EP0189087B1 - Voltage-dependent electric resistance (varistor) - Google Patents

Voltage-dependent electric resistance (varistor) Download PDF

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Publication number
EP0189087B1
EP0189087B1 EP86100376A EP86100376A EP0189087B1 EP 0189087 B1 EP0189087 B1 EP 0189087B1 EP 86100376 A EP86100376 A EP 86100376A EP 86100376 A EP86100376 A EP 86100376A EP 0189087 B1 EP0189087 B1 EP 0189087B1
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European Patent Office
Prior art keywords
layers
varistor
voltage
weight
electrical resistor
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EP86100376A
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German (de)
French (fr)
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EP0189087A1 (en
Inventor
Günter Dipl.-Ing. Ott
Franz Dr. Zettl
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Siemens Bauelemente OHG
Siemens AG
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Siemens Bauelemente OHG
Siemens AG
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01CRESISTORS
    • H01C7/00Non-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
    • H01C7/10Non-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
    • H01C7/1006Thick film varistors
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01CRESISTORS
    • H01C17/00Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/06Apparatus or processes specially adapted for manufacturing resistors adapted for coating resistive material on a base
    • H01C17/065Apparatus or processes specially adapted for manufacturing resistors adapted for coating resistive material on a base by thick film techniques, e.g. serigraphy
    • H01C17/06506Precursor compositions therefor, e.g. pastes, inks, glass frits
    • H01C17/06513Precursor compositions therefor, e.g. pastes, inks, glass frits characterised by the resistive component
    • H01C17/06533Precursor compositions therefor, e.g. pastes, inks, glass frits characterised by the resistive component composed of oxides
    • H01C17/06546Oxides of zinc or cadmium
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01CRESISTORS
    • H01C7/00Non-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
    • H01C7/10Non-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
    • H01C7/102Varistor boundary, e.g. surface layers
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01CRESISTORS
    • H01C7/00Non-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
    • H01C7/10Non-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
    • H01C7/105Varistor cores
    • H01C7/108Metal oxide
    • H01C7/112ZnO type

Definitions

  • the invention relates to a voltage-dependent electrical resistor (varistor) consisting of a ceramic, monolithic body made of a large number of 20 to 350 ⁇ m thick layers of varistor material with grain sizes of 7 to 20 ⁇ m based on zinc oxide (ZnO) with up to 6 mol. % of additions of oxides of one or more of the metals Bi, Sb, Co, Ni, Cr, Mn, Mg, B, Al, Ba and serving as coatings, at most 10 ⁇ m thick noble metal layers, which alternate with the varistor material layers and alternate to different locations of the side surfaces of the body and there are electrically conductive and opposite polar contacts with other metal layers.
  • a voltage-dependent electrical resistor consisting of a ceramic, monolithic body made of a large number of 20 to 350 ⁇ m thick layers of varistor material with grain sizes of 7 to 20 ⁇ m based on zinc oxide (ZnO) with up to 6 mol. % of additions of oxides of one or more of the metals Bi, Sb,
  • Such a varistor is described in the publication “Advances in Ceramics” (American Ceram. Society, Columbus) 1981, Vol. 1, pages 349 to 358.
  • the average grain size is given there as 10 ⁇ m.
  • the response voltage per grain boundary is 2 to 3 V.
  • the information for the thickness of the varistor material layers is 20 to 200 ⁇ m, the properties of varistors having a layer thickness of 40 ⁇ m or 150 ⁇ m being measured with 20 layers stacked one on top of the other.
  • the non-linearity coefficient a is given as 20 to 30, while the varistor voltage, measured at 1 mA, is given as 4 to 40 volts.
  • Fired-in silver electrodes are specified as metal layers for contacting the coatings arranged alternately in the monolithic body on its surface. There is no further information about the material of the linings inside the monolithic body. There is also no information about the porosity of the material.
  • I 2 is an ampere
  • I 1 1 mA
  • U 2 is the voltage measured at 1 A
  • U is the voltage measured at 1 mA.
  • the voltage that is measured at 1 mA is defined as the varistor voltage on page 52.
  • the varistor voltage is used to classify varistors.
  • Varistors for low voltages so-called low-voltage varistors, which are manufactured using conventional technology, have grain sizes of approximately 100 ⁇ m and even larger in order to keep the number of grain boundaries between the layers low.
  • Low-voltage varistors manufactured in this way cannot generally be used to protect against higher voltages because the heat generated in the ceramic body cannot be dissipated.
  • the present invention has for its object to improve a voltage-dependent electrical resistance (varistor) of the type specified in such a way that the range of the varistor voltage is expanded so that in this way and from the same material, varistors with different varistor voltages can be produced that the The amount of palladium usually used for such components is reduced and that, last but not least, improved heat dissipation results.
  • varistor voltage-dependent electrical resistance
  • the low porosity which should preferably be less than 1%, ensures that the metal of the internal electrodes cannot penetrate into pores, which results in a shortened electrode gap, which leads to an early flashover (short circuit) when the pulse is loaded.
  • the reduction in the bismuth content from usually more than 2 mol% to at most 1 mol% and preferably 0.6 mol% has the effect that, on the one hand, the grain growth is reduced and thus the grain size distribution is evened out, and on the other hand, that the reaction of the deposits with the Ceramic material is avoided at the sintering temperature, which prevents alloying of the palladium with the consequence of the island formation of the deposits.
  • the toppings preferably consist of 70% by weight of silver and 30% by weight of palladium.
  • the ceramic body consists of varistor material layers, the thickness of which is in the range from 35 ⁇ m to 350 ⁇ m, thicker layers resulting in higher varistor voltages in the range from 4 volts to 350 volts.
  • the varistor body is preferably 1 to 10 mm long, 1 to 3.6 mm wide and 0.5 to 3 mm thick where where the thickness is always less than the smallest length or width.
  • the low bismuth content enables sintering temperatures of up to 1150 ° C, which means that with thin layer thicknesses and a corresponding number of layers, varistors can be produced with a varistor voltage down to 4 V.
  • varistors are manufactured using multilayer technology in the same way as is known, for example, for ceramic multilayer capacitors.
  • organic binder materials e.g. polymethyl acrylates, methyl cellulose, polyvinyl alcohol
  • solvents e.g. water, ethyl methyl ketone
  • plasticizers phthalates, esters
  • a sample of the inner coverings made from the specified silver-palladium compound is applied to pieces of postcard size in this way, after which a corresponding number of such postcard-sized films are stacked on top of one another such that the alternating displacement of the coverings results in the finished body.
  • the layer varistor is separated from the stack in its raw form and - after passing through a tempering and binder burnout cycle common in multi-layer technology - sintered at temperatures up to 1150 ° C.
  • the varistor body 1 is shown schematically, which consists of layers 2 of varistor material.
  • the coverings 3 and 4 alternate with varistor material layers 2, the coverings 3 in the present case being guided to the right outer surface 5 and the coverings 4 to the left outer surface 6 of the ceramic body.
  • the ceramic body 1 consists of a monolithic block, in the interior of which the coatings 3 and 4 are arranged. It is also possible for the coverings 3 and 4 to protrude on the same side of the monolithic block, the ends to be contacted then alternatingly ending at different locations on this surface side and being contacted there with opposite poles.
  • opposite-pole means that the coatings 3 on the surface 5 with a further metal layer 7, e.g. made of silver or another solderable metal, which is connected to a pole of the voltage source or the circuit, while the coatings 4 on the surface side 6 by the further metal layer 8, also made of silver or the like, connected to each other The opposite pole of the voltage source or the circuit are connected.
  • Reference number 9 denotes the thickness of the layers 2 made of varistor material.
  • a prerequisite for the operation of the varistor is that the distances 10 and 11 between the top layer 3 and the bottom layer 4 and the surface 14 or the surface 15, as well as the distances 12 of the layers 3 from the metal layer 8 and the distances 13 of the metal layers 4 to the metal layer 7 are each greater than the thickness 9 of the layers 2 made of varistor material.
  • varistor material layers 2 ′ are present, for example, which do not contain any coatings 3 or 4. In FIG. 1, this is due to the boundary lines 16 and 17 between the top layer 2 provided with a covering 3 and the layer 2 ′ without a covering or between the lower layer 2 provided with the covering 4 and the layer 2 without a covering 'shown.
  • the varistor according to the invention can be provided with power supply wires 18 and 19, which are soldered to the metal layers 7 or 8 or attached in some other way.
  • the varistor according to the invention is to be used as a chip by placing it on and attaching it to contact points on printed conductor tracks, then instead of the current supply wires there may be contact surfaces which, in the present example, through the extensions 20 and 21 in the metal layer 7 on the surfaces 14 and 15, and are represented by extensions 22 and 23 of the metal layer 8 on the surfaces 14 and 15.
  • the grid spacing 24 between the power supply wires 18 and 19 is to be defined, as is known per se for such components.
  • the necessary spacing 25 between the extensions 20 and 22 or 21 and 23 can be determined by appropriate choice of dimensions.
  • the UI diagram shown in FIG. 2 shows one of the advantages of the present invention, which consists in the fact that the small amount of bismuth in the varistor material and the possible use of silver in larger amounts for the coatings 3 and 4 compared to the palladium make alloying away of the metal of the coverings and thus an island formation which deteriorates the properties does not occur.
  • the island formation which is caused by alloying away the linings (migration), causes the terminal voltage to rise sharply at high currents, because the series resistance of the linings increases sharply due to this island formation.
  • FIG. 3 shows a U-I diagram in which a varistor of the present invention (curve 30) is compared with known varistors (curves 28 and 29).
  • curve 30 a varistor of the present invention
  • curves 28 and 29 known varistors
  • Curve 28 applies to varistors which consist of 20 varistor material layers each with a thickness of 40 gm, while curve 29 applies to known varistors with 20 varistor material layers each 150 ⁇ m thick.
  • Curve 30 applies to varistors of the present invention made of 50 layers each 30 ⁇ m thick.
  • the heat dissipation from the body with coatings of 70% silver and 30% palladium, each with a thickness of 2.0 ⁇ m, is sufficiently large to ensure the functionality of the varistor To ensure even at high currents or voltages.
  • the diagram according to FIG. 4 shows the varistor voltage as a function of the sintering temperature at a sintering time of one hour for varistors which consist of 10 layers, with different layer thicknesses being present.
  • the varistor voltage is given in volts on the ordinate and the sintering temperature t s in ° C on the abscissa.
  • the coatings consist of 70% silver and 30% palladium and are 2 ⁇ m thick.
  • Curve 31 applies to varistors with 10 layers, each with a layer thickness of 165 ⁇ m.
  • Curve 32 applies to varistors consisting of 10 layers with a layer thickness of 77 pm each.
  • Curve 33 applies to varistors with 10 layers each with a thickness of 37 ⁇ m and curve 34 applies to varistors with 10 layers each with a layer thickness of 23 p.m.
  • the protection level of varistors is the terminal voltage of a current pulse of the indicated current intensity that occurs at a varistor.
  • the terminal voltage is shown in volts on the ordinate, while the sintering temperature t s is given in ° C on the abscissa.
  • the specified varistor material ensures a dielectric strength of 300 V / mm, which ensures sufficient slope (non-linearity exponent a) even with thin layers.

