JPS5936412B2 - capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a so-called MF (metallized film) type capacitor in which a plastic film is used as a substrate and a vapor-deposited conductive film is provided on the capacitor, in which an inorganic dielectric vapor-deposited film is used as a dielectric. It is something.

In recent years, Zn has been used in capacitor paper for vapor deposition type capacitors.
Alternatively, capacitors in which A7 or the like is vapor-deposited have been used, but recently, capacitors in which AA is vapor-deposited on plastic films, particularly polyethylene terephthalate, polycarbonate, polypropylene, etc., have been developed.

In these capacitors, the plastic film constitutes the dielectric, but in response to demands for smaller size and lower prices, plastic films have become thinner.
At present, a film with a thickness of 2 μm (polycarbonate film) has even been produced on a trial basis.

However, it is almost impossible to obtain a dielectric film with a thickness of 1 μm or less using the plastic film described above, so the inventors have investigated the use of vapor deposition to create a thin film of an inorganic dielectric material with excellent insulation properties. Ta.

In other words, there are a variety of inorganic dielectrics such as metal oxides, sulfides, and halides, but studies of deposited films of various materials have shown that silicon-based materials are particularly likely to form dielectric thin films. I found out.

The present invention will be explained in detail below.

In general, the conditions required for vapor-deposited inorganic thin films with a thickness of 1 μm or less for capacitor applications are (a) high insulation resistance (1014 Ω or more), (b) good crystallization on a low-temperature substrate, and (c) ) It is possible to evaporate continuously and stably for a long time.

Regarding (a), there are SiO□ and SiO, which have high insulation resistance among inorganic dielectric materials, and silicon-based materials satisfy the required characteristics regarding this condition.

Regarding (b), since the substrate is a polyolefin plastic film that is thermally weaker than inorganic materials, crystallization or adhesion strength on a low-temperature substrate is required.

SiO2 has characteristics that are fully satisfactory in this respect.

Furthermore, since SiO has the same adhesion strength as A[, it fully satisfies the required properties.

Next, an example in which fused silica is deposited by electron beam method will be described with reference to the drawings.

The substrate 1 was made of a polyester film or a polypropylene film, and the thickness of the deposited film constituting the dielectric 3 was about 1,000.

Note that the electrode 2 is composed of a vapor-deposited film of l.

The drawing shows a model of the insulation structure of the capacitor according to this embodiment.

The electrical properties are shown in Table 1.

As a comparative example, the electrical characteristics of a conventionally mass-produced film-type capacitor are also shown.

From the compositional analysis results of this deposited film, the dielectric 3 is composed of Si, S
It was a mixture of iO, 5in2, etc., which is a characteristic of vacuum-deposited films, and the properties shown in Table 1 were obtained with such a composition.

From this result, it was found that silicon or silicon oxide-based vapor deposited films are suitable as dielectrics.

Polyolefin plastic films are thin film substrates with great economic efficiency, but in order to be used as substrates for inorganic thin films, the high heat shrinkage rate will also affect the crystallinity of the thin film, and the heat shrinkage rate will be low. is 10% (120°CI5
A good dielectric thin film could not be obtained when the temperature exceeded 100 min).

As described above, since the dielectric of the present invention is constructed using a vapor-deposited thin film of silicon or its oxide, the dielectric can be easily made into a thin film and has excellent insulation properties. It is an industrial dog that can be used as a dog.

[Brief explanation of the drawing]

The drawing is a sectional view of a capacitor in one embodiment of the present invention. 1...Substrate, 2...Electrode, 3...
...Dielectric material.

Claims (1)

[Claims] 1. The substrate is made of a polyolefin plastic film with a heat shrinkage rate of 10% or less (120°C, 215 minutes),
A capacitor comprising one electrode on the substrate, a dielectric made of a vapor-deposited thin film of silicon or its oxide on the electrode, and the other electrode on the dielectric.