An illuminated keyboard includes keys; a spacer board on a base plate and comprising units each including two first groove connectors and two second groove connectors; an optically transmissive film circuit board on the spacer board and comprising a second circuitry, switch contacts, and first holes each with the first or second groove connector passing; a rubber plate of optically transmissive plastic and on the film circuit board, the rubber plate comprising resilient domes having a recessed top for retaining the key, a conductive bottom stem above the switch contact, and second holes grouped as groups each formed as four corners around the dome, the first or second groove connectors adapted to pass through the second holes; and an LED circuit board on the rubber plate and comprising a first circuitry and LEDs electrically connected to the first circuitry to be powered therefrom.