What is a Membrane Keyboard?
It is important for us to discuss first what membrane keyboard is in order to understand what makes a mechanical one so much better.
A membrane keyboard is a computer keyboard whose “keys” are not separate, moving parts, as with the majority of other keyboards, but rather are pressure pads that have only outlines and symbols printed on a flat, flexible surface. Very little, if any, tactile feedback is felt when using such a keyboard, and error-free blind typing is difficult. Wikipedia
On normal circumstances, current (white arrows) cannot cross the gap between the traces (red lines) on the bottom layer.
When a user hits a key, the top membrane layer is pressed down and makes contact with the bottom membrane layer. It allows current to flow and a keypress is now registered.
Majority of the keyboards produced are membranes because this design is inexpensive, relatively quiet, and is more portable. However, it does not give you as much tactile or audible feedback when you press a key. Key rollover is also an issue.
At the end of the day, both membrane and mechanical keyboards deliver the same functionality to its user — as an input device for our computers.
What is a Mechanical Keyboard?
The main difference between a mechanical keyboard and a membrane one is on the way it sends its signal. A mechanical keyboard does not have a top membrane that bridges the gap of the conductive traces on the bottom membrane.
It uses switches underneath the keys to send signals and determine when the user has pushed a key. There are more than one kind of switches and each one performs differently.
That being said, this addresses the key rollover issue that membrane keyboards have. Key rollover is the ability of a keyboard to correctly handle several simultaneous keystrokes.
Try this: If you are using a membrane keyboard, press the two SHIFT keys simultaneously and type some random words. Notice something different?
Some of the keys are not registering because the top membrane is already “stretched” from pressing the two SHIFT keys. This makes certain parts of the keyboard not come in contact with the bottom membrane even if pressed down.
The one and only job of a single switch of a mechanical keyboard is to tell whether or not that key was actuated. In theory, you can press all the keys simultaneously and it will all register.
This alone does not justify their price tags however. We have discussed the key difference between membranes and mechanicals, now let us talk about bells and whistles.