US3598763A - Manganese-modified zinc oxide voltage variable resistor - Google Patents

Manganese-modified zinc oxide voltage variable resistor Download PDF

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Publication number
US3598763A
US3598763A US872590A US3598763DA US3598763A US 3598763 A US3598763 A US 3598763A US 872590 A US872590 A US 872590A US 3598763D A US3598763D A US 3598763DA US 3598763 A US3598763 A US 3598763A
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United States
Prior art keywords
oxide
mole percent
manganese
voltage variable
zinc oxide
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Expired - Lifetime
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US872590A
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English (en)
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Michio Matsuoka
Takeshi Masuyama
Yoshio Iida
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Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/10—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material voltage responsive, i.e. varistors
    • H01C7/105—Varistor cores
    • H01C7/108—Metal oxide
    • H01C7/112—ZnO type
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics

Definitions

  • a voltage variable resistor ceramic composition consisting essentially of zinc oxide and, as an additive, manganese oxide.
  • the manganese-modified zinc oxide voltage variable resistor has improved voltage nonlinear properties due to the further addition of barium oxide, strontium oxide, lead oxide, uranium oxide, cobalt oxide, bismuth oxide and calcium oxide.
  • This invention relates to compositions of ceramic voltage variable resistors having non-ohmic resistance, and more particularly to compositions of varistors comprising zinc oxide having non-ohmic resistance due to the bulk thereof.
  • n a numerical value greater than 1. The value of n is calculated by the following equation:
  • V and V are the voltages at given currents I and 1 respectively.
  • the desired value of C depends upon the kind of application to which the resistor is to be put. It is ordinarily desirable that the value of n be as large as possible since this exponent determines the extent to which the resistors depart from ohmic characteristics.
  • varistors comprising germanium or silicon p-n junction diodes
  • it is difiicult to control the C-value over a wide range because the voltage variable property of these varistors is not attributed to the bulk but to the p-n junction.
  • silicon carbide varistors have the voltage variable property due to the contacts among the individual grains of silicon carbide bonded together by a ceramic binding material, and the C-value is controlled by changing a dimension in a direction in which the current flows through the varistors.
  • the silicon carbide varistors however, have a relatively low n-value and are prepared by firing in non-oxidizing atmosphere, especially for the purpose of obtaining a lower C-value.
  • An object of the present invention is to provide a composition of a voltage variable resistor having nonohmic properties due to the bulk thereof and having a controllable C-value.
  • Another object of the present invention is to provide a composition of a voltage variable resistor characterized by a high n-value.
  • reference character 10 designates, as a whole, a voltage variable. resistor comprising, as its active element, a sintered body having a pair of electrodes 2 and 3 applied to opposite surfaces thereof.
  • Said sintered body 1 is prepared in a manner hereinafter set forth and is in any form such as circular, square or rectangular plate form.
  • Wire leads 5 and 6 are attached conductively to the electrodes 2 and 3, respectively, by a connection means 4 such as solder or the like.
  • a voltage variable resistor according to the invention comprises a sintered body of a composition consisting essentially of 90.0 to 99.95 mole percent of zinc oxide and 0.05 to 10.0 mole percent of manganese oxide.
  • Such a voltage variable resistor has non-ohmic resistance due to the bulk itself. Therefore, its C-value can be changed without impairing the n-value by changing the distance between said opposite surfaces. The shorter distance results in the lower C-value.
  • n-value can be obtained when said sintered body consists essentially of 97.0 to 99.9 mole percent of zinc oxide and 0.1 to 3.0 mole percent of manganese oxide in accordance with the invention.
  • the n-value can be elevated when said sintered body is of a composition consisting essentially of 82.0 to 99.9 mole percent of zinc oxide, 0.05 to 10.0 mole percent of manganese oxide and 0.05 to 0.8 mole percent of one oxide selected from the group consisting of barium oxide and cobalt oxide.
  • n-value can be obtained when said sintered body consists essentially of 94.0 to 99.8 mole percent of zinc oxide, 0.1 to 3.0 mole percent of manganese oxide and 0.1 to 3.0 mole percent of one oxide selected from the group consisting of barium oxide and cobalt oxide.
