JP2962056B2 - Voltage non-linear resistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage non-linear resistor which is used for a surge absorbing element, a voltage stabilizing element, a lightning arrester and the like, and whose resistance changes according to an applied voltage.

[0002]

2. Description of the Related Art Voltage non-linear resistors (hereinafter, referred to as varistors) are widely used in surge absorbing elements, voltage stabilizing elements, lightning arresters and the like. Conventionally, these applications include SiC
Varistors and the like have been used. However, these varistors have disadvantages such as a small voltage nonlinear coefficient. As an improvement over these disadvantages, zinc oxide varistors containing zinc oxide (ZnO) as a main component have been developed. Zinc oxide varistors have a large voltage nonlinear coefficient α,
It has excellent surge resistance and is widely used (JP-B-55-46045, JP-B-55-48442). As the zinc oxide varistor, zinc oxide (Zn
O) as a main component, and bismuth oxide (Bi ₂
O ₃ ), cobalt oxide (CoO), manganese oxide (Mn)
O ₂ ), antimony oxide (Sb ₂ O ₃ ), etc.
Varistors fired at 000 ° C. to 1350 ° C. are examples.

[0003]

In a zinc oxide varistor, the voltage non-linear index (α) and the rise voltage (V _1mA ) are important factors for practical use in showing electrical characteristics. α indicates how the voltage of the electric circuit in which the varistor is inserted is controlled, and the larger the α, the better the rise. V _1mA is a value determined by a circuit voltage actually used, and is adjusted to a value specified in advance by a product. Also,
Not only α and V _{1 mA} but also the value of the leakage current (IR) are important factors. When a varistor is used for overvoltage protection, a smaller leakage current (IR) is desired.

By the way, in an electric circuit of a communication device,
The varistor is generally used under a constant voltage load, and is used as a so-called surge absorbing element that absorbs a large current pulse caused by opening and closing of a switch. However, the conventional varistor mainly composed of ZnO has a rising voltage (V) when a constant voltage load is applied for a long time.
_{1 mA} ) and the leakage current increases accordingly. Even when a large current pulse is applied, it has exactly the same disadvantage, and it is impossible to maintain excellent voltage non-linearity of a varistor containing ZnO as a main component.

In addition, in order to increase the voltage non-linear coefficient α in the ZnO varistor, it is essential to add bismuth oxide (Bi ₂ O ₃ ) as one of the subcomponents. Most of this varistor is made of bismuth oxide (Bi
_A structure in which the periphery of ZnO crystal grains made into a semiconductor is surrounded by countless vertical and horizontal lines by a high-resistance grain boundary layer mainly composed of ₂ O ₃ ). Certainly obtained by adding Bi ₂ O _3, large α good voltage nonlinearity, also rising voltage V _1mA was obtained as a practically appropriate value, Bi ₂ O
Compared to the case where ₃ is not added, it shows remarkably excellent characteristics and has a large practical value. However, this Bi ₂
O ₃ undergoes crystal transformation at a relatively low temperature, has a low melting point, and easily evaporates at a high temperature. Such instability of Bi ₂ O ₃ with respect to temperature is caused by deterioration of characteristics when a large current pulse is applied, that is, by applying a large surge current to V
One of the problems in improving the reliability of the varistor element is that _{1 mA} decreases and the leakage current (IR) increases.
Had one. Further, during sintering during the manufacturing process, Bi ₂ O ₃
It is easily affected by atmosphere such as evaporation of Bi ₂
It was extremely difficult to control the content of O ₃ constantly and uniformly. As a result, various characteristics of the varistor fluctuate,
This significantly impeded industrial productivity and was one of the difficulties in increasing the yield during mass production.

There is no other way to obtain a low V _{1 mA} except by increasing the sintering temperature or reducing the thickness of the element body. However, when the sintering temperature is increased, ZnO and additives evaporate, causing problems such as loss of varistor characteristics and fusion of elements during sintering.
There is a limit to the method of raising the sintering temperature at an upper limit of 0 ° C. On the other hand, in the method of reducing the thickness of the element, a thickness of 0.3 mm is a practical limit. Normally, a varistor is manufactured by pressing and sintering an element having a specified thickness. However, in order to make the rising voltage within ± 10% of the specified value, a thickness accuracy of at least 10% is required. It is very difficult to press-mold uniformly with a thickness of 0.3 mm or less and with an accuracy of within 10%, and the production yield is significantly reduced. When sintering a thin material of about 0.3 mm,
At a temperature of 00 ° C., evaporation of ZnO and additives from the element surface cannot be neglected, and satisfactory characteristics cannot be obtained. Further, if the thickness is less than 0.3 mm, the element is easily damaged at the time of manufacture or use, and the surface layer is deteriorated by the treatment at the time of applying a baked electrode, and the characteristics and stability are deteriorated. And making it too thin is not desirable. The same applies to a method of cutting after sintering and further polishing, and the leakage current (I) may be changed due to deterioration of the element surface layer or dropping of the element from the surface.
R) tends to increase and α decreases, and it is difficult to make the element thinner by cutting or polishing, and to lower the rising voltage (V _1mA ).

