JPH0437106A - Thin film capacitor - Google Patents

Abstract

PURPOSE:To obtain a thin film capacitor in which the surface of an inner electrode is not corroded and not intruded by flame sprayed metal of an outer electrode by providing an inner electrode arranged to the end of a substrate at each one layer of nickel or nickel-chromium alloy, and outer electrodes covered with protective films at dielectrics alternately laminated with the inner electrode and formed at both ends of the substrate. CONSTITUTION:Two or more layers of inner electrodes 2 in which nickel or nickel-chromium alloy is arranged at each layer to the end of a substrate 1 on the substrate 1 having insulation, and outer electrodes 5 in which dielectrics 3 of organic thin films alternately laminated with the electrodes 2 are covered with protective films 4 at both ends of the substrate 1 are provided. For example, Ni of 0.03mum thick of a film by a vacuum depositing method and an aromatic polyurea layer of 0.4mum thick of a film by a depositing polymerizing method are alternately laminated as the electrodes 2 on the substrate 1 of alumina covered with glass of 20mum thick except both ends, then a silicon nitride film of 2mum thick is formed as a protective film 4 by a plasma CVD method, and the electrodes 5 are formed of copper alloy of 20mum thick by a reduced pressure plasma spraying method.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to thin film capacitors used in various electronic devices.

BACKGROUND OF THE INVENTION In recent years, with the rapid miniaturization and higher performance of electronic devices, there has been an increasing demand for miniaturization of electronic components. Capacitors can be made smaller by increasing the dielectric constant of the dielectric or by reducing the thickness of the dielectric.

Conventional thin film capacitors, such as film capacitors that use organic materials as dielectrics, are made smaller by making the film thinner. In addition, in thin film capacitors whose dielectric material is an organic material, the internal electrodes are Ae or Ae, which have good conductivity.
E-alloy is used, and the external electrodes are formed by thermal spraying a metal such as Cu.

Problems to be Solved by the Invention However, in the above-mentioned conventional configuration, since the corrosion resistance of Ae or Ae alloy is weak, there is a problem that corrosion of the internal electrodes occurs due to the influence of alkaline components from the substrate and organic thin film under high temperature and high humidity. Another problem is that if the film thickness of the internal electrode is not sufficient, the internal electrode is likely to be eaten away by the sprayed metal of the external electrode during formation of the external electrode.

The present invention solves the above conventional problems, and aims to provide a thin film capacitor in which the surfaces of internal electrodes are not corroded and are not eaten by the sprayed metal of the external electrodes.

Means for Solving the Problems To achieve this object, the thin film capacitor of the present invention comprises:
Two or more internal electrodes made of nickel or nickel-chromium alloy arranged layer by layer up to the edge of the substrate on the surface of an insulating substrate (hereinafter referred to as the substrate), and organic thin films laminated alternately with the internal electrodes. The dielectric material is covered with a protective film, and external electrodes are provided at both ends of the substrate.

Function: With this configuration, the electrodes are not corroded by alkaline components from the substrate or the organic thin film (and the internal electrodes are not eaten away by the external electrodes).

EXAMPLE An example of the present invention will be described below with reference to the drawings.

As shown in FIG.
are alternately laminated, the surface of the internal electrode 3 except for both ends is covered with a protective film 4, and external electrodes 5 which are electrically connected to the internal electrode 3 are formed at both ends of the substrate 1.

EXAMPLES The present invention will be explained in more detail with reference to Examples below.

(Example 1) Ni with a thickness of 0.03 μm was deposited as an internal electrode 2 on a substrate 1 made of alumina whose surface, excluding both ends, was coated with glass with a thickness of 20 μm as a dielectric material. As 3, aromatic voluria films with a film thickness of 0.4 μm were alternately laminated by vapor deposition polymerization method, and then plasma CV was applied as protective film 4.
A silicon nitride film is formed with a thickness of 2 μm using the D method, and an external electrode 5 is formed of a copper alloy with a film thickness of 20 μm using a low pressure plasma spraying method.

(Example 2) A nickel-chromium alloy with a film thickness of 0.1 μm was deposited as an internal electrode 2 on an alumina substrate 1 by a sputtering method.
The dielectric material 3 has a film thickness of 0.2μ by vapor deposition polymerization.
After alternately laminating 20 layers of aromatic polyimide films with a thickness of 20 m, a 2 μm silicon nitride film was deposited as a protective film 4 using a plasma CVD method.
The external electrode 5 is formed of a steel alloy with a thickness of 10 μm using a low pressure plasma spraying method.

The thin film capacitor constructed as described above was subjected to a high humidity life test (left at a temperature of 60°C and humidity of 95% for 1000 hours), and the results showed that there was no corrosion of the internal electrodes and the capacitor remained stable with no change in capacitance. .

As described above, according to the present invention, by using nickel or nickel chromium alloy with strong corrosion resistance as the material of the internal electrodes, the surfaces of the internal electrodes are not corroded even in high humidity tests.
Furthermore, it is possible to prevent the internal electrodes from being eaten away by the sprayed metal on the external electrodes, resulting in high quality and high reliability.

Therefore, it is possible to achieve higher performance, smaller size, and lower cost of the thin film capacitor.

Effects of the Invention As is clear from the description of the embodiments above, the present invention has two or more layers of internal electrodes in which nickel or nickel-chromium alloy is disposed layer by layer on the surface of the substrate up to the edge of the substrate. The organic thin film dielectric layer alternately laminated with the internal electrodes is covered with a protective film, and the outer IT electrodes are provided at both ends of the substrate, so that the surface of the internal electrodes will not be corroded and the sprayed metal of the external electrodes will not be corroded. This makes it possible to create excellent thin-film capacitors that are of high quality and highly reliable and will not be devoured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a thin film capacitor according to an embodiment of the present invention. 1...Substrate, 2...Internal electrode, 3...
...Dielectric, 4...Protective film, 5...
・External electrode.

Claims (2)

[Claims] (1) Two or more layers of internal electrodes in which nickel or nickel-chromium alloy is disposed layer by layer up to the edge of the substrate on the surface of an insulating substrate, and organic thin films laminated alternately with the internal electrodes. A thin film capacitor that has a dielectric covered with a protective film and has external electrodes on both ends of the substrate. (2) The thin film capacitor according to claim 1, wherein a glass coating layer is provided on a surface of the substrate other than both ends.