  • the stability for ambient temperature and the electric load life test can be improved when said sintered body consists essentially of 82.0 to 99.9 mole percent of zinc oxide, 0.05 to 10.0 mole percent of manganese oxide and 0.05 to 8.0 mole percent of calcium oxide.
  • said sintered body consists essentially of 94.0 to 99.8 mole percent of zinc oxide, 0.1 to 3.0 mole percent of manganese oxide and 0.1 to 3.0 mole percent of calcium oxide.
  • the n-value 1s elevated when said sintered body consists essentially of 82.0 to 99.9 mole percent of zinc oxide, 0.05 to 10.0 mole percent of manganese oxide and 0.05 to 8.0 mole percent of one oxide selected from the group consisting of strontium oxide, lead oxide and uranium oxide.
  • the n-valu-e is further elevated when said sintered body 1s of a composition consisting essentially of 94.0 to 99.8 mole percent of zinc oxide, 0.1 to 3.0 mole percent of manganese oxide and 0.1 to 3.0 mole percent of one oxide selected from the group consisting of strontium oxide, lead oxide and uranium oxide.
  • a combination of a high n-value and a low C-value can be obtained when said sintered body is of a composition consisting essentially of 74.0 to 99.85 mole percent of zinc oxide, 0.05 to 10.0 mole percent of manganese oxide, 0.05 to 8.0 mole percent of bisumuth oxide and 0.05 to 8.0 mole percent of one oxide selected from the group consisting of strontium oxide, lead oxide and uranium oxide.
  • the C-value is lowered and the n value is extremely elevated when said sintered body is of a composition consisting essentially of 91.0 to 99.7 mole percent of zinc oxide, 0.1 to 3.0 mole percent of manganese oxide, 0.1 to 3.0 mole percent of bismuth oxide and 0.1 to 3.0 mole percent of one oxide selected from the group consisting of strontium oxide, lead oxide and uranium oxide.
  • the high n-value also can be obtained when said sintered body is of a composition consisting essentially of 74.0 to 99.85 mole percent of zinc oxide, 0.05 to 10.0 mole percent of manganese oxide, 0.05 to 8.0 mole percent of lead oxide, and 0.05 to 8.0 mole percent of one oxide selected from the group consisting of strontium oxide, cobalt oxide and barium oxide.
  • the extremely high n-value and the low C- value also can be obtained when said sintered body is of a composition consisting essentially of 91.0 to 99.7 mole percent of zinc oxide and 0.1 to 3.0 mole percent of manganese oxide, 0.1 to 3.0 mole percent of lead oxide and 0.1 to 3.0 mole percent of one oxide selected from the group consisting of strontium oxide, cobalt oxide and barium oxide.
  • a combination of a high n-value and a high stability can be obtained when said sintered body is of a composition consisting essentially of 74.0 to 99.85 mole percent of zinc oxide, 005 to 10.0 mole percent of manganese oxide, 0.05 to 8.0 mole percent of lead oxide and 0.05 to 8.0 mole percent of calcium oxide. Further, a combination a high n-value and a high stability can be extremely promoted when said sintered body is of a composition consisting essentially of 91.0 to 99.7 mole percent of zinc oxide, 0.1 to 3.0 mole percent of manganese oxide, 0.1 to 3.0 mole percent of lead oxide and 0.1 to 3.0 mole percent of calcium oxide.
  • the sintered body 1 can be prepared by a per se Well known ceramic technique.
  • the starting materials in the compositions described in the foregoing description are mixed in a wet mill so as to produce homogeneous mixtures.
  • the mixtures are dried and pressed in a mold into desired shapes at a pressure from 100 kg./cm. to 1000 kg./cm
  • the pressed bodies are sintered in air at a given temperature for 1 to 3 hours, and then furnace-cooled to room temperature (about 15 to about 30 C.).
  • the available sintering temperature is determined in view of electrical resistivity, non-linearity and stability and ranges from 1000 to 1450 C.
  • the pressed bodies are preferably sintered in a nonoxidizin'g atmosphere such as nitrogen and argon when it is desired to reduce the electrical resistivity.
  • the mixture can be preliminarily calcined at 700 to 1000 C. and pulverized for easy fabrication in the subsequent pressing step.
  • the mixture to be pressed can be admixed with a suitable binder such as water, polyvinyl alcohol, etc.
  • the sintered body be lapped at the opposite surfaces by abrasive powder such as silicon carbide in a particle size of 300 meshes to 1500 meshes.
  • the sintered bodies are provided, at the opposite surfaces therefore, with electrodes in any available and suitable method such as electroplating method, vacuum evaporation method, metallizing method by spraying or silver painting method.
