EP0193854A1 - Electrical resistance having a negative temperature coefficient, and production process therefor - Google Patents

Electrical resistance having a negative temperature coefficient, and production process therefor Download PDF

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Publication number
EP0193854A1
EP0193854A1 EP86102471A EP86102471A EP0193854A1 EP 0193854 A1 EP0193854 A1 EP 0193854A1 EP 86102471 A EP86102471 A EP 86102471A EP 86102471 A EP86102471 A EP 86102471A EP 0193854 A1 EP0193854 A1 EP 0193854A1
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EP
European Patent Office
Prior art keywords
solder
eyelet
coatings
power supply
supply elements
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Granted
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EP86102471A
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German (de)
French (fr)
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EP0193854B1 (en
Inventor
Gerald Kloiber
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Siemens Bauelemente OHG
Siemens AG
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Siemens Bauelemente OHG
Siemens AG
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Priority to AT86102471T priority Critical patent/ATE35343T1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C1/00—Details
    • H01C1/14—Terminals or tapping points or electrodes specially adapted for resistors; Arrangements of terminals or tapping points or electrodes on resistors
    • H01C1/1413—Terminals or electrodes formed on resistive elements having negative temperature coefficient
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C1/00—Details
    • H01C1/14—Terminals or tapping points or electrodes specially adapted for resistors; Arrangements of terminals or tapping points or electrodes on resistors
    • H01C1/144—Terminals or tapping points or electrodes specially adapted for resistors; Arrangements of terminals or tapping points or electrodes on resistors the terminals or tapping points being welded or soldered
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/28—Apparatus or processes specially adapted for manufacturing resistors adapted for applying terminals

Definitions

  • the invention relates to an electrical resistor with a negative temperature coefficient of its resistance value, generally referred to as a thermistor, NTC resistor or NTC thermistor, made of a disk made of densely sintered metal oxide ceramic with a small diameter, in particular 1.5 mm to 5 mm and a small thickness, in particular 0, 6 mm to 2.5 mm and with attached, firmly adhering and solderable coatings on the end faces of the pane and current supply elements fastened to them with solder.
  • a thermistor, NTC resistor or NTC thermistor made of a disk made of densely sintered metal oxide ceramic with a small diameter, in particular 1.5 mm to 5 mm and a small thickness, in particular 0, 6 mm to 2.5 mm and with attached, firmly adhering and solderable coatings on the end faces of the pane and current supply elements fastened to them with solder.
  • the invention further relates to a method for producing such an NTC resistor, in which current supply elements are applied to the sintered and coated disc and fastened by means of solder.
  • the coverings often consist of two or more layers of different metals, of which the first layer attached to the ceramic consists of a metal which forms a firm, ohmic contact with the ceramic material, provided such a contact is required, while the outer layer consists of an easily solderable, nobler metal.
  • a method for solderable, barrier layer-free contact assignment on ceramic PTC resistors in which the first layer consisting of aluminum or a predominantly aluminum-containing alloy is produced by screen printing and the second layer consists of copper , which is applied by flame spraying-thermocouples made of preferably small, disk-shaped NTC resistance elements with solderable coatings and with soldered on them, the resistance element carrying wires are produced in many variations, since one advantage of these designs is that they are simple, cheap and can be produced in large quantities in an automatic process.
  • the resistance drift of thermistor disks with soldered power supply elements is sometimes up to 100% of the initial resistance after repeated thermal shock loads.
  • the present invention is based on the object of specifying a small, disk-shaped NTC resistor with current supply elements soldered to solderable metallic coatings, the connection resistance of which with a temperature shock stress of 100-fold alternation between -60 ° C and +300 ° C, preferably -30 ° C up to +130 ° C has a drift of less than 1% and in which a stable mounting of the ceramic disc is ensured by the current supply elements carrying it, it is also the object of the invention to provide a method for producing such an NTC resistor.
  • the NTC resistor of the type specified at the outset is characterized in that the power supply elements are annular at one end as a largely closed eyelet, the outer diameter of which is at most 60% of the diameter of the disk coverings, the annular eyelet of each power supply element centrally soldered to the assignments, the solder surrounding the eyelet which A 4 sdehnung of the solder to the region of the eyelet is limited and the edge regions of the deposits from the solder are not covered.
  • the power supply elements consist of a solderable wire, the end of which is a largely closed, annular eyelet.
  • This wire can be, for example, a silver wire, a silver-plated copper wire or a tinned copper wire, the wire cross-section being between 0.2 mm and 0.8 mm, depending on the size of the thermistor disc
  • the power supply elements are molded parts which are punched from the sheet of a solderable metal, the material thickness of which is between 0.2 mm and 0.8 mm and in which the difference between the outer diameter and inner diameter of the eyelet located at one end is approximately twice the sheet thickness
  • each power supply element By forming one end of each power supply element as a largely closed, ring-shaped eyelet with a smaller outer diameter than the disk diameter, it is possible on the one hand to achieve a firmly bonded connection of the ceramic disk to the power supply elements, which has a peel strength of 15 N to 25 N, in particular of 20 N exhibit.
  • connection resistance of a disk thermistor produced in this way with soldered, supporting the ceramic disk Power supply elements have a drift of less than 1% of their initial value even with a hundredfold thermal cycling from -30 ° C to + 130 ° C
  • the invention thus enables the production of small, thermally stable disc thermistors according to the preamble of claim 1, which represent an inexpensive alternative to the previously customary shock-resistant NTC thermistors in the temperature range mentioned, in which, for example, platinum wires are sintered directly into the ceramic material or small thermistor disks with metallized end faces are held in clamping contact springs, which also make electrical contact with the assignments.
  • thermistors are often additionally melted into a glass housing and are much more expensive to manufacture than comparable NTC resistors according to the invention (see p. 13 of the SIEMENS delivery program mentioned).
  • each power supply element is designed as an annular eyelet, which is centrally soldered to the metallic coatings, is also found in US Pat. No. 2,606,955, but there is a capacitor made of a ceramic disk with metallic Provide surface coverings of the end faces of power supply elements, which consist of a wire, one end of which is shaped into an incompletely closed eyelet.
  • these eyelets are, however, attached to the coverings in the dip soldering process, which thus completely, also in the edge area, with Solder are covered.
  • the process of making an NTC resistor is characterized according to the invention in that for soldering each current supply element, solder is brought into connection with the ring-shaped eyelets in such an amount that the spread of the liquid solder remains essentially restricted to the area of the eyelet.
  • a method that can be used here is described, for example, in DE-PS 2 834 348.
  • the procedure is such that a precisely predetermined amount of a melt of a low-melting metal is fed to a compressed air nozzle, from which it is sprayed abruptly and completely onto the connecting wire and onto a surface of a metal layer in the vicinity of the connecting wire which is defined by a lateral seal.
  • solder in the form of a solder wire is brought into connection with the coatings in the middle of the disk, spreads radially when the solder joint is heated, and essentially covers only the area of the eyelet resting on the coatings.
  • a disc 1 which in practice e.g. has a diameter D of 3 mm and a thickness d of 1 mm, and which consists of densely sintered metal oxide ceramic and has a negative temperature coefficient of the resistance value.
  • the disc 1 On its end faces 2, 3, the disc 1 is provided with metallic coatings 4, 5.
  • barrier layer-free and adherent coatings 4, 5 consist, for example, of a first layer of aluminum or an alloy predominantly containing aluminum, which is produced by the screen printing process, and a second, solderable layer of copper, which is applied by flame spraying.
  • the power supply elements 6, 7 consist of a silver wire with a diameter of 0.4 mm, which is formed at one end 9 into a largely closed, annular eyelet 10, the outer diameter A of which is 1.5 mm.
  • solder 8 has only been shown on the end face 2 for better illustration of an eyelet 10.

