Alright, quiz time. Can you identify the source of following picture? Hint: it is the inside of a common electronic device (measuring 3″ x 4″):
No luck yet? How about we add the second layer of circuitry:
Still uncertain? Those are circuit traces you see, although not ones from a traditional circuit board. These traces are printed on thin, clear plastic. Oh, and you can ignore the black plastic bit in the lower right – that’s just a point through which a screw connects. Alright, one final layer, then I’ll reveal the final image:
That’s a layer of semi-transparent rubbery material. You’ve probably figured it out now, right? Would it help if I told you those domes you see are buttons? Well, try this:
Yep, it’s a keyboard. To be specific, it’s my Logitech LX710 wireless keyboard. Pretty exciting, huh? It works quite simply: whenever you press a key, those rubber domes, which have a small layer of carbon on their undersides, contact the two layers of circuitry, which are separated by another thin layer of clear plastic. These two layers, when pressed together by the rubber dome, complete an electrical circuit which tells the keyboard’s microcontroller unit (MCU) which key has been pressed. The MCU then processes and transmits this data back to the computer. End result? This article.