JPS6218004A - Voltage depending non-linear resistance body - 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 Field of Industrial Application The present invention protects semiconductors and circuits from abnormal high voltages, noise, and static electricity generated in electrical and electronic equipment.c7
) SrT 105 , CaxSr j−x TiO
5 (0.001≦x≦O-4), B2LySr1
The present invention relates to the magnetization of a voltage-dependent nonlinear resistor whose main component is one or more of -y TiO3 (0.001≦y≦0.4).

Conventional technology Traditionally, SiC varistors and Zn, which have voltage-dependent nonlinear resistance characteristics, have been used to absorb abnormally high voltages, remove noise, extinguish sparks, and take measures against static electricity in various electrical and electronic devices.
O-type varistors were used. The voltage-current characteristics of such a varistor can be approximately expressed as follows.

I=('l//C)α Here, Δ is the current, V is the voltage, C is a constant specific to the varistor, and α is the voltage nonlinear index.

The α of SiC varistors is about 2 to 7, and the α of some Zno varistors is as high as 50. Although such varistors have excellent performance in absorbing relatively high voltages,
Because the permittivity is low and the specific capacitance is small, it has little effect on absorbing low voltages below the varistor voltage (e.g. noise), and the galvanic loss (-δ) is still 6 to 1.
It is large at 0%.

On the other hand, semiconductor capacitors with an apparent dielectric constant of about 5×10′ and −δ of about 1% are used to remove these low voltage noises. However, if a current exceeding a certain limit is applied to such a semiconductor capacitor due to a surge or the like, it will be destroyed or will no longer function as a capacitor. Therefore, in recent years, a material containing 5rTi05 as a main component and having both the function of a crystal resistor and a capacitor has been developed. As shown in Japanese Patent Laid-Open No. 169316/1984, there are various manufacturing methods for this, including a method of diffusing a substance that increases the resistance of grain boundaries, and the mainstream is to use a substance that allows ohmic connection as the electrode. There is.

Problems to be Solved by the Invention When a substance capable of ohmic connection is used as the electrode material as described above, no barrier is created at the interface between the element and the electrode.
It does not increase the varistor voltage and is considered effective for devices with low varistor voltage.

However, since elements with low varistor voltage generally have large particle diameters and large variations, there is a problem that characteristics affected by the uniformity of particle diameters, such as surge resistance, vary widely.

The present invention solves these problems by absorbing variations in characteristics caused by the microstructure of the device using electrodes,
This reduces variations in characteristics.

Means for Solving the Problems In order to solve the above problems, the present invention uses 5rTiO
5, Cax5r1-xTiO2 (0.OO1≦x≦0.
4).

BaySr,, Tie, (0.oo1≦y≦0.4
), and non-ohmic electrodes are formed on an element having a composition having the functions of both a varistor and a capacitor.

By performing this operation, we can prevent variations in characteristics due to the microstructure of the element body from directly affecting the characteristics of the element, by using a non-ohmic material as the electrode and By forming a small barrier at the interface, it is possible to prevent the applied current from concentrating on large particles with low resistivity, and by allowing the current to flow relatively uniformly, it is possible to reduce variations in characteristics. can.

Example The present invention will be specifically described below with reference to Examples.

<Example 1> 5rTiO99,395no/% and Y2O5 at 0.10
0mo1%, CuO 0.300mod%, MnO□ 0.100mo1 (X and ZrO□ 0.005mo1%
After mixing in a ball mill for 30 hours, drying, Swt% polyvinyl alcohol
After adding 0 wt% and granulating, it is molded into a size of 10φlItM×1 with a press pressure of 1t/-.

After firing the above molded body in air at 1000°C for 1 hour, 1e
Soo'C - Bake for 2 hours. Then 110 in the air
Bake at 0°C for 6 hours. Figures 1 and 2 obtained in this way
The sintered body 10 shown in the figure has a C
U paste is printed and baked at 600° C. for 10 minutes in a non-oxidizing atmosphere to form electrodes 2 and 3.

Thereafter, the lead wires are joined with solder, and then an epoxy resin is applied and cured and dried.

The characteristics of the device thus obtained are shown in Table 1 below.

