What Are The Internal Parts Of Keyboard?

Keyboards made in the 70's to early 90's use to be made of plastic keys that had springs under them. The spring would hit a metal part of a printed circuit board that would send a signal to the computer's motherboard. The signal would be transformed into an ASCII code and resubmitted to temporary memory (RAM). The signals was then reconverted so a letter would be shown on a monitor. The CPU would send the letter(s), which are now in ASCII code, to the hard drive once the operator was finished typing and a signal was received from RAM for permanent storage.
         Today's keyboards are actually plastic keys with a mylar sheet inbetween the keys and rubber membrane. This sets up a static charge that is recognized by the computer;s motherboard. The process to see and save the letter follows the same procedure outlined above.
         In both cases, the keyboard is classified as an "output peripheral mechanical device". The difference between the two devices is that rubber membrane and mylar sheet. If any liquid (like hot coffee or tea) were poured over the keys on the top keyboard, the keyboard was permanently damaged. In the keyboard with the rubber membrane, the screws could be removed from the bottom of the keyboard, the mylar and rubber carefully taken out then wiped dry and cleaned.
         There were more moving parts to the older keyboard so they were more expensive. Since there are virtually no moving parts to today's keyboard, they are cheap to replace. If damage is done to either keyboard, you can clean it out. If a part is broken, however, simply buy a new one. I hope this answers your question.