EP0243256B1 - Zusammenstellungen für Thermistoren mit negativen Temperaturkoeffizienten - Google Patents

Zusammenstellungen für Thermistoren mit negativen Temperaturkoeffizienten Download PDF

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Publication number
EP0243256B1
EP0243256B1 EP87400895A EP87400895A EP0243256B1 EP 0243256 B1 EP0243256 B1 EP 0243256B1 EP 87400895 A EP87400895 A EP 87400895A EP 87400895 A EP87400895 A EP 87400895A EP 0243256 B1 EP0243256 B1 EP 0243256B1
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EP
European Patent Office
Prior art keywords
copper
atomic percent
nickel
barium
composition
Prior art date
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Expired - Lifetime
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EP87400895A
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English (en)
French (fr)
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EP0243256A1 (de
Inventor
Roland Carnet
Alain Lagrange
Jean-Pierre Caffin
Abel Rousset
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Compagnie Europeenne de Composants Electroniques LCC CICE
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Compagnie Europeenne de Composants Electroniques LCC CICE
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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
    • H01C7/04—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 having negative temperature coefficient
    • H01C7/042—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 having negative temperature coefficient mainly consisting of inorganic non-metallic substances
    • H01C7/043—Oxides or oxidic compounds

Definitions

  • the present invention relates to compositions for thermistors with negative temperature coefficient, more particularly compositions for thermistors with negative temperature coefficient having a low resistivity, this resistivity being stable over time.
  • compositions for thermistors with negative temperature coefficient more particularly compositions for thermistors with negative temperature coefficient having a low resistivity, this resistivity being stable over time.
  • Such a composition comprising manganese, nickel and copper oxides is known from BE-A 475 405.
  • CTN thermistors compositions for thermistors with a negative temperature coefficient based on semiconductor oxides
  • thermistors of this type have a resistivity between 1,000 a.cm and 100,000 ⁇ .cm.
  • the present invention therefore aims to remedy this drawback by proposing new compositions for NTC thermistors of low resistivity, namely less than 25a.cm with a resistivity of high stability over time at a temperature of approximately 125 ° C.
  • the subject of the present invention is a composition for NTC thermistors based on oxides, comprising at least four cations including manganese, nickel and copper, characterized in a first embodiment in that, the fourth cation being barium or strontium, the composition comprises 40 to 67.7% in atomic percentage of manganese, 20 to 33% in atomic percentage of nickel, 12 to 20% in atomic percentage of copper and 0.4 to 7% in atomic percentage of barium or strontium, the composition comprising 100% by atomic percentage and characterized in a second embodiment in that, the fourth cation being calcium, the composition comprises 45 to 67.2% in atomic percentage of manganese, 20 to 33% by atomic percentage of nickel, 12 to 20% by atomic percentage of copper and 0.8 to 2% by atomic percentage of calcium, the composition comprising 100% by atomic percentage.
  • the percentage of the element chosen from barium, calcium and strontium was chosen so as to obtain a resistivity of less than approximately 25a.cm with an AR / R variation ⁇ 3% after approximately 1000 hours.
  • calcium decreases the electrical resistivity.
  • the percentage of copper should be limited to 20% to avoid sintering problems. On the other hand, for a percentage of copper less than 12%, the desired percentage of aging cannot be obtained.
  • the nickel level was chosen taking into account the fact that, in a manganese-nickel system, the resistivity decreases with an increase in the nickel rate passing through a minimum at a nickel rate of 22% in atomic percentage and that beyond this point, the resistivity increases again with the nickel content, as shown on the curve in FIG. 2.
  • the nickel content will be between 20 and 33%, the upper limit being determined by the manufacturing process used. In fact, in the case of a conventional powder mixing process, the nickel content must not exceed 24% if the desired resistivity is to be obtained. In the case of a chemical process, the atomic percentage of Ni can be 33% while giving good results.
