The problem confronting manufacturers of printed circuit boards (2) of differing thickness is that, as the current density increases and the diameter of the holes decreases, the treatment effect on various locations on the outer side of the boards and inside the holes becomes more irregular. To resolve this problem, a conveyorized horizontal processing line and a method of wet-processing printed circuit boards (2) is described. To manufacture the printed circuit boards (2), data about the thickness of the workpiece (2) are acquired before it enters the conveyorized processing line and are stored in a data memory, the workpiece (2) is conveyed through the conveyorized processing line and a structural component, which is provided with at least one transport member (3) for the workpiece (2) and with at least one processing facility (6) and which is disposed above the conveying path (100) in the conveyorized processing line, is adjusted in such a manner that the structural component is raised or lowered and/or pivoted relative to the conveying path as a function of the thickness of the respective one of the workpieces passing said structural component.