EP0088220B1 - Contact member and method for its manufacture - Google Patents

Contact member and method for its manufacture Download PDF

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Publication number
EP0088220B1
EP0088220B1 EP83100717A EP83100717A EP0088220B1 EP 0088220 B1 EP0088220 B1 EP 0088220B1 EP 83100717 A EP83100717 A EP 83100717A EP 83100717 A EP83100717 A EP 83100717A EP 0088220 B1 EP0088220 B1 EP 0088220B1
Authority
EP
European Patent Office
Prior art keywords
layer
rhodium
contact member
silver
contact
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP83100717A
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German (de)
French (fr)
Other versions
EP0088220A2 (en
EP0088220A3 (en
Inventor
Cornelia Dipl.-Phys. Albert
Ulf Dipl.-Phys. Rauterberg
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
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Siemens AG
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Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Publication of EP0088220A2 publication Critical patent/EP0088220A2/en
Publication of EP0088220A3 publication Critical patent/EP0088220A3/en
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Publication of EP0088220B1 publication Critical patent/EP0088220B1/en
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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/02—Contacts characterised by the material thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H11/00—Apparatus or processes specially adapted for the manufacture of electric switches
    • H01H11/04—Apparatus or processes specially adapted for the manufacture of electric switches of switch contacts
    • H01H11/041—Apparatus or processes specially adapted for the manufacture of electric switches of switch contacts by bonding of a contact marking face to a contact body portion
    • H01H2011/046—Apparatus or processes specially adapted for the manufacture of electric switches of switch contacts by bonding of a contact marking face to a contact body portion by plating

Definitions

  • the invention relates to a contact element as prior art, which has on a preferably ferromagnetic carrier material at least two contact layers electroplated one above the other, of which the outer layer consists of rhodium and the underlying second layer of a noble metal.
  • the invention relates to a method for producing such contact elements.
  • the object of the invention is therefore to provide a contact element with a noble metal contact layer and a rhodium coating, which maintains a low contact resistance even at high switching numbers and does not tend to cold welding.
  • the noble metal layer consists of silver and the rhodium protective layer has a thickness between 0.2 ⁇ m and 2 ⁇ m.
  • the wafer-rhodium-plated contact elements coated with silver according to the invention do not tend to cold welding or gluing even after a long service life and thereby maintain a largely constant low contact resistance.
  • the contact resistance is even more constant than with correspondingly thin rhodium-plated contact layers made of gold or gold alloys.
  • the contacts according to the invention have the additional advantages that result from the use of the contact material silver. Silver is much cheaper than gold and also more resilient as a contact material.
  • rhodium-plated silver contacts Up to a layer thickness of approximately 2 pm rhodium, rhodium-plated silver contacts have lower resistance than pure rhodium contacts. Particularly good results can be achieved with a rhodium layer thickness between 0.3 pm and 1 pm.
  • the thickness of the silver layer is advantageously between 1 and 10 ⁇ m, preferably 2 to 5 ⁇ m.
  • a nickel layer with a thickness of about 2 to 4 pm and, if appropriate, a copper layer with a thickness of 2 to 10 ⁇ m is expediently provided below the silver layer in order to achieve a diffusion barrier between the preferably ferromagnetic carrier material and the silver contact layer.
  • Table 1 shows the development of the contact resistance for the different contact layers:
  • the silver contact layer For the application of the silver contact layer, an electrolyte is expediently used which is largely free of additions of gloss and wetting agents and is advantageously deposited using wave plating technology.
  • the rhodium layer which expediently has a sulfur content of 4 to 7% by weight, is advantageously produced using spray electroplating technology (“jet ptating”).
  • jet ptating spray electroplating technology
  • the layer thickness of the protective layer can be achieved particularly precisely. It is also advantageous to anneal the contact element after the contact layers have been applied.

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  • Contacts (AREA)
  • Electroplating Methods And Accessories (AREA)
  • Manufacture Of Switches (AREA)

Description

Die Erfindung bezieht sich auf ein Kontaktelement als Stand der Technik, welches auf einem vorzugsweise ferromagnetischen Trägermaterial mindestens zwei übereinander galvanisch aufgebrachte Kontaktschichten besitzt, wovon die äussere Schicht aus Rhodium und die darunter liegende zweite Schicht aus einem Edelmetall besteht. Ausserdem bezieht sich die Erfindung auf ein Verfahren zur Herstellung solcher Kontaktelemente.The invention relates to a contact element as prior art, which has on a preferably ferromagnetic carrier material at least two contact layers electroplated one above the other, of which the outer layer consists of rhodium and the underlying second layer of a noble metal. In addition, the invention relates to a method for producing such contact elements.

