JPH07201531A - Voltage non-linear resistor porcelain composition and voltage non-linear resistor porcelain - Google Patents

Abstract

PURPOSE:To enable a voltage non-linear resistor porcelain to be kept high in high-energy resistance making it retain a nun-linear index by a method wherein a specific element, a specific atom% of Pb, and at least a specific atom% of an element selected from V, Ge, Nb and Ta are added to porcelain composition mainly composed of zinc oxide. CONSTITUTION:Af least an element selected out of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, Co, at least an element selected from B, Al, Ga and In, 0.002 to 2 atom% of Pb, and 0.01 to 0.2 atom% of at least an element selected out of V, Ge, Nb and Ta are added to zinc oxide or a main component for the formation of a voltage non-linear resistor porcelain composition. 0.01 to 0.5 atom% of Bi is added to the porcelain composition. By this setup, a non-linear resistor porcelain of the above composition is enhanced in high energy resistance and stable in characteristics even if a large amount of energy is applied.

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 resistance ceramic composition and a voltage non-linear resistance ceramic.

[0002]

2. Description of the Related Art In recent years, semiconductor devices such as thyristors, transistors, integrated circuits, etc. and semiconductor circuits and their reactions have been rapidly developed, and the use of semiconductor devices and semiconductor circuits in measurement, control, communication equipment and power equipment has become widespread. Miniaturization and high performance of equipment are rapidly progressing. However, on the other hand, with such progress, the withstand voltage, surge withstand, and noise withstand performance of these devices and their parts have not been sufficient. Therefore, protecting these devices and parts from abnormal surges and noises, or stabilizing the circuit voltage has become an extremely important issue. To solve these problems, voltage non-linearity is extremely large, discharge withstand capacity is large, and life characteristics are excellent.
Moreover, there has been a demand for the development of inexpensive voltage nonlinear resistor porcelain compositions.

For these purposes, silicon carbide (SiC), selenium (Se), silicon (Si) or Z
Varistors containing nO as a main component are used. Above all, the varistor containing ZnO as a main component is generally characterized by a low limiting voltage and a large voltage non-linearity index.
Therefore, since it is suitable for protection against overvoltage of a device such as a semiconductor element having a small withstand current, it has been widely used instead of a varistor containing SiC as a main component.

Such a varistor containing ZnO as a main component is obtained by adding cobalt oxide, rare earth oxide, chromium oxide, aluminum oxide, potassium oxide, silicon oxide, calcium oxide, etc. as additives. It was

[0005]

However, the conventional varistor containing ZnO as a main component has an energy withstand capacity of about 600 J / cm ³ at the maximum, and the change in characteristics does not occur even when higher energy is applied. The few were desired. The energy tolerance is defined as follows. That is, a voltage pulse of a predetermined voltage of a square wave of 2 msec is applied to the sample, and the application of this voltage pulse is
When the voltage value is increased and repeated at intervals of several minutes, the varistor voltage gradually changes, but the rate of change is -10%.
Energy per unit volume (applied voltage × current × application time / element volume (unit: J / c) applied to the sample when reaching (ΔV _1mA / V _1mA × 100 = −10%)
m ³ )) is the energy tolerance.

With respect to the above requirements, the inventors of the present application have made earnest studies, and as a result, by adding a predetermined amount of Pb to a voltage nonlinear resistor ceramic composition containing ZnO as a main component, the energy-withstand capability of the varistor is improved. It turned out to increase.

However, when the energy resistance of the varistor is improved by adding Pb in this way, the non-linear index α will decrease this time, which may be undesirable depending on the object of use. Has occurred.

Therefore, an object of the present invention is to provide a voltage non-linear resistance ceramic composition and a voltage non-linear resistance ceramic which have a higher energy withstanding capability while at least maintaining the non-linear index α. To do.

