US3899451A - Oxide varistor - Google Patents

Oxide varistor Download PDF

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Publication number
US3899451A
US3899451A US396135A US39613573A US3899451A US 3899451 A US3899451 A US 3899451A US 396135 A US396135 A US 396135A US 39613573 A US39613573 A US 39613573A US 3899451 A US3899451 A US 3899451A
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Prior art keywords
mol
zno
basic composition
voltage
varistor
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Expired - Lifetime
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US396135A
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English (en)
Inventor
Noboru Ichinose
Yuhji Yokomizo
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Toshiba Corp
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Tokyo Shibaura Electric Co Ltd
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Priority claimed from JP47090446A external-priority patent/JPS529302B2/ja
Priority claimed from JP47090447A external-priority patent/JPS529303B2/ja
Priority claimed from JP47092897A external-priority patent/JPS5224233B2/ja
Application filed by Tokyo Shibaura Electric Co Ltd filed Critical Tokyo Shibaura Electric Co Ltd
Application granted granted Critical
Publication of US3899451A publication Critical patent/US3899451A/en
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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

Definitions

  • Bi203 wT OXIDE VARISTOR This invention relates to a varistor prepared from an oxide semiconducttor, and more particularly to an oxide varistor having greater voltage-current nonlinear coefficient.
  • a voltage nonlinear resistance element As one of circuit elements based on a semiconductor, a voltage nonlinear resistance element is known. SiC varistors are known as a typical example. The element of this kind has nonlinear voltage-current characteristics, namely, is sharply reduced in resistance with increasing voltage to permit electric current to be markedly increased accordingly and has consequently been widely used for absorbing abnormally high voltage or for stabilization of voltage.
  • the voltage-current characteristics of the varistor may be expressed approximately in the following equation:
  • the characteristics of the varistor may be indicated by C and a or the two other constants which can replace them. Since accurate determination of C presents extreme difficulties, C is generally substituted by voltage Vc at a certain current C (mA). With the varistor voltage thus designated as Vc the voltage-current characteristics of the varistor may be indicated by V(' and the nonlinear coefficient a.
  • An SiC varistor heretofore well known as a varistor element has as small a voltage nonlinear coefficient a as 37.
  • a zener diode is known as having a larger voltage nonlinear coefficient.
  • the zener diode is expensive and in addition has a limited usage voltage of 200 V at most and is consequently inconvenient for use with electronic devices requiring for high voltage.
  • the zener diode involves a greater variation with temperature in the rising voltage and a smaller surge resistance, thus presenting practical problems.
  • US. Pat. No. 3,632,529 discloses a voltage variable resistor ceramic composition consisting essentially of zinc oxide and 0.05 to 10.0 mol of strontium oxide and, as an additive, 0.05 to 8.0 mol of bismuth oxide, lead oxide, calcium oxide or cobalt oxide.
  • This ceramic composition is different from an oxide semiconductor composition of an oxide varistor according to this invention.
  • the voltage nonlinear coefficient of the ceramic composition is of the order of 10 and is lower than that (more than 30) of the oxide varistor according to this invention.
