JP2004079697A - Manufacturing method of nonlinear voltage resistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a nonlinear voltage resistor excellent in resistance to static discharge and concretely the nonlinear voltage resistor restraining the deterioration of insulation resistance so as to be small even when the test of resistance to static discharge is repeated at 30kV. <P>SOLUTION: The manufacturing method of the nonlinear voltage resistor is provided with a process to obtain mixed powder by mixing zinc oxide powder, manganese oxide powder or manganese compound powder and material powder containing bismuth oxide powder, a process to obtain calcination powder by crushing the mixed powder after calcining the same, a process to obtain a form by forming the calcined powder so as to have a predetermined configuration and a process to burn the form. In this case, the D<SB>50</SB>of the manganese oxide powder or the manganese compound powder is specified so as to be 1.0-1.7μm and the D<SB>90</SB>of the same is specified so as to be 2.0-3.5μm or the D<SB>50</SB>of the bismuth oxide power is specified so as to be 0.8-1.3μm and the D<SB>90</SB>of the same is specified so as to be 1.5-2.0μm. <P>COPYRIGHT: (C)2004,JPO

Description

【００１７】
表１に示すように、ＭｎＣＯ_３（ＭｎＯ_２），Ｂｉ_２Ｏ_３のうちいずれか一方のＤ_５０およびＤ_９０が本発明の範囲内にあるものは、バリスタ電圧が２５Ｖ以上と高く維持しながら、３０ｋＶ耐静電気放電試験を正負各１０回行っても、ＬｏｇＩＲ劣化幅を２．０００以下とすることができる。また、これらのＤ_５０およびＤ_９０を本発明の範囲内において小さくすればするほどＬｏｇＩＲ劣化幅をより小さくすることができ、特にＭｎＣＯ_３（ＭｎＯ_２）のＤ_５０を１．５μｍ以下、およびＤ_９０を２．５μｍ以下とした場合や、Ｂｉ_２Ｏ_３のＤ_５０を１．０μｍ以下、およびＤ_９０を１．７μｍ以下とした場合は、ＬｏｇＩＲ劣化幅を１．０００以下とすることができる。
【００１８】
ここで、請求項１においてマンガン酸化物粉末またはマンガン化合物粉末のＤ_５０の上限を１．７μｍ、かつＤ_９０の上限を３．５μｍとしたのは、試料番号５のように、Ｄ_５０が１．７μｍより大きく、Ｄ_９０が３．５μｍより大きい場合は、ＬｏｇＩＲ劣化幅が２．０００より大きくなってしまい、好ましくないからである。一方、マンガン酸化物粉末またはマンガン化合物粉末のＤ_５０の下限を１．０μｍ、かつＤ_９０の下限を２．０μｍとしたのは、Ｄ_５０を１．０μｍより小さく、Ｄ_９０を２．０μｍより小さくしたとしても、ＬｏｇＩＲ劣化幅をさらに低減する効果が実質的になくなり、工業的なメリットがないうえ、作製が困難だからである。
【００１９】
また、請求項２においてビスマス酸化物粉末のＤ_５０の上限を１．３μｍ、かつＤ_９０の上限を２．０μｍとしたのは、試料番号１１のように、Ｄ_５０が１．３μｍより大きく、Ｄ_９０が２．０μｍより大きい場合は、ＬｏｇＩＲ劣化幅が２．０００より大きくなってしまい、好ましくないからである。一方、ビスマス酸化物粉末のＤ_５０の下限を０．８μｍ、かつＤ_９０の下限を１．５μｍとしたのは、Ｄ_５０を０．８μｍより小さく、Ｄ_９０を１．５μｍより小さくしたとしても、ＬｏｇＩＲ劣化幅をさらに低減する効果がなくなり、工業的なメリットがないうえ、作製が困難だからである。
【００２０】
なお、実施例１においては、酸化マンガンとしてＭｎＯ_２を用いたが、これがＭｎ_３Ｏ_４等であっても構わない。
（実施例２）
Ｄ_５０が３．２μｍ、Ｄ_９０が７．１μｍのＭｎＣＯ_３、Ｄ_５０が１．８μｍ、Ｄ_９０が４．５μｍのＢｉ_２Ｏ_３を用いて得た仮焼粉末をさらに１φの小径ジルコニアメディアを用いた循環式微粉砕機であるナノミルで循環処理することによって、仮焼粉末のＤ_９０およびＤ_９９を表２に示すものとなるように調整したこと以外は、実施例１と同様にして積層型バリスタを得た。
【００２１】
上記のようにして得られた積層型バリスタの耐静電気放電特性を調べるために、積層型バリスタに対して３０ｋＶの静電気放電を正負各１０回行ったときのＩＲ劣化幅、すなわちＩＲの常用対数値（ＬｏｇＩＲ）を測定した。その結果を表２に示す。
【００２２】
【表２】

【００２３】
