Base plate
Provided by the ASK Keyboard Dictionary
Aka/also known as: back plate, backplate
A keyboard base plate is a plate that sits at the bottom (the base) of a keyboard whose assembly is separate from its cover set and is used as a rigid support for everything else on the assembly to rely on. On Model F and most buckling spring Model M keyboards, the base plate is also curved to provide a sculpt for its keys. Typically, it is metal to provide strong support, but it can be plastic. For keyboards that don't have an assembly separate from the cover set, its bottom cover piece will assume its purpose.