The present invention has been made to solve such a conventional problem, and has a large voltage non-linear coefficient α, a small leakage current, a voltage load and a large current pulse applied to a large current pulse. _An object of the present invention is to provide a voltage non-linear resistor having a small change of _{1 mA} and obtaining stable characteristics.

[0008]

A first aspect of the present invention is to use zinc oxide as a main component, cobalt, manganese, chromium and antimony as subcomponents, and oxides of these oxides, CoO, M
In terms of nO, Cr ₂ O _3, and Sb ₂ O ₃ , each was 0.
1 to 10.0 mol%, 0.05 to 10.0 mol%, 0.
05-6.0 mol% and 0.05-6.0 mol%,
Lead zinc borosilicate glass in a weight ratio of 0.50 to 20.0
% Of zirconium oxide (ZrO)
₂ ) A non-linear voltage resistor comprising a sintered body obtained by adding and mixing 0.05 to 5.0 mol% of ( ₂ ). In the second aspect of the present invention, zinc oxide is used as a main component, and cobalt, manganese, chromium, and antimony are used as accessory components.
These oxides, CoO, MnO, Cr ₂ O ₃ and Sb
0.1 to 10.0 mol% in terms of ₂ O ₃ , respectively.
A raw material in which 0.5 to 10.0 mol%, 0.05 to 6.0 mol%, and 0.05 to 6.0 mol%, and 0.50 to 20.0% by weight of zinc borosilicate glass are blended. Against
A voltage nonlinear resistor, characterized in that a sintered body obtained by the zirconium oxide (ZrO ₂₎ and 0.05 to 5.0 mol% added formulation. Further, according to the present invention, the internal electrode and the sintered body are alternately stacked, and the external electrode has a structure in which a portion to be taken out to the outside is alternately exposed on two opposite side surfaces of the stacked body. The described stacked voltage non-linear resistor is provided.

[0009]

According to the present invention, zinc oxide (ZnO) is a main component, and CoO, MnO, Cr ₂ O ₃ , Sb _{2 is} a sub component.
By using a sintered body to which a predetermined amount of zirconium oxide (ZrO ₂ ) has been added together with O ₃ and a component to be a high-resistance grain boundary layer component together with lead zinc borosilicate glass or zinc borosilicate glass, the voltage nonlinear coefficient α Is large,
A voltage non-linear resistor having a small leakage current, a small change in _V1mA with respect to a voltage load and application of a large current pulse, and very stable characteristics can be obtained.

Further, according to the present invention, a plurality of internal electrodes and a sintered body having the basic structure shown in FIG. There is provided a laminated voltage non-linear resistor having a structure alternately exposed on two opposite side surfaces. In FIG. 9, FIG.
9 (b) and FIG. 9 (c) are cross-sectional views of FIG. 9 (a) taken along cutting lines BB 'and CC', respectively, and viewed in the direction of the arrows. In the figure, 1 is a sintered body according to the present invention in which internal electrodes are sealed, 2 and 3 are internal electrodes, 4, 5
Is an external extraction electrode. Here, the sintered body has the above-described composition, and as a manufacturing method thereof, for example, a raw sheet is made by a doctor blade method using the raw material powder obtained by the above-described additive, and the raw sheet is formed on the raw sheet. After the internal electrodes are printed, a plurality of internal electrodes are laminated and integrated before sintering, and then cut to a predetermined size and sintered. This multilayer varistor has a thickness between electrodes of 0.
3 mm or less, for example, 10 μm to 20 μm, a varistor with a low rise voltage V _{1 mA} can be realized, the voltage nonlinear coefficient α is large, the leakage current is small, and the voltage load and the current pulse Very stable characteristics with small changes in _V1mA are obtained. Therefore,
As a ZnO varistor, the reliability is enhanced by voltage load and large current pulse, over voltage protection element, surge absorption element that absorbs large current pulse generated when switch is opened and closed, and low voltage surge absorption element such as IC and LSI, etc. It can be expected to be used in a wide range of applications such as communication equipment.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. Example 1 As a starting material, zinc oxide (Zn) having a purity of 99.9% or more was used.
O), cobalt oxide (CoO), manganese carbonate (MnC)
O ₃ ), chromium oxide (Cr ₂ O ₃ ), antimony oxide (S
b ₂ O ₃ ), zirconium oxide (ZrO ₂ ), and lead zinc borosilicate glass frit were used. A predetermined amount of these powders was weighed and mixed with pure water in a ball mill for 70 hours. Next, the mixed solution was filtered, and the mixed powder obtained by drying was pulverized with a raikai machine for 10 minutes, and heat-treated at a temperature of 600 ° C. for 2 hours. After the heat treatment, the mixture is pulverized by a ball mill, and a small amount of a binder (PVA2.
5% aqueous solution) and mixed with a raikai machine. Then, a sized powder was prepared using a sieve and had a diameter of 12 mm.
It was press-molded into a cylinder having a height of 15 mm. Firing is 1100
Performed for 1.5 hours at a temperature between 1C and 1300C.

