JPS5850723A - Composite function element - 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 The present invention provides a sintered body obtained by incorporating a small amount of silver oxide (Aq20) into strontium titanate-based semiconducting porcelain, which itself has voltage nonlinearity and has an extremely large dielectric constant. The present invention relates to a multi-functional device having the following functions.

Conventionally, Si has been used as a ceramic material with voltage nonlinear resistance.
There are C varistors and varistors whose main ingredient is zinc oxide.

Such a varistor has a current (Il-voltage characteristic approximately expressed by I-(v/c)''. Here, C is a constant specific to the varistor, and α is a voltage nonlinear index.

The SiC varistor utilizes a contact barrier between SiC particles, and α is about 2 to 7. In addition, zinc oxide varistors are made of zinc oxide (ZnO) with B12o3°Coo, M
It is an element obtained by adding a small amount of nO2, 5b203, etc. and firing it, and the voltage nonlinearity index α is as high as 60. Since such elements have excellent performance in absorbing high voltages, they are used for voltage stabilization of electronic devices and protection from abnormal high voltages (surges).

However, such conventional varistors have a small dielectric constant and a large dielectric loss angle (tan δ) of 6 to 10 inches, so they can only be used for varistor applications.

On the other hand, conventional grain boundary layer type semiconductor porcelain capacitor elements with large dielectric constants (to be more precise, apparent dielectric constants) have been developed by reoxidizing the grain boundaries of semiconductor ceramics such as barium titanate, strontium titanate, etc. This is an element obtained by insulating through compensation.

The apparent dielectric constant of this element reaches 60,000 to 60,000. In addition, if the composition and conditions are selected appropriately, tan δ can be reduced to 1%.
However, when a current of 1 mA or more passes through the element, it is destroyed and loses its function as a capacitor.
``The device of the present invention is an epoch-making multifunctional device that simultaneously has the functions of the two devices described above. That is, it is an element that has a complex function of passing high voltage current as a varistor at high voltage, and passing abnormal frequency band current as a capacitor at low voltage.

Nowadays, electrical and electronic equipment has come to require extremely sophisticated control, and not only for birth control, but also for consumer equipment due to the application of microcomputers, extremely high precision has come to be required. 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 damaged 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. and,
Such noise was removed using a circuit that combined a coil and a capacitor. However, artificially generated noise, especially from circuit breakers on power transmission lines, and noise caused by natural phenomena, especially from lightning surges, have a low fundamental frequency of about 6 to 20 KHz, and conventional coils and capacitors cannot be used. It was not possible to remove these noises by using only a combination of the following. 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. Since such a noise filter can remove noise over a very wide range, it is effective in preventing malfunctions of microcomputer-controlled equipment. However, such a noise filter has disadvantages in that the number of parts in the set increases, the cost is high, and it goes against the trend of miniaturization.

The device of the present invention has made it possible to solve these problems. That is, since the element of the present invention has a combined function of a varistor and a capacitor, a single element can serve the purpose in a conventional circuit in which a varistor and a capacitor are connected in parallel.

The device of the present invention is obtained by incorporating a very small amount of silver oxide (A(120)) into strontium titanate-based semiconductor porcelain. do.

FIG. 1 shows a cross-sectional view of the multifunctional device of the present invention, in which 1 is a sintered body of strontium titanate-based semiconducting porcelain, 2 and 3
is an electrode.

<Example> Strontium carbonate at 50.22 to 47.95 mol.

Titanium oxide: 49.7 to 48.71 moles, silver oxide: 0
．． 01 to 1.0 mole, and at least one of niobium oxide, tantalum oxide, and neodymium oxide to 0.05 to 0
．． After thoroughly mixing the composition containing 5 molt.
The mixture was calcined at a temperature of 1100 to 1260°C for 1 to 6 hours, pulverized, added with an organic binder, granulated, and molded. This molded body was fired in a reducing atmosphere at a temperature of 13oO to 1460°C for 1 to 6 hours to give a resistivity of 0.2 to 0.50 and no rust.
A sintered body having an average particle size of 20 to 60 μm was produced. The shape of this sintered body is 7.6φ×0.7t (mm). Thereafter, heat treatment was carried out in air for 0.6 to 6 hours at a temperature of 1000° C. to 1300° C. to obtain the sintered body 1 shown in FIG. Further, electrodes 2.3 were formed on both surfaces of this sintered body 1.

