a) arranging a press packet between press plates of a press, said press packet comprising a first metal plate and a second metal plate between which a printed circuit board composition is arranged, said printed circuit board composition comprising: a first layer of insulating material which is impregnated with polymerizable resins and disposed between a first metal sheet and a second metal sheet; and a first printed circuit board with engraved images of circuits,

b) pressing the press packet between the press plates,

c) applying a variable induction magnetic field in a parallel direction of the press packet so as to run generally parallel to largest planar surfaces of the first and second metal plates and the first and second metal sheets, said variable induction magnetic field generating an induced current in and thereby heating each of the first metal plate, the second metal plate, the first metal sheet, and the second metal sheet, causing, in turn, heating by thermal conduction of the first layer of insulating material;

d) raising the temperature in the press packet until the resins in the first layer of insulating material melt, liquefy and flow, causing adhesion between the first layer of said insulating material and the first and second metal sheets;

e) further raising the temperature in the press packet, so that the polymerizable resins in the first layer of insulating material are polymerised;

f) cooling the press packet until the first layer of insulating material has hardened; and

g) removing the press packet from between the press plates and separating the first and second metal plates from the press packet to obtain a rigid board.