  • US. Pat. No. 3,663,458 discloses a nonlinear bulktype resistor consisting essentially of a sintered body of 80.0 to 99.9 mol of ZnO, 0.05 to 10 mol Bi O and 0.05 to 10 mol in total of at least one member selected from the group consisting of C00, MnO In O Sb O TiO B 0 A1 0 SnO BaO, NiO, M00 Ta O Fe O and Cr O It will be evident from the following description that the composition of the sintered body is different from that of an oxide varistor according to this invention. According to this patent the content of SnO or TiO is as low as 0.05 to 10 mol and it is impossible to attain a predetermined performance in the practice of this invention. Furthermore, the resistor represents a relatively great change when electric current is supplied for a load life test.
  • An object of this invention is to provide an oxide varistor having a greater voltage nonlinear coefficient (a 30).
  • Another object of this invention is to provide a high performance oxide varistor capable of representing a lower rising voltage, a small change with temperature, a high surge resistance and a smaller change with time.
  • an oxide varistor prepared from a basic composition formed of to 14 mol of at least one Me'O 29 to mol of ZnO and l to 20 mol of Sb O l to 20 by weight of Bi O and 0.5 to 10 by weight of at least one Me" O based on said basic composition, wherein said Me' is a metal selected from the group consisting of Ti, Sn and Zr, and said Me" is a metal selected from the group consisting of Fe, Cr, Mn and Co.
  • FIG. 1 shows the content of Sb O and the resistivity of an Me'O -Zno-Sb O system in which the molar ratio of Me'O to ZnO is rendered constant;
  • FIG. 2 shows the molar ratio of Me'O to ZnO and the resistivity of the Me'O -Zno-Sb O system in which the content of sb og is rendered constant;
  • FIGS. 3A to 6C show a relation between the content of Bi- O and the voltage nonlinear coefficient a of an Me'O -Zno-Sb O -Bi O -Me" O system in which Me"' 0;; is used as a parameter.
  • An oxide varistor according to this invention can be prepared in the following manners. Accurately weighed out raw material metal oxides having a predetermined composition ratio are mixed together at a ball mill, etc., and after preliminarily sintered at a relatively low temperature, for example, at 600 to 900C, are powdered by the ball mill. As raw material used in this case, use
  • the powder so obtained is mixed with a binder such as polyvinyl alcohol, etc.
  • the mixture is shaped, under pressure of about I to 1,000 Kg/cm into a disc having a diameter of about 20 mm and a thickness of about 1 mm.
  • the disc is sintered generally in an air atmosphere at a temperature of about l,()00 to l,300C. During the sintering it is kept at a maximum temperature for about I to 6 hours. Then, electrodes are baked to the resultant disc to obtain a varistor.
  • oxide varistor according to this invention includes a basic composition formed of 70 to 14 mol of metal dioxide Me'O 29 to 85 mol of ZnO and l to 20 mol of Sb O
  • the metal dioxide is selected from TiO SnO Zro or a mixture thereof.
  • the content of Sb O is l to 20 mol
  • resistivity values as shown in FIG. 1 are obtained.
  • Sb O exceeds l mol the resistivity value is sufficiently lowered and is suitable for use as a varistor.
  • Sb O exceeds 20 mol the resistivity value is increased and is unsuitable for use as a varistor. Even if the resistivity presents no problem, sintered bodies are so porous that no desirable varistor is obtained from the practical viewpoint.
  • the content of Sb O be 5 to mol
  • the contents of Me'O and ZnO are 70 to 14 mol and 29 to 85 mol respectively.
  • the resistivity of the basic composition is as shown in FIG. 2.
  • the content of Me'O is outside the scope of 70 to 14 mol and the content of ZnO is outside the scope of 29 to 85 mol a resistivity is increased and the composition is unsuitable for the practice of this invention. Even if Me is replaced by Ti, Sn or Zr, the same trend will also be observed. Where it is desired to obtain a varistor having a relatively great voltage nonlinear coefficient,
  • the content of Me'O be in the range of 60 to 30 mol and the content of ZnO be in the range of 35 to 57 mol
  • the content of Me'O be 14 to mol or around 70 mol and the content of ZnO be 66 to 85 mol or around mol
