JPS589563B2 - Manufacturing method of voltage nonlinear resistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses at least N i O and Y2 as impurities.
The present invention relates to a method of manufacturing a resistor that contains O3 and whose sintered body itself has voltage nonlinear characteristics.

Voltage nonlinear resistors are one of the circuit elements that apply semiconductors, and representative examples include SiC varistors and Si
Varistors using sintered bodies of varistorium, selenium, cuprous oxide, or ZnO are known.

This type of element has non-linear voltage and current characteristics, and as the voltage increases, the resistance rapidly decreases and the current increases significantly, so it is widely used for absorbing abnormally high voltages and stabilizing voltage. .

However, SiC varistors are made by baking approximately 100 μm of SiC with a magnetic binder, and while they have the advantage of being able to withstand relatively high voltages, there is a limit to how thin the elements can be, making them unsuitable for low voltage applications. There is.

Further, Si varistors utilize a P-n junction of Si, and are of a so-called low voltage type, and their voltage-current characteristics cannot be changed arbitrarily, so their uses are limited.

Furthermore, varitas made of selenium, cuprous oxide, etc. utilize the voltage non-linear characteristics of the metal-semiconductor contact area on the element surface, and have the disadvantage that, like Si varistors, the voltage-current characteristics cannot be controlled arbitrarily. .

゛On the other hand, B I 2 03 , CoO and Sb20 as impurities
ZnO-based sintered varistors containing 3 and the like within 10 mol% each have features such as good voltage-current characteristics and scales that allow the voltage-current characteristics to be adjusted arbitrarily by controlling the thickness of the element. There is a lot of interest.

However, when looking at the symmetrical voltage-current characteristics, which is one of the features of this type of ZnO-based varistor, the rate of change in the negative direction is large when subjected to shock current, DC load, temperature/humidity cycles, etc., and the reliability is sufficiently satisfied. It is hard to say that it is possible.

In view of the above points, the present inventors conducted studies and found that a sintered zinc oxide (ZnO)-based voltage nonlinear product containing 0.01 to 10 mol% of nickel and yttrium as impurities in the form of NiOY203 was developed. In the 5 manufacturing methods for resistors, replacing a part of the raw material zinc oxide (ZnO) with metallic zinc (Zn) can significantly reduce the rate of change in the negative direction with respect to shock current, etc. It has been found that a high voltage nonlinear resistor can be obtained.

Therefore, the present invention seeks to provide a method for easily manufacturing a symmetrical voltage nonlinear resistor with good stability and high reliability.

To explain the present invention in detail below, the present invention uses at least nickel and yttrium as impurities such as NiO, Y2
In the method for producing a sintered zinc oxide-based voltage nonlinear resistor containing 0.01 to 10 mol% of the zinc oxide component as a starting material, the zinc oxide component as a starting material is limited to 0.01 to 10 mol% of the zinc oxide component as a starting material. A method of manufacturing a voltage nonlinear resistor characterized by substituting zinc with metal is carried out, for example, as follows.

That is, first, a zinc oxide (ZnO)-based mixed powder is prepared by adding and blending nickel oxide (N i O ) powder, yttrium oxide (Y203) powder, and metallic zinc (Zn) powder in an amount of 0.01 to 10 mol%, respectively. A desired molded article is obtained by using as a starting material a well-mixed mixture of this mixed powder, and if necessary, a binder such as polyvinyl alcohol.

Next, this molded body is fired in air at a high temperature, for example, about 1100°C or higher, and then silver paste is coated and baked on both main surfaces of the obtained sintered body, and electrodes are provided by baking to create a highly reliable voltage. A non-linear resistor element is obtained.

The nickel and yttrium added as impurities in the present invention are not limited to the above-mentioned oxides, but compounds that can become oxides during the heating and calcination process, such as carbonates and oxalates, may be used as starting materials.

However, the essential impurity component ratio of the lever is NiO and ¥20
It is always selected within the range of 0.01 to 10 mol.

The reason is that a voltage nonlinear resistor with the required high reliability cannot be obtained outside the above range.

In addition to the above-mentioned essential components as impurity components, for example, Ce, Pr
The nonlinearity may be improved and the resistance value may be controlled by further adding and blending rare earth elements such as.

