So, what exactly is this "mechanical switch" we keep talking about? At its simplest, it's the physical mechanism that sits beneath each keycap. It's a stark contrast to the mushy, indistinct rubber domes found in most standard office keyboards. A mechanical switch is a precision-engineered, spring-loaded component with its own housing, stem, and internal contacts. It's a self-contained little engine designed for a single purpose: to provide a consistent, reliable, and satisfying typing experience that can be tailored to individual preferences.
When you press a key, you're pushing the stem of the switch down. This action does two things: it compresses a spring, which provides a specific, measurable resistance and pushes the key back up, and it causes two metal contacts (or "leaves") to touch. This completes an electrical circuit, telling the keyboard's PCB that a key has been pressed. This elegant, simple mechanism is the foundation of everything that makes mechanical keyboards special, offering a level of tactile feedback and durability that rubber domes simply cannot match.
So, what exactly is this "mechanical switch" we keep talking about? At its simplest, it's the physical mechanism that sits beneath each keycap. It’s a stark contrast to the mushy, indistinct rubber domes found in most standard office keyboards. A mechanical switch is a precision-engineered, spring-loaded component with its own housing, stem, and internal contacts. It's a self-contained little engine designed for a single purpose: to provide a consistent, reliable, and satisfying typing experience that can be tailored to individual preferences.
When you press a key, you're pushing the stem of the switch down. This action does two things: it compresses a spring, which provides a specific, measurable resistance and pushes the key back up, and it causes two metal contacts (or "leaves") to touch. This completes an electrical circuit, telling the keyboard's PCB that a key has been pressed. This elegant, simple mechanism is the foundation of everything that makes mechanical keyboards special, offering a level of tactile feedback and durability that rubber domes simply cannot match.
The term "mechanical" distinguishes these keyboards from their more common "membrane" or "rubber dome" counterparts. The difference isn't just academic; it translates to a tangible improvement in typing feel, longevity, and customization.
Membrane/Rubber Dome Keyboards: In a typical office keyboard, a single rubber sheet lies under the keycaps. When you press a key, you're pushing down on a rubber dome, which collapses and presses two layers of a plastic membrane together to register the keystroke. This design is cheap to produce, but the feel is often described as "mushy" and inconsistent. The domes wear out over time, changing the feel of the keys, and you must "bottom out" (press the key all the way down) to actuate it.
Mechanical Keyboards: Each key has its own individual switch. This makes them more complex and expensive to produce, but it provides a far superior typing experience. Because each switch is a discrete unit, they offer unparalleled consistency and a lifespan that is orders of magnitude longer than a rubber dome sheet (typically 50-100 million keystrokes per switch versus 5-10 million for a rubber dome). This modularity also opened the door for the entire custom keyboard hobby, allowing users to mix and match switches, or even replace a single faulty switch instead of throwing away the entire keyboard.
To truly understand what makes switches different from one another, we need to look at the parts that make them up. The explosion of the custom keyboard scene, largely thanks to the expiration of Cherry's original MX switch patent, has led to countless manufacturers (like Gateron, Kailh, JWK, and more) creating their own variations. However, they all share the same fundamental anatomy:
Top Housing: This is the top part of the switch's casing. It holds the stem in place, guides its movement, and protects the internal components from dust. The material and design of the top housing are critical. A polycarbonate top housing is often used for switches intended for RGB lighting, as it's transparent and allows light to pass through. A nylon top housing is softer and produces a deeper, lower-pitched sound. The manufacturing tolerances of the top housing also determine how much the stem can move side-to-side, an undesirable characteristic known as stem wobble.
Stem: This is the heart of the switch's feel. The stem is what your keycap connects to, and when you press down, it travels inside the housing. The shape of the stem's "legs" is the most important factor in determining how a switch feels. A smooth, straight leg results in a linear switch. A leg with a carefully designed bump creates a tactile switch. A more complex, two-part leg design that creates an audible click results in a clicky switch. The material of the stem, most commonly POM (Polyoxymethylene), is chosen for its low-friction properties, contributing to the switch's overall smoothness.
Spring: The spring sits inside the switch, underneath the stem. It's responsible for the resistance you feel when you press a key and for pushing the key back up when you release it. The length and "weight" (measured in grams, e.g., 45g, 62g, 67g) of the spring determine how heavy or light the switch feels to press. Springs can be linear, progressive (getting heavier as you press down), or complex. They are a popular component for modification, as swapping the spring can completely change the feel of a switch.
Bottom Housing: This is the bottom part of the switch's casing. It holds the metal contact leaves and the spring, and it has the pins that connect the switch to the PCB. Most switches come in either 3-pin (plate mount) or 5-pin (PCB mount) varieties. The two extra plastic legs on a 5-pin switch provide extra stability when mounted directly to a PCB without a plate. Like the top housing, the material of the bottom housing (often nylon) plays a significant role in the overall sound profile of the switch.
Metal Contact Leaves: Tucked inside the bottom housing are two small metal contacts, typically made of a copper alloy. When you press the stem down, its legs push one of the leaves, causing it to make contact with the other. This completes the circuit and sends the signal to your computer. The quality and design of these leaves are critical for the switch's reliability and lifespan.
It's the subtle variations and combinations in these five components—the shape of the stem, the weight of the spring, the type of plastic used in the housing—that create the vast and diverse world of mechanical switches.
Now that you understand the basic anatomy of a switch, it's time to explore the three fundamental categories they fall into. Let's dive into The Three Switch Types to discover which one might be right for you.