Bei Mehrschichtkontakten für Relais und dergleichen ist es bekannt, die eigentliche Kontaktschicht aus Gold oder einer Goldlegierung zu fertigen und diese dann zur Verminderung der Kaltschweissneigung mit einer dünnen Rhodiumschicht zu überziehen (<Elektronik> 15/1981, Seite 58/59). Um durch die Rhodiumschicht den Kontaktwiderstand nicht allzu sehr zu erhöhen, wird diese Schutzschicht kleiner 1 µm, meist in der Grössenordnung von 0,1 µm Dicke gewählt. Die bisher bekannten rhodinierten Gold- oder Goldlegierungsschichten zeigen zwar in den meisten Anwendungsfällen befriedigende Ergebnisse, bezüglich des Kontaktwiderstandes und der Kaltschweissneigung, aber auch wegen der Kosten sind Verbesserungen wünschenswert.In the case of multilayer contacts for relays and the like, it is known to manufacture the actual contact layer from gold or a gold alloy and then to coat it with a thin rhodium layer to reduce the tendency to cold welding (<electronics> 15/1981, page 58/59). In order not to increase the contact resistance too much due to the rhodium layer, this protective layer is chosen to be smaller than 1 µm, usually in the order of 0.1 µm in thickness. The previously known rhodium-plated gold or gold alloy layers show satisfactory results in most applications, with regard to the contact resistance and the tendency to cold welding, but improvements are also desirable because of the costs.

Aufgabe der Erfindung ist es daher, ein Kontaktelement mit einer Edelmetall-Kontaktschicht und einem Rhodiumüberzug zu schaffen, welches auch bei hohen Schaltzahlen einen geringen Kontaktwiderstand beibehält und nicht zum Kaltschweissen neigt.The object of the invention is therefore to provide a contact element with a noble metal contact layer and a rhodium coating, which maintains a low contact resistance even at high switching numbers and does not tend to cold welding.

Erfindungsgemäss wird diese Aufgabe dadurch gelöst, dass die Edelmetallschicht aus Silber besteht und die Rhodium-Schutzschicht eine Dicke zwischen 0,2 µm und 2 µm besitzt. Die erfindungsgemäss mit Silber beschichteten und hauchrhodinierten Kontaktelemente neigen auch nach langer Lebensdauer noch nicht zum Kaltschweissen bzw. Kleben und behalten dabei einen weitgehend konstant niedrigen Kontaktwiderstand bei. Überraschenderweise ist der Kontaktwiderstand sogar konstanter als bei entsprechend hauchrhodinierten Kontaktschichten aus Gold oder Goldlegierungen. Darüber hinaus haben die erfindungsgemässen Kontakte die zusätzlichen Vorteile, die sich aus der Verwendung des Kontaktmaterials Silber ergeben. So ist Silber wesentlich billiger als Gold und als Kontaktwerkstoff auch belastbarer.According to the invention, this object is achieved in that the noble metal layer consists of silver and the rhodium protective layer has a thickness between 0.2 μm and 2 μm. The wafer-rhodium-plated contact elements coated with silver according to the invention do not tend to cold welding or gluing even after a long service life and thereby maintain a largely constant low contact resistance. Surprisingly, the contact resistance is even more constant than with correspondingly thin rhodium-plated contact layers made of gold or gold alloys. In addition, the contacts according to the invention have the additional advantages that result from the use of the contact material silver. Silver is much cheaper than gold and also more resilient as a contact material.

Bis zu einer Schichtdicke von etwa 2 pm Rhodium sind rhodinierte Silberkontakte niederohmiger als reine Rhodiumkontakte. Besonders gute Ergebnisse lassen sich erzielen bei einer Rhodiumschichtdicke zwischen 0,3 pm und 1 pm. Die Dicke der Silberschicht beträgt zweckmässigerweise zwischen 1 und 10 pm, vorzugsweise 2 bis 5 µm. Unterhalb der Silberschicht wird zweckmässigerweise eine Nickelschicht mit einer Dicke von etwa 2 bis 4 pm und darunter gegebenenfalls noch eine Kupferschicht in einer Dicke von 2 bis 10 µm vorgesehen, um eine Diffusionssperre zwischen dem vorzugsweise ferromagnetischen Trägermaterial und der Silber-Kontaktschicht zu erzielen.Up to a layer thickness of approximately 2 pm rhodium, rhodium-plated silver contacts have lower resistance than pure rhodium contacts. Particularly good results can be achieved with a rhodium layer thickness between 0.3 pm and 1 pm. The thickness of the silver layer is advantageously between 1 and 10 μm, preferably 2 to 5 μm. A nickel layer with a thickness of about 2 to 4 pm and, if appropriate, a copper layer with a thickness of 2 to 10 μm is expediently provided below the silver layer in order to achieve a diffusion barrier between the preferably ferromagnetic carrier material and the silver contact layer.

