JP3059193B2 - Voltage non-linear resistor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a voltage non-direct resistor, and more particularly to a voltage non-direct resistor mainly composed of zinc oxide (ZnO) used as an overvoltage protection element.

[Conventional technology]

Conventionally, varistors containing silicon carbide (SiC), selenium (Se), silicon (Si), or ZnO as a main component have been used for the purpose of overvoltage protection of electronic devices and electric devices. Among them, varistors and arrester elements containing ZnO as a main component generally have characteristics such as a low limiting voltage and a large voltage non-linear index. For this reason, it is suitable for protection against overvoltage of devices composed of devices having a small overcurrent capability, such as semiconductor devices, and has been widely used instead of varistors made of SiC. It is also widely used as an arrester element for the purpose of protecting power equipment.

On the other hand, rare earth elements containing ZnO as a main component
-5.0 atomic%, cobalt (Co) 0.1-10.0 atomic%, magnesium (Mg), at least one of calcium (Ca) 0.01-5.0 atomic%, potassium (K), cesium (C
s) and at least one of rubidium (Rb) from 0.01 to
1.0 atomic%, chromium (Cr) 0.01 to 1.0 atomic%, boron (B) 5 × 10 ^-4 to 1 × 10 ^-1 atomic%, aluminum (A
l), at least one of gallium (Ga) and indium (In) is added in an amount of 1 × 10 ^{−4 to} 5 × 10 ⁻² atomic%, and the resulting non-linear resistor is manufactured by firing. It is described in Japanese Patent Publication No. 25205/1992 that it has excellent surge resistance, surge withstand capability and power application life characteristics.

In addition, praseodymium containing ZnO as a main component is 0.1 to 5.
0 atomic%, cobalt (Co) 0.5-5.0 atomic%, potassium (K), cesium (Cs), rubidium (Rb) at least two elements of 0.06-0.6 atomic%, chromium (Cr) 0.05
Japanese Patent Publication No. Sho 62-14924 discloses that a voltage non-linear resistor produced by adding 0.5 to 0.5 atomic% and firing is excellent in voltage non-linearity.

[Problems to be solved by the invention]

However, such a voltage non-linear resistor still has the following problem.

The voltage non-linear resistor has a voltage per unit thickness (hereinafter, V _{1 mA} / t (V / mm)) when a current of 1 mA flows, and a surge energy absorbing capacity per unit volume (hereinafter, allowable energy (KJ / cm ³ )]. However, if V _{1 mA} / t is increased, the allowable energy is reduced. Therefore, V _{1 mA} / t is set to about 200 V / mm by, for example, changing the firing conditions and suppressing the growth of particles. However, for example, when used for a lightning arrester, it is desirable that _V1mA / t be 300 V / mm or more from the viewpoint of miniaturization such as reducing the height dimension and cost reduction.

The present invention has been made in view of the above-described points, and its object is to increase the V _{1 mA} / t to 300 V / mm or more by using the conventional method.
An object of the present invention is to provide a voltage non-linear resistor having an allowable energy equal to or higher than that when the voltage is set to 00 V / mm.

[Means for solving the problem]

In order to solve the above problems, the voltage non-linear resistor of the present invention is composed of ZnO as a main component, a rare earth element of 0.08 to 5.0 atomic%, Co of 0.1 to 10.0 atomic%, Mg, at least one of Mg and Ca of 0.01 to 5.0 atomic%. 5.0 at%, at least one of K, Cs and Rb
0.01-1.0 atomic%, Cr 0.01-1.0 atomic%, B 5 × 10 ^-4 〜
1 × 10 ^-1 atomic%, at least one of Al, Ga and In
× 10 ^{-4 to} 5 × 10 ^-2 atomic%, at least one of antimony (Sb), niobium (Nb), tantalum (Ta) and phosphorus (P) is 1 × 10 ^{-3 to} 5 × 10 ^-2 atomic% And fired.

Further, as another means, praseodymium containing ZnO as a main component is 0.1 to 5.0 atomic%, Co is 0.5 to 5.0 atomic%, and K is 0.05 to 5.0 atomic%.
0.5 atomic%, Cr 0.05-0.5 atomic%, antimony (Sb),
It is assumed that at least one kind of niobium (Nb) is added in a range of 1 × 10 ^{−3 to} 5 × 10 ⁻² atomic% and fired.