The obtained sintered body was cut and polished to a thickness of 1 mm, and a silver electrode having a diameter of 8 mm was baked. Characteristics such as α, V _1mA , leakage current, etc. were calculated by measuring voltage-current characteristics with a DC power supply. The varistor voltage is 1 mA current applied,
The voltage was 1 mm in thickness. The value of the leakage current (IR) was evaluated as a value at a voltage of 80% of _V1mA .
The large current pulse characteristic is 3000A (current waveform 8 × 20μ)
V) was applied once, and V _{1 mA} was measured to calculate the rate of change, and the characteristics were evaluated. The constant voltage load characteristic is such that a varistor voltage of 80
% DC voltage was applied for 1000 hours, _V1mA was measured, and the rate of change was calculated. Table 1
Indicates the composition ratio of the lead zinc borosilicate glass used. Tables 2 to 9 show the powder compositions used and the results of evaluation of the characteristics of the obtained sintered bodies. In the table, those marked with * are not included in the scope of the present invention.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

[Table 3]

[0016]

[Table 4]

[0017]

[Table 5]

[0018]

[Table 6]

[0019]

[Table 7]

[0020]

[Table 8]

[0021]

[Table 9]

FIG. The results of measuring the current-voltage characteristics over a wide range using 23 samples are shown. It is evident that it shows excellent characteristics over a wide current range, especially in the low current range, and reveals how little leakage current. FIG.
Is the No. of Tables 2 to 5. 19-No. Α obtained in 27 samples, which is a graph showing the value of V _1mA in relation to the amount of ZrO _2. As is clear from this figure, Zr
By adding O ₂ , α increases, and V _1mA also tends to increase. FIG. 19-No. 2
7 is a graph showing the value of leakage current (IR) obtained in Sample No. 7 in relation to the amount of ZrO ₂ added. As is apparent from this figure, a current leak by adding ZrO ₂ is reduced, and a minimum value at 0.5 to 1.0 mol%. FIG. 19-No. 27 is a graph showing a voltage change of V _{1 mA} after applying a DC voltage load and a large current pulse by using 27 samples in relation to the amount of ZrO ₂ added. When ZrO ₂ is added, V DC is applied to both DC voltage application and large current pulse application.
It reveals that the _1mA voltage change is extremely small.

CoO, MnO, Cr ₂ O ₃ , Sb
The composition ranges of ₂ O ₃ , lead zinc borosilicate glass and ZrO ₂ are 0.1 to 10.0 mol% and 0.05 to 1 mol%, respectively.
0.0 mol%, 0.05-6.0 mol%, 0.05-
6.0 mol%, 0.5 to 20.0% by weight and 0.
The reason why the content is limited to the range of 0.05 to 5.0 mol% is that even if the ratio is out of this range, the voltage non-linearity is exhibited, but this does not meet the purpose of the present invention.