  • the manganese ions are brought in the form of manganese oxide, the nickel ions in the form of nickel oxide, the copper ions in the form of copper oxide and the barium ions in the form of barium salt or oxide.
  • the manganese oxide will be in the form Mn0 2 , Mn 2 0 3 , Mns0 4 or a mixture of these elements, the nickel oxide in the NiO form, copper oxide in the form CuO, Cu 2 0, the barium salt or oxide in the form BaS0 4 , BaNOa, BaCO 3 , the salt or calcium oxide in the form CaS0 4 , CaNOa, CaCOa, strontium salt or oxide in the form SrS0 4 , SrNO 3 , SrCO 3 .
  • other types of oxides or salts can be envisaged.
  • the CTN thermistors having the compositions given above are produced using a powder technique known per se which consists in mixing the oxide powders in a grinder mixer, in drying them, in sieving them and in pressing them in the form of a disc in a known manner, then subjecting them to sintering at a temperature preferably between 1180 ° C. and 1250 ° C., the sintering preferably being carried out in a plateau of at least one hour.
  • the sintering temperature is important in the context of the present invention in order to obtain good stability of the resistivity over time.
  • the CTN thermistors having the compositions given above are obtained chemically, that is to say by heating a mixed oxalate of manganese, nickel, copper and barium or strontium or calcium, or a hydrate said oxalate, in an atmosphere consisting of a mixture of an inert gas and oxygen having a reduced partial pressure of oxygen at the decomposition temperature of the oxalate, the temperature is maintained until complete decomposition of the oxalate, the product obtained is heated in an inert atmosphere to a temperature between 420 ° C and 800 ° C for a time sufficient to obtain particles having the dimensions of the specific surface desired, then the compositions are transformed ceramic particles according to the usual methods.
  • Tests 1 to 10 of Table I and those of the other tables were carried out on thermistors prepared using the same process, namely a conventional process for the preparation of ceramics. Only the proportions between the various components or the sintering temperature have been modified as will be explained in each table. Tests 11 and 12 in Table 1 were carried out using the chemical method.
  • each thermistor has been prepared in a conventional manner. Powders of Mna0 4 , NiO, CuO and BaCO 3 or SrCOs or CaCO s incorporated in predetermined proportions so that the atomic percentages of the ions Mn, Ni, Cu and Ba or Sr or Ca are in accordance with the present invention been mixed and ground by liquid (water) in a mill containing zirconia beads, for example in a "Turbula" mill. The grinding was carried out for approximately two hours. A solution containing a polyvinyl alcohol binder is added to the slip for 1/4 hour. The composition thus obtained was dried in an oven at 120 ° C, then sieved through a 315 micron sieve.
  • the composition thus sieved was pressed in the form of discs using a hydraulic machine of known type under a pressure of between 3 and 4 tonnes / cm 2.
  • the discs thus obtained are sintered at a temperature between 1180 ° C and 1250 ° C , with a stop time of a total duration of one hour.
  • the sintering temperature is chosen as a function of the copper content, so as to obtain a resistivity and an A R / R ratio corresponding to those fixed.
  • the powders are prepared in the following manner: the manganese, nickel, copper and barium oxalates are mixed in the proportions corresponding to the formulas indicated in Table I, Examples 11 and 12. L 'mixed oxalate obtained is thermally decomposed at 700 ° C. The powder is shaped identically to the powder process previously described. The discs thus obtained are sintered at a temperature of 1180 ° C for two hours.
  • the discs are then covered with silver electrodes in a known manner and heat treated at 550 ° C.
  • Table 1 gives the influence of the barium level on a composition containing 15% Cu and 22% Ni.
  • the resistivity increases slightly with the barium content for a constant copper content.
  • the stability of ceramics containing barium is significantly improved since with a barium content of 0.4%, a relative change in resistance of 1.9% is obtained after 1000 hours.
  • Table II represents the influence of the percentage of copper when the percentage of barium is 1.6% and that of nickel 22%.
  • Table III represents the influence of the sintering temperature on certain compositions of the type of those tested in Table II.
  • Tables IV and V are identical to Table I and represent respectively the influence of the strontium rate and the calcium rate on the electrical characteristics of the NTC thermistors developed from the Mn, Ni, Cu system. In these tables, the thermistors are obtained using powder technology.