Abstract

A voltage-dependent resistor or varistor is composed of a monolithic ceramic body made up of a plurality of layers of varistor material containing zinc oxide, alternating with layers of precious metal serving as coatings on the layers and which are alternatingly electrically connected to separate locations on the exterior surfaces of the body. The porosity of the layers of varistor material does not exceed 5%; the proportion of bismuth is at most 1 mol %; and the precious metal coatings include 50-80% by weight of palladium.

Description

Die Erfindung betrifft einen spannungsabhängigen elektrischen Widerstand (Varistor) bestehend aus einem keramisch hergestellten, monolithischen Körper aus einer Vielzahl von 20 bis 350 µm dicken Schichten aus Varistormaterial mit Korngrössen von 7 bis 20 µm auf der Basis von Zinkoxid (ZnO) mit bis 6 Mol-% an Zusätzen von Oxiden eines oder mehrerer der Metalle Bi, Sb, Co, Ni, Cr, Mn, Mg, B, Al, Ba und als Beläge dienenden, höchstens 10 µm dicken Edelmetallschichten, die mit den Varistormaterialschichten abwechseln und alternierend zu verschiedenen Stellen der Seitenflächen des Körpers geführt und dort mit weiteren Metallschichten elektrisch leitend und gegenpolig kontaktiert sind.The invention relates to a voltage-dependent electrical resistor (varistor) consisting of a ceramic, monolithic body made of a large number of 20 to 350 μm thick layers of varistor material with grain sizes of 7 to 20 μm based on zinc oxide (ZnO) with up to 6 mol. % of additions of oxides of one or more of the metals Bi, Sb, Co, Ni, Cr, Mn, Mg, B, Al, Ba and serving as coatings, at most 10 µm thick noble metal layers, which alternate with the varistor material layers and alternate to different locations of the side surfaces of the body and there are electrically conductive and opposite polar contacts with other metal layers.

Es handelt sich somitum einen Varistor, der in Vielschichttechnik hergestellt ist.It is therefore a varistor that is manufactured using multilayer technology.

Ein solcher Varistor ist in der Veröffentlichung «Advances in Ceramics» (American Ceram. Society, Columbus) 1981, Vol. 1, Seiten 349 bis 358 beschrieben. Die durchschnittliche Komgrösse ist dort mit 10 µm angegeben. Die Ansprechspannung pro Korngrenze beträgt 2 bis 3 V. Die Angaben für die Dicke der Varistormaterialschichten sind 20 bis 200 µm, wobei die Eigenschaften an Varistoren mit einer Schichtdicke von 40 µm bzw. 150 µm bei 20 übereinander gestapelten Schichten gemessen wurden. Der Nichtlinearitäts-Koeffizient a ist mit 20 bis 30 angegeben, während die Varistorspannung, gemessen bei 1 mA, mit 4 bis 40 Volt angegeben ist.Such a varistor is described in the publication “Advances in Ceramics” (American Ceram. Society, Columbus) 1981, Vol. 1, pages 349 to 358. The average grain size is given there as 10 µm. The response voltage per grain boundary is 2 to 3 V. The information for the thickness of the varistor material layers is 20 to 200 µm, the properties of varistors having a layer thickness of 40 µm or 150 µm being measured with 20 layers stacked one on top of the other. The non-linearity coefficient a is given as 20 to 30, while the varistor voltage, measured at 1 mA, is given as 4 to 40 volts.

Als Metallschichten zur Kontaktierung der alternierend im monolithischen Körper angeordneten Beläge an seiner Oberfläche sind eingebrannte Silberelektroden angegeben. Nähere Angaben über das Material der Beläge im Inneren des monolithischen Körpers sind nicht enthalten. Ebenso fehlen Angaben über die Porosität des Materials.Fired-in silver electrodes are specified as metal layers for contacting the coatings arranged alternately in the monolithic body on its surface. There is no further information about the material of the linings inside the monolithic body. There is also no information about the porosity of the material.