  • the voltage variable properties are not practically affected by the kinds of electrodes used, but are affected by the thickness of the sintered bodies. Particularly, the C-value varies in proportion to the thickness of the sintered bo ies, While t e n-v lne is lmc t ind p dent of the thickness. This surely means that the voltage variable property is due to the bulk itself, but not to the electrodes.
  • Lead wires can be attached to the electrodes in a per se conventional manner by using conventional solder having a low melting point. It is convenient to employ a conductive adhesive comprising silver powder and resin in an organic solvent in order to connect the lead wires to the electrodes.
  • Voltage variable resistors acocrding to this invention have a high stability to temperature and in the load life test, which is carried out at 70 C. at a rating power for 500 hours.
  • the n-value and C-value do not change remarkably after heating cycles and load life test. It is advantageous for achievement of a high stability to humidity that the resultant voltage variable resistors are embedded in a humidity proof resin such as epoxy resin and phenol resin in a per se well known manner.
  • EXAMPLE 1 A mixture of zinc oxide and manganese oxide in a composition of Table 1 are mixed in a wet mill for 3 hours. The mixture is dried and then calcined at 700 C. for 1 hour. The calcined mixture is pulverized by the motor-driven ceramic mortar for 30 minutes and then pressed in a mold into a disc of 17.5 mm. in diameter and 2.5 mm. in thickness at the pressure of 500 kg./cm.
  • the pressed body is sintered in air at 1150 C. for 1 hour, and then furnace-cooled to room temperature (about 15 to about 30 C.).
  • the sintered disc is lapped at the opposite surfaces thereof by silicon carbide in a particle size of 600 meshes.
  • the resulting sintered disc has a size of 14 mm. in diameter and 1.5 mm. in thickness.
  • Silver point electrodes commercially available are attached to the opposite surfaces of the sintered disc by painting. Then lead wires are attached to the silver electrodes by soldering.
  • the electric characteristics of the resultant resistors are shown in Table 1. It will be readily understood that the zinc oxide sintered body incorporated with manganese oxide in an amount of 0.05 to 10.0 mole percent is available for the voltage variable resistor. Particularly, the addition of manganese oxide in an amount of 0.1 to 3.0 mole percent makes the voltage nonlinear property more excellent.
  • the pressed body is sintered in air at 1150 C. for 1 hour, and then furnace-cooled to room temperature.
  • the sintered disc is ground at the opposite surfaces thereof into the thickness shown in Table 2 by silicon carbide in a particle size of 600 meshes.
  • the ground disc is provided with the electrodes and lead wires at the opposite surfaces in a manner similar to that of Example 1.
  • the electric characteristics of the resultant resistors are shown in Table 2: the C-'value varies approximately in proportion to the thickness of the sintered disc While the n-value G (at 1 ma.)
  • Zinc oxide containing the additions of Tables 3 and 4 is fabricated into voltage variable resistors by the same process as that of Example 1.
  • the n-vaIues of the resulting resistors are shown in Tables 3 and 4. It will be readily seen that the combination of manganese oxide with one oxide selected from the group consisting of strontium oxide, lead oxide and uranium oxide as additives results in an excellent voltage-nonlinear property and a remarkably excellent n-value can be obtained by the additive combination of manganese oxide and lead oxide with one oxide selected from the group consisting of strontium oxide, cobalt oxide and barium oxide.
  • EXAMPLE 4 Zinc oxide containing the additions of Table 5 is fabricated into voltage variable resistors by the same process as that of Example 1. The n-values of the resulting resistors are shown in Table 5. It will be readily understood that the combination of manganese oxide with one oxide selected from the group consisting of barium oxide and cobalt oxide as additive results in an excellent voltage nonlinear property.
  • EXAMPLE 5 Zinc oxide incorporated with manganese oxide and calcium oxide in the compositions of Table 6 is fabricated into voltage variable resistors by the same process as that of Example 1. The resulting resistors are tested according to the methods used in the electronic components parts. The load life test is carried out at 70 C. ambient temperacludes 0.05 to 8.0 mole percent of lead oxide and 0.05 to References Cited 8.0 mole percent of one oxide selected from the group con- UNITED STATES PATENTS sisting of barium oxide, strontium oxide, cobalt oxide and calcium i 2,258,646 10/ 1941 Gnsdale 252579 10.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Thermistors And Varistors (AREA)
  • Compositions Of Oxide Ceramics (AREA)
US872590A 1968-11-08 1969-10-30 Manganese-modified zinc oxide voltage variable resistor Expired - Lifetime US3598763A (en)

