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
  • H01H1/021—Composite material

Definitions

• the invention relates to a contact material in the form of a layer of chalcogenides of transition metals from groups IVa to VIa of the Periodic Table of the Elements (PSE) on a substrate and a method for its production.
• PSE Periodic Table of the Elements
• contact materials based on precious metals are preferably used for most contact systems.
• the use and further development of contact materials are therefore primarily determined by the need for substitution of precious metals, which can be achieved by reducing the proportion of alloys, by geometrically minimizing the contact volume and by developing new contact materials that can do without precious metals.
• contact materials based on high-melting metals such as tungsten, molybdenum and rhenium are used today, which are characterized not only by their high melting points, but also by high hardness and strength, which results in a high wear and erosion resistance of the contacts made from them.
• high-melting metals such as tungsten, molybdenum and rhenium
• tungsten contacts can only be used to a limited extent with regard to their current carrying capacity due to the low electrical thermal conductivity, in addition, tungsten is unstable to oxygen above a temperature of 400 ° C and when switching in air, oxidic foreign layers are formed which lead to an external layer resistance and thus to an increase of the contact resistance. Contact forces of at least 1 N are therefore required for reliable contacting, or frictional actuation of the contacts must be provided.
• the starting semi-finished product for tungsten contacts is produced by powder metallurgy by pressing and sintering powder, however, because of the low ductility and the high strength, the mechanical processing of tungsten is difficult. Due to its physical properties, molybdenum does not achieve the excellent contact properties of tungsten. However, it is preferred as a cheaper metal for those cases that do not necessarily require the use of tungsten.
• the invention has for its object to provide contact materials based on transition metals of groups IVa to VIa of the PSE, from which thin and thick-film contacts of any configuration can be produced economically, which do not have the disadvantages mentioned above and which have the particular advantage that they have very low sliding friction coefficients.
• This object is achieved in that the structure of the layer is modified by particle bombardment.
• the chalcogenides preferably the transition metals titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and / or tungsten, are formed from the chalcogens sulfur, selenium and / or tellurium, advantageously in the chalcogenide layer is implanted with an implantation energy in the range from 0.5 keV to 400 keV and a dose in the range from 1015 to nx 1018 / cm2.
• inert gas ions preferably nitrogen ions, or noble gas ions, preferably argon ions, are implanted in the chalcogenide layer.
• a method for producing a contact material in the form of a layer of chalcogenides of transition metals of groups IVa to VIa of the Periodic Table of the Elements (PSE) deposited on a substrate by chemical or physical vapor deposition is characterized in that the structure of the layer is modified by particle bombardment .
• Layers of chalcogenides of transition metals have very low sliding friction coefficients, but have a relatively high contact resistance R K , so that they are not well suited as a contact material. Surprisingly, however, it has been found that the values for the contact resistance R K can be reduced by up to three orders of magnitude if the structure of the chalcogenide layers is modified during or after application to a substrate, which is advantageously achieved by particle bombardment, preferably by ion implantation can be.
• This effect is not based on doping the layer material with foreign ions, as it is e.g. is known from semiconductor technology.
• the reduction in the contact resistance of the layers according to the invention also results from bombardment with ions from elements which are generally not used for doping purposes, e.g. Noble gas or inert gas ions. It can be assumed that the improvement in the electrical conductivity or the reduction in the contact resistance of chalcogenide layers is a result of structural changes in the layers after particle bombardment. After bombardment with e.g. high-energy ions were found in studies on layers produced in the context of the present invention, an increase in the density of the layers by up to 40%.
• the particle bombardment is carried out while the layer is being applied.
• layers of greater thickness preferably a layer thickness in the range from 0.1 to 10 ⁇ m