That is, the mixing ratio of CoO is 0.1 mol%
If it is less than α, α becomes 20 or less, and the rate of change of _V1mA due to the voltage load and the large current pulse changes by 50% or more. 1
If it exceeds 0.0 mol%, the value of the leakage current (IR) becomes 20
μA or more, and the characteristics of low current deteriorate. In the case of MnO, when the compounding ratio is less than 0.05 mol%, practical voltage ratio linearity is exhibited, but the leakage current (IR) value is 20 μA.
As described above, when the rate of change of _V1mA due to the voltage load and the large current pulse becomes 40% or more and exceeds 10.0 mol%, α shows a practical value, but the value of the leakage current (IR) becomes 30
μA or more, and the characteristics of low current deteriorate. In the case of Cr ₂ O ₃ , if the blending ratio is less than 0.05 mol%, the rate of change of V _{1 mA} by a voltage load and a large current pulse becomes 40% or more, and if it exceeds 6.0 mol%, The current (IR) value was 20 μA or more, and the rate of change of V _{1 mA} by a large current pulse was 20% or more, and no improvement effect was observed. S
In the case of b ₂ O ₃ , if the compounding ratio is less than 0.05 mol%, the rate of change of V _{1 mA} by the voltage load and the large current pulse becomes 40% or more, and if it exceeds 6.0 mol%, the change by the large current pulse is caused. The rate of change of _V1mA is 30% or more. Also, 1300
Even at a high temperature of not less than ℃, sinterability is poor, production becomes difficult, and there is no practicality. For lead borosilicate zinc glass, voltage load is less than 0.5% by weight, next to the rate of change of V _1mA by a large current pulse is 42% to 85%, 20%
, The leakage current (IR) value becomes 20 μA or more, and the rate of change of V _{1 mA} by the voltage load and the large current pulse becomes 20% or more and 70% or more, respectively. Absent. In the case of ZrO ₂ , if the compounding ratio is less than 0.05 mol%, the rate of change of V _{1 mA} by a voltage load and a large current pulse is 70%, and if it exceeds 5.0 mol%,
The value of the leakage current (IR) becomes more 70Myuei, also voltage load, with the rate of change of V _1mA by a large current pulse of 30% or more, is bad unreliable high current characteristics. Therefore, the effective composition range of the present invention is CoO, MnO, Cr ₂ O ₃ , Sb.
The composition ranges of ₂ O ₃ , lead zinc borosilicate glass and ZrO ₂ are 0.1 to 10.0 mol% and 0.05 to 1 mol%, respectively.
0.0 mol%, 0.05-6.0 mol%, 0.05-
6.0 mol%, 0.5 to 20.0% by weight and 0.
It is limited to 05-5.0 mol%.

Example 2 As a starting material, zinc oxide (Zn) having a purity of 99.9% or more was used.
O), cobalt oxide (CoO), manganese carbonate (MnC)
O ₃ ), chromium oxide (Cr ₂ O ₃ ), antimony oxide (S
b ₂ O ₃ ), zirconium oxide (ZrO ₂ ), and lead zinc borosilicate glass frit were used. A predetermined amount of these powders was weighed and mixed with pure water in a ball mill for 70 hours. Next, the mixed liquid was filtered, and the mixed powder obtained by drying was pulverized for 10 minutes by a raikai machine,
Calcination was performed at a temperature of 50 ° C. for 2 hours. After calcination, the mixture is further pulverized again and dispersed in a solvent together with an organic binder to form a slurry. This is obtained by the doctor blade method.
A uniform raw sheet having a thickness of about μm to 200 μm is obtained.
This green sheet is punched into a size of 100 mm × 70 mm, and platinum, palladium, silver or an alloy composed of two or more of these is made into a paste as an internal electrode by a screen printing method. Screen print. A predetermined number of raw sheets on which internal electrodes are printed are stacked, and further, raw sheets on which no electrodes are printed are vertically stacked and pressed. Thereafter, it was cut into a predetermined size by a cutter, and baked at 1000 ° C. to 1300 ° C. for 1 hour. Silver electrodes were applied to both ends where the internal electrodes were exposed, and baked at 600 ° C. Characteristics such as α, V1 _mA, and leakage current were calculated by measuring voltage-current characteristics using a DC power supply. The varistor voltage was a voltage applied with a current of 1 _mA .

The value of the leakage current (IR) is 80% of V _{1 mA} .
Was evaluated as the value at the voltage. The current pulse characteristics are
After applying a pulse of 200 A (current waveform 8 × 20 μsec) once, V _{1 mA} was measured to calculate the rate of change, and the characteristics were evaluated using this. The constant voltage load characteristic is such that a DC voltage of 80% of the varistor voltage is set to 1000 in a constant temperature bath at a temperature of 80 ° C.
The rate of change was calculated by measuring _V1mA after the voltage was applied for a period of time, and the characteristics were evaluated using this. Table 1 shows the composition ratio of the lead zinc borosilicate glass used. Also, in Tables 10 to 13,
The powder composition used and the results of property evaluation of the obtained sintered body are shown. Here, the results in Tables 10 to 13 are such that the thickness of the sheet on which the internal electrodes are printed is 50 μm after baking, and the electrode area per sheet is 1.5 mm × 2.5 mm.
And 10 layers were laminated and Pt was used as an internal electrode. The outer shape of the entire sample has a thickness of 1.
5 mm and a size of 2.0 mm × 3.0 mm. In the table, those marked with * are not included in the scope of the present invention.

