How Does a Mechanical Keyboard Work?

Pop a keycap off a mechanical keyboard and there’s a small plastic and metal assembly underneath doing all the actual work. Understanding how does a mechanical keyboard work makes it a lot easier to understand why enthusiasts obsess over switch types in the first place.

The Core Idea: One Switch Per Key

Unlike membrane keyboards, which rely on layered rubber sheets pressing against a circuit board, a mechanical keyboard gives every single key its own independent switch. That switch is a small, self-contained mechanical assembly built from just a few core parts.

• Stem: the plastic piece that moves up and down inside the switch housing when a key is pressed.
• Spring: sits below the stem and pushes it back to the resting position after each press.
• Upper and lower housing: the plastic shell that holds everything in place and guides the stem’s movement.
• Contact leaves: thin metal strips that physically touch when the stem is pressed far enough down.

What Happens the Moment You Press a Key

The sequence is straightforward once broken down into steps:

1. Finger pressure pushes the keycap and stem downward inside the switch housing.
2. The stem compresses the spring beneath it as it travels.
3. At a specific point in that travel, called the actuation point, the stem allows the metal contact leaves to touch.
4. That contact completes a tiny electrical circuit, which the keyboard’s onboard controller detects.
5. The controller identifies which key was pressed and sends that signal to the computer.
6. Releasing the key lets the spring push the stem back up, separating the contacts and resetting the switch.

This entire cycle happens in milliseconds, and it happens independently for every single key, which is part of why mechanical keyboards handle multiple simultaneous key presses (rollover) more reliably than many membrane boards.

The Three Main Switch Feels, and Why They’re Different

Not every mechanical switch feels the same, because the internal stem shape changes how it interacts with the housing during travel.

• Linear switches (like Cherry MX Red): the stem moves straight down with no bump or click, just smooth, consistent resistance from the spring.
• Tactile switches (like Cherry MX Brown): the stem has a small internal bump, which creates a noticeable resistance point roughly at the actuation point, without an audible click.
• Clicky switches (like Cherry MX Blue): built with an internal mechanism that produces both a tactile bump and an audible click sound, often through a separate click jacket or leaf design inside the housing.

Fact Check: The “click” sound on clicky switches isn’t the keycap hitting the housing, it comes from a dedicated internal mechanism designed specifically to produce that sound at the actuation point, which is also why lubing clicky switches can mute or ruin that sound.

Actuation Point vs Bottoming Out

Two terms come up constantly in switch discussions, and they describe different points in a single keystroke.

• Actuation point: the exact travel distance where the switch registers the keystroke, often around 2mm into a 4mm total travel range on standard switches.
• Bottoming out: pressing the key all the way down until the stem physically hits the bottom of the housing, well past the actuation point.

Experienced typists often train themselves to release keys right around the actuation point instead of bottoming out every stroke, which reduces finger fatigue over long sessions.

How the Keyboard Talks to Your Computer

Beneath the switches sits a printed circuit board with a small microcontroller. That controller continuously scans the switch matrix, a grid of rows and columns, to detect which contacts have closed.

Once it identifies a keystroke, it translates that into a signal sent over USB or Bluetooth using the standard USB Human Interface Device (HID) protocol, which is the same universal language keyboards, mice, and controllers use to communicate with computers.

FAQ

1. Why do mechanical keyboards feel more “solid” than membrane ones?

Each key has its own dedicated spring and housing assembly rather than sharing a single rubber membrane sheet, which gives more consistent resistance and feedback per key.

2. What is the actuation point on a typical switch?

It varies by switch, but many common switches actuate around 2mm into their total travel distance, meaning a keystroke registers before the key is fully pressed down.

3. Do all mechanical switches use metal contacts?

Most traditional mechanical switches use metal leaf contacts, though some newer designs use optical or magnetic sensing instead of physical metal contact to register keystrokes.

4. Why can mechanical keyboards handle more simultaneous key presses?

Because each switch operates independently with its own circuit path, mechanical keyboards generally handle multiple simultaneous presses (rollover) more reliably than cheaper membrane keyboards, which can suffer from “ghosting.”

Final Take

At its core, a mechanical keyboard is just a grid of independent spring-loaded switches, each completing a tiny circuit every time it’s pressed. The stem shape decides whether that switch feels linear, tactile, or clicky, and the difference between actuation point and bottoming out explains why some typists feel faster or less fatigued on one switch type over another. It’s a simple mechanical idea, repeated across dozens of keys, that adds up to a very different typing experience than a membrane board.

Disclaimer: This article is written for general educational purposes based on publicly available technical resources, not as an engineering specification. Exact mechanisms can vary slightly by switch brand and model.