US3760318A - Process for making a voltage dependent resistor - Google Patents

Process for making a voltage dependent resistor Download PDF

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Publication number
US3760318A
US3760318A US00283283A US3760318DA US3760318A US 3760318 A US3760318 A US 3760318A US 00283283 A US00283283 A US 00283283A US 3760318D A US3760318D A US 3760318DA US 3760318 A US3760318 A US 3760318A
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US
United States
Prior art keywords
oxide
sintered body
ions
zinc oxide
voltage dependent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00283283A
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English (en)
Inventor
T Masuyama
M Matsuura
A Iga
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Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP46066188A external-priority patent/JPS5126999B2/ja
Priority claimed from JP46066187A external-priority patent/JPS5128439B2/ja
Priority claimed from JP46066186A external-priority patent/JPS5123035B2/ja
Priority claimed from JP46066185A external-priority patent/JPS5225950B2/ja
Priority claimed from JP46072797A external-priority patent/JPS5146267B2/ja
Priority claimed from JP46072798A external-priority patent/JPS5127000B2/ja
Priority claimed from JP46074351A external-priority patent/JPS5221200B2/ja
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Application granted granted Critical
Publication of US3760318A publication Critical patent/US3760318A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/49082—Resistor making

Definitions

  • ABSTRACT A voltage dependent resistor comprising a sintered body of zinc oxide having: (1). voltage dependent properties by itself, (2). at least one member selected from the group consisting of L: ions and Na ions diffused in the side surface thereof, and (3). two electrodes applies to the opposite surfaces thereof.
  • the invention also provides a process for making said resistor.
  • This invention relates to a preparation of a voltage dependent resistor due to the bulkthereof and more particularly a varistor comprising zinc oxide sintered body having Li ions or Na ions diffused from the side surface of the sintered body;
  • n l (V/C)" where V is the voltage across the resistor, I isthe current flowing through the resistor, C is a constant corresponding to the voltage at a given current and exponent n is a numerical value greater than 1. The value of n is calculated by the following equation:
  • V and V are voltages at a given currents I and 1 respectively.
  • the desired value of C depends upon the kind of application to which the resistor is tobe'put. It is ordinarily desirable that the value of n be as large as possible since this exponentdetermines the degree to which the resistors depart from ohmic characteristics.
  • the voltage dependent resistors comprising germanium or silicon p-n junction diodes are difficult to control the C-value over a wide range because the non-linearity of these voltage dependent resistors is not attributed to the bulk but to the p-n junction.
  • the silicon carbide varistors have the non-linearity due to the contacts among individual grains of silicon carbide bonded together by a ceramic binding material i.e., to the bulk and are controlled in the C-value by changing a dimension in a direction to which the current flows through the varistors.
  • the silicon carbide varistors have a rel atively low n-value ranging from 3 to 6 and are prepared by firing in non-oxidizing atmosphere, especially, in a purpose to obtain a lowerC-value.
  • voltage dependent resistors comprising sintered bodies of zinc oxide with additives such as bismuth oxide, uranium oxide, strontium oxide,'lead oxide, barium oxide, cobalt oxide and manganese oxide.
  • additives such as bismuth oxide, uranium oxide, strontium oxide,'lead oxide, barium oxide, cobalt oxide and manganese oxide.
  • the non-linearity of such voltage dependent resistors is attributed to the bulk thereof and is independent of the interface between the sintered bodies and electrodes. Therefore, it
  • Such voltage dependent resistors in a bulk type have more excellent properties in n-value, transient power dissipation and AC power dissipation than SiC varistors.
  • a disadvantage of the zinc oxide voltage-dependent resistors exists in their poor stability in an electric load life test in high humidity ambient. When DC. power is applied to the zinc oxide sintered body in a high humidity ambient, the sintered body shows a decrease in the surface electrical resistance. The decrease causes particularly an increase in the leakage current in the zinc oxide voltage-dependent resistor-of a bulk type and results in the poor non-linear property.
  • the deterioration of the non-linear property of the voltage-dependent resistor occurs still in the load of low power such as that lower than 0.01 watt in high humidity ambient, for example 90 percent R.H at 70 C ambient. Therefore, it is necessary that the sintered body are assured completely f0 ity' ambient.
  • Another object of thepresent invention is to provide a method for making a voltage dependent resistor characterized'by both a high n-value and a high stability for (Le. load in high humidity ambient.
  • FIGURE is a partly cross-sectional view of a voltage-dependent resistor in accordance with the invention.
  • reference character 10 designates, as a whole, a voltagedependent resistor comprising, as its active element, a sintered body having surfaces consisting of a side surface 2 and opposite surfaces 3 and 4 to which'a pair of electrodes 5 and 6 are applied.
  • Said sintered body 1 is prepared in a manner hereinafter set forth and have a diffusion layer of Li ions or Na ions 11 at said side surface 2 and is in any form-such as circular, square or rectangular plate form.