[0009]

The above objects are achieved by the present invention described in (1) to (9) below. (1) Zinc oxide as a main component, and as an additive to this, L
a, Ce, Pr, Nd, Sm, Eu, Gd, Tb, D
At least one of y, Ho, Er, Tm, Yb and Lu, Co, at least one of B, Al, Ga and In, 0.002 to 2 atomic% Pb, and 0.
A voltage non-linear resistor ceramic composition, to which 0.1 to 0.2 atomic% of at least one of V, Ge, Nb, and Ta is added. (2) The voltage nonlinear resistor porcelain composition according to (1) above, in which 0.01 to 0.5 atomic% of Bi is added. (3) Zinc oxide as a main component, and as an additive to this, L
a, Ce, Pr, Nd, Sm, Eu, Gd, Tb, D
At least one of y, Ho, Er, Tm, Yb and Lu, Co, at least one of B, Al, Ga and In, 0.002 to 2 atomic% Pb, and 0.
A voltage-nonlinear resistance porcelain composition, characterized in that 01 to 0.5 atomic% of Bi is added. (4) The voltage nonlinear resistor porcelain composition according to any one of the above (1) to (3), which contains 0.005 to 1 atomic% of Pb. (5) The voltage nonlinear resistor porcelain composition according to any one of (1) to (4), which contains at least one of Cr and Si. (6) The voltage nonlinear resistor porcelain composition according to any one of (1) to (5), which contains at least one of K, Rb, and Cs. (7) The voltage nonlinear resistor porcelain composition according to any one of (1) to (6), which contains at least one of Mg, Ca, Sr, and Ba. (8) A voltage nonlinear resistor ceramic obtained by firing the voltage nonlinear resistor ceramic composition according to any one of (1) to (7). (9) The voltage nonlinear resistor porcelain according to the above (8), wherein the firing is performed in an atmosphere having an oxygen concentration higher than air in at least a part of a temperature range of at least 500 ° C. in the firing step.

[0010]

In the voltage nonlinear resistor porcelain produced by the porcelain composition of the present invention, Pb is 0.002 to 0.002.
By the addition of 2 atomic%, the energy withstand capacity of about 600 J / cm ³ has been conventionally increased by about 10% or more, and by 40% at the maximum. As a result, it is possible to obtain a voltage nonlinear resistor porcelain with stable characteristics even if a large amount of energy is applied.

Further, the addition of V, Ge, Nb, Ta and Bi makes it possible to maintain and improve the non-linear index α which is decreased only by adding Pb, and particularly when Bi is added, the effect is large. This is V, Ge, Nb, Ta, Bi
It is considered that the addition of oxygen promotes the uptake of oxygen into the porcelain composition.

[0012]

SPECIFIC STRUCTURE In the voltage non-linear resistance ceramic composition of the present invention, zinc oxide is the main component, and L is used as an additive.
a (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Sm (samarium), E
u (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb
(Ytterbium) and Lu (lutetium), at least one of the rare earth elements, and Co (cobalt)
And at least one of Group IIIb elements that are B (boron), Al (aluminum), Ga (gallium), and In (indium).

The content of the above zinc oxide is, in terms of Zn, 80 atom% or more, preferably 8 atom% in the metal or metalloid element.
5 to 99 atomic% is preferable. This is because if the amount of Zn is too small, it is likely to deteriorate in a load life test in high temperature and high humidity.

The amount of the rare earth element added is preferably 0.05 to 5 atom%. This is because if it is less than 0.05 atom%, the non-linearity is lowered, and if it exceeds 5 atom%, the energy resistance is reduced.

The amount of Co added is 0.1 to 10 atomic%.
Is desirable. This is because if it is less than 0.1 atom%, the non-linearity is reduced, and if it exceeds 10 atom%, the energy resistance is reduced.

The group IIIb elements B, Al, Ga,
The added amount of In is preferably 1 × 10 ^-4 to 1 × 10 ^-1 atom%. When it is less than 1 × 10 ^-4 atom%, the limiting voltage increases, and when it exceeds 1 × 10 ^-1 atom%, the leak current increases.

In the voltage non-linear resistance ceramic composition of the present invention, Pb is further added. The addition amount is 0.002 to 2 atom%, particularly 0.005 to 1 atom%.
Is desirable. If the amount is out of the above range, the effect of improving the energy resistance cannot be recognized so much.

In the voltage non-linear resistance ceramic composition of the present invention, 0.01 to 0.2 atomic% of V, Ge,
At least one of Nb and Ta, or 0.01
It is preferable that Bi of 0.5 atomic% is added. The above V and the like and Bi may be added at the same time. V etc. and B
When i is added in the above range, the nonlinear index α is effectively improved, and when it is out of the above range, it is decreased. Of the above, it is most preferable to add bismuth oxide alone.