The present invention is characterized by using metallic zinc (Zn) as a starting material with a composition ratio of 0.01 to 10 mol % as a limit.

In other words, a part of the zinc oxide component, which is the main component of the voltage nonlinear resistor, is replaced with metallic zinc (Zn) at the stage of the starting material. The reason why the amount is selected to be 0.01 to 10 mol % in this step is that it is difficult to manufacture a highly reliable sintered voltage nonlinear resistor outside this range.

Next, examples of the present invention will be described.

Nickel oxide (NiO) is added to zinc oxide (ZnO) powder.
) powder, yttrium oxide (Y2 03 ) powder, and metal zinc (Zn) powder in an amount of 0.01 to 10 mol% each, and after thorough mixing, a diameter of 207ItTI was added.
L, molded into a disk with a thickness of 1 mm.

The molded bodies thus obtained were fired in air at a high temperature of 1100° C. or higher, and silver paste was coated on both sides of the resulting sintered bodies (discs) and baked to produce voltage nonlinear resistance elements.

The voltage-current characteristics of the resistance element produced above were measured using the following equation.

(In the formula, C and α are constants. In particular, α is an index indicating voltage nonlinear characteristics, and the larger the α value, the better the nonlinearity.

) By the way, the characteristics of this type of voltage non-linear resistor, ie, a varistor, are expressed by the voltage 1 at 1 mA instead of α and C.

For the resistor elements obtained as described above, the larger α was plotted for each 1, as shown in FIG.

In Fig. 1, curve A is based on metallic zinc (Z
Curves B, C, and D are comparative examples in which metal zinc (Zn) was not used as a starting material, and curve B is a case in which NiO and Y203 were used. Curve C shows the case where only N i O is included, and curve D shows the case where only Y203 is included.

As is clear from FIG. 1, the voltage nonlinear resistor manufactured by the method of the present invention always has a substantially constant nonlinearity α regardless of V1.

This is a big difference from the normal tendency that as the firing temperature increases, V1 decreases while α value also decreases.

Further, in the voltage nonlinear resistor according to the present invention, the sintered body itself has voltage nonlinearity.

For example, when various thicknesses of the resistor were selected and the characteristics of the electrodes were changed, the results were as shown in Table 1.

Furthermore, the suitability, that is, shock large current characteristics, DC load characteristics, and temperature/humidity cycle characteristics of the voltage nonlinear resistor element with V1 = 200V according to the present invention were determined, respectively, and the rate of change in the positive direction and the rate of change in the negative direction of (1) are expressed. -2.

Table 2 also shows cases of conventionally known ZnO-based voltage nonlinear resistor elements.

Incidentally, in the above measurement, the impact current characteristic is the rate of change in the positive and negative directions of the (1) value when a surge current of 500 A is applied 10,000 times, and it has excellent stability as a surge absorbing element.

In addition, the DC load characteristics are 85℃F, 2W load for 500 times continuously.
The rate of change in v1 after time application was investigated in relation to polarity, and in the case of this example, high temperature deterioration was also significantly suppressed.

Furthermore, the temperature/humidity cycle characteristics were determined by examining the rate of change for both polarities after 100 cycles of a 2W load in an atmosphere from -40°C to 85°C and a relative humidity of 95%.

As is clear from Table 2 above, the sintered ZnO-based varistor manufactured by the method of the present invention is characterized by its small polarity.

However, the small polarity characteristics of the lever are very important for maintaining and exhibiting symmetrical voltage-current characteristics, and these life characteristics and stability are important in practical terms from the standpoint of reliability and security as a varistor element. That's true.

[Brief explanation of drawings]

Figure 1 shows the rising voltage at 1 mA of a sintered zinc oxide voltage nonlinear resistor manufactured by the method of the present invention and a sintered zinc oxide voltage nonlinear resistor manufactured by a method other than the present invention. FIG. 3 is a curve diagram comparing and showing the relationship between and nonlinearity α.

Claims (1)

[Claims] 1 As impurities, at least nickel and yttrium are converted into NiO and Y2O3, respectively, from 0.01 to 1
In the method for manufacturing a sintered zinc oxide-based voltage nonlinear resistor containing 0.0 mol% of the zinc oxide component as a starting material,
A method for producing a voltage nonlinear resistor, characterized in that 1 to 10 mol% of zinc is substituted with metal zinc.