Etching tank for printed circuit boards - where etchant is applied via porous coating on rotating rolls

• Main Authors: BADTKE,DETLEF, MERKENSCHLAGER,HANS-HERMANN
• Format: Patent
• Language: English; German
• Published: 15.09.1977
• Edition: 2
• Subjects: CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS; METALLURGY; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLICMATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASSC23 AND AT LEAST ONEPROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25; NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; PRINTED CIRCUITS

Plant for the cleaning of flat workpieces with metal surfaces, by light etching, followed by pickling. An etching chamber is used with transport rolls carrying the workpieces along a horizontal path between at least one pair of etching rolls coated with a soft, porous material, which is continuously and uniformly coated with an etchant, e.g. CuCl2. The etching rolls are pref. coated with a rubber moss, and the upper roll(s) can pref. be adjusted vertically to vary the gap between the rolls. A closed, circulating system is pref. employed with pump, tank and pipes for the etchant, the lower etching roll(s) dipping into the etchant in the tank. Used partic. for the light etching of Cu coated printed circuit boards which are subsequently coated with a photo-polymer. In this case, the printed circuit boards are etched in CuCl2, washed, and then pickled in HCl, followed by further washing and drying. Only about 2 mu m of Cu is removed, which is very important e.g. in the contact holes in the boards.