表２に示すように、仮焼粉末のＤ_９０およびＤ_９９が本発明の範囲内にあるものは、バリスタ電圧が２５Ｖ以上と高く維持しながら、３０ｋＶ耐静電気放電試験を正負各１０回行っても、ＬｏｇＩＲ劣化幅を２．０００以下とすることができる。また、これらのＤ_９０およびＤ_９９を本発明の範囲内において小さくすればするほどＬｏｇＩＲ劣化幅をより小さくすることができ、特に仮焼粉末のＤ_９０を１．０μｍ以下、Ｄ_９９を１．３μｍ以下とした場合は、ＬｏｇＩＲ劣化幅を１．０００以下とすることができる。
【００２４】
ここで、請求項３において仮焼粉末のＤ_９０の上限を１．２μｍ、かつＤ_９９の上限を１．６μｍとしたのは、試料番号１５のように、Ｄ_９０が１．２μｍより大きく、Ｄ_９９が１．６μｍより大きい場合は、ＬｏｇＩＲ劣化幅が２．０００より大きくなってしまい、好ましくないからである。一方、仮焼粉末のＤ_９０の下限を０．８μｍ、かつＤ_９９の下限を１．０μｍとしたのは、Ｄ_９０を０．８μｍより小さく、Ｄ_９９を１．０μｍより小さくしたとしても、ＬｏｇＩＲ劣化幅をさらに低減する効果が実質的になくなり、工業的なメリットがないうえ、作製が困難だからである。
【００２５】
【発明の効果】
本発明の電圧非直線抵抗体の製造方法は、使用する酸化亜鉛粉末と、マンガン酸化物粉末またはマンガン化合物粉末と、ビスマス酸化物粉末とを含む原料粉末のうち、マンガン酸化物粉末またはマンガン化合物粉末のＤ_５０を１．０〜１．７μｍとし、かつＤ_９０を２．０〜３．５μｍとするか、ビスマス酸化物粉末のＤ_５０を０．８〜１．３μｍとし、かつＤ_９０を１．５〜２．０μｍとしているので、得られる電圧非直線抵抗体を耐静電気放電に優れたものとすることができる。
【００２６】
また、仮焼粉末のＤ_９０を１．２μｍ以下とし、かつＤ_９９を１．６μｍ以下としているので、得られる電圧非直線抵抗体を耐静電気放電に優れたものとすることができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a voltage non-linear resistor, particularly a voltage non-linear resistor mainly composed of zinc oxide.
[0002]
2. Description of the Related Art
Conventionally, as a voltage nonlinear resistor used in a varistor, a resistor mainly composed of zinc oxide having a high voltage nonlinear coefficient has been widely used. The following method is generally used as a method for manufacturing the voltage non-linear resistor. That is, oxide powders or compound powders of the elements constituting the voltage non-linear resistor are weighed and mixed so as to have a desired composition ratio. This is calcined at 700 to 900 ° C, a calcined powder obtained by pulverization is molded, and then calcined at 880 to 920 ° C. The voltage non-linear resistor mainly composed of zinc oxide manufactured in this way has an electrostatic discharge resistance of about 8 to 25 kV.
[0003]
On the other hand, in the mobile phone market in recent years, there is a strong demand for electronic components used in mobile phones to improve the anti-static discharge characteristics. In particular, varistors are required to satisfy the anti-static discharge characteristics of 30 kV. Have been.
[0004]
However, the conventional voltage non-linear resistor has a problem that the insulation resistance is significantly deteriorated when the positive and negative 30 kV electrostatic discharge tests are performed 10 times each.
[0005]
An object of the present invention is to provide a method for manufacturing a voltage non-linear resistor excellent in electrostatic discharge resistance, specifically, a voltage non-linear resistor capable of suppressing the deterioration of insulation resistance to a small degree even when an electrostatic discharge test of 30 kV is repeated. To provide.