Abstract

An electrical resistor having a negative temperature coefficient for incremental resistance values has a resistance wafer with solderable coatings on opposite sides thereof and current lead elements soldered to the coatings, with the soldered ends of the lead elements being each coiled to form an annular eye, the soldering covering only the region of the eye and leaving the remainder of the coatings outside of the eye free of solder.

Description

Die Erfindung betrifft einen elektrischen Widerstand mit negativem Temperaturkoeffizienten seines Widerstandswertes, allgemein als Heißleiter, NTC-Widerstand oder NTC-Thermistor bezeichnet, aus einer Scheibe aus dichtgesinterter Metalloxidkeramik mit geringem Durchmesser, insbesondere 1,5 mm bis 5 mm und geringer Dicke, insbesondere 0,6 mm bis 2,5 mm und mit an den Stirnseiten der Scheibe angebrachten, festhaftenden und lötfähigen Belegungen und daran mit Lot befestigten Stromzuführungselementen.The invention relates to an electrical resistor with a negative temperature coefficient of its resistance value, generally referred to as a thermistor, NTC resistor or NTC thermistor, made of a disk made of densely sintered metal oxide ceramic with a small diameter, in particular 1.5 mm to 5 mm and a small thickness, in particular 0, 6 mm to 2.5 mm and with attached, firmly adhering and solderable coatings on the end faces of the pane and current supply elements fastened to them with solder.

Die Erfindung betrifft ferner ein Verfahren zur Herstellung eines solchen NTC-Widerstandes, bei dem an die gesinterte und mit Belegungen versehene Scheibe Stromzuführungselemente angelegt und mittels Lot befestigt werden.The invention further relates to a method for producing such an NTC resistor, in which current supply elements are applied to the sintered and coated disc and fastened by means of solder.

Scheibenheißleiter für Temperaturen von -60 °C bis +300 °C, vorzugsweise von -30 °C bis +150 °C werden zB. aus den Oxiden der Übergangsmetalle Mangan, Eisen, Kobalt Kupfer, Nickel und Zink durch Pressen unter hohem Druck und anschließendes Sintern hergestellt (vgl. SIEMENS-Heißleiter-Lieferprogramm 1984/85 von Juli 1984, Seite 2). Der dabei entstehende Keramikkörper läßt zunächst keine Lötverbindungen zu.Disc thermistor for temperatures from -60 ° C to +300 ° C, preferably from -30 ° C to + 1 50 ° C, for example. made from the oxides of the transition metals manganese, iron, cobalt copper, nickel and zinc by pressing under high pressure and subsequent sintering (see SIEMENS thermistor delivery program 1984/85 from July 1984, page 2). The resulting ceramic body initially does not allow any soldered connections.

