U.S. Pat. No. 4,755,271 and U.S. Pat. No. 4,776,939 disclose electroplating apparatures, in which printed circuit boards are passed horizontally through a treatment chamber. At the edge of the treatment chamber and optionally separated by a shield, are provided conveyors, such as chain conveyors, which grip the circuit boards in tong-like manner from the side and in this way guide them through the treatment chamber. In the latter copper is electrolytically applied, the power supply being provided via the tongs. When using tong guides on both sides only one circuit board width can be treated.
DE-32 36 545 C2 discloses an apparatus, in which the lateral guidance of the circuit boards is provided by contact rolls positioned behind a shield. A sliding guide can be provided on the other circuit board side.
These arrangements only operate in a satisfactory manner with circuit boards of a uniform size. When using circuit boards which are narrower than the passage path, as a result of their one-sided guidance and contacting they pass asymmetrically through the treatment chamber. As the treatment liquid, i.e. the electrolyte is vigorously moved, they are then unreliably guided or the guides on the free side must be separately adjusted for each circuit board width. Therefore it is not possible to treat several circuit board sizes in alternating manner in the apparatus. In the case of electrolytic treatment the asymmetry also requires a partial covering of the anodes, because otherwise the electroplating application is non-uniform over the width.