The creation of a plastic keyboard involves converging several parallel manufacturing streams into a single final assembly line. Processes such as housing injection molding, keycap fabrication, switch manufacturing, and PCBA (Printed Circuit Board Assembly) surface-mount soldering take place in specialized factories. The final assembly line then handles switch insertion, keycap installation, integration into the bottom housing, and the assembly of remaining components. Keycap legends are applied during the keycap fabrication stage using dye-sublimation or double-shot injection molding; the final assembly plant’s role is to “assemble these pre-made modules into a functional keyboard.”
I. Housing Injection Molding
The housing consists of a top cover and a bottom cover, typically injection-molded from ABS or PC plastic. Molten plastic is injected into a mold; once cooled, the part is ejected to form the housing shell. Positioning posts and screw bosses are located at the corners of both the top and bottom covers to facilitate PCB mounting and the joining of the two halves. The housing undergoes surface finishing and visual inspection before entering the final assembly line.
II. Keycap Fabrication
Keycaps are manufactured independently at a specialized facility, utilizing processes such as dye-sublimation or double-shot injection molding.
III. Switch Manufacturing
Switches are produced by specialized manufacturers. Core processes for mechanical switches include metal leaf stamping, contact riveting, spring assembly, injection molding of the stem and top housing, and bottom housing encapsulation. Magnetic switches add a magnet insertion step to this process and require higher precision regarding the concentricity of the stem and magnet. Before leaving the factory, switches undergo electrical continuity testing and random sampling for tactile feel.
IV. PCBA SMT and Soldering
The process flow includes loading the bare PCB, solder paste printing, component placement via SMT machines, reflow soldering, AOI (Automated Optical Inspection), wave soldering for through-hole components, and electrical testing. Mechanical keyboard PCBAs require soldering switch sockets or preparing solder pads, while magnetic switch keyboards require the mounting of Hall-effect sensors. Once the PCBA is complete, it undergoes functional testing to verify that signals from every key position are functioning correctly.
V. Final Assembly Line
Station 1: PCBA and Positioning Plate Assembly. The PCBA and positioning plate are aligned and secured together to form the foundational structure of the keyboard’s internal assembly.
Station 2: Switch Insertion. Insert the switches one by one into the switch sockets on the positioning plate and PCBA. For hot-swappable keyboards, switches are inserted directly into the sockets, whereas for solderable keyboards, the switches are already soldered to the PCBA. For magnetic-switch keyboards, the magnet position must be aligned with the Hall effect sensor.
Station 3: Keycap Pressing. A robotic arm picks up the full set of pre-printed keycaps, aligns them with the switch stems using an alignment stage, and a pneumatic press drives them all in simultaneously, ensuring uniform insertion depth.
Station 4: Internal Assembly Insertion. The assembled internal unit (with switches and keycaps installed) is placed into the designated recess of the bottom case, aligning the four corner positioning posts. The USB ribbon cable is routed through the opening at the rear of the bottom case.
Station 5: Top Case Assembly and Fastening. The top and bottom cases are joined, and screws are tightened in a diagonal pattern. Some keyboards utilize snap-fit structures or ultrasonic welding instead of screws.
Station 6: Labeling and Accessory Packing. Product nameplates, anti-slip pads, and serial number labels are affixed to the bottom of the keyboard. Accessories such as wrist rests, keycap pullers, and spare switches are packed into the box at this station.
VI. Finished Product Testing and Packaging
The assembled keyboard is connected to a computer to run testing software; each key is actuated repeatedly to record error rates and response latency. Magnetic-switch keyboards undergo additional testing for Rapid Trigger (RT) accuracy and sensor consistency. Finished products that pass inspection are cleaned of dust and packaged for warehousing.