In der Veröffentlichung «Journal of Applied Physics», 54 (5) Mai 1983, Seiten 2764 bis 2772, die sich ebenfalls, wie auch die oben diskutierte Veröffentlichung, mit Niederspannungsvaristoren befasst, ist auf Seite 2765, linke Spalte, unter Bezugnahme auf die oben angegebene Veröffentlichung ausgeführt, Varistoren in Vielschichttechnik würden veringerte Stromdichte bei Überspannungen und hohe Kapazität aufweisen, ohne dass das Grundproblem der Korngrössenverteilung damit gelöst werde.In the publication "Journal of Applied Physics", 54 (5) May 1983, pages 2764 to 2772, which also, like the publication discussed above, deals with low-voltage varistors, on page 2765, left column, with reference to the above published publication, varistors in multi-layer technology would have reduced current density at overvoltages and high capacitance without solving the basic problem of grain size distribution.

In der SIEMENS-Broschüre «Edelgasgefüllte Überspannungsableiter; Metalloxid-Varistoren SIOV» von November 1984 sind auf den Seiten 44 bis 63 im einzelnen die theoretischen Grundlagen über Metalloxid-Varistoren auf der Basis von Zinkoxid erläutert, und es sind auch die Definitionen für die einzelnen Begriffe enthalten.In the SIEMENS brochure «Noble gas-filled surge arresters; Metal oxide varistors SIOV »from November 1984 on pages 44 to 63 explain in detail the theoretical basics about metal oxide varistors based on zinc oxide, and the definitions for the individual terms are also included.

So ist auf Seite 48 der Nichtlinearitätsexponent a angegeben mitSo on page 48 the non-linearity exponent a is given with

Figure imgb0001
I2 ist dabei ein Ampere, I1 = 1 mA, U2 ist die bei 1 A gemessene Spannung und U, ist die bei 1 mA gemessene Spannung.
Figure imgb0001
I 2 is an ampere, I 1 = 1 mA, U 2 is the voltage measured at 1 A and U, is the voltage measured at 1 mA.

Als Varistorspannung ist auf Seite 52 die Spannung definiert, die bei 1 mA gemessen wird. Die Varistorspannung dient zur Klassifizierung von Varistoren.The voltage that is measured at 1 mA is defined as the varistor voltage on page 52. The varistor voltage is used to classify varistors.

Varistoren für geringe Spannungen, sogenannte Niederspannungsvaristoren, die nach der üblichen Technik hergestellt werden, haben Korngrössen von ca. 100 µm und auch noch darüber, um die Zahl der Korngrenzen zwischen den Belägen gering zu halten.Varistors for low voltages, so-called low-voltage varistors, which are manufactured using conventional technology, have grain sizes of approximately 100 µm and even larger in order to keep the number of grain boundaries between the layers low.

Ein derartig grob kristallisierendes Material führt aber zu dem Problem, dass die Korngrössenverteilung stark streut und damit die Steilheit der I-U-Kennlinie (Nichtlinearität-Koeffizient a) stark absinkt.However, such a coarsely crystallizing material leads to the problem that the grain size distribution scatters strongly and thus the steepness of the I-U characteristic (non-linearity coefficient a) drops sharply.

Derartig hergestellte Niederspannungs-Varistoren sind in aller Regel zum Schutz gegen höhere Spannungen nicht einsetzbar, weil dann die Abfuhr der im Keramikkörper entstehenden Wärme nicht gewährleistet ist.Low-voltage varistors manufactured in this way cannot generally be used to protect against higher voltages because the heat generated in the ceramic body cannot be dissipated.

Der vorliegenden Erfindung liegt die Aufgabe zugrunde, einen spannungsabhängigen elektrischen Widerstand (Varistor) der eingangs angegebenen Art dahingehend zu verbessern, dass der Bereich der Varistorspannung erweitert wird, dass auf diesem Wege und aus dem gleichen Material Varistoren mit unterschiedlichen Varistorspannungen hergestellt werden können, dass die Menge des für derartige Bauelemente üblicherweise verwendeten Palladiums verringert wird und dass nicht zuletzt eine verbesserte Wärmeableitung resultiert.The present invention has for its object to improve a voltage-dependent electrical resistance (varistor) of the type specified in such a way that the range of the varistor voltage is expanded so that in this way and from the same material, varistors with different varistor voltages can be produced that the The amount of palladium usually used for such components is reduced and that, last but not least, improved heat dissipation results.

Zur Lösung dieser Aufgabe ist der spannungsabhängige elektrische Widerstand der eingangs angegebenen Art erfindungsgemäss dadurch gekennzeichnet, dass

  • a) die Porosität der Varistormaterialschichten des Keramikkörpers 5% nicht übersteigt,
  • b) der Anteil an Wismuth (Bi, gerechnet als Bi203) im Varistormaterial 0,4 bis höchstens 1 Mol-% (entsprechend 2 bis 5 Gew.-%) beträgt und
  • c) die Beläge aus 50 bis 80 Gew.-% Silber (Ag) und 50 bis 20 Gew.-% Palladium (Pd) bestehen.
To achieve this object, the voltage-dependent electrical resistance of the type specified at the outset is characterized in that
  • a) the porosity of the varistor material layers of the ceramic body does not exceed 5%,
  • b) the proportion of bismuth (Bi, calculated as Bi 2 0 3 ) in the varistor material is 0.4 to at most 1 mol% (corresponding to 2 to 5% by weight) and
  • c) the coatings consist of 50 to 80 wt .-% silver (Ag) and 50 to 20 wt .-% palladium (Pd).

Durch die geringe Porosität, die vorzugsweise weniger als 1 % betragen soll, wird gewährleistet, dass das Metall der Innenelektroden nicht in Poren eindringen kann, wodurch nämlich eine verkürzte Elektrodenstrecke entsteht, die bei Impulsbelastung zu einem frühzeitigen Überschlag (Kurzschluss) führt. Die Verringerung des Wismuthanteiles von üblicherweise mehr als 2 Mol-% auf höchstens 1 Mol-% und vorzugsweise 0,6 Mol-% bewirkt, dass einerseits das KornwacHstum verringert und damit die Korngrössenverteilung vergleichmässigt wird, und andererseits, dass die Reaktion der Beläge mit dem Keramikmaterial bei der Sintertemperatur vermieden wird, wodurch ein Weglegieren des Palladiums mit der Folge der Inselbildung der Beläge vermieden wird.The low porosity, which should preferably be less than 1%, ensures that the metal of the internal electrodes cannot penetrate into pores, which results in a shortened electrode gap, which leads to an early flashover (short circuit) when the pulse is loaded. The reduction in the bismuth content from usually more than 2 mol% to at most 1 mol% and preferably 0.6 mol% has the effect that, on the one hand, the grain growth is reduced and thus the grain size distribution is evened out, and on the other hand, that the reaction of the deposits with the Ceramic material is avoided at the sintering temperature, which prevents alloying of the palladium with the consequence of the island formation of the deposits.

Vorzugsweise bestehen die Beläge aus 70 Gew.- % Silber und 30 Gew.-% Palladium.The toppings preferably consist of 70% by weight of silver and 30% by weight of palladium.