Die elektrische Kontaktierung einer solchen Keramikscheibe erfolgt üblicherweise durch Aufbringen von gut festhaftenden, metallischen Belegungen auf die Stirnseiten der Scheibe. Derartige Verfahren sind hinreichend bekannt (DE-OS 1 947 799, US-PS 3 676 211 sowie US-PS 3 793 604).The electrical contacting of such a ceramic disk is usually carried out by applying firmly adhering, metallic coatings to the end faces of the disk. Such methods are well known (DE-OS 1 947 799, US Pat. No. 3,676,211 and US Pat. No. 3,793,604).

Sollen an diese Belegungen Stromzuführungselemente angelötet werden, bestehen die Belegungen oft aus zwei oder mehr Schichten unterschiedlicher Metalle, von denen die an der Keramik anliegende, erste Schicht aus einem Metall besteht, das mit dem Keramikmaterial einen festhaftenden, ohmschen Kontakt bildet, sofern ein solcher Kontakt erforderlich ist, während die äußere Schicht aus einem gut lötbaren, edleren Metall besteht.If power supply elements are to be soldered to these coverings, the coverings often consist of two or more layers of different metals, of which the first layer attached to the ceramic consists of a metal which forms a firm, ohmic contact with the ceramic material, provided such a contact is required, while the outer layer consists of an easily solderable, nobler metal.

Aus der DE-OS 2 838 508 ist beispielsweise ein Verfahren zur lötfähigen, sperrschichtfreien Kontaktbelegung an keramischen PTC-Widerständen bekannt, bei dem die erste, aus Aluminium oder einer überwiegend Aluminium enthaftenden Legierung bestehende Schicht im Siebdruckverfahren hergestellt ist und die zweite Schicht aus Kupfer besteht, das durch Flammspritzen aufgetragen ist-Thermofühler aus vorzugsweise kleinen, - scheibenförmigen NTC-Widerstandselementen mit lötfähigen Belegungen und mit auf diesen festgelöteten, das Widerstandselement tragenden Anschlußdrähten werden in vielen Variationen hergestellt, da ein Vorteil dieser Ausführungen darin liegt, daß sie einfach, billig und in einem automatischen Verfahren in hohen Stückzahlen produziert werden können.From DE-OS 2 838 508, for example, a method for solderable, barrier layer-free contact assignment on ceramic PTC resistors is known, in which the first layer consisting of aluminum or a predominantly aluminum-containing alloy is produced by screen printing and the second layer consists of copper , which is applied by flame spraying-thermocouples made of preferably small, disk-shaped NTC resistance elements with solderable coatings and with soldered on them, the resistance element carrying wires are produced in many variations, since one advantage of these designs is that they are simple, cheap and can be produced in large quantities in an automatic process.

Die bereits genannte US-PS 3 676 211 offenbart ein Verfahren, bei dem mit lötfähigen Belegungen versehene Keramikscheiben zwischen zueinander gekreuzte Anschlußdrähte geklemmt werden, die parallel und radial auf der Elektrodenoberfläche aufliegen, in einem automatisierten Verfahren tauchgelötet und bei Bedarf mit einem isolierenden Überzug versehen werden.The already mentioned US Pat. No. 3,676,211 discloses a method in which ceramic disks provided with solderable coatings are clamped between mutually crossed connecting wires which lie parallel and radially on the electrode surface, dip-soldered in an automated process and, if necessary, provided with an insulating coating .

Die ebenfalls bereits genannte US-PS 3 793 604 beschreibt eine Ausführung von Scheibenthermistoren, bei der sich die Strecke, auf der der Anschlußdraht mit der Belegung verlötet ist, nicht mehr bis zum Rand der Keramikscheibe erstreckt, sondern nurmehr über die Hälfte des Scheibendurchmessers in der Mitte der Scheibe, was eine verbesserte Haftfähigkeit der angelöteten Anschlußdrähte bewirken soll.The already mentioned US Pat. No. 3,793,604 describes an embodiment of disk thermistors in which the distance on which the connecting wire is soldered to the covering no longer extends to the edge of the ceramic disk, but only over half the disk diameter in the Middle of the washer, which should improve the adhesion of the soldered connecting wires.

Werden solche Thermistoren mit radial angelöteten Anschlußdrähten rasch wechselnden Temperaturen ausgesetzt, kommt es also zu einer Temperaturschockbeanspruchung, so sind die Lötverbindungen starken mechanischen Belastungen ausgesetzt was von den unterschiedlichen thermischen Ausdehnungseigenschaften von Keramik einerseits und Anschlußdraht andererseits herrührtIf such thermistors with radially soldered connecting wires are exposed to rapidly changing temperatures, so if there is a thermal shock stress, the soldered connections are exposed to strong mechanical loads, which results from the different thermal expansion properties of ceramic on the one hand and connecting wire on the other

Die Widerstandsdrift von Heißleiterscheiben mit angelöteten Stromzuführungselementen beträgt nach mehrmaliger Temperaturschockbeanspruchung teilweise sogar bis zu 100% des Anfangswiderstandes.The resistance drift of thermistor disks with soldered power supply elements is sometimes up to 100% of the initial resistance after repeated thermal shock loads.