[Action]

As described above, the present invention further includes Sb, N in addition to the voltage non-linear resistor component disclosed in Japanese Patent Publication No. 1-25205.
b, Ta, at least one of P is added and fired, or the voltage nonlinear resistor component disclosed in the above-mentioned JP-B-62-14924 is further added with at least one of Sb and Nb and fired. As a result, the grain growth during firing is suppressed and a sintered body having a small grain size is formed, so that the grain boundary layer per unit thickness is increased, and a voltage non-linear resistor having a high V _{1 mA} / t is obtained. be able to. In addition, the addition of Sb, Nb, Ta or P can provide a high V _{1 mA} / t without lowering the uniformity of the sintered body.
In the region described above, an allowable energy value equal to or higher than that of the voltage nonlinear resistor disclosed in the above-mentioned publication can be provided.

〔Example〕

 Hereinafter, the present invention will be described based on examples.

The voltage non-linear resistor according to the present invention is manufactured by firing and sintering a mixture of ZnO and a metal or a compound as an additional component at a high temperature in an oxygen-containing atmosphere. The additional component is added in the form of a metal oxide, but a compound that can be converted into an oxide in the firing step, for example, a carbonate, a hydroxide, a fluoride and a solution thereof, or the like, or a single element may be used. It can be used and converted into an oxide during the firing process.

The voltage non-linear resistor according to the present invention is obtained by adding a powder of an additional component metal or compound to ZnO powder, mixing them thoroughly, calcining at 500 to 1000 ° C. for several hours in air before firing, and then calcining the calcined product. It is manufactured by sufficiently pulverizing and shaping into a predetermined shape, and then firing in air at a temperature of about 1100 to 1400 ° C. for several hours. If the firing temperature is lower than 1100 ° C, the sintering is insufficient and the characteristics are unstable. At a temperature higher than 1400 ° C., it is difficult to obtain a homogeneous sintered body, voltage non-linearity is reduced, and there is a difficulty in reproducibility such as control of characteristics, and it is difficult to obtain a practical product.

Next, a specific example of the voltage non-linear resistor according to the present invention will be described.

Pr ₆ O ₁₁ in Example 1 ZnO _{powder, Co 3 O 4, MgO,} K 2 CO 3, Cr 2 O 3, B 2 O 3, Al 2 O 3
Powder and additionally Sb ₂ O ₃ , Nb ₂ O ₅ , WO ₃ , Ta ₂ O ₅ or P ₂ O
_At least one of the _five powders was added in an amount corresponding to a predetermined atomic% described in Tables 1 to 6 described below, mixed well, and then calcined at 500 to 1000 ° C for several hours. Next, the calcined product was sufficiently pulverized, and a binder was added thereto to form a disc having a diameter of 17 mm under pressure, followed by firing for 1 hour in air at 1100 to 1400 ° C. to obtain a sintered body. The sintered body thus obtained was polished into a sample having a thickness of 2 mm, electrodes were baked on both surfaces thereof to produce an element, and the electrical characteristics of the element were measured.

The electrical characteristics are as follows: The electrode voltage V _{1 mA} when a current of 1 mA is applied to the element, a square wave current with a width of 2 ms is applied 20 times, and the current value without penetrating breakdown and creepage breakdown and the limiting voltage at that time The allowable energy was determined.

When the composition of the voltage non-linear resistor is variously changed, the measurement results of the electrical characteristics corresponding thereto are shown in Tables 1 to 6. Table 1 shows the case where Sb is added to the basic composition. Similarly, Table 2 shows Nb, Table 3 shows W (Reference Example), Table 4 shows Ta, and Table 5 shows
P, Table 6 shows the case where Nb and W were added. The composition shown in each table is represented by atomic% calculated from the ratio of the number of atoms of the additive element to the total number of atoms of each component metal element in the blended raw material. The use of a V _1mA / t is V _1mA per unit thickness in place of V _1mA in each table, it is marked with the allowable energy ratio instead of the allowable energy. The allowable energy ratio is a ratio to the allowable energy value when V _{1 mA} / t in the voltage non-linear resistor described in the above-mentioned publication is approximately 200 V / mm.

