SOLDERABILITY ENHANCEMENT BY SILVER IMMERSION PRINTED CIRCUIT BOARD MANUFACTURE

• Main Authors: SOUTAR ANDREW MCINTOSH, MCGRATH PETER THOMAS
• Format: Patent
• Language: English
• Published: 17.11.2011
• Subjects: ADHESIVES; APPLYING LIQUIDS OR OTHER FLUENT MATERIALS TO SURFACES, IN GENERAL; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; CHEMICAL PAINT OR INK REMOVERS; CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING COMPOSITIONS, e.g. PAINTS, VARNISHES ORLACQUERS; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; CORRECTING FLUIDS; DIFFUSION TREATMENT OF METALLIC MATERIAL; DYES; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; FILLING PASTES; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; INKS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS; METALLURGY; MISCELLANEOUS APPLICATIONS OF MATERIALS; MISCELLANEOUS COMPOSITIONS; NATURAL RESINS; PAINTS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; PERFORMING OPERATIONS; POLISHES; PRINTED CIRCUITS; PROCESSES FOR APPLYING LIQUIDS OR OTHER FLUENT MATERIALS TOSURFACES, IN GENERAL; SPRAYING OR ATOMISING IN GENERAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TRANSPORTING; USE OF MATERIALS THEREFOR; WOODSTAINS

A process used during manufacture of printed circuit boards comprises protecting metal pads and/or through-holes to provide a tarnish-resistant and solderable coating. In the method, the pads and/or through-holes are bright-etched, metal plated, preferably by an immersion process, and treated with a tarnish inhibitor. The tarnish inhibitor may be incorporated into the immersion plating bath. The metal plating is usually with silver or bismuth and the pads and/or through-holes comprise copper.