the metal thin film of metallized film capacitors has the following problems. That is, in the case of aluminum, there is a drawback that the #♀ kite capacity decreases in continuous durability tests, and this problem becomes more serious as the thickness of the aluminum thin film becomes thinner.

Since zinc has poor moisture resistance to begin with, it has the disadvantage that its moisture resistance deteriorates dramatically as the thickness of the KL material increases.

In addition, conventionally, copper thin films are sometimes used as acoustic capacitors, but there is a drawback that the copper thin film is oxidized when used at a hot pot temperature, resulting in a significant decrease in the conductivity of the capacitor. Uses are limited.

Purpose of the Invention The present invention is intended to eliminate the drawbacks of the prior art, and aims to increase the withstand voltage of metallized film capacitors, reduce the volume, and save resources. be.

DESCRIPTION OF THE INVENTION To achieve this object, the present invention provides a metallized film having a thin copper film on a plastic film, and a thin film of aluminum or zinc on the edge of the side where the end face electrode is provided. Adjacent turn? It is provided so as to overlap the top or bottom of the copper thin film so as to extend inside the edge of the plastic film.

DESCRIPTION OF EMBODIMENTS Examples of the present invention will be described below with reference to FIGS. 1 to 5 of the drawings.

That is, a metallized film in which a copper thin film 2 is provided on a plastic film 1 is used, and the edge portion (
Thin films 3 of aluminum or zinc are superimposed on the left and right sides in FIG. This thin film 3 is provided to prevent only the copper thin film 2 from being exposed. This structure prevents the copper thin film 2 from coming into contact with oxygen in the air, so that oxidation does not progress. Also, by overlapping and adhering to the adjacent metallized film or dielectric film, it has the effect of thinning the copper thin film, which is susceptible to oxidation. but,
The edge portion on the side where the end electrode is provided is shifted so as not to overlap with the metallized film or dielectric film of the adjacent layer in order to make good electrical contact with the end electrode. In addition, in conventional metallized film capacitors using only copper thin films, oxidation of this portion has been a particular problem.

FIG. 1 shows a first embodiment in which a thin film 3 of aluminum or zinc is superimposed on the top of the same thin film 2, and FIG. 2 shows a second embodiment in which a thin film 3 of aluminum or zinc is superimposed on the bottom.

The third embodiment shown in FIG. 3 differs from FIG. 1 in that a thin copper film 2 is formed on the entire surface of the plastic film 1. In a typical metallized film capacitor, the edge of the metal thin film is slightly set back from the edge of the plastic film 1, as shown in FIG. 1, in order to withstand voltage. In Figure 3, the first one is copper thin Il! A2 is provided on the entire surface, and a thin film 4 is used as a capacitor. Although FIGS. 1 to 3 are examples of a single-sided metalized film, the structure of the present invention can also be applied when a double-sided metalized film and a laminated dielectric film are used.

In each case, details will be given using the first example as a representative with specific numerical values.
I will explain to f■.

A polyethylene terephthalate film having a thickness of 4 μm was used as the glass film 1, and a thin copper film was formed on the film by vapor deposition so that the resistance of the vapor-deposited film was 1oQ/hole. A thin aluminum film was also formed by vapor deposition on the edge on the side where the end face electrodes were to be provided. The thickness of the aluminum thin film at this time is approximately 2 to 4 Ω/hole in terms of vapor deposited film resistance.

For comparison, aluminum and # were individually deposited twice, first on the facing part and then on the edge part, and the deposited film on the facing part was 10Ω/hole as above.

The edge portion on the side where the end face electrode was provided was set to 2 to 4 Ω/hole. A pair of each of these three types of metallized films was wound up, and zinc was metal sprayed as end surface electrodes. After welding the lead wires to the end electrodes, the capacitor element was placed in a polyester resin case and sealed with a two-component epoxy resin.

Evaluation-1 Continuous high temperature durability test and high temperature storage test were conducted. Figure 4 shows the results of the high temperature continuous surface J test, and Figure 5 shows the results of the high temperature storage test. In addition, in the characteristic curve in the figure,
A is the one using the metallized film of the present invention, and A is the one using the vapor-deposited film of only aluminum (conventional example).
Indicated by High temperature continuous durability test conditions are AC 3oov and temperature 8
6c1 high 1 fatigue test 1 test condition (RI temperature 120C was used.

As is clear from FIG. 4, in characteristic curve B using a steam shield film made only of aluminum, the capacitance significantly decreases with time. This ('J1) is caused by electrical oxidation of aluminum and conversion to aluminum oxide, which is an Ae-related material. When the capacitor is disassembled, the edge of the vapor-deposited film recedes, and a small circle appears in the medium-heated part. Traces of oxidative deterioration of the deposited film were confirmed, and it was observed that the deposited film was oxidized near the end electrodes and became slightly transparent.In the characteristic curve A of the metallized film using copper and aluminum according to this example, , compared with characteristic curves B and C of the conventional example, the rate of change in capacitance is small and stable.Although not shown in Fig. 4, a thin film of zinc is used instead of a thin film of aluminum on the edge. A stable capacitance result was also obtained in a configuration using .

FIG. 6 shows the rate of change in capacitance when left at high temperature without applying any voltage. In this case, characteristic curve B using a vapor-deposited film made only of aluminum becomes more accurate. On the other hand, in characteristic curve A using the metallized film according to this example, the capacitance decreases only slightly.

Effects of the Invention As described above, according to the present invention, the decrease in capacitance is smaller in the high temperature continuous durability test and the high temperature storage test compared to the conventional electrode configuration, and furthermore, the copper thin film is generally used in conventional capacitors. Compared to an aluminum thin film or a zinc thin film, the film thickness is thinner for the same vapor-deposited film resistance value, so a high-voltage metallized film capacitor with low voltage drop during self-recovery and excellent self-recovery properties is obtained. It is something that can be done.

[Brief explanation of drawings]

Figures 1 to 3 are comparative characteristic diagrams showing the results of one metal test in an example of the present invention, and Figure 5 is a comparative characteristic diagram showing the results of the same high temperature storage test.・Plastic film, 2-... Copper thin film, 3... Aluminum or zinc thin film. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 4 Time opening (H) Figure 5 Time CH)

Claims (1)

[Claims] A thin film of aluminum or zinc is applied to the edge of the metallized film on the side where the electrode is provided on the edge of the metallized film in which a thin copper film is provided on the plastic film so that the thin film extends inside the edge of the plastic film adjacent to the thin copper film. A metallized film capacitor is provided on top or bottom of the copper thin film.