ABSTRACT
A reed switch is a pair of blades in a magnetic material, such as 52-alloy, sealed in a glass tube together with an inert gas. A reed switch pulls in at the point where the attractive force curve touches the load line. Contact plating as well as sealing is the most important process in the manufacture of reed switches. The quality of contact plating determines the contact characteristics of the reed switch. In ordinary reed switches, except for some changeover-type reed switches, which use a special plating, gold is plated onto 52-alloy as a ground layer, and rhodium or ruthenium in some cases is plated on the background layer. Rhodium is a commonly used contact material for reed switches. A non-magnetic chip is welded to the normally closed blade of a changeover-type reed switch. Rhenium, like tungsten, has a higher melting point than both rhodium and ruthenium, and is one of the quite useful contact materials for high-power reed switches.
