Multilayer PCB

A PCB is called Multilayer PCB, if it has 3 or more layers(sheets) of copper foil, insulated from each other(by lamination or coating) and joined together to form a single piece. A Multilayer PCB has an Inner Layer Core present at the center of all the layers and coated with a Copper layer from both sides, while layers of prepreg are used for insulation. Alternating layers of prepeg and core materials are laminated together under high temperature and pressure to produce Multilayer PCBs,ensuring that the adhesive is properly melted and their is no air gap in between to maintain its rgidity.