JPH04370B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a multi-functional element having both a varistor function and a capacitor function.

Conventional configurations and their problems Conventionally, there are SiC varistors and varistors whose main component is zinc oxide as ceramics with voltage non-linear resistance characteristics. Such a varistor has a current (I)-voltage (V) characteristic approximately expressed as I=(V/C). Here, C is a constant specific to the varistor, and α is a voltage nonlinear index.
The SiC varistor uses a contact barrier between SiC particles, and the voltage nonlinearity index α is 2 to 2.
It is about 7. Furthermore, a zinc oxide varistor is an element obtained by adding a small amount of metal oxide such as Bi ₂ O ₃ , CoO, MnO ₂ , Sb ₂ O ₃ to zinc oxide (ZnO) and firing it. This is an element with an index α as high as 50. Since such elements have excellent performance in absorbing high voltages, they are used for the purpose of stabilizing electronic equipment and protecting against abnormal high voltages (surges). However, such conventional varistors have a small dielectric constant and a large dielectric loss angle (tan δ) of 5 to 10%, so they can only be used for varistor applications.

On the other hand, as capacitors, dielectric ceramics whose main components are barium titanate (BaTiO ₃ ) and strontium titanate (SrTiO ₃ ), which have large dielectric constants, are widely used as small, large-capacity capacitors in electronic circuits. However, the element has 1mA
If more current flows through the capacitor, it will be destroyed and lose its function as a capacitor.

BACKGROUND ART Recently, electronic equipment has come to require extremely sophisticated control, and not only industrial equipment but also consumer equipment has come to require extremely high precision due to the application of microcomputers. Furthermore, since logic circuits constituting microcomputers and the like operate using pulse signals, they inevitably have the disadvantage of being susceptible to noise. Therefore, once electronic computers, banking machines, traffic control equipment, etc. malfunction or are destroyed due to noise or surges, it becomes a social problem. Noise filters have conventionally been used as a measure against such problems. Noise is an interfering voltage other than the intended signal voltage when operating electronic equipment, and can be divided into those generated artificially and those generated by natural phenomena. Such noise was removed using a circuit that combined a coil and a capacitor.
However, artificially generated noise, especially those caused by the opening and closing of circuit breakers on power transmission lines, and noise caused by natural phenomena, especially those caused by lightning surges, have a low fundamental frequency of about 5 to 20 KHz.
Conventional combinations of coils and capacitors alone have not been able to eliminate these noises.
In view of these problems, noise filters that use a voltage nonlinear resistor (varistor) between lines or between lines and ground have recently been frequently used. Such a noise filter can remove noise over an extremely wide range, and is therefore effective in preventing malfunctions of microcomputer-controlled equipment. However, such noise filters have disadvantages in that the number of parts within the set increases, which increases costs and goes against the technological trend of miniaturization.

OBJECTS OF THE INVENTION In view of the above-mentioned drawbacks, an object of the present invention is to provide a method for manufacturing a multi-functional element that can inexpensively produce a multi-functional element having both a varistor function and a capacitor function.

Composition of the Invention In order to achieve this object, the method for manufacturing a multifunctional device according to the present invention uses powder obtained by finely pulverizing a dielectric ceramic sintered body that can be used as a ceramic capacitor, and zinc oxide as the main components. It is characterized by spraying powder containing several types of metal oxides onto opposing surfaces of a flat metal plate using a plasma spraying method to form a dielectric and a voltage nonlinear resistor. Since the device obtained by this method has the combined functions of a varistor and a capacitor,
A single element can serve the purpose of a conventional circuit in which a varistor and a capacitor are connected in parallel.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a multifunctional device of the present invention, and FIG. 2 is an equivalent circuit thereof. In the figure,
1 is a flat metal plate, 2 is a dielectric, 3 is a voltage nonlinear resistor, 4 is an insulator, and 5 is an electrode. Further, 6 is a varistor, and 7 is a capacitor.

