Heat Rise:

An indirect measurement of a contact resistance used by rating agencies. The temperature rise of a contact carrying a prescribed current is measured to determine acceptable limit.

Flash Plating:

Plating thickness of 10 micro inches (0.00001) or less, typically done with gold plate.

Hermetic:

An environmental seal specification grade that requires no air, gas or liquid will leak into, or out of, the switch.

Flux:

Chemical used for cleaning metal surfaces for welding. Fluxes turn contaminated metal surfaces into clean, solderable part.