Der vorliegenden Erfindung liegt die Aufgabe zugrunde, einen kleinen, scheibenförmigen NTC-Widerstand mit an lötfähigen metallischen Belegungen angelöteten Stromzuführungselementen anzugeben, dessen Anschlußwiderstand bei einer Temperaturschockbeanspruchung von 100-fachem Wechsel zwischen - 60 °C und +300 °C, vorzugsweise -30 °C bis +130 °C eine Drift von weniger als 1 % aufweist und bei dem eine stabile Halterung der Keramikscheibe durch die sie tragenden Stromzuführungselemente gewährleistet ist, femer ist es Aufgabe der Erfindung, ein Verfahren zur Herstellung eines solchen NTC-Widerstandes anzugeben.The present invention is based on the object of specifying a small, disk-shaped NTC resistor with current supply elements soldered to solderable metallic coatings, the connection resistance of which with a temperature shock stress of 100-fold alternation between -60 ° C and +300 ° C, preferably -30 ° C up to +130 ° C has a drift of less than 1% and in which a stable mounting of the ceramic disc is ensured by the current supply elements carrying it, it is also the object of the invention to provide a method for producing such an NTC resistor.

Zur Lösung dieser Aufgabe ist der NTC-Widerstand der eingangs angegebenen Art erfindungsgemäß darurch gekennzeichnet, daß die Stromzuführungselemente an ihrem einen Ende ringförmig als weitgehend geschlossene Öse ausgebildet sind, deren Außendurchmesser höchstens 60 % des Durchmessers der Belegungen der Scheibe beträgt, die ringförmige Öse jedes Stromzuführungselementes mittig auf den Belegungen festgelötet ist, das Lot die Öse umschließt, die A4sdehnung des Lotes auf den Bereich der Öse beschränkt ist und die Randbereiche der Belegungen vom Lot nicht bedeckt sind.To solve this problem, the NTC resistor of the type specified at the outset is characterized in that the power supply elements are annular at one end as a largely closed eyelet, the outer diameter of which is at most 60% of the diameter of the disk coverings, the annular eyelet of each power supply element centrally soldered to the assignments, the solder surrounding the eyelet which A 4 sdehnung of the solder to the region of the eyelet is limited and the edge regions of the deposits from the solder are not covered.

In einer vorteilhaften Ausführung bestehen die Stromzuführungselemente aus einem lötfähigen Draht, dessen Ende zu einer weitgehend geschlossenen, ringförmigen Öse . geformt ist Dieser Draht kann beispielsweise ein Silberdraht,ein versilberter Kupferdraht oder ein verzinnter Kupferdraht sein, wobei der Drahtquerschnitt je nach Größe der Heißleiterscheibe zwischen 0,2 mm und 0,8 mm beträgtIn an advantageous embodiment, the power supply elements consist of a solderable wire, the end of which is a largely closed, annular eyelet. This wire can be, for example, a silver wire, a silver-plated copper wire or a tinned copper wire, the wire cross-section being between 0.2 mm and 0.8 mm, depending on the size of the thermistor disc

Die Stromzuführungselemente sind in einer anderen vorteilhaften Ausführungsform der Erfindung Formteile, die aus dem Blech eines lötfähigen Metalles gestanzt sind, deren Materialstärke zwischen 0,2 mm und 0,8 mm beträgt und bei denen die Differenz zwischen Außendurchmesser und Innendurchmesser der am einen Ende befindlichen Öse etwa das Doppelte der Blechstärke beträgtIn another advantageous embodiment of the invention, the power supply elements are molded parts which are punched from the sheet of a solderable metal, the material thickness of which is between 0.2 mm and 0.8 mm and in which the difference between the outer diameter and inner diameter of the eyelet located at one end is approximately twice the sheet thickness

Durch die Ausbildung eines Endes jedes Stromzuführungselementes als weitgehend geschlossene, ringförmige Öse mit einem kleineren Außendurchmesser als dem Scheibendurchmesser gelingt es zum einen, eine festhaftende Verbindung der Keramikscheibe mit den Stromzuführungselementen zu erzielen, die eine Abziehfestigkeit von 15 N bis 25 N, insbesondere von 20 N aufweisen.By forming one end of each power supply element as a largely closed, ring-shaped eyelet with a smaller outer diameter than the disk diameter, it is possible on the one hand to achieve a firmly bonded connection of the ceramic disk to the power supply elements, which has a peel strength of 15 N to 25 N, in particular of 20 N exhibit.