[0006]
[Means for Solving the Problems]
The present invention has been made in view of the above objects.
The method for producing a voltage non-linear resistor according to the present invention includes the steps of mixing a raw material powder containing a zinc oxide powder, a manganese oxide powder or a manganese compound powder, and a bismuth oxide powder to obtain a mixed powder; After calcining the powder, a voltage non-linear process comprising a step of pulverizing to obtain a calcined powder, a step of forming the calcined powder into a predetermined shape to obtain a compact, and a step of firing the compact. a method of manufacturing a resistor, said manganese oxide powder or manganese compound _{D 50} of the powder and 1.0～1.7Myuemu, and characterized by a 2.0~3.5μm the _{D 90.}
[0007]
A step of mixing a raw material powder containing a zinc oxide powder, a manganese oxide powder or a manganese compound powder, and a bismuth oxide powder to obtain a mixed powder; A method for producing a voltage non-linear resistor, comprising: a step of obtaining a calcined powder; a step of molding the calcined powder into a predetermined shape to obtain a molded body; and a step of calcining the molded body. the _{D 50} of the oxide powder and 0.8～1.3Myuemu, and characterized by a 1.5~2.0μm the _{D 90.}
[0008]
As described above, the manganese oxide used as the raw material powder powder or manganese compound powder or by adjusting the bismuth oxide powder of one of the at least one D ₅₀ and D _90, the voltage non-linear with improved antistatic discharge characteristics It can be a resistor. Note that D ₅₀ is a value at which the cumulative value of the volume particle size distribution is 50%, and D ₉₀ is a value at 90%.
[0009]
The present inventors have paid attention to the fact that discharged static electricity passes through a portion of a zinc oxide crystal grain boundary having a low interface state and causes insulation deterioration, and by uniformly increasing this interface state, static electricity is reduced. It has been found that deterioration of insulation resistance due to discharge can be suppressed. That is, by removing the coarse particles from one of the raw material powders containing manganese element or bismuth element which is a component forming the interface state of the zinc oxide crystal grain boundary, the raw material powder containing other elements is removed. Is improved, and the interface state at the zinc oxide crystal grain boundary is uniformly increased. As a result, deterioration of insulation resistance due to electrostatic discharge can be suppressed.
[0010]
A step of mixing a raw material powder containing a zinc oxide powder, a manganese oxide powder or a manganese compound powder, and a bismuth oxide powder to obtain a mixed powder; A method for producing a voltage non-linear resistor comprising: a step of obtaining a calcined powder; a step of forming the calcined powder into a predetermined shape to obtain a molded body; and a step of calcining the molded body. the _{D 90} of the baked powder and 1.2μm or less, and characterized by a 1.6μm or less _{D 99.}
[0011]
As described above, by adjusting the manganese oxide powder or manganese compound powder or regardless of D _50, D ₉₀ of bismuth oxide powder,, D ₉₀ and D ₉₉ of the calcined powder is used as raw material powder, antistatic discharge A voltage nonlinear resistor having improved characteristics can be obtained. D ₉₉ is a value at which the cumulative value of the volume particle size distribution is 99%.
[0012]
The present inventors have paid attention to the fact that the discharged static electricity passes through the thin portion of the zinc oxide crystal grain boundary phase and causes insulation deterioration, and reduces the thickness variation of the grain boundary phase to reduce the variation in the thickness of the grain boundary phase. It has been found that deterioration of insulation resistance can be suppressed. That is, by reducing D _{90 and} especially D ₉₉ of the calcined powder, it is possible to suppress the variation in the crystal particle diameter of zinc oxide, and to suppress the variation in the thickness of the grain boundary phase. As a result, deterioration of insulation resistance due to electrostatic discharge can be suppressed.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the method for manufacturing the voltage non-linear resistor of the present invention will be described.
(Example 1)
First, powders of ZnO, Bi ₂ O ₃ , MnCO ₃ , MnO ₂ , Co ₂ O ₃ , and Sb ₂ O ₃ were prepared as raw material powders. Among them, Bi ₂ O ₃ powder, MnCO ₃ powder, and MnO ₂ powder were prepared so as to satisfy D ₅₀ and D ₉₀ shown in Table 1. Note that D ₅₀ and D ₉₀ of the Bi ₂ O ₃ powder, MnCO ₃ powder, and MnO ₂ powder were adjusted by wet pulverization with a ball mill which is a container driving medium mill. This raw material powder was weighed so as to have the following composition ratio, and was wet-mixed with a ball mill to obtain a mixed powder.
