PROCESS FOR SELECTIVELY APPLYING A FINISHING LAYER AND ONE OF TIN OR TIN/LEAD ALLOY TO METAL OR METALLIZED ARTICLES

摘要

The aim is selectively to apply a finishing layer (V) of a precious metal or precious metal alloy to selected areas of metal or metallized articles. To that end, the finishing layer (V) is first applied by galvanic metal deposition to areas which are larger than the selected areas. An etch-resistant layer (S) is then applied precisely to the selected areas by electro-dipcoating; this layer is used to enhance the etching selectivity of the process by which the exposed finishing layer is etched away. Tin or tin/lead alloy is then applied to spcific areas of the articles (T) by galvanic metal deposition, the etch-resistant layer (S) serving as the galvanic resist which prevents contamination of the finishing layer (V) with tin or tin/lead alloy. Removal of the etch-resistant layer (S) leaves a finishing layer (V) which precisely covers the selected areas. The finishing material removed during the selectivity enhancement process is then, for example, salvaged from the etching solution by electrolysis.