Question of the Week - is plating necessary for tactile metal domes?
Metal switch domes are stamped from a stainless steel alloy. A common misconception about stainless steel is rust does not easily form on its surface. However, what really happens is visible rust is prevented by the formation of chromium oxide “rust” on the surface of the stainless steel.
A small percentage of chromium is found in all stainless steel alloys. e chromium oxide is transparent and seals the surface so that iron particles do not form iron oxide. e chromium oxide is what makes stainless steel “stainless.”
Chromium oxide is non-conductive and results in resistance, which makes for an unsuitable switch surface. While stainless steel domes can be plated with nickel, which does a respectable job of preventing chromium oxide growth, gold plating prevents chromium oxide growth and electrically performs better as a switch surface.