In Tables 1 to 6, samples No. 1 and No. 2 contained Pr, Co, Mg, ZnO in ZnO.
It is equivalent to a conventional voltage nonlinear resistor manufactured by adding only K, Cr, B, and Al, and is also shown for comparison.
No. 1 and No. 2 have different firing conditions. That is, sample No. 2
Is fired at a temperature lower than No. 1, and V _{1 mA} / t is 300 V / mm or more. However, comparing the allowable energy ratios, when V _{1 mA} / t is set to 300 V / mm or more,
It can be seen that the allowable energy is greatly reduced and cannot be put to practical use.

When V _{1 mA} / t, which is the object of the present invention, is set to 300 V / mm or more, the voltage non-linear resistor having an allowable energy equal to or more than that when V _{1 mA} / t is 200 V / mm is shown in Tables 1 and 2. Table, 4th
From Tables 6 to 6, samples No. 4 to 7 and No. 10 to 1 are common to each table.
3, No.16-18, No.21-23, No.26-28, No.31-34, No.37-4
0, No. 43 to No. 45. Taken together, the addition amount of each subcomponent suitable for the voltage nonlinear resistor of the present invention is such that Pr is 0.08 to
5.0 atomic%, Co is 0.1-10.0 atomic%, Mg is 0.01-5.0 atomic%,
K is 0.01 to 1.0 at%, Cr is 0.01 to 1.0 at%, B is 5 × 10 ^-4
１1 × 10 ^-1 atomic%, Al is 1 × 10 ^{-4 to} 5 × 10 ^-2 atomic%, and at least one of Sb, Nb, Ta or P is 1 × 10 ^-1 atomic% in total.
^It can be seen that the range is ^{-3 to} 5 × 10 ^-2 atomic%.

As described above, the voltage nonlinear resistor of the present invention is a composition system containing ZnO containing an appropriate amount of Pr, Co, Mg, K, Cr, B, Al as a subcomponent,
Further, by adding at least one of Sb, Nb, Ta, and P in an appropriate amount, an excellent surge energy absorbing ability can be provided even in a region where V _{1 mA} / t is as high as 300 V / mm or more. This is because Pr, Co, Mg, K, Cr, B, Al, Sb, Nb, Ta, P
Are achieved only when an appropriate amount of each of them coexists, and when these subcomponents are added alone, the voltage non-linearity is extremely poor, almost only ohmic characteristics are obtained, and it is impossible to put to practical use .

Note that, in the present embodiment, only Pr has been exemplified as the rare earth element to be added as an auxiliary component, but a rare earth element other than Pr may be used. Mg is also Ca or Mg and Ca added simultaneously, K is additionally Cs or Rb, or K, Cs, Rb is added simultaneously, A
l may be Ga or In or Al, Ga, In added simultaneously. Even in such a composition system, the same effect as described above was added to the addition of Sb, Nb, Ta, or P, which is the main feature of the present invention, as a result of another experiment.

Example 2 Pr ₆ O ₁₁ , CO ₃ O ₄ , K ₂ CO ₃ , Cr ₂ O ₃ powder and at least one of Sb ₂ O ₃ , Nb ₂ O ₅ and WO ₃ powder are described later in the ZnO powder. Was added in an amount corresponding to the predetermined atomic% described in Tables 7 to 10 above, mixed well, and then calcined at 500 to 1000 ° C. for several hours. Next, the calcined product was sufficiently pulverized, and a binder was added thereto to form a disc having a diameter of 17 mm under pressure, followed by firing for 1 hour in air at 1100 to 1400 ° C. to obtain a sintered body. The sintered body thus obtained was polished into a sample having a thickness of 2 mm, electrodes were baked on both surfaces thereof to produce an element, and the electrical characteristics of the element were measured.

The electrical characteristics are as follows: The electrode voltage V _{1 mA} when a current of 1 mA is applied to the element, a square wave current with a width of 2 ms is applied 20 times, and the current value without penetrating breakdown and creepage breakdown and the limiting voltage at that time The allowable energy was determined.

When the composition of the voltage non-linear resistor is variously changed, the measurement results of the electrical characteristics corresponding to those are shown in Tables 7 to 10. Table 7 shows that when Sb was added, and Table 8 also shows that Nb,
Table 9 shows W (reference example), and Table 10 shows the case where Nb and W were added. The composition shown in each table is represented by atomic% calculated from the ratio of the number of atoms of the additive element to the total number of atoms of each component metal element in the blended raw material. The V _1mA is V _1mA per unit thickness in place of V _1mA in the tables
Using / t, the allowable energy ratio is described instead of the allowable energy. The allowable energy ratio is a ratio to the allowable energy value when V _{1 mA} / t in the voltage non-linear resistor described in the above-mentioned publication is approximately 200 V / mm.