Nachfolgend werden anhand der Tabellen 1 und 2 einige Versuchsergebnisse dargestellt, die einen Vergleich zwischen den erfindungsgemässen rhodinierten Silberschichten von Relaiskontakten und entsprechend rhodinierten Goldkobaltschichten hinsichtlich ihres Kontaktwiderstandes und ihrer Klebneigung zeigen.Some test results are shown below with the aid of Tables 1 and 2, which show a comparison between the rhodium-plated silver layers of relay contacts according to the invention and correspondingly rhodium-plated gold cobalt layers with regard to their contact resistance and their tendency to stick.

In Tabelle 1 ist die Entwicklung des Kontaktwiderstandes bei den verschiedenen Kontaktschichten gezeigt:

Figure imgb0001
Table 1 shows the development of the contact resistance for the different contact layers:
Figure imgb0001

Im Neuzustand lagen die Kontaktwiderstände aller Schichten, also sowohl der rhodinierten Silberschichten als auch der rhodinierten Gold-Kobaltschichten unter 40 mΩ. Die rhodinierten Silberschichten blieben mit ihrem Kontaktwiderstand bis zum Ende der Messung bei 108 Schaltspielen immer unter 50 mQ, während bei den Gold-Kobaltschichten dieser Wert ab 105 Schaltspielen sporadisch überschritten wurde.When new, the contact resistance of all layers, i.e. both the rhodium-plated silver layers and the rhodium-plated gold-cobalt layers, was below 40 mΩ. The rhodium-plated silver layers always remained below 50 mQ with their contact resistance up to the end of the measurement with 10 8 switching cycles, while with the gold-cobalt layers this value was exceeded sporadically from 10 5 switching cycles.

Zur Untersuchung der Klebneigung (Kaltschweissneigung) wurden die gleichen Chargen wie in Tabelle 1 verwendet. In der Tabelle ist in

Figure imgb0002
der zweiten Spalte der jeweils verwendete Kontaktwerkstoff und in der dritten Spalte die Zahl der klebenden Kontakte im Neuzustand dargestellt. Für die Messung wurde der Begriff <Kleber> bzw. ,klebender Kontakt> so definiert, dass der Ansprechwert der Relais beim ersten Ansprechen gegenüber dem normalen Betrieb um 15% oder mehr überhöht ist.The same batches as in Table 1 were used to investigate the tendency to stick (cold sweat). The table is in
Figure imgb0002
 the second column shows the contact material used and in the third column the number of adhesive contacts when new. For the measurement, the term <adhesive> or "adhesive contact" was defined in such a way that the response value of the relays is increased by 15% or more compared to normal operation when the relay is activated for the first time.

Aus Tabelle 2 ergibt sich, dass die hauchrhodinierten Silberschichten im Neuzustand bei keinem einzigen Kontakt Klebneigung zeigten, während dies bei den hauchrhodinierten Gold-Kobaltschichten bei einem Relais der Fall war. Bei den hauchrhodinierten Silberschichten trat bis zum Versuchsende nach 108 Schaltspielen kein Kleben auf, während bei den hauchrhodinierten Gold-Kobaltschichten über 2,5 106 Schaltspielen - insbesondere bei geringer Rhodiumschichtdicke - verstärkt Kontaktkleben festgestellt wurde. Insgesamt zeigt sich aufgrund der Versuchsergebnisse, dass die erfindungsgemässen hauchrhodinierten Silberkontaktschichten, auch bei hohen Schaltspielzahlen sowohl konstant niedrige Übergangswiderstände als auch eine äusserst geringe Klebneigung im Vergleich zu den untersuchten Gold-Kobaltschichten zeigen.It can be seen from Table 2 that the wafer-rhodium-plated silver layers showed no tendency to stick when not in contact with one another, whereas this was the case with the wafer-rhodium-plated gold-cobalt layers in the case of a relay. In the ultra-rhodium-plated silver layers, no sticking occurred after 10 8 switching operations until the end of the experiment, while in the ultra-rhodium-plated gold-cobalt layers over 2.5 106 switching operations - particularly with a thin rhodium layer thickness - increased contact sticking was found. Overall, the test results show that the wafer-rhodium-plated silver contact layers according to the invention, both at high switching cycles, show both consistently low contact resistances and an extremely low tendency to stick in comparison to the gold cobalt layers examined.

