Discolored Silver plating switches

Almost all solder terminals and terminations are plated with a contact-enhancing material. For example, C&K switches use different kinds of plating for the soldering of switch terminals:

  • Pure Tin plating with specific bath solder
  • Silver plating
  • Gold plating

In most cases, there is no aging impact on pure tin and gold plating switches terminals. However, on silver plating switches such as KMR223GLFG from C&K, tarnishing may occur. Sometimes this discoloration of yellow/ blue/brown in silver termination can appear.


The silver tarnishing is a normal phenomenon, due to the combination of silver sulphide and silver oxide. This is only a cosmetic discoloration and has no impact on the switch’s function. This phenomenon cannot be avoided due to the fact that the silver plating is sensitive to environmental factors that cannot be precluded. This phenomenon is related to four factors:

  • Light
  • Atmosphere
  • Humidity
  • Temperature

More discoloration technical information, please see

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