Plate

What are keyboard plates?

Keyboard plates go on top of the PCB. Switches snap into the plate, ensuring that they are not askew. This is especially helpful in the case of 3-pin switches, which can be quite askew thanks to the lack of additional support legs. The plate also protects the PCB, making sure that the top side of the PCB is not exposed to the elements. The plate can affect the typing feel and the sound of the keyboard. Brass plates are firm; they will provide a higher pitch sound compared to, say, a POM plate, which will provide a low thock. There is no "best plate." It is entirely up to preference which plates are good and which plates are bad.

Are plates necessary?

Plates are not necessary in a keyboard. In fact, most Cherry keyboards are plateless, meaning that they do not make use of a plate. They can improve typing feel for those who enjoy a softer bottom out. However, they do have drawbacks--as mentioned above, removing the plate can make the keyboard look messy due to the switches and therefore the keycaps being misaligned. The PCB has to be specifically designed with plateless mount in mind in order for this to work.