Ferner ist es vorteilhaft, wenn der Keramikkörper aus Varistormaterialschichten besteht, deren Dicke im Bereich von 35 µm bis 350 µm liegt, wobei dickere Schichten höhere Varistorspannungen im Bereich von 4 Volt bis 350 Volt ergeben.It is also advantageous if the ceramic body consists of varistor material layers, the thickness of which is in the range from 35 μm to 350 μm, thicker layers resulting in higher varistor voltages in the range from 4 volts to 350 volts.

Der Varistorkörper ist vorzugsweise 1 bis 10 mm lang, 1 bis 3,6 mm breit und 0,5 bis 3 mm dick, wobei die Dicke stets geringer als die geringste Länge bzw. Breite ist.The varistor body is preferably 1 to 10 mm long, 1 to 3.6 mm wide and 0.5 to 3 mm thick where where the thickness is always less than the smallest length or width.

Die bevorzugte Zusammensetzung des Varistormaterials ist wie folgt (Angaben in Mol-% und jeweils dahinter in Klammer gesetzt in Gew.-%):

  • Zn0 94,6 (87,3), Bi203 0,6 (3,2), Sb203 1,6 (5,1), C0304 0,4 (1,1), Ni0 1,3 (1,1), Cr2O3 0,6 (1,1), MnC03 0,8 (1,02), Mg0 0,06 (0,003), B203 0,033 (0,05), AI203 0,002 (0,017) und BaC03 0,005 (0,001
The preferred composition of the varistor material is as follows (data in mol% and in brackets in% by weight):
  • Zn0 94.6 (87.3), Bi 2 0 3 0.6 (3.2), Sb 2 0 3 1.6 (5.1), C 03 0 4 0.4 (1.1), Ni0 1.3 (1.1), Cr 2 O 3 0.6 (1.1), MnC0 3 0.8 (1.02), Mg0 0.06 (0.003), B 2 0 3 0.033 (0.05 ), AI 2 0 3 0.002 (0.017) and BaC0 3 0.005 (0.001

Der geringe Wismuthanteil ermöglicht Sintertemperaturen bis 1150°C, wodurch bei dünnen Schichtdicken und entsprechender Anzahl der Schichten Varistoren mit einer Varistdrspannung bis herab zu 4 V hergestellt werden können.The low bismuth content enables sintering temperatures of up to 1150 ° C, which means that with thin layer thicknesses and a corresponding number of layers, varistors can be produced with a varistor voltage down to 4 V.

Die Herstellung dieser Varistoren in Vielschichttechnik erfolgt in der gleichen Weise, wie dies beispielsweise für keramische Vielschichtkondensatoren bekannt ist. Es wird in diesem Zusammenhang auf die USA-Patentschriften 2 736 080 und 3 235 939 sowie auf die DE-PS 1 282 119 verwiesen.These varistors are manufactured using multilayer technology in the same way as is known, for example, for ceramic multilayer capacitors. In this connection, reference is made to US Pat. Nos. 2,736,080 and 3,235,939 as well as to DE-PS 1 282 119.

Aus dem Ausgangsmaterial, das durch Feinmahlung eine mittlere Korngrösse von etwa 1 µm aufweist, wird durch Zuhilfenahme von organischen Bindermaterialien (z.B. Polymethylacrylate, Methylcellulose, Polyvinylalkohol) und Lösungsmitteln (z.B. Wasser, Ethylmethylketon) sowie Weichmachern (Phthalate, Ester) - wie es an sich bekannt ist - ein Schlicker hergestellt, der dann mittels üblicher Technologien (Kalandrierung, Abstreiftechnik - doctor blade) zu einer sehr dünnen Folie ausgezogen wird. Auf diese so hergestellten Folien wird auf Stücke von etwa Postkartengrösse ein Muster der inneren Beläge aus der angegebenen Silber-Palladiumverbindung aufgetragen, wonach eine entsprechende Zahl solcher postkartengrossen Folien derart übereinander gestapelt wird, dass die alternierende Versetzung der Beläge im fertigen Körper resultiert. Schliesslich wird nach einem Pressvorgang aus dem Stapel der Schichtvaristor in Rohform abgetrennt und - nach dem Durchlauf eines in der Vielschichttechnik üblichen Temper- und Binderausbrennzyklus - bei Temperaturen bis 1150°C gesintert.From the starting material, which has an average grain size of about 1 µm due to fine grinding, organic binder materials (e.g. polymethyl acrylates, methyl cellulose, polyvinyl alcohol) and solvents (e.g. water, ethyl methyl ketone) as well as plasticizers (phthalates, esters) are used - as is per se is known - a slip is produced, which is then drawn out into a very thin film using conventional technologies (calendering, stripping technology - doctor blade). A sample of the inner coverings made from the specified silver-palladium compound is applied to pieces of postcard size in this way, after which a corresponding number of such postcard-sized films are stacked on top of one another such that the alternating displacement of the coverings results in the finished body. Finally, after a pressing process, the layer varistor is separated from the stack in its raw form and - after passing through a tempering and binder burnout cycle common in multi-layer technology - sintered at temperatures up to 1150 ° C.

Dieses Verfahren ist, wie ausgeführt, hinreichend bekannt, wobei auch Variationen der speziellen Herstellungsweise bekannt sind.As stated, this method is well known, although variations in the specific production method are also known.

Die Erfindung wird nachfolgend anhand der Figuren näher erläutert. Es zeigen:

  • Fig. 1 schematisch einen Schichtvaristor,
  • Fig. 2 ein U-I-Diagramm, das die Verbesserung durch die Erfindung darstellt,
  • Fig. 3 ein Diagramm zu Vergleich mit dem Stand der Technik,
  • Fig. 4 ein Diagramm über die Abhängigkeit der Varistorspannung von der Sintertemperatur und
  • Fig. 5 ein Diagramm über die Abhängigkeit des Schutzpegels von der Sintertemperatur.
The invention is explained in more detail below with reference to the figures. Show it:
  • 1 schematically shows a layer varistor,
  • 2 is a UI diagram illustrating the improvement of the invention;
  • 3 is a diagram for comparison with the prior art,
  • Fig. 4 is a diagram of the dependence of the varistor voltage on the sintering temperature and
  • Fig. 5 is a diagram of the dependence of the protection level on the sintering temperature.

In Fig. 1 ist der Varistorkörper 1 schematisch gezeigt, der aus Schichten 2 aus Varistormaterial besteht. Die Beläge 3 und 4 wechseln mit Varistormaterialschichten 2 ab, wobei die Beläge 3 im vorliegenden Fall zur rechten Aussenoberfläche 5 und die Beläge 4 zur linken Aussenoberfläche 6 des Keramikkörpers geführt sind. Durch den Sintervorgang besteht der Keramikörper 1 aus einem monolithischen Block, in dessen Innerem die Beläge 3 und 4 angeordnet sind. Es ist auch möglich, dass die Beläge 3 und 4 an der gleichen Seite des monolithischen Blockes herausragen, wobei die zu kontaktierenden Enden dann alternierend an verschiedenen Stellen in dieser Oberflächenseite enden und dort gegenpolig kontaktiert werden.In Fig. 1, the varistor body 1 is shown schematically, which consists of layers 2 of varistor material. The coverings 3 and 4 alternate with varistor material layers 2, the coverings 3 in the present case being guided to the right outer surface 5 and the coverings 4 to the left outer surface 6 of the ceramic body. As a result of the sintering process, the ceramic body 1 consists of a monolithic block, in the interior of which the coatings 3 and 4 are arranged. It is also possible for the coverings 3 and 4 to protrude on the same side of the monolithic block, the ends to be contacted then alternatingly ending at different locations on this surface side and being contacted there with opposite poles.