  • Wire leads 8 and 9 are attached conductively to the electrodes 5 and 6, respectively, by a connection means 7 such as solder or the like.
  • a process for making a voltage dependent resistor characterized by a high humidity resistance comprises: f
  • Said zinc oxide sintered body havng. voltage dependent properties by itself can be prepared by using a.
  • C cobalt oxide
  • MnO manganese oxide
  • SrO antimony oxide
  • PbO lead oxide
  • the diffusion process referred to herein can be achieved by any suitable and available method such as firing said sintered body covered, at the side surface, with powder of lithium compound or sodium compound which is converted into lithium oxide or sodium oxide at the firing temperature.
  • a prefereable method is to coat said sintered body with a paste including the lithium compound or the sodium compound at the side surface-and to heat at a given temperature for a given time.
  • An assurance of humidity stability requires a diffusion length not less than 0.01mm in accordance with the present invention.
  • the diffusion length can be easily controlled by diffusion temperature and diffusion time in a manner per se well known in the art. The higher diffusion temperature or the longer diffusion time results in the longer diffusion length.
  • lithium ions achieve a higher stability for humidity at the same diffusion length.
  • the D.C. stability of resultant resistor in high humidity is remarkably improved when said paste comprises, as a solid ingredient, 0.5 to 10.0 wt. parts of U 0 and at least one member selected from the group consisting of 0.01 to 10.0 wt. parts of C00. 0.01 to 10.0 wt. parts of MnO, 0.01 to 10.0 wt. parts of Ag O, 0.01 to 10.0 wt. parts of Cr O and 0.01 to 10.0 wt. parts of MO.
  • the resultant resistor shows excellent D.C. stability in high humidity test when said paste comprises, as a solid ingredient, 0.8 to 10.0 wt. percent lithium oxide (Li,O),-50.0 to 80.0 wt. percent of barium oxide (BaO) and 10.0 to 40.0 wt. percent of boron trioxide (8,0,).
  • the sintered body 1 can be prepared by a per se well known ceramic technique.
  • the starting materials comprising zinc oxide powder and additives such as bismuth oxide, cobalt oxide, manganese oxide, antimony oxide, barium oxide, strontium oxide, lead oxide, uranium oxide and tin oxide 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 IOOKg/cm. to LOOOKg/cm.
  • the mixed slurry can be fabricated into the desired shape by extruding method and then dried.
  • the pressed or extruded bodies are sintered in air at a temperature of 1,000 to 1,450 C for l to 5 hours, and then furnace-cooled to room temperature.
  • the sintering temperature is determined from the view of electrical resistivity, nonlinearity and stability.
  • the electrical resistivity also can be reduced by airquenching from the sintering temperature to room temperature.
  • the mixtures may be preliminarily calcined at 700 to 1,000 C and pulverized for easy fabrication in the subsequent pressing step.
  • the mixtures may be admixed with a suitable binder such as water, polyvinyl alcohol, etc.
  • the said sintered body 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.
  • the sintered body is coated, at a side surface, with a paste including, Li oxide powder or Na oxide powder fired at a given temperature in oxidizing atmosphere so as to diffuse Li ions or Na ions into the bulk of said sintered body and then cooled to room temperature.
  • Said paste comprises, as a solid ingredient, lithium oxide powder with or without further additives or sodium oxide powder and, as a binding material, an organic resin such as epoxy, vinyl and phenol resin in an organic solvent such as butyl acetate, toluene or the like.
  • Said lithium oxide or sodium oxide can be replaced with any lithiumcompound or sodium compound such as oxalate, carbonate, nitrate, sulfate, iodide, bromide, fluoride, amid, hydroxyde, imide, or oxychloride which is converted into, lithium oxide or sodium oxide which diffuses easily into said sintered body as lithium ions or sodium ions at the firing temperature.
  • the binding material is burned out during firing.
  • the firing temperature and time depend on the weight of lithium or sodium component included in the applied paste and should be controlled so that the Li ions or Na ions diffuses into said sintered body to the depth not less than 0.01 mm. Therefore, the higher diffusion temperature requires the shorter diffusion time.
  • the side surface layer of sintered body having Li ions or Na ions diffused therein shows very high electrical resistivity and assures a high humidity stability.
  • the firing temperature higher than 1,000 C results in the rapid diffusion of Li ions and Na ions and makes it too difficult to control the diffusion time to a given value of the diffusion depth.
  • the sintered body is applied with electrodes at the opposite surfaces of the sintered body.
  • Said electrodes can be made by any available methodsuch as heating of noble metal paint, electroless or electrolytic plating of Ag, Cu, Ni, Sn etc., vacuum evapolating Al, Zn, Sn etc. and flame spraying of Cu, Sn, Al, Zn etc. in accordance with the prior well known technique.
  • said electrodes are formed by heating noble metal paint at a higher temperature than said diffusion temperature, said process of forming two electrodes is preferably carried out before said diffusing process.
  • Lead wires can be attached to the electrodes in a per se conventional manner by using conventional solder. It is convenient to employ a conductive adhesive com- EXAMPLE 2 Starting materials according to Table 2 are completed to the voltage dependent resistor and tested in the same manner as that of Example 1 except the following processes;