[0027]

[Table 10]

[0028]

[Table 11]

[0029]

[Table 12]

[0030]

[Table 13]

FIG. The results of measuring the current-voltage characteristics over a wide range using 14 samples are shown.
It is clear that it shows excellent characteristics over a wide current range, especially in the low current range,
It reveals how little leakage current is.
FIG. 10-No. 18 obtained in a sample of alpha, is a graph showing the value of V _1mA in relation to the amount of ZrO _2. As is clear from this figure, even when the thickness between the electrodes is about 50 μm, α is 30 or more, showing excellent characteristics, and α is increased by adding ZrO ₂ . Further, a low voltage of about 10 to 20 V can be obtained for V _{1 mA} . FIG. 10
-No. 18 samples obtained in leakage current of the value of (IR) in relation to the amount of ZrO _2, is a graph showing. As is apparent from this figure, a current leak by adding ZrO ₂ is reduced, and a minimum value at 0.5 to 1.0 mol%. FIG. 19 ~
No. 27 is a graph showing a voltage change of V _{1 mA} after applying a DC voltage load and a current pulse of 200 A with respect to 27 samples in relation to the amount of ZrO ₂ added. ZrO ₂
It has been clarified that the voltage change of _V1mA is extremely small both when a DC voltage is applied and when a 200 A current pulse is applied.

Example 3 As a starting material, zinc oxide (Zn) having a purity of 99.9% or more was used.
O), cobalt oxide (CoO), manganese carbonate (MnC)
O ₃ ), chromium oxide (Cr ₂ O ₃ ), antimony oxide (S
b ₂ O ₃ ), zirconium oxide (ZrO ₂ ) and zinc borosilicate glass frit were used. A predetermined amount of these powders was weighed and mixed with pure water in a ball mill for 70 hours. Next, the mixed solution was filtered, and the mixed powder obtained by drying was pulverized with a raikai machine for 10 minutes, and heat-treated at a temperature of 600 ° C. for 2 hours. After heat treatment, the mixture is pulverized with a ball mill, and a small amount of binder (PVA2.5%
Aqueous solution), mixed with a raikai machine, and then sieved to prepare a sized powder, having a diameter of 12 mm and a height of 1 mm.
It was press-molded into a 5 mm cylinder. Firing at 1100 ° C-1
Performed at a temperature of 300 ° C. for 1.5 hours.

The obtained sintered body was cut and polished to a thickness of 1 mm, and a silver electrode having a diameter of 8 mm was baked. Characteristics such as α, V _1mA , leakage current, etc. were calculated by measuring voltage-current characteristics with a DC power supply. Varistor voltage, the thickness at the current 1 _mA is applied of 1
The voltage per mm was used. The value of the leakage current (IR) is V
_It was evaluated as a value at a voltage of 80% of _{1 mA} . The large current pulse characteristic is 3000 A (current waveform 8 × 20 μs
The rate of change was calculated by measuring _V1mA after applying the pulse c) once, and the characteristics were evaluated. The constant voltage load characteristic was measured by measuring _V1mA after applying a DC voltage of 80% of the varistor voltage for 1000 hours in a constant temperature bath at a temperature of 80 ° C., and calculating the rate of change. Table 14 shows
The composition ratio of the used zinc borosilicate glass is shown. Tables 15 to 22 show the powder compositions used and the results of the property evaluation of the obtained sintered bodies. In the table, those marked with * are not included in the scope of the present invention.

[0034]

[Table 14]

[0035]

[Table 15]

[0036]

[Table 16]

[0037]

[Table 17]

[0038]

[Table 18]

[0039]

[Table 19]

[0040]

[Table 20]

[0041]

[Table 21]

[0042]

[Table 22]

FIG. The results of measuring the current-voltage characteristics over a wide range using 23 samples are shown. It is evident that it shows excellent characteristics over a wide current range, especially in the low current range, and reveals how little leakage current. FIG. 19-No. 2
7 is a graph showing the values of α and V _{1 mA} obtained in Sample _No. 7 in relation to the amount of ZrO ₂ added. As is clear from this figure, the addition of ZrO ₂ increases α, reaches a maximum value at 1.0 mol%, and shows an increasing tendency of V _{1 mA} . FIG. 19-No.
The value of the leakage current (IR) obtained from the sample No. 27 was calculated as ZrO ₂
4 is a graph shown in relation to the amount of addition of the present invention. As is clear from this figure, the leakage current is reduced by adding ZrO ₂ , and reaches a minimum value at 1.0 mol%. FIG.
No. 3 is No. 15 in Tables 15 to 18. 19-No. 27 is a graph showing a voltage change of V _{1 mA} after applying a DC voltage load and a large current pulse with respect to 27 samples in relation to the addition amount of ZrO ₂ . It is clear that when ZrO ₂ is added, the voltage change of V _{1 mA} is extremely small both when applying a DC voltage and when applying a large current pulse.