Die Beläge 3 und 4 sind miteinander gegenpolig und elektrisch leitend verbunden. Gegenpolig bedeutet in vorliegendem Fall, dass die Beläge 3 an der Oberfläche 5 mit einer weiteren Metallschicht 7, z.B. aus Silber oder einem anderen lötfähigen Metall, verbunden sind, die an einem Pol der Spannungsquelle oder der Schaltung angeschlossen ist, während die Beläge 4 an der Oberflächenseite 6 durch die weitere Metallschicht 8, ebenfalls aus Silber oder ähnlichem, miteinander verbunden sind, die mit dem Gegenpol der Spannungsquelle oder der Schaltung verbunden sind.The pads 3 and 4 are connected to each other with opposite poles and electrically conductive. In the present case, opposite-pole means that the coatings 3 on the surface 5 with a further metal layer 7, e.g. made of silver or another solderable metal, which is connected to a pole of the voltage source or the circuit, while the coatings 4 on the surface side 6 by the further metal layer 8, also made of silver or the like, connected to each other The opposite pole of the voltage source or the circuit are connected.

Mit dem Bezugszeichen 9 ist die Dicke der Schichten 2 aus Varistormaterial bezeichnet.Reference number 9 denotes the thickness of the layers 2 made of varistor material.

Voraussetzung für die Wirkungsweise des Varistors ist, dass die Abstände 10 bzw. 11 zwischen dem obersten Belag 3 und dem untersten Belag 4 und der Oberfläche 14 bzw. der Oberfläche 15 sowie die Abstände 12 der Beläge 3 zur Metallschicht 8 und die Abstände 13 der Metallbeläge 4 zur Metallschicht 7 je grösser sind als die Dicke 9 der Schichten 2 aus Varistormaterial. Zur Erzielung der notwendigen Grösse der Abstände 10 und 11 sind beispielsweise Varistormaterialschichten 2' vorhanden, die keine Beläge 3 bzw. 4 enthalten. In Fig. 1 ist dies durch die Grenzlinien 16 und 17 zwischen der mit einem Belag 3 versehenen oberen Schicht 2 und der ohne Belag vorhandenen Schicht 2' bzw. zwischen der unteren, mit dem Belag 4 versehenen Schicht 2 und der ohne Belag vorhandenen Schicht 2' dargestellt.A prerequisite for the operation of the varistor is that the distances 10 and 11 between the top layer 3 and the bottom layer 4 and the surface 14 or the surface 15, as well as the distances 12 of the layers 3 from the metal layer 8 and the distances 13 of the metal layers 4 to the metal layer 7 are each greater than the thickness 9 of the layers 2 made of varistor material. In order to achieve the necessary size of the distances 10 and 11, varistor material layers 2 ′ are present, for example, which do not contain any coatings 3 or 4. In FIG. 1, this is due to the boundary lines 16 and 17 between the top layer 2 provided with a covering 3 and the layer 2 ′ without a covering or between the lower layer 2 provided with the covering 4 and the layer 2 without a covering 'shown.

Der Varistor nach der Erfindung kann mit Stromzuführungsdrähten 18 und 19 versehen sein, die an die Metallschichten 7 bzw. 8 angelötet oder anderweitig befestigt sind.The varistor according to the invention can be provided with power supply wires 18 and 19, which are soldered to the metal layers 7 or 8 or attached in some other way.

Soll der Varistor nach der Erfindung als Chip durch Auflegen auf und Befestigen an Kontaktstellen gedruckter Leitungsbahnen verwendet werden, dannkönnen anstelle der Stromzuführungsdrähte Kontaktflächen vorhanden sein, die im vorliegenden Beispiel durch die Verlängerungen 20 und 21 in der Metallschicht 7 auf die Oberflächen 14 und 15, sowie durch Verlängerungen 22 und 23 der Metallschicht 8 auf die Oberflächen 14 und 15 dargestellt sind.If the varistor according to the invention is to be used as a chip by placing it on and attaching it to contact points on printed conductor tracks, then instead of the current supply wires there may be contact surfaces which, in the present example, through the extensions 20 and 21 in the metal layer 7 on the surfaces 14 and 15, and are represented by extensions 22 and 23 of the metal layer 8 on the surfaces 14 and 15.

Für den Einsatz in gedruckten Schaltungen, bei denen die Kontaktstellen in einem Rastermass (einfaches oder gerades Vielfaches von 2,5 mm) angeordnet sind, ist der Rastermassabständ 24 zwischen den Stromzuführungsdrähten 18 und 19 festzulegen, wie dies an sich für derartige Bauelemente bekannt ist.For use in printed circuits in which the contact points are arranged in a grid dimension (simple or even multiple of 2.5 mm), the grid spacing 24 between the power supply wires 18 and 19 is to be defined, as is known per se for such components.

Andererseits kann der notwendige Rastermassabstand 25 zwischen den Verlängerungen 20 und 22 bzw. 21 und 23 durch entsprechende Wahl der Abmessungen festgelegt sein.On the other hand, the necessary spacing 25 between the extensions 20 and 22 or 21 and 23 can be determined by appropriate choice of dimensions.

Man erkennt aus Fig. 1, dass die Beläge 3 und 4 bei ihrer Ausführungsform der Erfindung in einer Dicke von bis 5 µm und vorzugsweise 2 µm für eine gute Ableitung der im Inneren des monolithischen Blockes entstehenden Wärme sorgen, da sie durch die Verwendung von relativ mehr Silber als Palladium dicker ausgeführt sein können, als es für reine Palladiumschichten wegen derHerstellung möglich und wegen der relativ hohen Kosten für reines Palladium sinnvoll ist.It can be seen from Fig. 1 that the pads 3 and 4 in their embodiment of the invention in a thickness of up to 5 microns and preferably 2 microns for a good Dissipation of the heat generated in the interior of the monolithic block ensures that it can be made thicker than palladium due to the use of relatively more silver than palladium because of the production and is reasonable because of the relatively high cost of pure palladium by using relatively more silver.

Das in Fig. 2 dargestellte U-I-Diagramm zeigt einen der Vorteile der vorliegenden Erfindung, der darin besteht, dass durch die geringe Menge Wismuth im Varistormaterial und die dadurch mögliche Verwendung von Silber in gegenüber dem Palladium grösserer Menge für die Beläge 3 und 4 ein Weglegieren des Metalls der Beläge und damit eine die Eigenschaften verschlechternde Inselbildung nicht eintritt.The UI diagram shown in FIG. 2 shows one of the advantages of the present invention, which consists in the fact that the small amount of bismuth in the varistor material and the possible use of silver in larger amounts for the coatings 3 and 4 compared to the palladium make alloying away of the metal of the coverings and thus an island formation which deteriorates the properties does not occur.

In Fig. 2 kommt dies dadurch zum Ausdruck, dass bei herkömmlichen Varistoren die Kurve 26 bei Stromstärken im oberen Bereich plötzlich steil ansteigt, während die Kurve 27 für Varistoren gemäss der Erfindung in diesem oberen Bereich einen beträchtlich verringerten Anstieg aufweist.This is expressed in FIG. 2 by the fact that in conventional varistors the curve 26 suddenly rises steeply at current intensities in the upper region, while the curve 27 for varistors according to the invention has a considerably reduced increase in this upper region.

