The invention relates to a circuit board unit and a method for production thereof. The circuit board unit comprises a circuit board topmost laminate with conductive tracks on the upper side for mounting surface-mountable devices. The circuit board topmost laminate features a thickness dimensioned such that the anticipated heat dissipated by the surface-mountable devices is transported from the upper side to the underside of the circuit board laminate to good effect. The circuit board unit further comprises an electrically insulating laminate arranged under the circuit board topmost laminate, inserts made of a material with good heat conductivity and electrical insulation embedded in the electrically insulating laminate at sites below surface-mountable devices with high heat dissipation, and a cooling plate arranged below the electrically insulating laminate and the inserts.