Incidentally, CoO, MnO, Cr ₂ O ₃ , Sb ₂
The composition ranges of O ₃ , zinc borosilicate glass and ZrO ₂ are 0.1 to 10.0 mol% and 0.05 to 10.0 mol%, respectively.
Mol%, 0.05 to 6.0 mol%, 0.05 to 6.0 mol%, 0.5 to 20.0% and 0.05 to
The reason why the content is limited to 5.0 mol% is that even if the ratio is out of this range, the voltage non-linearity is exhibited, but this does not meet the purpose of the present invention.

That is, the mixing ratio of CoO is 0.1 mol%
If it is less than α, α becomes 20 or less, and the rate of change of _V1mA due to the voltage load and the large current pulse changes by 50% or more. 1
If it exceeds 0.0 mol%, the value of the leakage current (IR) becomes 50%.
μA or more, and the characteristics of low current deteriorate. In the case of MnO, if the compounding ratio is less than 0.05 mol%, practical voltage nonlinearity is exhibited, but the leakage current (IR) value is 30 μA.
As described above, when the rate of change of _V1mA due to the voltage load and the large current pulse becomes 40% or more and exceeds 10.0 mol%, α shows a practical value, but the value of the leakage current (IR) becomes 40
μA or more, and the characteristics of low current deteriorate. In the case of Cr ₂ O ₃ , if the blending ratio is less than 0.05 mol%, the rate of change of V _{1 mA} by a voltage load and a large current pulse becomes 40% or more, and if it exceeds 6.0 mol%, The current (IR) value is 30 μA or more, the change rate of V _{1 mA} by a large current pulse is 20% or more, and no improvement effect is observed.
In the case of Sb ₂ O ₃ , if the compounding ratio is less than 0.05 mol%,
50% change rate of _V1mA due to voltage load and large current pulse
When the molar ratio exceeds 6.0 mol%, the rate of change of _V1mA by a large current pulse becomes 30% or more. Also, 130
Even at a high temperature of 0 ° C. or higher, the sinterability is poor, the production becomes difficult, and there is no practicality. For zinc borosilicate glass,
Voltage load is less than 0.5% by weight, next to the rate of change of V _1mA by a large current pulse is 52% to 84%, more than 20%, the value of the leakage current (IR) becomes more 200 .mu.A, low current Characteristics are worsened. In addition, the rate of change of _V1mA due to the large current pulse is 20% or more and 70% or more, respectively, and the characteristics in the high current region are poor and unreliable. ZrO ₂
In the case of, when the compounding ratio is less than 0.05 mol%, the voltage load,
50% change rate of _V1mA due to large current pulse and 5.0
If it exceeds mol%, the value of the leakage current (IR) becomes 60 μA or more, and the rate of change of V _{1 mA} by a voltage load or a large current pulse is 40% or more, and the high current characteristics are poor and unreliable. Therefore, the effective composition range of the present invention is CoO, Mn.
The composition ranges of O, Cr ₂ O ₃ , Sb ₂ O ₃ , zinc borosilicate glass and ZrO ₂ are each 0.1 to 10 mol%,
0.05 to 10.0 mol%, 0.05 to 6.0 mol%,
0.05-6.0 mol%, 0.5-20.0% by weight
And 0.05 mol% to 5.0 mol%.