In the voltage non-linear resistance ceramic composition of the present invention, at least one of Cr and Si may be added. In this case, the addition amount is 0.01 to 1 atomic% for Cr and 0.001 to 1 for Si.
It is desirable to set it in the range of 0.5 atomic%.

The voltage nonlinear resistor porcelain composition of the present invention may further contain 0.01 to 1 atom% of at least one of Group Ia elements which are K, Rb and Cs.

In the voltage nonlinear resistor porcelain composition of the present invention, Mg, Ca, Sr and Ba are further included II
0.01 to 4 atomic% of at least one of the a-group elements
It may be contained.

The voltage non-linear resistor porcelain, which is a sintered body obtained by firing the voltage non-linear resistor porcelain composition having such a composition, has grains of about 1 to 100 μm. Grain contains secondary components such as cobalt and aluminum together with the main component ZnO, and it is considered that other secondary components, particularly lead added according to the present invention, are present in the grain boundaries. The above-mentioned subcomponents cobalt, aluminum, lead, V and the like and Bi and the like are present in the porcelain composition in the form of oxides like the main component ZnO.

The voltage nonlinear resistor porcelain according to the present invention is
With the above composition, a varistor voltage (V _1mA ) per 1 mm of 20 to 250 V, 15 to 80, _{1 mA} to 10
Non-linearity (α) in mA and 600-900 J / cm
Has an energy capacity of ³ .

Then, such a sintered body is attached with electrodes and the like according to a conventional method to obtain a voltage non-linear resistance element. At this time, you may coat with glass etc. Further, it can be used for all voltage non-linear resistance elements for household electric appliances, industrial equipment and the like.

Next, the firing process of the voltage non-linear resistor ceramic according to the present invention will be described.

At this time, the firing may be carried out according to a conventional method, but it is desirable to carry out the steps as described below.

As shown in the time chart of FIG. 1, the firing process of the voltage non-linear resistor porcelain in the present invention comprises a series of steps including a heating and heating step, a temperature holding step and a cooling step. The temperature in the temperature holding step varies depending on the material composition, but is usually set in the range of 1100 to 1300 ° C, and the holding time is usually set in the range of 1 hour to 10 hours. The temperature in this temperature holding step is P
The temperature is about 100 ° C. lower than that of the conventional one in which b is not added. The temperature raising / lowering rate is usually 50 to 400 per hour.
Set to ° C. Although FIG. 1 shows that the rate of temperature increase and the rate of temperature decrease are the same, they do not necessarily have to be the same.

In the present invention, it is desirable that all or part of the temperature range of at least 500 ° C. or higher in the above firing step is performed in an atmosphere having an oxygen concentration higher than that of air. This has the effect of preventing the evaporation of lead, bismuth, vanadium components, etc., and promoting the uptake of oxygen into the porcelain composition.

The firing atmosphere at this time is preferably as high as the oxygen concentration, and most preferably substantially 100% oxygen, that is, an oxygen atmosphere.

As the raw material, an oxide such as ZnO or a compound which becomes an oxide by firing, such as carbonate,
Oxalate, nitrate, chloride and the like may be used. Raw material Z
The particle size of nO may be about 0.1 to 5 μm, and the particle size of the additive raw material powder may be about 0.1 to 3 μm. The additive may be added as a solution. Further, lead may be added in a glass state.

[0031]

EXAMPLES Hereinafter, the voltage non-linear resistor ceramic composition of the present invention will be specifically described with reference to examples.

