Switch Construction
01 Switch housing
The switch housing is the case that encapsulates all the internal parts. The tops are usually clear plastic now, so that RGB lighting is brighter. The bottoms can be any colour. Most switch housings are very similar as they follow a standard, enabling you to swap them out easily. There are also two types of switch mounting. PCB-mounted switches have two additional prongs on the bottom of the switch that grips into the PCB. These make the switch more stable. Plate-mounted switches don’t have these prongs as they grip onto the plate of the keyboard. This is usually a little bit less stable and can often give the switch an additional wobbly feel.
02 Stem
The stem on the switch is the little plastic plunger. The keycap attaches to this part. The most common stem is the Cherry MX style “+” shape. There are other kinds though: Topre uses an “O” shape, and in the past Kailh has used boxes. Now the majority of stems are using the Cherry + shape – it is far easier to get keycaps for these that fit a wide range of switches.
03 Spring
The spring is what gives the switch its resistance or weight, and it is also this that resets the key after each press. The weight in these springs is measured in cN (centinewtons), but this is very close to grams: 1 cN = 1.019 gram (0.04 oz). This means that switch weights are often seen as 45g rather than 45cN.
04 Leaf
The leaf inside the switch is a thin piece of copper, folded in such a way that when the stem is pressed it will complete a circuit and send the signal saying the switch has been pressed. This can also be used to give the switch a tactile feedback, and make those signature clicky sounds. In some switches, however, click bars are used for this. Different thicknesses are used by different manufacturers, and the tolerances between them can change significantly, especially on cheaper switches, which will increase or decrease a switch’s long-term durability.
Switch colours
You will often hear a colour attached to the brand of switch, for example Cherry MX Greens, or Kailh Reds. This denotes the specification of the switch. The colours are not universal over different brands: A Kailh Brown is weighted at 45cN, whereas a Cherry MX Brown is 55cN. 10 cN is a big difference in terms of switch feel, so it is worth trying out a board with the weighting you’re curious about before you commit to buying it.