Die Inselbildung, die durch Weglegieren der Beläge (Migration) zustande kommt, ruft ein starkes Ansteigen der Klemmenspannung bei hohen Strömen hervor, weil der Serienwiderstand der Beläge durch diese Inselbildung stark ansteigt.The island formation, which is caused by alloying away the linings (migration), causes the terminal voltage to rise sharply at high currents, because the series resistance of the linings increases sharply due to this island formation.

In Fig. 3 ist ein U-I-Diagramm gezeigt, in welchem ein Varistor der vorliegenden Erfindung (Kurve 30) mit bekannten Varistoren (Kurven 28 und 29) verglichen wird. Massstab und Kurvenverlauf der Fig. 3 ist der Fig. 2 der eingangs erwähnten Veröffentlichung «Advances in Ceramics» entnommen.3 shows a U-I diagram in which a varistor of the present invention (curve 30) is compared with known varistors (curves 28 and 29). The scale and curve of FIG. 3 is taken from FIG. 2 of the publication “Advances in Ceramics” mentioned at the beginning.

Die Kurve 28 gilt für Varistoren, die aus 20 Varistormaterialschichten je einer Dicke von 40 gm bestehen, während die Kurve 29 für bekannte Varistoren mit 20 Varistormaterialschichten je einer Dicke 150 µm gilt.Curve 28 applies to varistors which consist of 20 varistor material layers each with a thickness of 40 gm, while curve 29 applies to known varistors with 20 varistor material layers each 150 µm thick.

Kurve 30 gilt für Varistoren der vorliegenden Erfindung aus 50 Schichten je einer Dicke von 30 µm.Curve 30 applies to varistors of the present invention made of 50 layers each 30 µm thick.

Man erkennt aus Fig. 3, dass die bekannten Varistoren bereits bei 10 Ampere eine stark ansteigende Klemmenspannung bis zu 100 Volt ergeben, während ein solcher Anstieg bei Kurve 30 nicht erfolgt. Er würde erfolgen, wie es die Kurve 30' zeigt, wenn die Regeln dervorliegenden Erfindung nicht eingehalten werden.It can be seen from FIG. 3 that the known varistors result in a strongly increasing terminal voltage of up to 100 volts even at 10 amperes, while such an increase does not take place in curve 30. It would occur as curve 30 'shows if the rules of the present invention are not followed.

Trotz der hohen Anzahl von 50 Schichten, wodurch die Stabilität des Varistors wesentlich erhöht wird, ist die Wärmeabfuhr aus dem Körper bei Belägen aus 70% Silber und 30% Palladium mit einer Dicke von je 2,0 µm ausreichend gross, um die Funktionsfähigkeit des Varistors auch bei hohen Stromstärken bzw. Spannungen zu gewährleisten.Despite the high number of 50 layers, which significantly increases the stability of the varistor, the heat dissipation from the body with coatings of 70% silver and 30% palladium, each with a thickness of 2.0 µm, is sufficiently large to ensure the functionality of the varistor To ensure even at high currents or voltages.

Das Diagramm nach Fig. 4 zeigt die Varistorspannung in Abhängigkeit von der Sintertemperatur bei einer Sinterzeit von einer Stunde für Varistoren, die aus 10 Schichten bestehen, wobei unterschiedliche Schichtdicken vorhanden sind.The diagram according to FIG. 4 shows the varistor voltage as a function of the sintering temperature at a sintering time of one hour for varistors which consist of 10 layers, with different layer thicknesses being present.

Die Varistorspannung ist in Volt auf der Ordinate und die Sintertemperatur ts in °C auf der Abszisse angegeben. Auch hier bestehen die Beläge aus 70% Silber und 30% Palladium und sind 2 µm dick.The varistor voltage is given in volts on the ordinate and the sintering temperature t s in ° C on the abscissa. Here too, the coatings consist of 70% silver and 30% palladium and are 2 µm thick.

Kurve 31 gilt für Varistoren aus 10 Schichten mit einer Schichtdicke von jeweils 165 µm. Kurve 32 gilt für Varistoren aus 10 Schichten mit einer Schichtdicke von je 77 pm.Curve 31 applies to varistors with 10 layers, each with a layer thickness of 165 µm. Curve 32 applies to varistors consisting of 10 layers with a layer thickness of 77 pm each.

Kurve 33 gilt für Varistoren aus 10 Schichten mit einer Dicke von je 37 µm und Kurve 34 gilt für Varistoren aus 10 Schichten mit einer Schichtdicke von je 23 p.m.Curve 33 applies to varistors with 10 layers each with a thickness of 37 µm and curve 34 applies to varistors with 10 layers each with a layer thickness of 23 p.m.

Man erkennt aus Fig. 4, dass mit abnehmender Schichtdicke und zunehmender Sintertemperatur jeweils abnehmende Varistorspannungen erzielt werden können.It can be seen from FIG. 4 that decreasing varistor voltages can be achieved with decreasing layer thickness and increasing sintering temperature.

Durch die relativ hohe Sintertemperatur von bis zu 1080°C wird eine sehr hohe Dichte, d.h. eine sehr geringe Porosität der Schichten aus Keramikmaterial erzielt, wodurch die elektrischen Eigenschaften der Varistoren wesentlich verbessert werden. Die erhöhte Sintertemperatur ist durch den geringen Wismuth- anteil möglich. Fig. 5 zeigt Kurven, die den Schutzpegel in Abhängigkeit von der Sintertemperatur verdeutlichen.Due to the relatively high sintering temperature of up to 1080 ° C, a very high density, i.e. achieved a very low porosity of the layers of ceramic material, which significantly improves the electrical properties of the varistors. The increased sintering temperature is possible due to the low bismuth content. 5 shows curves which illustrate the protection level as a function of the sintering temperature.

Der Schutzpegel von Varistoren ist die an einem Varistor auftretende Klemmenspannung eines Stromimpulses der indizierten Stromstärke.The protection level of varistors is the terminal voltage of a current pulse of the indicated current intensity that occurs at a varistor.

Auf der Ordinate ist die Klemmenspannung in Volt aufgetragen, während auf der Abszisse die Sintertemperatur ts in °C angegeben ist.The terminal voltage is shown in volts on the ordinate, while the sintering temperature t s is given in ° C on the abscissa.

Es sind 4 Kurvenpaare 35, 36, 37 und 38 angegeben, und zwar für Schichtdicken im gesinterten Zustand von 165, 77, 37 und 23 µm. Die jeweils obere Kurve gilt für eine Stromstärke von 10 A und die jeweils untere Kurve gilt für eine Stromstärke von 5 A.Four pairs of curves 35, 36, 37 and 38 are given, specifically for layer thicknesses in the sintered state of 165, 77, 37 and 23 µm. The upper curve applies to a current of 10 A and the lower curve applies to a current of 5 A.

Man erkennt auch aus dem Diagramm gemäss Fig. 5, dass mit abnehmender Schichtdicke und zunehmenter Sintertemperatur abnehmende Werte der Klemmenspannung erzielt werden.It can also be seen from the diagram according to FIG. 5 that with decreasing layer thickness and increasing sintering temperature, decreasing values of the terminal voltage are achieved.

Das angegebene Varistormaterial gewährleistet eine Spannungsfestigkeit von 300 V/mm, wodurch auch bei dünnen Schichten eine ausreichende Steilheit (Nichtlinearitätsexponent a) gewährleistet ist.The specified varistor material ensures a dielectric strength of 300 V / mm, which ensures sufficient slope (non-linearity exponent a) even with thin layers.