Example 4 As a starting material, zinc oxide (Zn) having a purity of 99.9% or more was used.
O), cobalt oxide (CoO), manganese carbonate (MnC)
O ₃ ), chromium oxide (Cr ₂ O ₃ ), antimony oxide (S
b ₂ O ₃ ), zirconium oxide (ZrO ₂ ) and zinc borosilicate glass frit were used. A predetermined amount of these powders was weighed and mixed with pure water in a ball mill for 70 hours. Next, the mixed liquid was filtered, and the mixed powder obtained by drying was pulverized for 10 minutes by a raikai machine,
Calcination was performed at a temperature of 0 ° C. for 2 hours. After calcination, the mixture is further pulverized again and dispersed in a solvent together with an organic binder to form a slurry. This is 10 μm by the doctor blade method.
A uniform raw sheet having a thickness of about 200 μm is formed. This raw sheet is punched into a size of 100 mm x 70 mm,
Platinum, palladium, silver or an alloy composed of two or more of them is formed into a paste as an internal electrode thereon by screen printing, and is screen-printed to a predetermined size. A predetermined number of raw sheets on which internal electrodes are printed are stacked, and further, raw sheets on which no electrodes are printed are vertically stacked and pressed. Thereafter, it was cut into a predetermined size by a cutter, and baked at 1000 ° C. to 1300 ° C. for 1 hour. Silver electrodes were applied to both ends where the internal electrodes were exposed, and baked at 600 ° C. Characteristics such as α, V _{1 mA} and leakage current were calculated by measuring voltage-current characteristics using a DC power supply. The varistor voltage was a voltage applied with a current of 1 _mA . The value of the leakage current (IR) was evaluated as a value at a voltage of 80% of _V1mA .
The current pulse characteristic is 200 A (current waveform 8 × 20 μs
The rate of change was calculated by measuring _V1mA after applying the pulse c) once, and the characteristics were evaluated. The constant voltage load characteristic was measured by measuring _V1mA after applying a DC voltage of 80% of the varistor voltage for 1000 hours in a constant temperature bath at a temperature of 80 ° C., and calculating the rate of change. Table 14 shows the composition ratio of the used zinc borosilicate glass. Tables 23 to 26 show the powder compositions used and the results of the property evaluation of the obtained sintered bodies. Here, the results in Tables 23 to 26 show that the thickness of the sheet on which the internal electrodes were printed was 50 μm after baking, and the electrode area per sheet was 1.5 mm × 2.5 mm and 10 layers were laminated. Then, an electrode using Pt as an internal electrode was obtained. The outer shape of the entire sample is 1.5 mm thick and 2.0 mm × 3.0.
mm. In the table, those marked with * are not included in the scope of the present invention.

[0047]

[Table 23]

[0048]

[Table 24]

[0049]

[Table 25]

[0050]

[Table 26]

FIG. The results of measuring the current-voltage characteristics over a wide range using 14 samples are shown. It is evident that it shows excellent characteristics over a wide current range, especially in the low current range, and reveals how little leakage current. FIG.
No. 5 in Table 23 is No. 10-No. 18 obtained in a sample of alpha, is a graph showing the value of V _1mA in relation to the amount of ZrO _2. As is clear from this figure, even when the thickness between the electrodes is about 50 μm, α is 30 or more, showing excellent characteristics, and α is increased by adding ZrO ₂ . Further, V _{1 mA} a value of about 25~40V is obtained. FIG. 10-No. 18 samples obtained in leakage current of the value of (IR) is a graph showing the relationship between the addition amount of ZrO _2. As is clear from this figure, the leakage current is reduced by adding ZrO _2, and reaches a minimum value at 0.5 mol% to 1.0 mol%.
FIG. 19-No. 27 is a graph showing a voltage change of V _{1 mA} after applying a DC voltage load and a current pulse of 200 A with respect to 27 samples in relation to the amount of ZrO ₂ added. It is clear that when ZrO ₂ is added, the voltage change of V _{1 mA} is extremely small both when a DC voltage is applied and when a current pulse of 200 A is applied.

[0052]

As is apparent from the above description, the voltage non-linear resistor according to the present invention has a large voltage non-linear coefficient α, a small leakage current, and has a low V.sub.V with respect to a voltage load and a large current pulse application. Very stable characteristics with a small change of _{1 mA} can be obtained. Further, such excellent characteristics were obtained because zirconium, zinc borosilicate (lead) zinc glass and other subcomponents were interposed around the ZnO crystal grains as a grain boundary layer. The structure makes the characteristics as a varistor excellent. In addition, the voltage non-linear resistor of the present invention has a firing temperature of 1000 ° C. to 1300 ° C.
It is suitable for a single-plate type varistor having a value of _V1mA per 1 mm of thickness of 250 V or more when lead zinc borosilicate glass is used and 400 V or more when zinc borosilicate glass is used. Further, the laminated voltage non-linear resistor according to the present invention can easily make the thickness between the electrodes 0.3 mm or less, for example, 10 μm or 20 μm, and has a large voltage non-linear coefficient α and a small leakage current. It is characterized in that the change of _V1mA with respect to voltage load and application of current pulse is small and very stable characteristics can be obtained. In this laminated voltage non-linear resistor, a varistor with a low V _{1 mA} is obtained when lead zinc borosilicate glass is used, and a varistor with a high V _{1 mA} is obtained when zinc borosilicate glass is used.
The voltage non-linear resistor of the present invention having such features is:
As a ZnO varistor excellent for overvoltage protection element, surge absorption element that absorbs large current pulse generated when opening and closing a switch, low voltage surge absorption element such as IC and LSI, etc.
It can be expected to be used in a wide range of applications such as communication equipment.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between voltage and current characteristics in Example 1 of the present invention.