Darüberhinaus wird in Verbindung mit dem weiteren kennzeichnenden Merkmal, nach dem das Lot weitgehend auf den Bereich der Öse beschränkt bleibt und die Randgebiete der Belegungen nicht bedeckt, das überraschende und unerwartete Ergebnis erzielt, daß der AnsChlußwiderstand eines derart hergestellten Scheibenheißleiters mit gelöteten, die Keramikscheibe tragenden Stromzuführungselementen selbst bei einer hundertfachen Temperaturwechselbeanspruchung von -30 °C auf + 130 °C eine Drift von weniger als 1% seines Ausgangswertes aufweistIn addition, in connection with the further characteristic feature, according to which the solder remains largely confined to the area of the eyelet and does not cover the peripheral areas of the coverings, the surprising and unexpected result is achieved that the connection resistance of a disk thermistor produced in this way with soldered, supporting the ceramic disk Power supply elements have a drift of less than 1% of their initial value even with a hundredfold thermal cycling from -30 ° C to + 130 ° C

Die Erfindung ermöglicht somit die Herstellung kleiner, gegenüber Temperaturschockbeanspruchung stabiler Scheibenheißleiter nach dem Oberbegriff des Anspruches 1, die im genannten Temperaturbereich eine preisgünstige Alternative zu den bisher üblichen schockfesten NTC-Thermistoren darstellen, bei denen beispielsweise Platindrähte direkt in das Keramikmaterial eingesintert werden oder kleine Heißleiterscheiben mit metallisierten Stirnseiten in klemmenden Kontaktfedem gehalten werden, die auch den elektrischen Kontakt zu den Belegungen herstellen.The invention thus enables the production of small, thermally stable disc thermistors according to the preamble of claim 1, which represent an inexpensive alternative to the previously customary shock-resistant NTC thermistors in the temperature range mentioned, in which, for example, platinum wires are sintered directly into the ceramic material or small thermistor disks with metallized end faces are held in clamping contact springs, which also make electrical contact with the assignments.

Diese Thermistoren sind vielfach zusätzlich in Glasgehäuse eingeschmolzen und in ihrer Herstellung wesentlich teuerer als vergleichbare NTC-Widerstände gemäß der Erfindung (vgl.S. 13 des genannten SIEMENS-Lieferprogrammes).These thermistors are often additionally melted into a glass housing and are much more expensive to manufacture than comparable NTC resistors according to the invention (see p. 13 of the SIEMENS delivery program mentioned).

Das Merkmal nach Anspruch 1, wonach ein Ende eines jeden Stromzuführungselementes als ringförmige Öse ausgebildet ist, die auf den metallischen Belegungen zentral festgelötet ist, findet sich zwar auch in der US-PS 2 606 955, jedoch ist dort ein Kondensator aus einer Keramikscheibe mit metallischen Oberflächenbelegungen der Stimseiten von Stromzuführungselementen versehen, die aus einem Draht bestehen, dessen eines Ende zu einer nicht vollständig geschlossenen Öse geformt ist Diese Ösen werden jedoch im Gegensatz zur Lehre der Erfindung im Tauchlötverfahren auf den Belegungen befestigt, die somit völlig, auch im Randbereich, mit Lot bedeckt sind.The feature of claim 1, according to which one end of each power supply element is designed as an annular eyelet, which is centrally soldered to the metallic coatings, is also found in US Pat. No. 2,606,955, but there is a capacitor made of a ceramic disk with metallic Provide surface coverings of the end faces of power supply elements, which consist of a wire, one end of which is shaped into an incompletely closed eyelet. In contrast to the teaching of the invention, these eyelets are, however, attached to the coverings in the dip soldering process, which thus completely, also in the edge area, with Solder are covered.

In der mehrfach erwähnten US-PS 3 793 604 wird zwar darauf hingewiesen, daß sich die Abziehfestigkeit von geraden Anschlußdrähten, die radial auf metallische Belegungen von scheibenförmigen Keramikwiderständen aufgelötet sind, deutlich erhöhen läßt, wenn der Anschlußdraht nicht bis in den Randbereich der Belegungen aufliegt, sondem nur in der Mitte der Scheibe festgelötet wird, jedoch werden auch hier im Gegensatz zur Erfindung die Anschlußdrähte im Tauchlötverfahren an den Belegungen befestigt, so daß diese vollständig mit Lot bedeckt sind; eine Verbesserung der Stabilität bei Temperaturschockbeanspruchung wird bei derartigen Thermistoren nicht erzielt.In the repeatedly mentioned US Pat. No. 3,793,604, it is pointed out that the peel strength of straight connecting wires, which are radially soldered onto metallic coatings of disk-shaped ceramic resistors, can be significantly increased if the connecting wire does not lie up to the edge area of the coatings, is only soldered in the middle of the disk, but here too, in contrast to the invention, the connecting wires are attached to the coatings by dip soldering, so that they are completely covered with solder; an improvement in the stability in the event of temperature shock stress is not achieved with such thermistors.

Keine der genannten Veröffentlichungen gibt somit dem Fachmann einen Hinweis darauf, zur Beseitung der bekannten Drift des Widerstandswertes von kleinen Heißleiterscheiben mit angelöteten Stromzuführungselementen bei Temperaturschockbeanspruchung so vorzugehen, wie es die Erfindung lehrt.None of the publications mentioned thus gives the person skilled in the art an indication of how to proceed in order to eliminate the known drift in the resistance value of small thermistor disks with soldered-on current supply elements when subjected to temperature shock, as taught by the invention.

