The assembled plastic keypads (API) combine plastic keys with a silicone base. The plastic keys can be transparent with printing on the backside, spray-coated or metalization. The silicone base is made of translucent material giving an excellent backlighting.
As to the assembly there are several ways for attaching the keys to the silicone:
Transparent plastic keys, printed at the backside that are glued to the silicone
Plastic keys pushed onto the silicone (“push-fit”)
This type of keypad can be used in combination with PET- or metal domes and is widely used in mobile phones, automotive and payment terminals.