JPS5842219A - 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 is a composite material in which a sintered body obtained by incorporating a trace amount of aluminum oxide into strontium titanate-based semiconducting porcelain has voltage nonlinearity and has an extremely large dielectric constant. It relates to functional elements.

Conventionally, 8i was used as a ceramic with voltage non-linear resistance.
There are C varistors and varistors whose main ingredient is zinc oxide.

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

The 8iC varistor utilizes a contact barrier between SiC particles, and α is about 2 to 7. Zinc oxide varistors are made of zinc oxide (ZnO) and Bi2O.

This is an element obtained by adding a small amount of Coo, MnO2, 8b203, etc. and firing it, and its voltage nonlinearity index α is as high as 50. 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 -δ of 5 to 10 inches, so
It can only be used for barista purposes.

On the other hand, conventional grain boundary layer type semiconductor ceramic capacitor elements with a large dielectric constant (more precisely, apparent dielectric constant) have been developed by reoxidizing or valence-compensating the grain boundaries of O semiconductor ceramics such as barium titanate and strontium titanate. This is an element obtained by insulation.

The apparent dielectric constant of this element reaches 50,000 to 60,000. In addition, if the composition and conditions are appropriately selected, a capacitor of 1 δ can be used as a small capacitor with a large capacity. However, when a current of 11xlm 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 having 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 with the application of microcomputers, not only industrial equipment but also consumer porcelain has come to require extremely high precision. 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, the fundamental frequency of artificially generated noise, especially that caused by circuit breakers on power transmission lines, and noise caused by natural phenomena, especially those caused by lightning surges, is low, around 6 to 20 KHz, and conventional coils and capacitors cannot be used. These noises could not be removed by the combination alone. In view of these problems, noise filters that use a voltage nonlinear resistor (varistor) between lines or thin ground have recently been frequently used. Since such a noise filter can remove a very wide range of noise, 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 element of the present invention can solve these problems. It became so. That is, since the element of the present invention is equipped with a composite circuit of a varistor and a capacitor, it is possible to perform the function with a single element in a circuit that connects a varistor and a capacitor in parallel. The device is obtained by incorporating a very small amount of aluminum oxide into a strontium titanate-based semiconductor ceramic.The contents of the present invention will be explained in detail below with reference to the accompanying drawings, which are examples.

FIG. 1 shows a cross-sectional view of the multifunctional device of the present invention, in which 1 is a sintered body of strotium titanate-based semiconducting porcelain.

2 and 3 are electrodes.

<Example> 50.22 to 47.95 moles of strontium carbonate,
49.7 to 48.71 mol of titanium oxide, 0.01 to 1.0 mol of aluminum oxide, and 0.06 to 0.6 mol of at least one of oxidized aluminum, tackle oxide, and neodymium oxide. After thoroughly mixing the composition containing the powder, it is calcined at a temperature of 110°C to 1260°C for 1 to 6 hours, pulverized, added with an organic (organic) (inder), and granulated.
Molded. This molded body was heated to 13oo~1 in a reducing atmosphere.
Baked in the range of 450'G for 1 to 5 hours to achieve a specific resistance of 0.2
A sintered body having an average particle size of 20 to 50 μm was prepared using ~o, s, and Dos.

The shape of this sintered body is 7.6φXO,7t (-).

Thereafter, heat treatment was performed in the air for 0.6 to 6 hours at a temperature of 1000 to 130°C to obtain the sintered body 1 shown in FIG.

Furthermore, electrodes 2 and 3 were formed on both surfaces of this sintered body 1. The electrode diameter was 5.0φ (all).The characteristics of the device thus obtained are shown in the table below. In the table below, IT'NSr is the composition amount of titanium acid and strontium carbonate converted into the atomic ratio of titanium/strontium. ε is the dielectric constant at 1 KHz, and -δ is the dielectric loss angle. α is 1 mm and 101
This is the voltage nonlinearity index calculated from the varistor voltage for 11 people. 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. In the test, the applied pulse was a current waveform of 8×20μ, and the current peak value at which the varistor voltage v11nA significantly deteriorated by θ10 with respect to the initial value was defined as the surge withstand capacity. The number of pulse applications is two.

(hereinafter referred to as a margin), but a range of 0.97 to 1,036 is particularly good. In addition, the amount of aluminum oxide added is 0.
．． Since the sintered body has polycrystalline grains with uniform grain growth in the range of 0.01 to 1.0 molar, the surge resistance is large. If the amount of aluminum oxide added is less than 0.01 molt, α is 3
The surge resistance was also 605 or less. still,
If the amount of aluminum oxide added exceeds 1.0 molty, the sintered body will have polycrystalline grains with non-uniform grain growth, and the sintered body will be prone to bending, resulting in large variations in properties and poor surge resistance. t) is small at 70A or less.

Niobium oxide, tantalum oxide, and neodymium oxide are compatible with each other, and are dissolved in the lattice of microcrystals mainly composed of strontium titanate during firing in the range of p, o, ots to 0.6 molti, and the valence can be controlled. However, the resistance of the sintered body was able to be in the range of 0.2-0.5 Ω. If the amount is greater or less than this range, the specific resistance will increase, making it impossible to increase the surge resistance. Samples A3°T~10.13~15 in the above table fall within the scope of the present invention, and the others are comparative examples.

Next, use these elements to create a circuit as shown in Figure 29.
As a result of examining the output situation for noise input 1 as shown in FIG. 16, it was possible to suppress the noise as shown in the output situation curve of FIG. 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. Furthermore, although the conventional filter circuit including the varistor shown in FIG. 4 can achieve the same effect as the circuit shown in FIG. 2 using the element of the present invention, the number of components is large due to the varistor. Figures 2 to 4
In the figure, 4 is the element of the present invention, 5 is a coil, 6 is a capacitor,
7 is a barista.

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

[Brief explanation of the drawing]

FIG. 1 is a cross-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, and FIG.
4 and 4 are circuit diagrams of conventional noise filter circuits, and FIG. 5 is a diagram showing the states of input noise and output noise corresponding to the circuits shown in FIGS. 2 to 4, respectively. 1... Sintered body of strontium titanate semiconducting porcelain, 2, 3... Electrode. Name of agent: Patent attorney Toshio Nakao and 1 other person
lUA Figure 2 Figure 3/ Figure 4/ Figure 5 - Lateral method! LCMlh)

Claims (1)

[Claims] The ratio of the number of atoms of titanium and strontium is 097 to 1.0
36, and aluminum oxide in the range of 0.01 to 1.
It contains at least one element among niobium, tartan, and neodymium as a valence control element, and the content is in the range of 0.06 to 0.0 molar as an oxide.
A multifunctional device 0 formed by forming one or more pairs of electrodes on the surface of a sintered body of strontium titanate-based semiconductor ceramic having a concentration of 55 mol-〇