Multilayer PCB's

 

Multilayer pcb's are boards with Three or more copper layers, this is achieved by manufacturing the desired number of double sided boards (called inner layers) and bonding them together with glue (pre-preg), standard processes are then followed to complete the board. PW Circuits have multilayer approval BS123300-003 to a maximum of 32 layers.

Mirco via's & via's are connecting holes through the whole board, when there are multiple layers of conductor patterns and you only require some of them to be connected buried & blind via's can be used, buried via's connect inner layers together but not to the surface layers, blind via's connect one of the surface layers to one or more of the inner layer.