Für das Aufbringen der Silberkontaktschicht wird zweckmässigerweise ein Elektrolyt verwendet, der weitgehend frei von Glanzzusätzen und Netzmitteln ist und vorteilhafterweise in Schwallgalvaniktechnik abgeschieden wird. Die Rhodiumschicht, die zweckmässigerweise einen Schwefelanteil von 4 bis 7 Gew. % besitzt, wird dagegen vorteilhafterweise in Spritzgalvaniktechnik (,Jet-Ptating>) erzeugt. Dadurch lässt sich die Schichtdicke der Schutzschicht besonders genau erzielen. Von Vorteil ist es ausserdem, das Kontaktelement nach dem Aufbringen der Kontaktschichten zu tempern.For the application of the silver contact layer, an electrolyte is expediently used which is largely free of additions of gloss and wetting agents and is advantageously deposited using wave plating technology. In contrast, the rhodium layer, which expediently has a sulfur content of 4 to 7% by weight, is advantageously produced using spray electroplating technology (“jet ptating”). As a result, the layer thickness of the protective layer can be achieved particularly precisely. It is also advantageous to anneal the contact element after the contact layers have been applied.

Claims (9)

1. A contact member having at least two contact layers which are electrodeposited one above another on a carrier material which is preferably ferro-magnetic, the outer layer of said contact member consisting of rhodium and the underlying second layer of a precious metal, characterised in that the rhodium layer has a thickness of between 0.2 µm and 2 pm and the underlying layer of precious metal consists of silver.
2. A contact member as claimed in Claim 1, characterised in that the rhodium layer has a thickness of between 0.3 and 1 pm.
3. A contact member as claimed in Claim 1 or Claim 2, characterised in that the rhodium layer has a sulphur content of 4 to 7% by weight.
4. A contact member as claimed in one of Claims 1 to 3, characterised in that the silver layer has a thickness of 1 to 10 µm, preferably 2 to 5 µm.
5. A contact member as claimed in one of Claims 1 to 4, characterised in that a nickel layer having a thickness of 2 to 4 µm is arranged below the silver layer.
6. A contact member as claimed in one of Claims 1 to 5, characterised in that an additional copper layer having a thickness of 2 to 10 pm is arranged between the carrier material and the layer of precious metal.
7. A process for the production of a contact member as claimed in Claim 1, characterised in that the silver layer and the rhodium layer are consecutively applied onto the carrier material which may be coated with copper and/or nickel, the silver layer by a bath- or swell-electrodeposition technique and the rhodium layer by an electro-spraying technique.
8. A process as claimed in Claim 7, characterised in that for the application of the silver layer, a particularly pure electrolyte is used which is substantially free from brighteners and wetting agents.
9. A process as claimed in Claim 7 or Claim 8, characterised in that the contact member is annealed after the application of the contact layers.
EP83100717A 1982-01-29 1983-01-26 Contact member and method for its manufacture Expired EP0088220B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3203037 1982-01-29
DE3203037A DE3203037C2 (en) 1982-01-29 1982-01-29 Contact element and process for its manufacture

Publications (3)

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EP0088220A2 EP0088220A2 (en) 1983-09-14
EP0088220A3 EP0088220A3 (en) 1985-05-15
EP0088220B1 true EP0088220B1 (en) 1987-06-03

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EP83100717A Expired EP0088220B1 (en) 1982-01-29 1983-01-26 Contact member and method for its manufacture

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EP (1) EP0088220B1 (en)
JP (1) JPS58133717A (en)
DE (2) DE3203037C2 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0227972B1 (en) * 1985-12-06 1989-08-02 Siemens Aktiengesellschaft Contact element for electrical switch contacts
DE3813142A1 (en) * 1988-04-20 1989-11-09 Duerrwaechter E Dr Doduco Strip-shaped or sheet-shaped semi-finished product for electrical contacts
DE19530512C1 (en) * 1995-08-18 1996-10-17 Siemens Ag Electrical layered contact element used in weak current relays

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1802932B2 (en) * 1968-10-14 1974-11-14 W.C. Heraeus Gmbh, 6450 Hanau Method for producing an electrical switch contact
DE2038929B2 (en) * 1969-08-29 1978-03-16 N.V. Philips' Gloeilampenfabrieken, Eindhoven (Niederlande) Contact for a switching device in communications engineering
DE2442212A1 (en) * 1974-09-04 1976-03-25 Licentia Gmbh Rhodium coating on electric contacts - formed galvanically in at least two stages with intervening firing to improve adhesion
GB1517702A (en) * 1974-09-19 1978-07-12 Fujitsu Ltd Electrical contact
JPS5913811B2 (en) * 1976-11-18 1984-04-02 富士通株式会社 Manufacturing method of switch movable body
JPS54129359A (en) * 1978-03-30 1979-10-06 Nippon Electric Co Lead switch

Also Published As

Publication number Publication date
DE3203037C2 (en) 1984-03-08
DE3203037A1 (en) 1983-08-18
JPS58133717A (en) 1983-08-09
DE3371958D1 (en) 1987-07-09
EP0088220A2 (en) 1983-09-14
EP0088220A3 (en) 1985-05-15

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