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Thermistors And Varistors (AREA)
  • Compositions Of Oxide Ceramics (AREA)
US00283283A 1971-08-27 1972-08-24 Process for making a voltage dependent resistor Expired - Lifetime US3760318A (en)

Applications Claiming Priority (7)

Application Number Priority Date Filing Date Title
JP46066188A JPS5126999B2 (enrdf_load_stackoverflow) 1971-08-27 1971-08-27
JP46066187A JPS5128439B2 (enrdf_load_stackoverflow) 1971-08-27 1971-08-27
JP46066186A JPS5123035B2 (enrdf_load_stackoverflow) 1971-08-27 1971-08-27
JP46066185A JPS5225950B2 (enrdf_load_stackoverflow) 1971-08-27 1971-08-27
JP46072797A JPS5146267B2 (enrdf_load_stackoverflow) 1971-09-17 1971-09-17
JP46072798A JPS5127000B2 (enrdf_load_stackoverflow) 1971-09-17 1971-09-17
JP46074351A JPS5221200B2 (enrdf_load_stackoverflow) 1971-09-22 1971-09-22

Publications (1)

Publication Number Publication Date
US3760318A true US3760318A (en) 1973-09-18

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Family Applications (1)

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US00283283A Expired - Lifetime US3760318A (en) 1971-08-27 1972-08-24 Process for making a voltage dependent resistor

Country Status (8)

Country Link
US (1) US3760318A (enrdf_load_stackoverflow)
CA (1) CA970476A (enrdf_load_stackoverflow)
FR (1) FR2150879B1 (enrdf_load_stackoverflow)
GB (1) GB1387674A (enrdf_load_stackoverflow)
HK (1) HK6977A (enrdf_load_stackoverflow)
IT (1) IT962223B (enrdf_load_stackoverflow)
NL (1) NL174887C (enrdf_load_stackoverflow)
SE (1) SE382135B (enrdf_load_stackoverflow)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3811103A (en) * 1972-09-20 1974-05-14 Matsushita Electric Ind Co Ltd Voltage-nonlinear resistors
US3872582A (en) * 1972-12-29 1975-03-25 Matsushita Electric Ind Co Ltd Process for making a voltage dependent resistor
US3905006A (en) * 1972-12-29 1975-09-09 Michio Matsuoka Voltage dependent resistor
US3916366A (en) * 1974-10-25 1975-10-28 Dale Electronics Thick film varistor and method of making the same
US3999159A (en) * 1974-04-05 1976-12-21 Matsushita Electric Industrial Co., Ltd. Voltage-dependent resistor
US4064475A (en) * 1976-07-12 1977-12-20 Allen-Bradley Company Thick film varistor and method of making the same
US4069465A (en) * 1976-07-12 1978-01-17 Allen-Bradley Company Cylindrical varistor and method of making the same
EP0074177A3 (en) * 1981-08-24 1983-08-31 General Electric Company Metal oxide varistor with controllable breakdown voltage and capacitance
US4452728A (en) * 1983-02-18 1984-06-05 Westinghouse Electric Corp. Voltage stable nonlinear resistor containing minor amounts of aluminum, boron and selected alkali metal additives
US4495482A (en) * 1981-08-24 1985-01-22 General Electric Company Metal oxide varistor with controllable breakdown voltage and capacitance and method of making
US4692735A (en) * 1984-04-25 1987-09-08 Hitachi, Ltd. Nonlinear voltage dependent resistor and method for manufacturing thereof
US20110079755A1 (en) * 2009-10-01 2011-04-07 Abb Technology Ag High field strength varistor material
US20110204287A1 (en) * 2008-11-17 2011-08-25 Mitsubishi Electric Corporation Voltage nonlinear resistor, lightning arrester equipped with voltage nonlinear resistor, and process for producing voltage nonlinear resistor
US20180099910A1 (en) * 2016-10-12 2018-04-12 Thinking Electronic Industrial Co., Ltd. Varistor composition and multilayer varistor