Bei grobkristallinem Material mit einer Spannungsfestigkeit kleiner als 150 V/mm entstehen Probleme durch zu wenige Körner bei starker Streuung im Durchmesser, wie dies in der oben erwähnten Veröffentlichung «Jounal of Applied Physics» erläutert ist.In the case of coarsely crystalline material with a dielectric strength of less than 150 V / mm, problems arise due to too few grains with a large scatter in the diameter, as explained in the above-mentioned publication "Jounal of Applied Physics".

BezugszeichenlisteReference symbol list

  • 1 keramisch hergestellter, monolithischer Körper1 ceramic, monolithic body
  • 2 Schichten aus keramischem Varistormaterial mit Belägen 3, 42 layers of ceramic varistor material with coverings 3, 4
  • 2' Schichten aus keramischem Varistormaterial ohne Beläge2 'layers of ceramic varistor material without coverings
  • 3 Beläge aus im Körper 1 angeordneten Metallschichten3 coverings made of metal layers arranged in the body 1
  • 4 Beläge aus im Körper 1 angeordneten Metallschichten4 coverings made of metal layers arranged in the body 1
  • 5 Seitenfläche des Körpers 15 side surface of the body 1
  • 6 Seitenfläche des Körper 16 side surface of the body 1
  • 7 weitere Metallschicht auf der Seitenfläche 57 further metal layer on the side surface 5
  • 8 weitere Metallschicht auf der Seitenfläche 68 further metal layer on the side surface 6
  • 9 Dicken der Schichten 29 thicknesses of layers 2
  • 10 Abstand zwischen oberem Belag 3 und Oberfläche 1410 Distance between the top surface 3 and surface 14
  • 11 Abstand zwischen unterem Belag und Oberfläche 1511 Distance between lower covering and surface 15
  • 12 Abstand der Beläge 3 zur Metallschicht 812 distance of the pads 3 to the metal layer 8
  • 13 Abstand der Beläge 4 zur Metallschicht 713 distance of the pads 4 to the metal layer 7
  • 14 Oberfläche des Körpers 114 surface of the body 1
  • 15 Oberfläche des Körpers 115 surface of the body 1
  • 16 Grenzlinie zwischen oberer Schicht 2 mit Belag 3 und Schicht 2' ohne Belag16 boundary line between upper layer 2 with coating 3 and layer 2 'without coating
  • 17 Grenzlinie zwischen unterer Schicht 2 mit Belag 4 und Schicht 2' ohne Belag17 boundary line between lower layer 2 with coating 4 and layer 2 'without coating
  • 18 Stromzuführungsdraht, an der Metallschicht 7 befestigt18 power supply wire, attached to the metal layer 7
  • 19 Stromzuführungsdraht, an der Metallschicht 8 befestigt19 power supply wire, attached to the metal layer 8
  • 20 Verlängerung der Metallschicht 7 auf die Oberfläche 1420 extension of the metal layer 7 to the surface 14
  • 21 Verlängerung der Metallschicht 7 auf die Oberfläche 1521 Extension of the metal layer 7 to the surface 15
  • 22 Verlängerung der Metallschicht 8 auf die Oberfläche 1422 Extension of the metal layer 8 to the surface 14
  • 34 Verlängerung der Metallschicht 8 auf die Oberfläche 1534 Extension of the metal layer 8 to the surface 15
  • 24 Rastermassabstand zwischen den Stromzuführungsdrähten 18 und 1924 pitch between the power supply wires 18 and 19
  • 25 Rastermassabstand zwischen Verlängerungen 20 und 22 bzw. 21 und 2325 pitch between extensions 20 and 22 or 21 and 23
  • 26 U-I-Kurve für bekannte Varistoren26 U-I curve for known varistors
  • 27 U-I-Kurve für Varistoren gemäss Erfindung27 U-I curve for varistors according to the invention
  • 28 U-I-Kurve für bekannte Varistoren aus 20 Schichten, je 40 µm dick28 U-I curve for known varistors made of 20 layers, each 40 µm thick
  • 29 U-I-Kurve für bekannte Varistoren aus 20 Schichten, je 150 µm dick29 U-I curve for known varistors from 20 layers, each 150 µm thick
  • 30 U-I-Kurve für Varistoren gemäss der Erfindung aus 50 Schichten, je 30 µm dick30 U-I curve for varistors according to the invention of 50 layers, each 30 µm thick
  • 30' U-I-Kurvenverlauf, wenn nicht nach Erfindung30 'U-I curve shape, if not according to the invention
  • 31 V-ts-Kurve für Varistoren aus 10 Schichten, je 165 µm dick31 Vt s curve for varistors consisting of 10 layers, each 165 µm thick
  • 32 V-ts-Kurve für Varistoren aus 10 Schichten, je 77 µm dick32 Vt s curve for varistors consisting of 10 layers, each 77 µm thick
  • 33 V-ts-Kurve für Varistoren aus 10 Schichten, je 37 µm dick33 Vt s curve for varistors from 10 layers, each 37 µm thick
  • 34 V-ts-Kurve für Varistoren aus 10 Schichten, je 23 µm dick34 Vt s curve for varistors consisting of 10 layers, each 23 µm thick
  • 35 V-ts-Kurve für Varistoren aus 10 Schichten, je 165 µm dick35 Vt s curve for varistors with 10 layers, each 165 µm thick
  • 36 V-ts-Kurve für Varistoren aus 10 Schichten, je 77 µm dick36 Vt s curve for varistors from 10 layers, each 77 µm thick
  • 37 V-ts-Kurve für Varistoren aus 10 Schichten, je 37 µm dick37 Vt s curve for varistors consisting of 10 layers, each 37 µm thick
  • 38 V-ts-Kurve für Varistoren aus 10 Schichten, je 23 µm dick38 Vt s curve for varistors from 10 layers, each 23 µm thick

Claims (8)

1. A voltage-dependent, electrical resistor (varistor) consisting of a monolithic ceramic body (1) consisting of a plurality of layers (2) which have a thickness of 20 to 350 µm and are made of varistor material with grain sizes of 7 to 22 µm with a zinc oxide base with up to 6 mol % additions of oxides of one or more of the metals Bi, Sb, Co, Ni, Cr, Mn, Mg, B, Al, Ba, and noble metal layers which serve as coatings (3, 4), have a maximum thickness of 10 µm, and alternate with the varistor material layers (2) and which lead alternately to different places on the side faces (5, 6) of the body (1) where they are contacted with further metal layers (7, 8) in electrically conducing and oppositely-poled manner, characterised in that
a) the porosity of the varistor material layers (2) of the ceramic body (1) does not exceed 5%
b) the bismuth component (Bi, calculated as Bi203) in the varistor material is from 0.4 to a maximum of 1 mol % (corresponding to 2 to 5 weight %), and
c) the coatings consist of 50 to 80 weight % silver (Ag) and 50 to 20 weight % palladium (Pd).
2. A voltage-dependent electrical resistor as claimed in Claim 1, characterised in that the porosity of the varistor material layers (2) is less than 1 %.
3. A voltage-dependent electrical resistor as claimed in Claim 1 or 2, characterised in that the bismuth component amounts to 0.6 mol % (corresponding to 3.2 weight % Bi203).
4. A voltage-dependent electrical resistor as claimed in Claim 1, 2 or 3, characterised in that the coatings (3, 4) consist of 70 weight % Ag and 30 weight % Pd.
5. A voltage-dependent electrical resistor as claimed in one of Claims 1 to 4, characterised in that the ceramic body (1) consists of layers (2) of varistor material whose thickness (9) is in the range of 20 m to 350 m, where thicker layers (2) result in higher varistor voltages in the range of 4 volts to 350 volts.
6. A voltage-dependent electrical resistor as claimed in one of Claims 1 to 5, characterised in that the varistor body (1) is preferably 1 to 10 mm long, 1 to 3.6 mm wide and 0.5 to 3 mm thick, the thickness (9) always being less than the shortest length and width.
7. A voltage-dependent electrical resistor as claimed in one of Claims 1 to 6, characterised in that the varistor material has the following composition (quoted in mol % in each case followed in brackets by weight %):
ZnO 94.6 (87.3), Bi203 0.6 (3.2), Sb203 1.6 (5.1), Co304 0.4 (1.1), NiO 1.3 (1.1), Cr203 0.6 (1.1), MnC03 0.8 (1.02), MgO 0.06 (0.003), B203 0.033 (0.05), AI203 0.002 (0.017) and BaC03 0.005 (0.001).
EP86100376A 1985-01-17 1986-01-13 Voltage-dependent electric resistance (varistor) Expired EP0189087B1 (en)

