The key tops and key stems are assembled in the keyboard panel. The FPC (flexible
printed circuit) board with rubber contacts is fitted to the base plate. See Fig. 1.16.
The FPC board is a single sheet of film (FPC) on which an electrode pattern is printed in
layers. When the key top is pressed, the key actuator presses the rubber contact; the
conductive part of the contact connects both of the electrodes to output the
predetermined signal for the key.
Fig. 1.16 Key Top/Key Stem Assembly