Pure water and a dispersant were put into a polyethylene pot containing resin-processed balls, and ZnO powder as a main component and Co ₃ O ₄ , Pr ₆ O ₁₁ , and C as additives were put in the pot.
_{r 2 O 3, Al (NO} 3) 3 · 9H 2 O, In 2 O 3,
K ₂ CO ₃ , SiO ₂ , CaCO ₃ , PbO, Bi ₂ O
₃ , V ₂ O ₅ , GeO ₂ , Ta ₂ O ₅ , Nb ₂ O ₅ and other additives in an amount corresponding to the predetermined atomic% (percentage conversion of metallic element only) shown in Table 1 and Table 2. Was added and blended. Then, the pot was placed on a rotary table and mixed. The mixture is then transferred to an evaporation dish and dried in a dryer,
This was crushed, then granulated while adding a binder, transferred to an evaporation dish and dried with a drier. Samples 1 to 39 are V,
Ge, Nb, and Ta are added in an amount of 0 to 0.5 atom%,
The addition amounts of other additives are fixed except that the addition amount of Bi is changed between 0 and 1.0 atomic%.

[0033]

[Table 1]

[0034]

[Table 2]

This has a diameter of 12.0 mm and a thickness of 2.0 m.
discoid in pressing the m (green density 3 to 4 g / cm ³⁾
Then, after holding at 500 to 800 ° C. for several hours to remove the binder, it was fired in oxygen at 1100 to 1300 ° C., which is lower than the conventional firing temperature, for several hours to obtain a sintered body.
Print silver paste on both sides and apply 500-700
Samples 1, 3 to 39, which are elements, that is, voltage non-linear resistance elements, were prepared by baking at ° C to form electrodes. Also, sample 1
Samples 2 and 40 were obtained in the same manner except that firing was carried out in air at 36 and 36. Then, the electrical characteristics of these samples 1 to 40 were measured.

The electrical characteristics are as follows: Varistor voltage (V) per 1 mm, non-linear index α at 1 mA to 10 mA,
And the above energy tolerance (J / cm ³ ) was measured.
The above results are also shown in Tables 1 and 2. The nonlinear index α is shown by the following equation. α = log (10/1) / log (V _10mA / V _1mA ) Here, V _10mA and V _1mA are 10 mA and 1 mA, respectively.
Shows the varistor voltage at.

As can be seen from Tables 1 and 2, V, G
When the amount of e, Nb, or Ta added is about 0.005 atom%, no effect is exhibited on the non-linear index α. The effect was shown. However, if the added amount of V or the like exceeds the above range, not only the non-linear index α decreases, but also the energy resistance amount tends to decrease on the contrary.
Further, as can be seen from Table 1 and Table 2, when the added amount of Bi is about 0.05 atomic%, the effect of improving the nonlinear index α is not so significant, and the Bi content is 0.01 to 0.5.
The effect of improving the non-linear index α was shown in atomic%. However, when the amount of Bi added exceeds the above range, the nonlinear index α is the same as when the above V or the like is added beyond the range of the present invention.
Of energy consumption, and on the contrary, the energy withstand capacity tended to decrease from the conventional value.

Further, in the sample 36 fired in an oxygen atmosphere, the non-linear index α was 38, but in the sample amount 40 fired in the air, the non-linear index α was reduced to 15, so the firing was performed. Is preferably performed in an atmosphere having a higher oxygen partial pressure than air.

In the above samples 1 to 40, C
Although an example in which all of r, K, Si, and Ca are added is shown, as shown in Table 1, the one in which only Cr is added among the above-mentioned Cr, K, Si, and Ca is the sample 41 and the above-mentioned whole. When the electrical characteristics were measured in the same manner as described above using Sample 42 in which was not added, as in the above, the tendency of increase in energy resistance and non-linear index α was similarly recognized.

In Sample 14, 0.05 atomic%
In addition to Ge, 0.05 atomic% Nb and 0.0
5 atomic% of Ta (Ge, Nb, and Ta in total added amount of 0.
Electrical properties were measured in the same manner as described above using Sample 43 with the addition of 15 atom%), and as shown in Table 1, the same tendency of increase in energy resistance and nonlinear index α was recognized. .

Next, in Sample 36, as shown in Table 3, Samples 50 to 61 were prepared by changing the added amount of Pb between 0 and 5 atomic%.

[0042]

[Table 3]

When the electrical characteristics of these samples were measured in the same manner as above, the amount of Pb added was 0.002 to 2
It was confirmed that there was an effect of improving energy withstand in the range of atomic%. As shown in Tables 4 and 5, in the sample in which V, Ge, Nb, and Ta were added in the above preferable amounts instead of Bi, the sample 70 in which the addition amount of Pb was changed in the same manner as above was used. .About.93, the same electrical characteristics as above were measured, and the same results as those of Samples 50 to 61 were obtained. That is, the addition of Pb is 0.00
It is preferably in the range of 2 to 2 atomic%.