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Application Number Priority Date Filing Date Title
AT86100376T ATE35344T1 (en) 1985-01-17 1986-01-13 VOLTAGE DEPENDENT ELECTRICAL RESISTANCE (VARISTOR).

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DE3501419 1985-01-17
DE3501419 1985-01-17

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EP0189087A1 EP0189087A1 (en) 1986-07-30
EP0189087B1 true EP0189087B1 (en) 1988-06-22

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EP (1) EP0189087B1 (en)
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* Cited by examiner, † Cited by third party
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DE3725454A1 (en) * 1987-07-31 1989-02-09 Siemens Ag ELECTRICAL MULTI-LAYER COMPONENT WITH A SINTERED, MONOLITHIC CERAMIC BODY AND METHOD FOR PRODUCING THE ELECTRICAL MULTI-LAYER COMPONENT
DE3725455A1 (en) * 1987-07-31 1989-02-09 Siemens Ag ELECTRICAL MULTI-LAYER COMPONENT WITH A SINTERED, MONOLITHIC CERAMIC BODY AND METHOD FOR PRODUCING THE ELECTRICAL MULTI-LAYER COMPONENT
EP0302294B1 (en) * 1987-07-31 1992-07-29 Siemens Aktiengesellschaft Component with fillable layers comprising a sintered monolithic ceramic body, and method of making it
JP2552309B2 (en) * 1987-11-12 1996-11-13 株式会社明電舎 Non-linear resistor
US5075665A (en) * 1988-09-08 1991-12-24 Murata Manufacturing Co., Ltd. Laminated varistor
JPH077613B2 (en) * 1990-02-02 1995-01-30 東京電力株式会社 Suspended lightning arrester
GB2242066B (en) * 1990-03-16 1994-04-27 Ecco Ltd Varistor structures
GB2242068C (en) * 1990-03-16 1996-01-24 Ecco Ltd Varistor manufacturing method and apparatus
GB2242065C (en) * 1990-03-16 1996-02-08 Ecco Ltd Varistor ink formulations
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
EP0476657A1 (en) * 1990-09-21 1992-03-25 Siemens Aktiengesellschaft Thermistor with negative temperature coefficient produced by multilayer technology
DE4030479C2 (en) * 1990-09-26 1993-11-25 Siemens Ag Electrical resistance in chip design
JP3121119B2 (en) * 1992-06-16 2000-12-25 ローム株式会社 Method of forming external electrodes of multilayer ceramic capacitor
JP2674523B2 (en) * 1993-12-16 1997-11-12 日本電気株式会社 Ceramic wiring board and manufacturing method thereof
JP3077056B2 (en) * 1996-09-12 2000-08-14 株式会社村田製作所 Multilayer electronic components
EP0883901A1 (en) * 1996-11-11 1998-12-16 Zoran Zivic MULTILAYER ZnO POLYCRYSTALLINE DIODE
US7336468B2 (en) 1997-04-08 2008-02-26 X2Y Attenuators, Llc Arrangement for energy conditioning
US7321485B2 (en) 1997-04-08 2008-01-22 X2Y Attenuators, Llc Arrangement for energy conditioning
US9054094B2 (en) 1997-04-08 2015-06-09 X2Y Attenuators, Llc Energy conditioning circuit arrangement for integrated circuit
US6444504B1 (en) 1997-11-10 2002-09-03 Zoran Zivic Multilayer ZnO polycrystallin diode
JPH11273914A (en) * 1998-03-26 1999-10-08 Murata Mfg Co Ltd Laminated varistor
US5999398A (en) * 1998-06-24 1999-12-07 Avx Corporation Feed-through filter assembly having varistor and capacitor structure
DE19903456A1 (en) * 1999-01-28 2000-08-10 Philips Corp Intellectual Pty Multi-component component
DE19931056B4 (en) 1999-07-06 2005-05-19 Epcos Ag Multilayer varistor of low capacity
JP3498211B2 (en) * 1999-12-10 2004-02-16 株式会社村田製作所 Multilayer semiconductor ceramic electronic components
US6717506B2 (en) * 2000-11-02 2004-04-06 Murata Manufacturing Co., Ltd. Chip-type resistor element
US20050212648A1 (en) * 2004-03-23 2005-09-29 Inpaq Technology Co., Ltd. Low-capacitance laminate varistor
WO2006093830A2 (en) 2005-03-01 2006-09-08 X2Y Attenuators, Llc Internally overlapped conditioners
DE102005028498B4 (en) * 2005-06-20 2015-01-22 Epcos Ag Electrical multilayer component
CN103180915A (en) * 2010-11-03 2013-06-26 埃普科斯股份有限公司 Ceramic multilayered component and method for producing a ceramic multilayered component
JP6231127B2 (en) * 2012-12-27 2017-11-15 リテルヒューズ・インク Zinc oxide based varistor and method for producing the same
DE102015120640A1 (en) 2015-11-27 2017-06-01 Epcos Ag Multi-layer component and method for producing a multilayer component
DE102016104990A1 (en) 2016-03-17 2017-09-21 Epcos Ag Ceramic material, varistor and method for producing the ceramic material and the varistor
TWI667667B (en) * 2016-09-26 2019-08-01 立昌先進科技股份有限公司 Process for producing smd multilayer varistor to increase printing layres of inner electrode and smd multilayer varistor made by the same
WO2020149034A1 (en) * 2019-01-16 2020-07-23 パナソニックIpマネジメント株式会社 Varistor assembly

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2736080A (en) * 1956-02-28 walker etal
US3235939A (en) * 1962-09-06 1966-02-22 Aerovox Corp Process for manufacturing multilayer ceramic capacitors
DE1282119B (en) * 1966-05-18 1968-11-07 Siemens Ag Process for manufacturing electrical components using the thin film method
JPS5823921B2 (en) * 1978-02-10 1983-05-18 日本電気株式会社 voltage nonlinear resistor
FR2523993A1 (en) * 1982-03-24 1983-09-30 Cables De Lyon Geoffroy Delore Silk screen printing paste contg. metal oxide(s) as active materials - used for varistor prodn.

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ATE35344T1 (en) 1988-07-15
JPH0353761B2 (en) 1991-08-16
US4675644A (en) 1987-06-23
DE3660342D1 (en) 1988-07-28
JPS61170005A (en) 1986-07-31
EP0189087A1 (en) 1986-07-30

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