• layers of greater thickness can be modified in their structure, for which purpose advantageously low-energy ions with an implantation energy in the range from 0.5 keV to 100 keV and a dose in the range from 1015 to nx 1018 / cm2, preferably a dose in the range from 3 x 1015 to 1016 / cm2.
• the particle bombardment is carried out after the layer has been applied.
• This method is particularly suitable if layers of smaller thickness, preferably in the range from a monolayer to 2 ⁇ m, are to be modified in their structure.
• This is advantageously carried out by implantation of higher-energy ions with an implantation energy in the range from 50 keV to 400 keV and a dose in the range from 1015 to n x 1018 / cm2, preferably a dose in the range from 3 x 1015 to 1016 / cm2.
• inert gas ions preferably nitrogen ions, or noble gas ions, preferably argon ions, are implanted in the chalcogenide layer.
• the chalcogenide layer is produced by cathode sputtering, the deposition process advantageously being supported by a magnetic field, that is to say using a magnetron.
• the chalcogenide layers can also be deposited using other methods known for depositing thin or thick layers.
• chemical vapor deposition such as plasma-assisted deposition from the gas phase, reactive cathode sputtering, plasma-assisted deposition from the gas phase, vapor deposition, ion plating processes with a high bias on the substrate or ionization should be considered here of the layer material to be deposited in the arc, optionally in a reactive gas phase from, for example Hydrogen sulfide gas or sulfur in the gas phase.
• contact materials are provided which do not require any precious metals, from which contacts of any confi guration can be produced and which have particularly low sliding friction coefficients, even in a vacuum, which is very favorable for the production of, for example, contacts which are to be exposed to mechanical sliding or grinding stress.
• a particular advantage of the contact materials according to the invention and the contact layers produced from them is that their contact resistance is undesirably increased less than in the case of contacts made of pure base metals due to an external layer resistance as a result of the formation of foreign or cover layers by, for example, oxidizing action of the surrounding medium.
• the layers according to the invention show a particularly good adhesive strength on steel substrates; intermediate layers that improve adhesion are not necessary here.
• cathode sputtering process which is preferably provided for the production of the chalcogenide layers
• ion implantation process which is preferably provided for the structural change of the chalcogenide layers
• chalcogenides of the transition metals titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and / or tungsten come into consideration, which need not be stoichiometric chalcogenides.
• Implantation parameters for argon Layer thickness 0.43 ⁇ m: Implantation energy 150 keV dose 3x 1015 / cm2 Implantation energy 400 keV dose 1x 1016 / cm2 Implantation parameters for nitrogen: Layer thickness 0.11 ⁇ m: Implantation energy 150 keV dose 1x 1016 / cm2 Layer thickness 0.43 ⁇ m: Implantation energy 100 keV dose 1x 1016 / cm2 Implantation energy 150 keV dose 3x 1015 / cm2 Implantation energy 150 keV dose 1x 1016 / cm2
• argon or nitrogen ions e.g. silicon or hydrogen ions can also be implanted in the chalcogenide layers.
• the implantation parameters can be determined without difficulty by the person skilled in the art in the context of the present method.
• the table below shows the values for the coefficient of friction ⁇ and the values for the contact resistance R K before and after ion implantation for different chalcogenide layers.
• the values for the respective contact resistance were measured using a gold counter electrode.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Composite Materials (AREA)
• Materials Engineering (AREA)
• Contacts (AREA)
• Manufacture Of Switches (AREA)
• Physical Vapour Deposition (AREA)
• Conductive Materials (AREA)

Applications Claiming Priority (2)

Publications (3)

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ID=6346371

Family Applications (1)

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Cited By (1)

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• 1988
  • 1988-02-01 DE DE3802869A patent/DE3802869A1/de active Granted
• 1989
  • 1989-01-25 EP EP89200156A patent/EP0327157B1/fr not_active Expired - Lifetime
  • 1989-01-25 DE DE58907989T patent/DE58907989D1/de not_active Expired - Fee Related
  • 1989-01-25 AT AT89200156T patent/ATE108282T1/de active
  • 1989-01-31 JP JP1019935A patent/JPH01232614A/ja active Pending

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