[0044]

[Table 4]

[0045]

[Table 5]

Next, in sample 36, as shown in Table 6, Ga (in the form of Ga ₂ O ₃ ) and In were used instead of Al.
Samples 100 and 101 were prepared by adding the same amount (in the form of In ₂ O ₃ ) to each other, and Rb was used instead of K.
(In the form of Rb ₂ CO ₃ )) and Cs (in the form of Cs ₂ CO ₃ ) added in the same amount, respectively, sample 102 and sample 1.
It was set to 03. Furthermore, in the sample 35, Mg (MgCO
₃ in the form) 3.0 have been added atomic% Sample 104,
Sample 105 was prepared by adding 0.005 atomic% of B (in the form of B ₂ O ₃ ).

[0047]

[Table 6]

When the electrical characteristics of the above samples 100 to 105 were measured in the same manner, as shown in Table 6, good results were obtained with respect to the energy tolerance and the nonlinear index α as in the above.

Next, the ZnO powder was mixed with praseodymium Pr.
Other rare earth lanthanum La, cerium Ce, neodymium Nd, samarium Sm, europium Eu, gadolinium Gd, terbium Tb, dysprosium Dy, holmium Ho, erbium Er, thulium Tm, ytterbium Yb, lutetium Lu, and other additives. Table 5
Samples 111 to 1 were added in the same manner as above.
23 was prepared, and the electrical characteristics of these samples 111 to 123 were measured under the same conditions as above. The results are shown in Table 7.

[0050]

[Table 7]

As can be seen from Table 7, Pr as a rare earth element is used.
When adding other than the same as when adding Pr,
Good results were obtained in terms of energy resistance.

[Brief description of drawings]

FIG. 1 is a time chart showing an example of a firing pattern of a voltage nonlinear resistor ceramic according to the present invention.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] May 2, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0042

[Correction method] Change

[Correction content]

[0042]

[Table 3]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

[0044]

[Table 4]

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0045

[Correction method] Change

[Correction content]

[0045]

[Table 5]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiyuki Yamazaki 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDC Corporation (72) Masatada Yodogawa 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDC Within the corporation

Claims (9)

[Claims] 1. A main component is zinc oxide, and as an additive thereto, La, Ce, Pr, Nd, Sm, Eu, Gd, T.
b, Dy, Ho, Er, Tm, Yb and at least one of Lu, Co, at least one of B, Al, Ga and In, and 0.002 to 2 atomic% Pb
And 0.01 to 0.2 atomic% of V, Ge, Nb and T
At least one kind of a is added, The voltage non-linear resistor ceramic composition characterized by the above-mentioned. 2. The voltage nonlinear resistor porcelain composition according to claim 1, wherein Bi is added in an amount of 0.01 to 0.5 atom%. 3. Zinc oxide as a main component, to which La, Ce, Pr, Nd, Sm, Eu, Gd, T are added as additives.
b, Dy, Ho, Er, Tm, Yb and at least one of Lu, Co, at least one of B, Al, Ga and In, and 0.002 to 2 atomic% Pb
And 0.01 to 0.5 atomic% of Bi are added, The voltage non-linear resistance ceramic composition. 4. The voltage non-linear resistor porcelain composition according to claim 1, which contains 0.005 to 1 atomic% of Pb. 5. The voltage nonlinear resistor porcelain composition according to claim 1, containing at least one of Cr and Si. 6. The voltage non-linear resistor ceramic composition according to claim 1, comprising at least one of K, Rb and Cs. 7. The voltage non-linear resistor ceramic composition according to claim 1, containing at least one of Mg, Ca, Sr and Ba. 8. A voltage non-linear resistor porcelain obtained by firing the voltage non-linear resistor porcelain composition according to claim 1. 9. The firing comprises at least 50 firing steps.
In at least a part of the temperature range of 0 ° C. or higher,
9. The voltage nonlinear resistor porcelain according to claim 8, which is carried out in an atmosphere having a higher oxygen concentration than air.