  • An oxide varistor according to this invention contains, as an additive to the base Me'O -ZnO-Sb O composition, 1 to 20 weight of Bi O and 0.5 to 10 weight of Me" O
  • the Me" O is selected from Fe O Cr O Mn O- C0 0 or a mixture thereof.
  • FIGS. 3A to 6C show the voltage nonlinear coefficient a of resistors obtained by adding varying amounts of Bi O to a basic composition formed of 30 mol of Me'O 60 mol of ZnO and 10 mol of Sb O in which Me' O is used as a parameter.
  • FIGS. 3A to 6C show the case where Me' is Ti; figures with the suffix [2 added show the case where Me is Sn; and figures with the suffix 0 added show the case where Me' is Zr.
  • FIGS. 3A to 3C show the case where Me" is Fe; FIGS. 4A to 4C where Me" is Cr; FIGS. 5A to SC where Me" is Mn; and FIGS. 6A to 6C where Me" is Co.
  • An oxide varistor according to this invention has as high a voltage nonlinear coefficient 01 as more than 30 and presents extremely small changes with temperature in the rising voltage and a high surge resistance, thus attaining a high performance. Therefore, the varistor is suitably applicable to an arrester, a surge suppressor for vacuum breaker, etc., as well as to the protection of communication instruments against surge and the suppression of abnormal voltage involved in a microwave oven.
  • an oxide varistor according to this invention can be manufactured at lower cost, since the raw material is obtained at low cost.
  • the powders were mixed with polyvinyl alcohol acting as a binder and shaped under a pressure of 1,000 Kg/cm
  • the shaped powders were heated to a temperature ranging l,l00 to l,300C and kept at that temperature for 2 hours for sintering, thereby obtaining 147 discs having a diameter of 20 mm and a thickness of 1 mm.
  • silver electrodes were baked to the disc, resulting in a varistor.
  • An elemental Ag or Ag O may likewise be used as a starting material for silver electrodes. Since the sintered mass is stable to temperature, the electrode could be baked to the sintered disc over a wider range of about 400 to 800C.
  • the varistor having a voltage y (A/ 2) a basic composition formed of 14 to mol or about v 70 mol Of Me'O- 64 to 85 mol or about mol 7;; 2 4100 g 1 of ZnO and l to 20 mol of Sb O has a particularly 2: low rise volmge- 93 0:00i 34 20 324 With respect to some of the above-mentioned exam- 100 0.003 3240 35.1
  • the varistors outside the scope of this invention 2 gig for example, the sample Nos. 13, 26, 62, 75, l l 1, etc., 2, 8 1 the voltage nonlinear coefficient a exceeds 30 and they 9 0.002 3970 72.5 are favorably compared with some of the varistors acm O'003 4220 cordin to this invention.
  • An oxide varistor prepared from a basic composition consisting of a total of 70 to 14 mol of at least one compound of the formula Me'O 29 to 85 mol of ZnO and l to 20 mol of sb o and containing 1 to 20 by weight of Bi O and a total of 0.5 to by weight of at least one Me" O based on the weight 12 of said basic composition, wherein said Me is selected from the group consisting of Ti, Sn and Zr, said Me" is selected from the group consisting of Fe, Cr, Mn and Co.
  • the oxide varistor according to claim 1 wherein said basic composition consists of 60 to 30 mol of Me'O 35 to 57 mol of ZnO and 5 to 15 mol of Sb O 3.
  • the oxide varistor according to claim 1, wherein the amount of said Me'0 of the basic composition is 20 to 14 mol and the amount of said ZnO of the basic composition is 66 to 85 mol 4.
  • An oxide varistor having a nonlinear voltage coefficient (a) greater than 30, a change with temperature in rising voltage of less than 0.003%/C and a surge resistance of more than 3,000 A/cm said oxide varistor being prepared from a basic composition consisting of a total of 70 to 14 mol of at least one compound of the formula Me'O 29 to mol of ZnO and l to 20 mol of Sb O and containing 1 to 20 by weight of Bi O and a total of 0.5 to 10 by weight of at least one Me" O based on the weight of said basic composition, wherein said Me is selected from the group consisting of Ti, Sn and Zr, and said Me" is selected from the group consisting of Fe, Cr, Mn and Co.