_{98.00mol% ZnO + 0.50mol% Bi 2} O 3 + 0.50mol% MnCO 3 ( or _{0.50mol% MnO 2) + 0.50mol%} Co 2 O 3 + 0.50mol% Sb 2 O 3
Next, the obtained mixed powder was calcined at 850 ° C. for 2 hours and pulverized with a ball mill to obtain a calcined powder. This calcined powder was put into an organic solvent together with an organic binder, and mixed to form a ceramic slurry. This ceramic slurry was formed by a doctor blade method and dried to obtain a ceramic green sheet. A predetermined number of the ceramic green sheets having the internal electrode paste printed thereon were laminated and pressed to form a laminate.
[0014]
Next, the laminate is cut into a predetermined shape and fired at 880 to 920 ° C. for 3 hours to obtain a sintered body including a voltage non-linear resistor and an internal electrode. The electrode paste was applied and baked at 900 ° C. to obtain a laminated varistor.
[0015]
In order to investigate the electrostatic discharge resistance characteristics of the multilayer varistor obtained as described above, the range of IR deterioration when positive and negative 10 times of 30 kV electrostatic discharge was performed on the multilayer varistor, that is, the common logarithmic value of IR (LogIR) was measured. Table 1 shows the results.
[0016]
[Table 1]

[0017]
As shown in Table _{1, MnCO 3 (MnO 2)} , which one of _{D 50} and _{D 90} any one of _Bi 2 _{O 3} is within the scope of the present invention, while maintaining the varistor voltage is as high as more than 25V , And 30 kV anti-static discharge test can be performed 10 times each for positive and negative, the LogIR deterioration width can be reduced to 2.000 or less. Further, the smaller the D ₅₀ and D ₉₀ within the range of the present invention, the smaller the LogIR degradation width can be. Particularly, the D ₅₀ of MnCO ₃ (MnO ₂ ) is 1.5 μm or less, and _{When 90 is set} to 2.5 μm or less, or when D ₅₀ of Bi ₂ O ₃ is set to 1.0 μm or less and D _{90 is set} to 1.7 μm or less, the LogIR deterioration width can be set to 1.000 or less. .
[0018]
Here, 1.7 [mu] m and the upper limit of the manganese oxide powder or manganese compound powder of _{D 50} as defined in claim 1, and had a 3.5μm upper limit of _{D 90,} as in Sample No. _{5, D 50} 1 If it is larger than 0.7 μm and D ₉₀ is larger than 3.5 μm, the LogIR deterioration width becomes larger than 2.000, which is not preferable. On the other hand, 1.0 .mu.m the lower limit of the manganese oxide powder or manganese compound powder of _{D 50,} and was a 2.0μm lower limit of _{D 90 is} less than 1.0 .mu.m and _{D 50,} from 2.0μm to _{D 90} This is because even if the size is reduced, the effect of further reducing the LogIR degradation width is substantially lost, and there is no industrial merit, and the fabrication is difficult.
[0019]
Further, 1.3 .mu.m the upper limit of bismuth oxide powder _{D 50} as defined in claim 2, and had a 2.0μm upper limit of _{D 90,} as in Sample No. _{11, D 50} is greater than 1.3 .mu.m, If D ₉₀ of greater than 2.0μm is, log IR degradation width becomes larger than 2.000, it is not preferable. On the other hand, 0.8 [mu] m the lower limit of the bismuth oxide powder _{D 50,} and was a 1.5μm lower limit of _{D 90 has} a _{D 50} less than 0.8 [mu] _m, even smaller than 1.5μm and _{D 90} This is because the effect of further reducing the degradation range of LogIR is lost, there is no industrial merit, and the fabrication is difficult.
[0020]
In addition, in Example 1, MnO ₂ was used as manganese oxide, but this may be Mn ₃ O ₄ or the like.
(Example 2)
A calcined powder obtained using MnCO ₃ having D ₅₀ of 3.2 μm and D ₉₀ of 7.1 μm and Bi ₂ O ₃ having D ₅₀ of 1.8 μm and D ₉₀ of 4.5 μm is further reduced to 1φ small-diameter zirconia media. The laminate was laminated in the same manner as in Example 1 except that D ₉₀ and D ₉₉ of the calcined powder were adjusted to be those shown in Table 2 by circulating with a nanomill which is a circulating pulverizer using the same. A mold varistor was obtained.