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JP8212568 1968-11-08

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US (1) US3598763A (de)
CA (1) CA918408A (de)
DE (1) DE1956817B2 (de)
FR (1) FR2023507A1 (de)
GB (1) GB1286134A (de)
NL (1) NL150257B (de)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3764566A (en) * 1972-03-24 1973-10-09 Matsushita Electric Ind Co Ltd Voltage nonlinear resistors
DE2500291A1 (de) 1974-02-20 1975-08-21 Matsushita Electric Ind Co Ltd Spannungsabhaengiger widerstand
US4041436A (en) * 1975-10-24 1977-08-09 Allen-Bradley Company Cermet varistors
US4045374A (en) * 1974-10-21 1977-08-30 Matsushita Electric Industrial Co., Ltd. Zinc oxide voltage-nonlinear resistor
US4077915A (en) * 1975-09-18 1978-03-07 Tdk Electronics Co., Ltd. Non-linear resistor
DE2835562A1 (de) * 1977-08-18 1979-03-01 Trw Inc Material fuer einen glasartigen elektrischen widerstand und verfahren zu dessen herstellung
US4147670A (en) * 1975-12-04 1979-04-03 Nippon Electric Co., Ltd. Nonohmic ZnO ceramics including Bi2 O3, CoO, MnO, Sb2 O.sub.3
US4172922A (en) * 1977-08-18 1979-10-30 Trw, Inc. Resistor material, resistor made therefrom and method of making the same
US5115221A (en) * 1990-03-16 1992-05-19 Ecco Limited Varistor structures
US5155464A (en) * 1990-03-16 1992-10-13 Ecco Limited Varistor of generally cylindrical configuration
US5235310A (en) * 1990-03-16 1993-08-10 Harris Corporation Varistor having interleaved electrodes
US5837178A (en) * 1990-03-16 1998-11-17 Ecco Limited Method of manufacturing varistor precursors
US5973588A (en) * 1990-06-26 1999-10-26 Ecco Limited Multilayer varistor with pin receiving apertures
US6183685B1 (en) 1990-06-26 2001-02-06 Littlefuse Inc. Varistor manufacturing method

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3764566A (en) * 1972-03-24 1973-10-09 Matsushita Electric Ind Co Ltd Voltage nonlinear resistors
DE2500291A1 (de) 1974-02-20 1975-08-21 Matsushita Electric Ind Co Ltd Spannungsabhaengiger widerstand
DE2500291B2 (de) 1974-02-20 1977-02-10 Matsushita Electric Industrial Co., Ltd., Kadotna, Osaka (Japan) Spannungsabhaengiger widerstand mit einer spannungsabhaengigkeit allein aufgrund der masse seines gesinterten koerpers
US4045374A (en) * 1974-10-21 1977-08-30 Matsushita Electric Industrial Co., Ltd. Zinc oxide voltage-nonlinear resistor
US4077915A (en) * 1975-09-18 1978-03-07 Tdk Electronics Co., Ltd. Non-linear resistor
US4041436A (en) * 1975-10-24 1977-08-09 Allen-Bradley Company Cermet varistors
US4147670A (en) * 1975-12-04 1979-04-03 Nippon Electric Co., Ltd. Nonohmic ZnO ceramics including Bi2 O3, CoO, MnO, Sb2 O.sub.3
US4146677A (en) * 1977-08-18 1979-03-27 Trw Inc. Resistor material, resistor made therefrom and method of making the same
DE2835562A1 (de) * 1977-08-18 1979-03-01 Trw Inc Material fuer einen glasartigen elektrischen widerstand und verfahren zu dessen herstellung
US4172922A (en) * 1977-08-18 1979-10-30 Trw, Inc. Resistor material, resistor made therefrom and method of making the same
US5115221A (en) * 1990-03-16 1992-05-19 Ecco Limited Varistor structures
US5155464A (en) * 1990-03-16 1992-10-13 Ecco Limited Varistor of generally cylindrical configuration
US5235310A (en) * 1990-03-16 1993-08-10 Harris Corporation Varistor having interleaved electrodes
US5837178A (en) * 1990-03-16 1998-11-17 Ecco Limited Method of manufacturing varistor precursors
US6334964B1 (en) 1990-03-16 2002-01-01 Littelfuse, Inc. Varistor ink formulations
US6743381B2 (en) 1990-03-16 2004-06-01 Littlefuse, Inc. Process for forming varistor ink composition
US5973588A (en) * 1990-06-26 1999-10-26 Ecco Limited Multilayer varistor with pin receiving apertures
US6183685B1 (en) 1990-06-26 2001-02-06 Littlefuse Inc. Varistor manufacturing method

Also Published As

Publication number Publication date
NL150257B (nl) 1976-07-15
DE1956817B2 (de) 1972-06-22
NL6916845A (de) 1970-05-12
FR2023507A1 (de) 1970-08-21
GB1286134A (en) 1972-08-23
CA918408A (en) 1973-01-09
DE1956817A1 (de) 1970-07-02

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