First, 0.01 to 1.0 mol % of SrO, SnO ₂ and ZrO ₂ were added to BaTiO ₃ powder and thoroughly mixed.
This is molded to a diameter of 25 mm and a thickness of 5 mm, and
It was baked at a temperature of 1 to 3 hours. Next, the sintered body was pulverized to produce a fine dielectric powder. The average powder diameter is approximately 20 μm. Next, to the ZnO powder, 0.5 mol% of Bi ₂ O ₃ , 0.5 mol% of Co ₂ O ₃ , 0.5 mol% of MnO ₂ , 1.0 mol% of Sb ₂ O ₃ ,
Cr ₂ O ₃ was added at a ratio of 0.5 mol % and mixed thoroughly. This was molded to a diameter of 25 mm and a thickness of 5 mm, and heated to 1250℃.
It was baked for 2 hours. Next, the sintered body was pulverized to produce a fine powder of a voltage nonlinear resistor. The average particle size is approximately 20 μm. Next, a flat aluminum metal plate 1 was prepared, and dielectric fine powder was sprayed onto one side of the plate by plasma spraying to form a dielectric 2. Next, fine powder of a voltage nonlinear resistor was sprayed onto the other surface of the metal plate 1 by plasma spraying to form a voltage nonlinear resistor 3. Next, an insulator 4 made of resin or glass was formed on the upper end of the metal plate 1, and then an electrode 5 was formed on the surfaces of the dielectric 2 and the voltage nonlinear resistor 3. This electrode 5 is formed across both surfaces of the dielectric 2 and the voltage nonlinear resistor 3. In this way, a multifunctional device was obtained. Note that the plasma spraying method is a method in which an oxide is melted at a high temperature by an electric arc, and at the same time is blown away by a high-pressure inert gas, and the oxide is adhered to an object to form a film. The thermal spraying conditions in this example were to melt the powder with an electric arc of 60 to 80 KW, the spraying distance was 10 cm, and Ar was used as the inert gas.

The shape of the multifunctional device obtained in this way is 10 mm.
×10mm, and the thickness of aluminum metal plate 1 is 1mm
So, the thickness of dielectric 2 and voltage nonlinear resistor 3 is
It was 100 μm to 1 mm. In addition, the performance is capacitance 3
~10nF, tanδ1.5~2%, varistor voltage 40~
It was 200V, α was 20-40, and surge resistance was 500-1000A. These properties can be varied by varying the plasma spray time. Further, the thermal spraying time in the example is 30 seconds to 2 minutes.

Although BaTiO ₃ ceramic was used as the dielectric material,
Considering the effects of the present invention, with magnetic capacitor materials,
Any material whose dielectric material can be formed by plasma spraying is effective.

Further, although an aluminum plate was used as the metal plate, any metal plate to which a sprayed material can be attached by plasma spraying and which functions as an electrode is also effective.

Effects of the Invention As described above in detail, the method for manufacturing a multi-functional device according to the present invention can be easily achieved by forming a dielectric material and a voltage nonlinear resistor on opposing surfaces of a metal plate by plasma spraying. It is possible to provide an element that has both the functions of a capacitor and a varistor, and it has great practical value as a noise countermeasure component for electronic equipment.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a multifunctional device obtained by the method of the present invention, and FIG. 2 is a diagram showing its equivalent circuit. DESCRIPTION OF SYMBOLS 1... Metal plate, 2... Dielectric material, 3... Voltage nonlinear resistor, 5... Electrode.

Claims (1)

[Claims] 1 Powder obtained by finely pulverizing a sintered body of dielectric porcelain and powder containing zinc oxide as a main component and several kinds of metal oxides are applied to opposing surfaces of a flat metal plate using a plasma spraying method. 1. A method for manufacturing a multi-functional element, which comprises thermally spraying each to form a dielectric material and a voltage nonlinear resistor, and then forming an electrode across both surfaces thereof.