In Tables 7 to 10, samples No. 1 and No. 2 contained Pr, Co, K, and C in ZnO.
r corresponds to a conventional voltage non-linear resistor manufactured by adding only r, and is also shown for comparison.
o.2 has different firing conditions. That is, sample No.2 is No.1
When calcined at a lower temperature, _V1mA / t is 300 V / mm or more. However, comparing the allowable energy ratios, it can be seen that when V _{1 mA} / t is set to 300 V / mm or more, the allowable energy is significantly reduced and cannot be put to practical use.

When V _{1 mA} / t, which is the object of the present invention, is set to 300 V / mm or more, the voltage non-linear resistor having an allowable energy equal to or more than that when V _{1 mA} / t is 200 V / mm is shown in Tables 7 and 8. Table, Tenth
From the table, sample Nos. 4 to 8, No. 11 to 13, No. 16
No. 18, No. 21 to No. 23, No. 26 to No. 28. Taken together, the addition amounts of each subcomponent suitable for the voltage nonlinear resistor of the present invention are as follows: Pr is 0.1 to 5.0 atomic%, Co is 0.5 to 5.0 atomic%, and K is 0.05 to 0.05 atomic%.
It can be seen that 0.50.5 at%, Cr is 0.05 で 0.5 at%, and at least one of Sb and Nb is in the range of 1 × 10 ^{−3 to} 5 × 10 ^{−2 at} %.

As described above, the voltage non-linear resistor according to the present invention is obtained by adding a suitable amount of Pr, Co, K, Cr as a subcomponent to ZnO,
b, by adding at least one appropriate amount of Nb, V _1mA
Even in a high region where / t is 300 V / mm or more, it is possible to have excellent surge energy absorbing ability. This is Zn
O is achieved only when an appropriate amount of each of Pr, Co, K, Cr, Sb, and Nb coexists in O. When these subcomponents are added alone, the voltage nonlinearity is extremely poor, and only an almost ohmic characteristic is obtained. It cannot be obtained and cannot be put to practical use.

〔The invention's effect〕

As described above, the voltage non-linear resistor of the present invention containing ZnO as a main component, other subcomponents such as rare earth elements, and further adding at least one of Sb, Nb, Ta, and P and firing the same is V V _1mA / t even in the high region where _1mA / t is 300V / mm or more
Of about 200 V / mm can be obtained. This is extremely effective in reducing the size of equipment to which the voltage non-linear resistor is applied, for example, a lightning arrester and reducing the cost.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Tsuda 1-1-1, Tanabe-Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (56) References JP-A-60-46005 (JP, A) Hei 1-25205 (JP, B2) JP-B 62-14924 (JP, B2)

Claims (2)

(57) [Claims] 1. A zinc oxide as a main component, and at least one rare earth element as an auxiliary component in a total amount of 0.08 to 5.0 atomic%, cobalt of 0.1 to 10.0 atomic%, and at least one of magnesium and calcium of 0.01 to 5.0 atomic%. Atomic%, at least one of potassium, cesium, and rubidium in a total amount of 0.01 to 1.0 atomic%, chromium of 0.01 to 1.0 atomic%, boron of 5 × 10 ^-4 to 1 × 10 ^-1 atomic%, aluminum, gallium, and indium At least one of them is 1 × 10 ^{-4 in} total
-5 × 10 ^-2 atomic% and at least one of antimony, niobium, tantalum and phosphorus in a total amount of 1 × 10 ^{-3 to} 5 × 10
^A non-direct voltage low antibody characterized by being added and calcined in the range of ^-2 atomic%. 2. Zinc oxide as a main component, and praseodymium of 0.1 to 5.0 at% and cobalt of 0.5 to 5.0 as a subcomponent.
Atomic%, potassium 0.05-0.5 atomic%, chromium 0.05-
A non-voltage direct low antibody characterized in that 0.5 at%, at least one of antimony and niobium is added in a total amount of 1 × 10 ^{−3 to} 5 × 10 ^{−2 at} % and calcined.