How computer keyboards are made
Under the keys of a typical keyboard are plastic sheets printed with conductive traces, produced by reel-to-reel printing.
- stations
- 6
- things upstream
- 77
- raw sources
- 25
- steps from the ground
- 9
The short version
Keycaps are injection molded from plastic. Under them, a rubber dome or scissor mechanism sits above a stack of plastic membrane sheets printed with conductive traces, or above a circuit board with individual switches. A small controller scans the key matrix and reports which keys were pressed.
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Mold the keycaps
Molten plastic fills steel molds, one cavity per keycap. Legends are printed or lasered on afterward.
Goes in -
Print the membrane sheets
Conductive traces are printed on plastic sheets by reel-to-reel machines. The sheets are cut and punched afterward.
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Stack the switch layers
Two printed sheets are stacked with a spacer between them. When a key presses them together, the contacts touch and complete a circuit.
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Add domes or springs
Rubber domes or scissor mechanisms, or separate mechanical switches, go above each switch position to give the key its feel.
Goes in -
Wire the controller
A small circuit board scans the grid of keys. It sends the computer a scan code that tells it which physical key was pressed or released.
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Fit caps and test
Caps are pressed on, and every key is checked for a clean signal.
Worth repeating
- Key Tronic's 1978 capacitive keyboard used a sponge pad with a conductive-coated Mylar sheet, and the company rapidly became the largest independent keyboard maker.
- Standard ANSI keys sit on three-quarter inch spacing.
Back to the ground
Follow every input upstream and computer keyboard starts as these 25 raw sources.
Everything it is made of See it on the map
Open the whole family tree
Where it goes next
Computer keyboard feeds 1 line directly.
Keep walking
Sources
Cite this page: "How computer keyboards are made." Assembly Line, 2026-11-03. https://assemblyline.org/make/computer-keyboard