Thanks for the reply Robert
I want to know, under which circumstances do we use multi layered boards, what are its applications, like whether it decreases the space or increases performance, etc.
The aplications that i've seen with it is mainly to save space and jumpers on the board
also the layers not on the surface are better protected from phisical damage to the board
there might be in some cases a performance improvement i think than if more than 1 "wire ways" tracks have to be exactly the same distance for resistance purpose or must have a minimum distance for capacitive purposes
but than we talk already far out of the just ordinairy aplications in my opinion