PRINTED CIRCUIT BOARD MANUFACTURE

• Main Authors: PETER THOMAS MCGRATH, ANDREW MCINTOSH SOUTAR
• Format: Patent
• Language: English
• Published: 30.09.2005
• 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 BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR 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; PRINTED CIRCUITS; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION

A PROCESS USED DURING MANUFACTURE OF PRINTED CIRCUIT BOARDS COMPRISES PROTECTING METAL PADS AND/OR THROUGH-HOLES TO PROVIDE A TRANISH-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. THE METAL PLATING IS USUALLY WITH SILVER OR BISMUTH AND THE PADS AND/OR THROUGH-HOLES COMPRISE COPPER.