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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)

Claims (5)

1. Verbindung für NTC-Thermistoren auf Oxid-Basis, die wenigstens vier Katione enthält, unter ihnen das Mangan, das Nickel und das Kupfer, dadurch gekennzeichnet, daß das vierte Kation das Barium oder das Strontium ist und daß die Verbindung 40 bis 67,6 Atom-% Mangan, 20 bis 33 Atom-% Nickel, 12 bis 20 Atom-% Kupfer sowie 0,4 bis 7 Atom-% Barium oder Strontium beträgt, wobei die Verbindung 100% in Atom-% beträgt.
2. Verbindung für NTC-Thermistoren auf Oxid-Basis, die wenigstens vier Katione beträgt, unter ihnen das Mangan, das Nickel und das Kupfer, dadurch gekennzeichnet, daß das vierte Kation Kalzium ist und daß die Verbindung 45 bis 67,2 Atom-% Mangan, 20 bis 33 Atom-% Nickel, 12 bis 20 Atom-% Kupfer sowie 0,8 bis 2 Atom-% Kalzium enthält, wobei die Verbindung 100% in Atom-% beträgt.
3. Verbindung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß das Mangan in Form von Manganoxid, das Nickel in Form von Nickeloxid, das Kupfer in Form von Kupferoxid und das Barium, das Strontium sowie das Kalzium in Form von Salz zugeführt werden.
4. Verbindung nach Anspruch 3, dadurch gekennzeichnet, daß das Manganoxid sich in der Form Mn02, Mn203, Mn304, das Nickeloxid in der Form NiO, das Kupferoxid in der Form CuO, Cu20, das Bariumsalz in der Form CaCO3, CaS04, CaNO3 und das Strontiumsalz in der Form SrCO3, SrS04, SrN03 befinden.
5. Verfahren zum Herstellen von NTC-Thermistoren, das eine Verbindung nach einem der Ansprüche 1 bis 4 aufweist, welche darin besteht, Pulver der Verbindung zu vermischen, sie zu trocknen, zu sieben, sie in Scheibenform zu pressen und die Scheiben einem Sinternverfahren unterzuziehen, dadurch gekennzeichnet, daß die Sinterntemperatur zwischen 1180°C und 1300°C beträgt.
EP87400895A 1986-04-25 1987-04-17 Zusammenstellungen für Thermistoren mit negativen Temperaturkoeffizienten Expired - Lifetime EP0243256B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT87400895T ATE57788T1 (de) 1986-04-25 1987-04-17 Zusammenstellungen fuer thermistoren mit negativen temperaturkoeffizienten.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8606026A FR2598021B1 (fr) 1986-04-25 1986-04-25 Compositions pour thermistances a coefficient de temperature negatif
FR8606026 1986-04-25

Publications (2)

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EP0243256A1 EP0243256A1 (de) 1987-10-28
EP0243256B1 true EP0243256B1 (de) 1990-10-24

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EP87400895A Expired - Lifetime EP0243256B1 (de) 1986-04-25 1987-04-17 Zusammenstellungen für Thermistoren mit negativen Temperaturkoeffizienten

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EP (1) EP0243256B1 (de)
AT (1) ATE57788T1 (de)
DE (1) DE3765684D1 (de)
FR (1) FR2598021B1 (de)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2652675B1 (fr) * 1989-10-03 1994-01-28 Lcc Cie Europ Composants Electro Composition pour thermistances a coefficient de temperature negatif et de tres faible resistivite electrique.
CN111606693A (zh) * 2020-06-01 2020-09-01 东阳市聚冉电子科技有限公司 一种高温负温度系数热敏电阻材料的制备方法

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE914748C (de) * 1941-08-10 1954-07-08 Western Electric Co Elektrisches Widerstandsmaterial
BE475405A (de) * 1942-03-27
FR1129167A (fr) * 1955-07-19 1957-01-16 Csf Perfectionnements aux thermistances
US4324702A (en) * 1979-11-02 1982-04-13 Matsushita Electric Industrial Co., Ltd. Oxide thermistor compositions

Also Published As

Publication number Publication date
FR2598021B1 (fr) 1990-10-19
ATE57788T1 (de) 1990-11-15
DE3765684D1 (de) 1990-11-29
FR2598021A1 (fr) 1987-10-30
EP0243256A1 (de) 1987-10-28

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