The electrode diameter was 6.0φ (Wrrn).

The characteristics of the device thus obtained are shown in the table below.

In the table below, NTi/NSr is the composition amount of titanium oxide and strontium carbonate converted into the atomic ratio of titanium and strontium. ε is 1KHz
tan δ is the dielectric loss angle. α is a voltage nonlinear index calculated from the varistor voltage at 1 mA and 10 mA. Surge withstand capacity is a value that indicates how much large current such as lightning surge can be absorbed by the element, and the greater the surge withstand capacity, the better the varistor is.

The test applied a pulse with a current waveform of 8 x 20 μsec.
Then, the varistor voltage v1mA is (E)1 with respect to the initial value.
The current peak value at which the current deteriorates by 0% was defined as the surge withstand capacity. The number of pulse applications is two.

(Left below) As is clear from the table above, the NTi/Nsr ratio is 0.9.
It has the function of a varistor and a capacitor in the range of 0 to 1.26, but the range of 0.97 to 1.036 is particularly good. Further, the amount of silver oxide added is 0.01 to 1.
Since the sintered body has polycrystalline grains with uniform grain growth in the 0 molar range, the surge resistance is large. When the amount of silver oxide added was less than 0.01 mole, α was 6 or less, and the surge resistance was also about tsoA. If the amount of silver oxide added exceeds 1.0 molar ratio, the sintered body will have polycrystalline grains with non-uniform grain growth, and the sintered body will tend to bend.
In addition to the large variation in characteristics, the surge withstand capacity is still 10OA.
Small as below.

Niobium oxide, tantalum oxide, and neodymium oxide are compatible with each other, and during firing, they form a solid solution in the lattice of microcrystals mainly composed of strontium titanate in the range of O,OS ~ 0.6 molar ratio, and control the valence. and the resistance of the sintered body is 0.
．． It was possible to set it in the range of 2 to 0.60. If the amount is greater or less than this range, the resistivity will increase,
It was not possible to increase surge resistance. Samples with diameters of 3°7 to 10.13 to 15 in the table above fit into the cylinder of the present invention, and the others are comparative examples.

Next, we made a circuit as shown in Fig. 2 using such an element, and investigated the output situation with respect to the noise human power a shown in Fig. 6. As a result, the output situation curve in Fig. 6 shows the noise I was able to hold it down. Incidentally, the output condition of the conventional filter circuit shown in FIG. 3 is like the output condition curve C in FIG. 6, and noise is not sufficiently removed. Further, although the conventional filter circuit including the varistor shown in FIG. 4 can obtain the same effect as the circuit shown in FIG. 2 using the element of the present invention,
There are many parts including the varistor. In FIGS. 2 to 4, 4 is an element of the present invention, 6 is a coil, 6 is a capacitor, and 7 is a varistor.

As described above, the device of the present invention has an unprecedented complex function and can play the two roles of a converter and a capacitor at the same time. It contributes to high performance and low cost, and has great utility as it can be applied to prevent malfunction and destruction of microcomputer-controlled equipment in the future, and its industrial value is enormous. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a multifunctional device of the present invention, FIG. 2 is a circuit diagram of a noise filter circuit using the device of the present invention, FIGS. 3 and 4 are circuit diagrams of a conventional noise filter circuit, and FIG. 6
The figure is a diagram showing the situations of input noise and output noise corresponding to the circuits shown in FIGS. 2 to 4. 1... Sintered body of strontium titanate semiconducting porcelain, 2, 3... Electrode. Name of agent: Patent attorney Toshio Nakao 1 person @I
Ba @2 Figure 581 →Use 1 (separate 2)

Claims (1)

[Claims] The ratio of the number of atoms of titanium and strontium is 0.97 to 1.
036, contains silver oxide in the range of 0.01 to 1.0 mole, and contains at least one element among niobium, tantalum, and neodymium as a valence control element, and the content is in the range of oxide. A multi-functional device comprising one or more pairs of electrodes formed on the surface of a sintered body of strontium titanate-based semiconductor porcelain having a strontium titanate-based semiconductor porcelain having a molecular weight ranging from O,OS to 0.5 mol.