Abstract: A substantially uniform and nevertheless low feed line resistance of the conductor paths (L.sub.i) can be realized for all heating elements in an ink jet printer by a suitable dimensioning of a transition structure (UV) of a conductor path layout disposed on a thin-film substrate. This transition structure connects the conductor paths of close spacing (LA) in the region of the heating elements (RH) to the conductor paths of wide spacing (LB) in the region of the bonding contacts to each other. For this purpose a dimensioning requirement is required, which in case of predetermined input values, i.e. the conductor path widths (d.sub.a, d.sub.b) and the separation distance widths (s.sub.a, s.sub.b) furnishes in the two regions and in the separation distance width (s.sub.v) of the transition structure (UV) as starting value the conductor width (d.sub.v) in the transition structure (UV).