The invention relates to a method and an apparatus for making an air gap (L, 1a) over at least one conductor (5, 5a) on a printed circuit board (1), minimizing the losses in the conductor (5, 5a). The well known Sequential Build Up (SBU) technology is used, wherein a carrier (3) with the conductor (5, 5a) is covered by a photosensitive varnish layer (7, 7a). An opening (8, 8a) is made in the varnish layer (7, 7a) above the conductor (5, 5a) by a photographic method. A metal layer (11, 11a) is then fastened to the varnish layer (7, 7a) covering at least said opening 88, 8a) so that an air gap (L, 1a) is formed between the conductor (5, 5a) and the metal layer (11, 11a). The resulting circuit board (1) has an air gap (L, 1a) well adapted to the conductor (5, 5a). According to an alternative inventive method the carrier (3) also comprises a lower conductor (5b) placed opposite to the conductor (5a) described above on the opposite side of the carrier. In the same way as above the lower carrier (5b) is provided with an air gap (1b). A layer (13) of dielectric material can be fixed to the metal layer (11) to obtain a more rigid construction.