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3503029A (en) * 1968-04-19 1970-03-24 Matsushita Electric Ind Co Ltd Non-linear resistor
US3611070A (en) * 1970-06-15 1971-10-05 Gen Electric Voltage-variable capacitor with controllably extendible pn junction region

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3503029A (en) * 1968-04-19 1970-03-24 Matsushita Electric Ind Co Ltd Non-linear resistor
US3611070A (en) * 1970-06-15 1971-10-05 Gen Electric Voltage-variable capacitor with controllably extendible pn junction region

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3811103A (en) * 1972-09-20 1974-05-14 Matsushita Electric Ind Co Ltd Voltage-nonlinear resistors
US3872582A (en) * 1972-12-29 1975-03-25 Matsushita Electric Ind Co Ltd Process for making a voltage dependent resistor
US3905006A (en) * 1972-12-29 1975-09-09 Michio Matsuoka Voltage dependent resistor
US3999159A (en) * 1974-04-05 1976-12-21 Matsushita Electric Industrial Co., Ltd. Voltage-dependent resistor
US3916366A (en) * 1974-10-25 1975-10-28 Dale Electronics Thick film varistor and method of making the same
US4064475A (en) * 1976-07-12 1977-12-20 Allen-Bradley Company Thick film varistor and method of making the same
US4069465A (en) * 1976-07-12 1978-01-17 Allen-Bradley Company Cylindrical varistor and method of making the same
US4495482A (en) * 1981-08-24 1985-01-22 General Electric Company Metal oxide varistor with controllable breakdown voltage and capacitance and method of making
EP0074177A3 (en) * 1981-08-24 1983-08-31 General Electric Company Metal oxide varistor with controllable breakdown voltage and capacitance
US4452728A (en) * 1983-02-18 1984-06-05 Westinghouse Electric Corp. Voltage stable nonlinear resistor containing minor amounts of aluminum, boron and selected alkali metal additives
US4692735A (en) * 1984-04-25 1987-09-08 Hitachi, Ltd. Nonlinear voltage dependent resistor and method for manufacturing thereof
US20110204287A1 (en) * 2008-11-17 2011-08-25 Mitsubishi Electric Corporation Voltage nonlinear resistor, lightning arrester equipped with voltage nonlinear resistor, and process for producing voltage nonlinear resistor
US8562859B2 (en) * 2008-11-17 2013-10-22 Mitsubishi Electric Corporation Voltage nonlinear resistor, lightning arrester equipped with voltage nonlinear resistor, and process for producing voltage nonlinear resistor
US20110079755A1 (en) * 2009-10-01 2011-04-07 Abb Technology Ag High field strength varistor material
US9672964B2 (en) * 2009-10-01 2017-06-06 Abb Schweiz Ag High field strength varistor material
US20180099910A1 (en) * 2016-10-12 2018-04-12 Thinking Electronic Industrial Co., Ltd. Varistor composition and multilayer varistor
US10233123B2 (en) * 2016-10-12 2019-03-19 Thinking Electronic Industrial Co., Ltd. Varistor compositions and multilayer varistor

Also Published As

Publication number Publication date
GB1387674A (en) 1975-03-19
HK6977A (en) 1977-02-11
FR2150879B1 (enrdf_load_stackoverflow) 1976-10-29
NL174887C (nl) 1984-08-16
FR2150879A1 (enrdf_load_stackoverflow) 1973-04-13
IT962223B (it) 1973-12-20
NL174887B (nl) 1984-03-16
DE2242621A1 (de) 1973-03-29
CA970476A (en) 1975-07-01
DE2242621B2 (de) 1975-11-20
NL7211572A (enrdf_load_stackoverflow) 1973-03-01
SE382135B (sv) 1976-01-12

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