Table 1> However, the varistor voltage is the voltage when a current of 1 mA flows, +OmAα+mA, calculated per 1tg of element thickness.
indicates the maximum applied current value at which the change in varistor voltage after applying a pulse of 20 μsec is within ±10%.

<Example 2> An element body was prepared in the same manner as in Example 1, and λg-Cu alloy paste was applied to the side plane of the sintered body 1 only in a portion smaller than the plane, and heated at 650°C at 916°C in a non-oxidizing atmosphere. Baking for minutes, attaching leads, and applying resin coating.

The characteristics of the device thus obtained are shown in Table 2 below.

Table 2〉 Note that the SrTiO3 shown in Examples 1 and 2 above was used before Sr;
Although the ratio is 1.0, the Sr/Ti ratio may be lower than that.

<Example 3> 5rCO,, CaCO3, BaC0. , TiO2 were weighed and mixed according to the composition ratio shown in Table 3 below, and 10o
.

Calcinate at °C for 6 hours. Using the powder thus obtained as the main raw material, 0.100mo 1% of L2L2o3, 5i
n2 0, 300 mo#%, MnO2 0.1oo
After weighing and blending mo1%, mixing with a ball mill etc. for 30 hours and drying, add 5Wt'X polyvinyl alcohol to 1%.
After adding 0 wt% and granulating, 1. It is molded into a size of 10φ111MX1tyttytt with a press pressure of O/cm2. Then, the molded body is fired in air at 1000°C for 1 hour, and then fired at 1500°C for 2 hours in an atmospheric gas mixture of N2:H2=9:1. Thereafter, the sintered body 1 was fired at 1100'C for 6 hours in the air, and an Ag-Cu alloy paste was applied on the side plane of the sintered body 1 obtained in this way, leaving edges, and after drying, N2:H2=20=1 Heating is carried out in a gas atmosphere at a temperature increase rate of 630 to 800'C/hr, and when the temperature reaches 630'C, the atmosphere is changed to atmospheric air. Then, after holding at 630'C for 10 minutes, it was heated again in N2 for 80 minutes.
Cool at a rate of 00 °C/hr. After forming the electrodes 2 and 3 in this manner, the lead wires are joined by soldering and resin coating is applied. The characteristics of the device thus obtained are also shown in Table 3 below.

(Left below) However, the varistor voltage is calculated based on an element thickness of 1 mm.
The voltage when a human current flows, Tom□α1o□, is 8×2
Varistor voltage (V,
,, /7ffff ) indicates the maximum applied current value within a range of ±10%.

Still, Cax Sr 1- x TiO5, B 1L
The reason for specifying the values of X and y of yS r + -y T io 5 is that if it is less than 0.001, the effect of substitution with Ca and Ba will not be seen, and if it exceeds 0.4, the particle size will be too small. Therefore, both the varistor characteristics and the capacitor characteristics deteriorate, which is undesirable.

As shown above, even when non-ohmic electrodes are used, 85% of the variation in varistor voltage is within ±5%, and there is no problem in practical use.

Effects of the Invention As described above, according to the present invention, by using a non-ohmic electrode, it is possible to improve the microstructure of the element body.
l- no Ii ζノ) entering φgu Furudate tobenko Otsu no l i-gi/]sa1
Although a barrier is formed at the electrode interface because f-rays are less likely to be reflected, variations can be reduced and surge resistance can be considerably improved. Furthermore, since materials that could not be used in the past can be used as electrodes, it is possible to select electrode materials that suit the purpose of use, and there is considerable flexibility in manufacturing.

[Brief explanation of the drawing]

FIG. 1 is a top view showing an element according to the present invention, and FIG. 2 is a sectional view thereof. 1... Sintered body, 2.3... Electrode. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure f-2/3-rfl Figure 2

Claims (1)

[Claims] SrTiO_3, Ca_xSr_1_-_xTiO_
3) (0.001≦x≦0.4), Ba_5_r_-_
1TiO_3 (0.001≦y≦0.4) as a main component and has a composition that functions as both a varistor and a capacitor, and a non-ohmic electrode is formed on the element. Linear resistor.