A multi-layered printed circuit board, PCB, includes first windings for a first side of a planar magnetic transformer and second windings for a second side of the planar magnetic transformer. The PCB further includes conductive layers configured as the first windings, conductive layers configured as the second windings, and layers of an isolation material. Each layer of the isolation material is arranged between two conductive layers to provide electrical isolation between the two conductive layers. A group of two or more adjacent conductive layers are all conductive layers of the first windings and are all arranged between two conductive layers of the second windings. The thickness of the isolation material between the group of adjacent conductive layers of the first windings is less than the thickness of the isolation material between a conductive layer of the second windings and a conductive layer of the first windings.