It is relatively common to include small surface mounted LEDs into membrane switches. This is a very simple way to add annunciators to a switch. A standard membrane switch keypad is not thick enough to accommodate the package size of most surface mounted LEDs. For this reason, the overlay may be embossed in the window area, or extra fillers may be added to the switch construction. Silver conductive epoxies are used to mount the LEDs to the circuit. These epoxies are not very flexible, and consequently switches with embedded LEDs should not be bent in the LED areas prior to being installed. Stiffeners can be added to the switch construction to add rigidity when needed.
Data sheets and engineering samples for embedded LEDs are available from:www.jcftechnology.com