Producing Multilayer Boards

Multilayer boards are PCBs with a theoretically unlimited number of conducting layers separated by insulating layers. Multilayers are usually made up on the inside of doublesided boards, while the outer layers consist of single-sided boards. Prepregs are laminates with no conducting layer which are also used as insulators. Heat and pressure is used to bond each layer to form a multilayer board.

The external layers, TopLayer and BottomLayer, are usually base materials with one conductive layer. Depending on the through-hole plating process used, the external layers are structured before or after the bonding – galvanic plating before, chemistry-free plating after. The inner layers of a multilayer are mostly base materials with two conductive layers and are always structured before the bonding lamination.