04 Mar 2012

Mechanical keyboards explained

No Comments Technology

Mechanical keyboards have been around for as long as we’ve had keyboards. If you were born before 1990 then your first interaction with a computer was most likely by way of a keyboard with “mechanical” keys. However due to concerns over cost, size and complexity, mechanical keyboards quickly fell out of favor just as the PC started becoming ubiquitous in our homes. For decades, not a single new PC from a major manufacturer was shipped with a mechanical keyboard included. It wasn’t long before mechanical keyboards like the classic IBM Model M became synonymous with all that is old and eccentric about early computing. Only a handful of smaller niche manufacturers continued to sell mechanical keyboards.

Recently however, there has been a rather sudden and surprising resurgence in interest for mechanical keyboards. Just in the last two years, several major peripheral manufacturers have added mechanical keyboards to the high end of their product line-ups. Manufacturers are coming out of the woodwork to tout mechanical keyboard technology as the latest must-have for your tech collection. All of them quick to suggest that mechanical keyboards are on a different level compared to that inferior lump of plastic you’re currently tapping away on.

Suddenly the ol’ Model M is no longer an unwanted relic of the past that you couldn’t even give away to your cousin who’d just dumped a can of Coke on his shiny USB macro-enabled back-lit keyboard. Now it’s a treasured and sought after precision instrument, the veritable Stradivarius of typing peripherals. Refurbished original Model M’s, now over 20 years old, are commanding prices well over $80 and selling like hotcakes.

Now that they’re back in style, what are mechanical keyboards? What makes them different from “normal” keyboards? Are they worth the price? Do I need one?

What’s so “mechanical” about them?

Mechanical keyboards are so named in order to contrast them to “standard” keyboards, referring your everyday common keyboard, which nearly all use a “membrane” key design. In the classic arch-typical membrane keyboard design, the individual keys are actually protrusions on a single, continuous sheet of flexible material. Instead of a membrane sheet, “mechanical keyboards” use individual mechanical switches for every key.

In reality, this is a bit of a generalization as there are numerous individual key technologies and designs that can be classified as “mechanical” and “membrane”. Before we get into why you really, truly want to buy yourself a mechanical keyboard this very moment, let’s take a quick look at some of the more common keyboard designs and what makes them different.

Keyboard switch technologies

Membrane keyboard

The ubiquitous ”standard” keyboard. They are made up of three layers. The bottom layer is a grid of open circuits that detect key presses when the circuits on the grid are closed or shorted. The top layer is a soft membrane usually made of plastic, silicone or rubber. A grid of conductive material is set into the membrane, lining up with the conductive grid on the bottom layer. The middle layer exists to separate the top and bottom layers so they are not normally in contact. In many designs, the middle layer is just air. When the top membrane layer is brought down into contact with the grid of the bottom layer, the conductive material set into the membrane closes the circuit, registering as a key press. 

In many membrane designs, there is an additional fourth layer of plastic key tops that rest on top of the membrane layer. The keys usually have a wide top to accommodate the size of fingers, while the bottom of the keys comes to a narrow point. When pressed, the keys push/stab the membrane down, causing one of the circuits on the grid to close. In some designs the key tops aren’t used and you press on the membrane directly (ie. microwave number pad keys).

Membrane keyboards are very cheap to build. They wear out quickly and age as the membrane loses elasticity. They provide poor tactile feedback and are often described as having a “mushy” feel. To type on a membrane keyboard, you must press the membrane all the way down in order to ensure key presses are properly registered. This is called bottoming out, it increases hand fatigue and slows down touch typing.

Chiclet keyboard

Chiclet keyboards are actually just membrane keyboards where the membrane has rectangular shaped thicker areas built-in that the user uses as buttons. The thicker rectangular button areas of the membrane are pressed directly and there is no fourth plastic button layer. They have the same general characteristics as other membrane keyboards.

Dome switch

Dome switches are another type of membrane keyboard. This time the membrane has dome shapes built into it. When the user presses a key (either a plastic key piece or directly on the membrane) the dome collapses, causing the membrane layer to make contact with the bottom conductive grid. Most dome switches have the same characteristics as all other membrane keyboards. However domes that are reinforced with metal feel similar to mechanical keyboards. Metal dome keyboards collapse crisply, providing good tactile feedback to the user, much like a mechanical switch.