Es handelt sich vielmehr um einen unerwarteten und überraschenden Effekt, der dem Fachmann vom Stand der Technik in keiner Weise nahegelegt wird.Rather, it is an unexpected and surprising effect, which is in no way suggested to the person skilled in the art from the prior art.

Das Verfahren zur Herstellung eines NTC-Widerstandes der. eingangs genannten Art ist erfindungsgemäß dadurch gekennzeichnet, daß zum Anlöten jedes Stromzuführungselementes Lot in einer derart bemessenen Menge mit den aufliegenden ringförmigen Ösen in Verbindung gebracht wird, daß die Ausbreitung des flüssigen Lotes im wesentlichen nur auf den Bereich der Öse beschränkt bleibt.The process of making an NTC resistor. The type mentioned at the outset is characterized according to the invention in that for soldering each current supply element, solder is brought into connection with the ring-shaped eyelets in such an amount that the spread of the liquid solder remains essentially restricted to the area of the eyelet.

Ein Verfahren, das hier anwendbar ist, ist beispielsweise in der DE-PS 2 834 348 beschrieben. Dabei wird für einen anderen Zweck so vorgegangen, daß eine genau vorgegebene Menge einer Schmelze eines niedrigschmelzenden Metalls einer Preßluftdüse zugeführt, aus dieser stoßartig und vollständig auf den Anschlußdraht und auf eine durch eine seitliche Dichtung festgelegte Fläche einer Metallschicht in der Umgebung des Anschlußdrahtes aufgespritzt wird.A method that can be used here is described, for example, in DE-PS 2 834 348. For another purpose, the procedure is such that a precisely predetermined amount of a melt of a low-melting metal is fed to a compressed air nozzle, from which it is sprayed abruptly and completely onto the connecting wire and onto a surface of a metal layer in the vicinity of the connecting wire which is defined by a lateral seal.

Es ist vorteilhaft, wenn das Lot in Form eines Lötdrahtes in der Mitte der Scheibe mit den Belegungen in Verbindung gebracht wird, sich beim Erhitzen der Lötstelle radial ausbreitet und dabei im wesentlichen nur den Bereich der auf den Belegungen aufliegenden Öse bedeckt.It is advantageous if the solder in the form of a solder wire is brought into connection with the coatings in the middle of the disk, spreads radially when the solder joint is heated, and essentially covers only the area of the eyelet resting on the coatings.

Die Zeichnungen zeigen ein Ausführungsbeispiel der Erfindung. Dabei zeigt im einzelnen

  • Fig. 1 die Stirnseite eines erfindungsgemäßen NTC-Widerstandes in Draufsicht und
  • Fig. 2 einen vertikalen Schnitt durch einen erfindungsgemäßen NTC-Widerstand längs der Linie 11-11 in Fig. 1.
The drawings show an embodiment of the invention. It shows in detail
  • Fig. 1 shows the front of an NTC resistor according to the invention in plan view and
  • FIG. 2 shows a vertical section through an NTC resistor according to the invention along the line 11-11 in FIG. 1.

In beiden Figuren sind gleiche Teile mit gleichen Bezugszeichen versehen.In both figures, the same parts are provided with the same reference symbols.

In dem Ausführungsbeispiel ist eine Scheibe 1 gezeigt, die in der Praxis z.B. einen Durchmesser D von 3 mm und eine Dicke d von 1 mm aufweist, und die aus dichtgesinterter Metalloxidkeramik besteht und einen negativen Temperaturkoeffizienten des Widerstandswertes besitzt. An ihren Stirnseiten 2, 3 ist die Scheibe 1 mit metallischen Belegungen 4, 5 versehen.In the exemplary embodiment, a disc 1 is shown, which in practice e.g. has a diameter D of 3 mm and a thickness d of 1 mm, and which consists of densely sintered metal oxide ceramic and has a negative temperature coefficient of the resistance value. On its end faces 2, 3, the disc 1 is provided with metallic coatings 4, 5.

Diese sperrschichtfreien und festhaftenden Belegungen 4, 5 bestehen beispielsweise aus einer ersten Schicht aus Aluminium oder einer überwiegend Aluminium enthaltenden Legierung, die im Siebdruckverfahren hergestellt ist, und einer zweiten, lötfähigen Schicht aus Kupfer, die durch Flammspritzen aufgetragen ist.These barrier layer-free and adherent coatings 4, 5 consist, for example, of a first layer of aluminum or an alloy predominantly containing aluminum, which is produced by the screen printing process, and a second, solderable layer of copper, which is applied by flame spraying.

Es ist aber auch möglich und je nach der verwendeten Oxidkeramik ausreichend, die Belegungen 4, 5 unmittelbar auf den Stirnseiten 2, 3 der Scheibe 1 durch Auftragen und Einbrennen des an sich hinreichend bekannten Einbrennsilbers zu erzeugen (vgl. die bereits genannte US-PS 3 793 604).However, it is also possible and, depending on the oxide ceramic used, sufficient to produce the coatings 4, 5 directly on the end faces 2, 3 of the disk 1 by applying and baking the baking silver, which is well known per se (cf. the already mentioned US Pat. No. 3 793 604).