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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)
US396135A 1972-09-11 1973-09-11 Oxide varistor Expired - Lifetime US3899451A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP47090446A JPS529302B2 (enrdf_load_stackoverflow) 1972-09-11 1972-09-11
JP47090447A JPS529303B2 (enrdf_load_stackoverflow) 1972-09-11 1972-09-11
JP47092897A JPS5224233B2 (enrdf_load_stackoverflow) 1972-09-18 1972-09-18

Publications (1)

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US3899451A true US3899451A (en) 1975-08-12

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US (1) US3899451A (enrdf_load_stackoverflow)
CA (1) CA1001399A (enrdf_load_stackoverflow)
CH (1) CH604341A5 (enrdf_load_stackoverflow)
DE (1) DE2345753C3 (enrdf_load_stackoverflow)
FR (1) FR2199173B1 (enrdf_load_stackoverflow)
GB (1) GB1450581A (enrdf_load_stackoverflow)
IT (1) IT997586B (enrdf_load_stackoverflow)
SE (1) SE385750B (enrdf_load_stackoverflow)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4054531A (en) * 1974-11-07 1977-10-18 Tdk Electronics Co., Ltd. Ceramic dielectric composition
US4165351A (en) * 1975-09-25 1979-08-21 General Electric Company Method of manufacturing a metal oxide varistor
US4296002A (en) * 1979-06-25 1981-10-20 Mcgraw-Edison Company Metal oxide varistor manufacture
US4394297A (en) * 1981-05-26 1983-07-19 Phillips Petroleum Company Zinc titanate catalyst
EP0074177A3 (en) * 1981-08-24 1983-08-31 General Electric Company Metal oxide varistor with controllable breakdown voltage and capacitance
US4495482A (en) * 1981-08-24 1985-01-22 General Electric Company Metal oxide varistor with controllable breakdown voltage and capacitance and method of making
US4516105A (en) * 1981-07-16 1985-05-07 Tokyo Shibaura Denki Kabushiki Kaisha Metal oxide varistor with non-diffusable electrodes
US5382385A (en) * 1991-09-30 1995-01-17 Somar Corporation Sintered varistor material with small particle size
US6184771B1 (en) * 1998-05-25 2001-02-06 Kabushiki Kaisha Toshiba Sintered body having non-linear resistance characteristics

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5366561A (en) * 1976-11-26 1978-06-14 Matsushita Electric Ind Co Ltd Thick film varistor composition
JPS53143952A (en) * 1977-05-21 1978-12-14 Mitsubishi Electric Corp Protective device for anomalous voltage

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3669907A (en) * 1966-12-07 1972-06-13 Matsushita Electric Ind Co Ltd Semiconductive elements
US3778743A (en) * 1973-02-23 1973-12-11 Matsushita Electric Ind Co Ltd Voltage-nonlinear resistors
US3805114A (en) * 1972-03-01 1974-04-16 Matsushita Electric Ind Co Ltd Voltage-nonlinear resistors
US3806765A (en) * 1972-03-01 1974-04-23 Matsushita Electric Ind Co Ltd Voltage-nonlinear resistors

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3669907A (en) * 1966-12-07 1972-06-13 Matsushita Electric Ind Co Ltd Semiconductive elements
US3805114A (en) * 1972-03-01 1974-04-16 Matsushita Electric Ind Co Ltd Voltage-nonlinear resistors
US3806765A (en) * 1972-03-01 1974-04-23 Matsushita Electric Ind Co Ltd Voltage-nonlinear resistors
US3778743A (en) * 1973-02-23 1973-12-11 Matsushita Electric Ind Co Ltd Voltage-nonlinear resistors

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4054531A (en) * 1974-11-07 1977-10-18 Tdk Electronics Co., Ltd. Ceramic dielectric composition
US4165351A (en) * 1975-09-25 1979-08-21 General Electric Company Method of manufacturing a metal oxide varistor
US4296002A (en) * 1979-06-25 1981-10-20 Mcgraw-Edison Company Metal oxide varistor manufacture
US4394297A (en) * 1981-05-26 1983-07-19 Phillips Petroleum Company Zinc titanate catalyst
US4516105A (en) * 1981-07-16 1985-05-07 Tokyo Shibaura Denki Kabushiki Kaisha Metal oxide varistor with non-diffusable electrodes
EP0074177A3 (en) * 1981-08-24 1983-08-31 General Electric Company Metal oxide varistor with controllable breakdown voltage and capacitance
US4495482A (en) * 1981-08-24 1985-01-22 General Electric Company Metal oxide varistor with controllable breakdown voltage and capacitance and method of making
US5382385A (en) * 1991-09-30 1995-01-17 Somar Corporation Sintered varistor material with small particle size
US6184771B1 (en) * 1998-05-25 2001-02-06 Kabushiki Kaisha Toshiba Sintered body having non-linear resistance characteristics

Also Published As

Publication number Publication date
CH604341A5 (enrdf_load_stackoverflow) 1978-09-15
DE2345753B2 (de) 1977-07-21
CA1001399A (en) 1976-12-14
AU6002673A (en) 1975-03-06
FR2199173B1 (enrdf_load_stackoverflow) 1976-10-01
FR2199173A1 (enrdf_load_stackoverflow) 1974-04-05
IT997586B (it) 1975-12-30
DE2345753C3 (de) 1978-03-09
SE385750B (sv) 1976-07-19
DE2345753A1 (de) 1974-03-21
GB1450581A (en) 1976-09-22

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