Scissor switch

Scissor switches are a variety of dome switch where the membrane dome is supported by two plastic pieces that interlock in a way similar to how scissors work. The scissor mechanism allows the switches to be designed with much shorter travel distance, making them desirable for use in laptop keyboards.  Otherwise, they have similar characteristics as membrane keyboards.

Mechanical switch

Mechanical switch keyboards use individual mechanical switches for each key. They typically work by separating two conductive points mechanically with a spring-loaded lever or similar mechanism. When the button is pressed the two conductive points are pushed together and touch, forming a complete circuit which the keyboard detects as a key press. There are a wide variety of mechanical switch designs and they differ slightly in their characteristics. While some mechanical switches are designed to produce a sound when they are closed, they don’t necessarily have to.

“Cherry” is the manufacturer of one of the most common mechanical key switch designs used in keyboards today. Their MX product line includes several switch designs with different characteristics and are easily distinguished by the color of the switch. Cherry MX Blue switches are the most common and are designed to have tactile feedback and a click sound when pressed (two ‘clicks’ when combined with the sound of the key bottoming out). Cherry MX Brown switches are similar to Blues except they don’t produce an extra sound. Cherry MX Black switches are designed to have linear key travel, so there is no tactile sensation at all until the key bottoms out. Blacks also do not produce a sound. Cherry MX Red switches are similar to blacks but require less pressure to depress, making them easier to press.

In terms of marketing, Cherry MX Blues and Browns are said to be better for typing and Cherry MX Blacks and Reds are said to be ideal for gaming. Ultimately it’s mostly a matter of personal preference.

Buckling spring

This is a special variety of mechanical switch where the key cap presses down on a spring. The spring is held captive in a cylinder designed to cause the spring to buckle and collapse instead of compressing neatly. When the spring buckles, it causes the mechanism to complete a circuit, registering a key press. The sudden buckling of the spring creates an excellent tactile sensation and an audible “click” sound. This switch design is also very durable, as proven by the numerous 25+ year old IBM Model M keyboards still operating happily across the globe.

Buckling springs have similar general characteristics as the Cherry MX Blue switches, in that they produce an extra sound when pressed and they provide tactile feedback. However buckling springs tend to feel slightly smoother than Cherry MX Blues, with more consistent pressure both before and after the actuation point.

Mechanical keyboards vs membrane

Compared to membrane keyboards, mechanical switch keyboards (including and especially buckling spring) provide a superior user experience. Standard membrane keyboards have a mushy feel with poor tactile feedback. Dome style membrane keyboards can be designed to provide a suitably satisfying tactile sensation when pressed, but the majority of available membrane keyboards are not designed this way.

Mechanical switch keyboards also generally last much longer. Membrane keys are generally said to have a useful life of 5 million keystrokes, while scissor keys are slightly better at 10 million keystrokes. Cherry MX switches, on the other hand, are good for  50 million keystrokes. Buckling spring switches are nearly indestructible. The original IBM Model M keyboards were made over 20 years ago and their buckling spring keys continue to operate.

Pros of mechanical keys

  • Excellent tactile feedback
  • Faster touch typing (with proper technique)
  • High durability & longevity
  • Sound like you’re typing twice as fast

Cons of mechanical keys

  • They often make a lot of noise
  • They are relatively expensive
  • Limited selection & availability (compared to membrane keyboards)

Do you need one?

Need is a very strong word. So no, you don’t “need” a mechanical keyboard, but if you’ve read this far then you probably want one, badly. And rightly so. Mechanical keyboards definitely provide real and tangible benefits over the typical membrane keyboard design. Their tactile feedback is addictive and their longevity helps offset the higher cost. Even the louder than usual clicky sound they make grows on you and can become soothing, almost cathartic (for the keyboard’s owner anyway). For anyone who has spent a significant amount of time with a mechanical keyboard, going back to mushy membrane keys would be unthinkable torture.

If you spend a significant amount of time on your computer, do yourself a favor and get a mechanical keyboard. Not only will you sound like you’re typing twice as fast, but your overall computing experience will be that much better.

Written by
An information security practitioner based in the Greater Toronto area.