Die Stromzuführungselemente 6, 7, bestehen in diesem Beispiel aus einem Silberdraht mit einem Durchmesser von 0,4 mm, der an einem Ende 9 zu einer weitgehend geschlossenen, ringförmigen Öse 10 geformt ist, deren Außendurchmesser A 1,5 mm beträgt.In this example, the power supply elements 6, 7 consist of a silver wire with a diameter of 0.4 mm, which is formed at one end 9 into a largely closed, annular eyelet 10, the outer diameter A of which is 1.5 mm.

Diese Ösen sind zentral auf die Belegungen 4, 5 aufgelegt und mit Lot 8 auf den Belegungen 4, 5 befestigt. Das Lot 8 umschließt die Ösen 10 und bedeckt die Belegungen 4, 5 im wesentlichen nur im Bereich der Ösen 10, während die Randbereiche 11 der Belegungen 4, 5 von Lot 8 frei bleiben.These eyelets are placed centrally on the assignments 4, 5 and fastened with lot 8 on the assignments 4, 5. The solder 8 encloses the eyelets 10 and covers the bindings 4, 5 is substantially only in the region of the eyelets 10, while the edge portions 1 1 of the deposits 4, 5 remain free of solder. 8

In Fig. 2 wurde das Lot 8 zur besseren Darstellung einer Öse 10 nur auf der Stirnseite 2 gezeigt.In FIG. 2, the solder 8 has only been shown on the end face 2 for better illustration of an eyelet 10.

Claims (5)

1. Elektrischer Widerstand mit negativem Temperaturkoeffizienten des Widerstandswertes (NTC-Widerstand) aus einer Scheibe (1) aus dichtgesinterter Metalloxidkeramik mit geringem Durchmesser (D), insbesondere 1,5 mm bis 5 mm und geringer Dicke (d), insbesondere 0,6 mm und 2,5 mm und mit an den Stimseiten (2, 3) der Scheibe (1) angebrachten, festhaftenden und lötfähigen metallischen Belegungen (4, 5) und daran mit Lot (8) befestigten Stromzuführungselementen (6, 7), dadurch gekennzeichnet, daß die Stromzuführungselemente (6, 7) an ihrem einen Ende (9) ringförmig als weitgehend geschlossene Öse (10) ausgebildet sind, deren Außendurchmesser (A) höchstens 60 % des Durchmessers (B) der Belegungen (4, 5) der Scheibe (1) beträgt, die ringförmige Öse (10) jedes Stromzuführungselementes (6, 7) mittig auf den Belegungen (4, 5) festgelötet ist, daß das Lot (8) die Öse (10) umschließt die Ausdehnung des Lotes (8) auf den Bereich der Öse - (10) beschränkt ist und die Randbereiche (11) der Belegungen (4, 5) vom Lot (8) nicht bedeckt sind.1. Electrical resistance with a negative temperature coefficient of resistance (NTC resistance) from a disc (1) made of densely sintered metal oxide ceramic with a small diameter (D), in particular 1.5 mm to 5 mm and a small thickness (d), in particular 0.6 mm and 2.5 mm and with on the face sides (2, 3) of the pane (1) attached, firmly adhering and solderable metallic coatings (4, 5) and current supply elements (6, 7) attached to them with solder (8), characterized in that that the power supply elements (6, 7) are annular at one end (9) as a largely closed eyelet (10), the outer diameter (A) of which is at most 60% of the diameter (B) of the coverings (4, 5) of the disc (1 ), the ring-shaped eyelet (10) of each power supply element (6, 7) is centered on the coverings (4, 5) is soldered that the solder (8) the eyelet (10) encloses the extent of the solder (8) is limited to the area of the eyelet - (10) and the edge areas (11) of the coatings (4, 5) from the solder (8) are not covered. 2- Elektrischer Widerstand nach Anspruch 1, dadurch gekennzeichnet, daß die Stromzuführungselemente (6, 7) aus einem dünnen, insbesondere 0,2 mm bis 0,8 mm starken, lötfähigen Draht bestehen, dessen eines Ende (9) zu einer weitgehend geschlossenen, ringförmigen Öse (10) geformt ist2- Electrical resistance according to claim 1, characterized in that the power supply elements (6, 7) consist of a thin, in particular 0.2 mm to 0.8 mm thick, solderable wire, one end (9) of which is largely closed, annular eyelet (10) is shaped 3. Elektrischer Widerstand nach Anspruch 1, dadurch gekennzeichnet , daß die Stromzuführungselemente (6, 7) aus Blech eines lötfähigen Metalles gestanzte Formteile sind, deren Materialstärke zwischen 0,2 mm und 0,8 mm beträgt und bei denen die Differenz zwischen Außendurchmesser (A) und innendurchmesser (I) der am einen Ende (9) befindlichen Öse (10) etwa das Doppelte der Blechstärke beträgt3. Electrical resistance according to claim 1, characterized in that the power supply elements (6, 7) are stamped from sheet metal of a solderable metal, the material thickness is between 0.2 mm and 0.8 mm and in which the difference between the outer diameter (A ) and inner diameter (I) of the eyelet (10) located at one end (9) is approximately twice the sheet thickness 4. Verfahren zur Herstellung eines elektrischen Widerstandes nach einem der Ansprüche 1, 2 oder 3, bei dem an die gesinterte und mit Belegungen (4, 5) versehene Scheibe - (1) die Stromzuführungselemente (6, 7) angelegt und dann mittels Lot (8) befestigt werden, dadurch gekennzeichnet, daß zum Anlöten jedes Stromzuführungselementes (6, 7) Lot (8) in einer derart bemessenen Menge mit den Belegungen (4, 5) und den aufliegenden ringförmigen Ösen - (10) in Verbindung gebracht wird, daß die Ausbreitung des flüssigen Lotes (8) im wesentlichen nur auf den Bereich der Öse (10) beschränkt bleibt.4. A method for producing an electrical resistor according to one of claims 1, 2 or 3, in which the current-supply elements (6, 7) are applied to the sintered disc (4, 5) and provided with coatings (4, 5) and then by means of solder ( 8) are fastened, characterized in that for soldering each current supply element (6, 7) solder (8) in such a dimensioned amount is connected to the coverings ( 4 , 5) and the ring-shaped eyelets (10) lying thereon in such a way that the spread of the liquid solder (8) remains essentially restricted to the area of the eyelet (10). 5. Verfahren zur Herstellung eines elektrischen Widerstandes nach Anspruch 4, dadurch gekennzeichnet, daß das Lot (8) in Form eines Lötdrahtes in der Mitte der Scheibe - (1) mit den Belegungen (4, 5) in Verbindung gebracht wird, sich beim Erhitzen der Lötstelle radial ausbreitet und dabei im wesentlichen nur den Bereich der auf den Belegungen - (4, 5) aufliegenden Öse (10) bedeckt.5. A method for producing an electrical resistor according to claim 4, characterized in that the solder (8) in the form of a solder wire in the middle of the disc - (1) with the coatings (4, 5) is brought into contact when heated the solder joint radially spreads out and essentially covers only the area of the eyelet (10) resting on the coverings - ( 4 , 5).
EP86102471A 1985-03-07 1986-02-26 Electrical resistance having a negative temperature coefficient, and production process therefor Expired EP0193854B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT86102471T ATE35343T1 (en) 1985-03-07 1986-02-26 ELECTRICAL RESISTOR WITH NEGATIVE TEMPERATURE COEFFICIENT OF RESISTANCE AND METHOD FOR ITS MANUFACTURE.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3508163 1985-03-07
DE3508163 1985-03-07