[0021]
In order to investigate the electrostatic discharge resistance characteristics of the multilayer varistor obtained as described above, the range of IR deterioration when positive and negative 10 times of 30 kV electrostatic discharge was performed on the multilayer varistor, that is, the common logarithmic value of IR (LogIR) was measured. Table 2 shows the results.
[0022]
[Table 2]

[0023]
As shown in Table 2, the calcined powders having D ₉₀ and D ₉₉ within the range of the present invention were subjected to a 30 kV electrostatic discharge test 10 times each for positive and negative while maintaining the varistor voltage as high as 25 V or more. Also, the LogIR deterioration width can be set to 2.000 or less. Also, log IR degradation width the smaller within the scope of the present invention these _{D 90} and _{D 99} can more be reduced that the, particularly following calcination powder 1.0μm the _{D 90 of, D 99} 1. When it is 3 μm or less, the LogIR degradation width can be 1.000 or less.
[0024]
Here, 1.2 [mu] m and the upper limit of _{D 90} of the calcined powder according to claim 3, and was a 1.6μm upper limit of _{D 99,} as in Sample No. _{15, D 90} is greater than 1.2 [mu] m, If D ₉₉ is larger than 1.6 μm, the LogIR deterioration width becomes larger than 2.000, which is not preferable. On the other hand, the lower limit of D ₉₀ of the calcined powder was set to 0.8 μm and the lower limit of D ₉₉ was set to 1.0 μm, even if D ₉₀ was smaller than 0.8 μm and D ₉₉ was smaller than 1.0 μm. This is because the effect of further reducing the LogIR degradation width is substantially lost, and there is no industrial merit, and the production is difficult.
[0025]
【The invention's effect】
The method for producing a voltage non-linear resistor according to the present invention includes the steps of: using a zinc oxide powder, a manganese oxide powder or a manganese compound powder, and a manganese oxide powder or a manganese compound powder among the raw material powders containing the bismuth oxide powder. a _{D 50} of the 1.0～1.7Myuemu, and either the 2.0~3.5μm the _{D 90,} the _{D 50} of the bismuth oxide powder and 0.8～1.3Myuemu, and _{D 90} 1 Since the thickness is set to 0.5 to 2.0 μm, the obtained voltage non-linear resistor can have excellent resistance to electrostatic discharge.
[0026]
Further, a calcined powder of a D ₉₀ and 1.2μm or less, and since the 1.6μm or less D _99, it is possible to improve the resulting voltage nonlinear resistor in antistatic discharge.

Claims (3)

Zinc oxide powder, manganese oxide powder or manganese compound powder, and a step of mixing a raw material powder containing a bismuth oxide powder to obtain a mixed powder,
After calcining the mixed powder, pulverizing to obtain a calcined powder,
A step of molding the calcined powder into a predetermined shape to obtain a molded body,
Baking the molded body;
A method for manufacturing a voltage non-linear resistor comprising:
Method of preparing the manganese oxide powder or a manganese compound _{D 50} of the powder and 1.0～1.7Myuemu, and the voltage nonlinear resistor, characterized in that the 2.0~3.5μm the _{D 90.} Zinc oxide powder, manganese oxide powder or manganese compound powder, and a step of mixing a raw material powder containing a bismuth oxide powder to obtain a mixed powder,
After calcining the mixed powder, pulverizing to obtain a calcined powder,
A step of molding the calcined powder into a predetermined shape to obtain a molded body,
Baking the molded body;
A method for manufacturing a voltage non-linear resistor comprising:
Method for producing a voltage nonlinear resistor in which said bismuth oxide _{D 50} of the powder and 0.8～1.3Myuemu, and the 1.5~2.0μm the _{D 90.} Zinc oxide powder, manganese oxide powder or manganese compound powder, and a step of mixing a raw material powder containing a bismuth oxide powder to obtain a mixed powder,
After calcining the mixed powder, pulverizing to obtain a calcined powder,
A step of molding the calcined powder into a predetermined shape to obtain a molded body,
Baking the molded body;
A method for manufacturing a voltage non-linear resistor comprising:
A method for producing a voltage non-linear resistor, wherein D ₉₀ of the calcined powder is 1.2 μm or less and D ₉₉ is 1.6 μm or less.