FIG. 2 shows a voltage nonlinear coefficient α according to the first embodiment of the present invention;
5 shows the relationship between V _{1 mA} and the amount of ZrO ₂ added.

FIG. 3 shows the relationship between leakage current (IR) and the amount of ZrO ₂ added in Example 1 of the present invention.

FIG. 4 is a diagram showing a relationship between a voltage change of V _{1 mA} after application of a DC voltage load and a large current pulse and an addition amount of ZrO ₂ in Example 1 of the present invention.

FIG. 5 is a diagram showing a relationship between voltage and current characteristics in Embodiment 2 of the present invention.

FIG. 6 shows a voltage nonlinear coefficient α according to a second embodiment of the present invention;
FIG. 3 is a diagram showing a relationship between V _{1 mA} and the amount of ZrO ₂ added.

FIG. 7 is a diagram showing the relationship between leakage current (IR) and the amount of ZrO ₂ added in Example 2 of the present invention.

FIG. 8 is a diagram showing a relationship between a DC voltage load and a voltage change after application of a 200 A current pulse and an addition amount of ZrO ₂ in Example 2 of the present invention.

FIG. 9 is a perspective view and a cross-sectional view of a multilayer voltage nonlinear resistor according to the present invention.

FIG. 10 is a diagram showing a relationship between voltage and current characteristics in Embodiment 3 of the present invention.

FIG. 11 is a diagram showing the relationship between the voltage nonlinear coefficient α, V _{1 mA} and the addition amount of ZrO ₂ in Example 3 of the present invention.

FIG. 12 shows leakage current (IR) in Embodiment 3 of the present invention.
FIG. 4 is a diagram showing the relationship between the amount of ZrO _{2 and} the amount of ZrO ₂ added.

FIG. 13 is a diagram showing a relationship between a change in voltage of V1 _mA after application of a DC voltage load and a large current pulse and an addition amount of ZrO ₂ in Example 3 of the present invention.

FIG. 14 is a diagram showing a relationship between voltage and current characteristics in Example 4 of the present invention.

FIG. 15 is a diagram showing the relationship between the voltage nonlinear coefficient α, V _{1 mA} and the addition amount of ZrO ₂ in Example 4 of the present invention.

FIG. 16 shows leakage current (IR) in Example 4 of the present invention.
FIG. 4 is a diagram showing the relationship between the amount of ZrO _{2 and} the amount of ZrO ₂ added.

FIG. 17 shows a change in voltage of V _{1 mA} and Zr after application of a DC voltage load and a 200 A current pulse in Example 4 of the present invention.
FIG. 3 is a diagram showing the relationship between the amounts of O ₂ added.

[Explanation of symbols]

 1 Sintered body 2, 3 Internal electrode 4, 5 External extraction electrode

Claims (3)

(57) [Claims] [Claim 1] as a main component zinc oxide, cobalt as an auxiliary component, manganese, chromium and antimony, these oxides, CoO, MnO, respectively in terms of Cr ₂ O ₃ and Sb ₂ O ₃ 0.1 ~ 10.0 mol%, 0.05 ~
10.0 mol%, 0.05-6.0 mol% and 0.0
Zirconium oxide (ZrO ₂ ) is added in an amount of 0.05 to 5.0 mol% with respect to a raw material in which 5 to 6.0 mol% and a lead zinc borosilicate glass are mixed in a weight ratio of 0.50 to 20.0%. A non-linear voltage resistor comprising a sintered body obtained by addition and blending. 2. Cobalt, manganese, chromium and antimony as main components, and cobalt, manganese, chromium and antimony as sub-components, each of which is 0.10 in terms of these oxides, CoO, MnO, Cr ₂ O ₃ and Sb ₂ O _3. ~ 10.0 mol%, 0.05 ~
10.0 mol%, 0.05-6.0 mol% and 0.0
0.05 to 5.0 mol% of zirconium oxide (ZrO ₂ ) is added to a raw material in which 5 to 6.0 mol% and zinc borosilicate glass are mixed in a weight ratio of 0.50 to 20.0%. A voltage non-linear resistor comprising a sintered body obtained by blending. 3. A structure in which a plurality of internal electrodes and a sintered body are alternately laminated, and a portion of the internal electrodes to be taken out to the outside is alternately exposed on two opposing side surfaces of the laminated body.
Or the laminated voltage non-linear resistor according to item 2.