Publications (2)

Publication Number Publication Date
EP0193854A1 true EP0193854A1 (en) 1986-09-10
EP0193854B1 EP0193854B1 (en) 1988-06-22

Family

ID=6264523

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86102471A Expired EP0193854B1 (en) 1985-03-07 1986-02-26 Electrical resistance having a negative temperature coefficient, and production process therefor

Country Status (5)

Country Link
US (1) US4695818A (en)
EP (1) EP0193854B1 (en)
JP (1) JPS61207001A (en)
AT (1) ATE35343T1 (en)
DE (1) DE3660341D1 (en)

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WO2009010313A1 (en) * 2007-07-13 2009-01-22 Auto-Kabel Managementgesellschaft Mbh Coated motor vehicle battery sensor element and method for producing a motor vehicle battery sensor element

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JPH0684612A (en) * 1992-08-31 1994-03-25 Somar Corp Production of small varistor
JPH10261507A (en) * 1997-03-18 1998-09-29 Murata Mfg Co Ltd Thermistor element

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DE2052489A1 (en) * 1969-10-27 1971-05-13 Matsushita Electric Ind Co Ltd Method for attaching wires to a flat object and machine for carrying out this method
US3793604A (en) * 1973-04-09 1974-02-19 Gte Sylvania Inc High strength electrical lead for disk type thermistors

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US2606955A (en) * 1949-02-03 1952-08-12 Jeffers Electronics Inc Electrical condenser
US2686244A (en) * 1951-04-19 1954-08-10 Lockheed Aircraft Corp Electrical attachnent of temperature sensing devices and the like
DE2052489A1 (en) * 1969-10-27 1971-05-13 Matsushita Electric Ind Co Ltd Method for attaching wires to a flat object and machine for carrying out this method
US3793604A (en) * 1973-04-09 1974-02-19 Gte Sylvania Inc High strength electrical lead for disk type thermistors

Cited By (2)

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Publication number Priority date Publication date Assignee Title
WO2009010313A1 (en) * 2007-07-13 2009-01-22 Auto-Kabel Managementgesellschaft Mbh Coated motor vehicle battery sensor element and method for producing a motor vehicle battery sensor element
US8319499B2 (en) 2007-07-13 2012-11-27 Auto Kabel Managementgesellschaft Mbh Coated motor vehicle battery sensor element and method for producing a motor vehicle battery sensor element

Also Published As

Publication number Publication date
JPS61207001A (en) 1986-09-13
JPH0563001B2 (en) 1993-09-09
DE3660341D1 (en) 1988-07-28
EP0193854B1 (en) 1988-06-22
ATE35343T1 (en) 1988-07-15
US4695818A (en) 1987-09-22

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