PROCESS FOR STRIPPING TIN OR TIN-LEAD ALLOY FROM COPPER

摘要

A process for selectively stripping tin or tin-lead alloys from a copper substrate without significant loss of copper therefrom. The substrate coated with tin or tin-lead alloy is subjected to the action of a first stripping composition containing an oxidant for the metal or metals and an acceptor for the cation or cations so oxidized. When the stripping has reached the stage at which a thin film of tin remains on the substrate the latter is subjected to the action of a second stripping composition comprising an alkali metal hydroxide and an alkali metal chlorite until the film of tim has been removed and replaced by a film of copper oxide. The latter can be removed by known treatment with aqueous acid. The process is also applicable to stripping etch resists from copper substrates after completion of the etching step in formation of a printed circuit board.