A technique in which the solder mask is applied in advance of the tin-lead plating. This results in lighter circuit boards because the tin-lead alloy is only used to plate the pads.
Solder Mask Over Bare Copper. A printed wiring board manufacturing technique whereby solder mask is applied over bare copper, exposed and developed, and then the board is dipped in molten solder to coat the exposed copper.
"Solder mask over bare copper." SMOBC is a type of printed circuit board that has the metallic resist removed. Copper conductor circuits are protected from the atmosphere via a polymer coating.