JPS5846049B2 - metallized dielectric capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to metalized dielectric capacitors constructed from metalized films or paper.

A metallized dielectric capacitor, which is made of a dielectric material such as polypropylene film (hereinafter simply referred to as PP film) on which metal is vapor-deposited, has a rated voltage that is higher than the capacitor's partial discharge inception voltage due to the high withstand voltage of the dielectric film. However, in this case, partial discharge of the capacitor causes the vapor deposited metal to scatter, causing a decrease in capacitor capacitance.

Therefore, adhesion strength between the dielectric film and the vapor-deposited metal and adhesion strength between the vapor-deposited metals is required.

Conventionally, when zinc is used as the vapor-deposited metal, a method is used in which silver, copper, etc. are pre-evaporated before zinc vapor deposition in order to improve the strength of the vapor-deposited film and make the vapor-deposited film uniform. The drawback is that the adhesion strength between the dielectric and the deposited metal film is insufficient for the high withstand voltage applied to the capacitor.

In addition, for conventional dielectric materials such as PP film or paper,
Aluminum deposited metal is known to have excellent bond strength.

However, in metallized dielectric capacitors, after the element is formed, molten metal is sprayed on both end faces of the element in order to draw out the lead wires, forming a metallic part.
Aluminum has a disadvantage in that it has lower adhesive strength than zinc when bonding to metals such as solder.

A feature of the present invention is to solve the above-mentioned problems by focusing on mixed vapor deposition when forming the electrodes of metallized dielectric capacitors, and in particular selecting appropriate metals such as aluminum and zinc to perform mixed vapor deposition. Increases the adhesion strength of the metal layer to the body, reduces deterioration of capacitance and tan δ characteristics due to vapor-deposited metal scattering due to partial discharge even when high voltage is applied, and improves the strength of the metallized part at the end of the element. The object of the present invention is to obtain a metalized dielectric capacitor with a high temperature.

In the present invention, a mixed vapor deposition layer of aluminum and zinc is formed on a dielectric material, and this is used as an electrode layer of a metallized dielectric capacitor, but a mixed vapor deposition method using different metals is conventionally known.

In this method, component metals are simultaneously evaporated from separate evaporation sources, a desired concentration is obtained by controlling the deposition rate of each component, and the component metals are simultaneously coagulated into an alloy film.

The mixed vapor deposition method has been used to deposit compound semiconductor thin films or dielectric mixed thin films, but there is no example of it being used as a conductive thin film for a metallized dielectric capacitor as in the present invention.

The present inventors selected aluminum and zinc from among the metals to be mixed and deposited to form an alloy film, as they meet the required characteristics of the metal thin film of a metallized dielectric capacitor.

And the mixing ratio is aluminum:zinc = 0.01
:1 to 1:1 weight ratio.

Embodiments of the present invention will be described with reference to the drawings.

Figure 1 shows a model of the metallized dielectric capacitor of the present invention, in which aluminum and zinc are respectively evaporated from separate evaporation sources onto a dielectric material 1 such as a film such as PP film or polyester film or insulating paper. Evaporation is performed and simultaneous mixed vapor deposition is performed to form an aluminum/zinc mixed vapor deposited film 2.

By winding this, a metallized dielectric capacitor element having the aluminum/zinc mixed vapor deposited layer 2 as an electrode is obtained.

The metallized dielectric capacitor of the present invention can be obtained by injecting molten zinc metal onto both end faces of the capacitor element to form metallic parts.

FIG. 2 shows the voltage vs. tan δ characteristics of a non-impregnated capacitor in which a metallized PP film capacitor element coated with zinc metallicon is shielded from the outside air by a thermosetting epoxy resin.

A shows an example of the present invention, b shows a conventional case of zinc vapor deposition with preliminary copper vapor deposition, and C shows a conventional case of only aluminum vapor deposition.

The applied voltage value on the horizontal axis is expressed as a multiplier with respect to the rated voltage E.

The measurement conditions were a temperature of 23° C., a frequency of 60 Hz, and a number of test pieces of 20.

As is clear from FIG. 2, embodiments of the present invention provide voltage vs.
Good anδ characteristics.

This is considered to be because the capacitor of the present invention has excellent adhesion strength between both end surfaces of the element and the metallic contact portion.

Figure 3 shows the same thing as in Figure 2 at 90
The figure shows the rate of change in capacitor capacitance due to continuous application of an AC voltage above the partial discharge inception voltage in a °C atmosphere.

The measurement conditions were a frequency of 60 Hz and 20 pieces per test.

FIG. 4 shows t for the same thing as in FIG.
It shows changes in andδ characteristics.

The measurement conditions were a temperature of 23°C, a frequency of 60Hz, and the number of samples tested was 2.
There are 0 pieces.

Figure 5 shows the same thing as in Figure 2, 9
The results of an AC voltage step-up breakdown test in a 0°C atmosphere are shown.

The measurement conditions were 0. '25 E/1 minute step-up, 20 pieces tested.

a and blc in FIG. 3.4.5 represent the same things as in FIG. 2.

In the continuous AC voltage application test at a voltage higher than the partial discharge inception voltage shown in Figure 3.4, it was clear that the vapor deposited metal scattering caused by the partial discharge caused a decrease in the capacitor capacitance, and furthermore, as a deterioration in the tanδ characteristics, especially in b and c. However, Example a of the present invention has been shown to be excellent against partial discharge.

Furthermore, the AC voltage step-up breakdown test shown in FIG. 5 also showed excellent withstand voltage.

This represents an improvement in the strength of the deposited metal film against partial discharge of the metallized PP film capacitor according to the present invention.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the basic structure of a metallized dielectric capacitor element according to an embodiment of the present invention, and FIGS. 2 to 5 are graphs showing embodiments for explaining the present invention. 1... Dielectric, 2... Aluminum.
Zinc mixed vapor deposition layer, a...Example of the present invention, b.
・・・Example of zinc evaporation with conventional copper pre-evaporation, C: Example of conventional evaporation of aluminum only.

Claims (1)

[Claims] 1. A metallized dielectric capacitor characterized in that a mixed vapor deposited layer of aluminum and zinc is provided on a dielectric, and an electrode is constituted by a conductive layer made of the mixed vapor deposited layer.