Abstract: In the electroplating of zinc diecastings with a copper layer, the electrolyte penetrates into the pores of the zinc diecasting. When the temperature is increased later, this leads to vaporization of the electrolyte liquid in the pores and to blistering or flaking of the copper layer. It is proposed that plating be carried out in two steps. In the first step, only a thin copper layer of less than 1 ?m is applied and the plated parts are then treated at a temperature which leads to vaporization of the electrolyte liquid. The thin copper layer is still sufficiently porous for the vapour to be able to escape. Only the solid constituents of the electrolyte remain. The copper layer is then thickened to a final thickness of from about 20 to 30 ?m. In this plating step, electrolyte liquid no longer penetrates into the pores of the zinc diecasting. The parts which are coated in this way display no blistering or flaking of the copper layer after storage at a temperature of 150° C.

Abstract: In order to produce bright to brilliant, leveled copper-tin alloy coatings, galvanic baths are used which contain 1 to 60 g/l copper in the form of copper(I) cyanide, 1 to 50 g/l tin in the form of alkali stannate, 0 to 10 g/l zinc in the form of zinc cyanide, 1 to 200 g/l of one or several complex binders (e.g., oligosaccharides and/or polysaccharides), 1 to 100 g/l free alkali metal cyanide, 1 to 50 g/l free alkali metal hydroxide, 0 to 50 g/l alkali metal carbonate 0.01 to 5 g/l brightener (e.g., alkene sulfonate, alkyne sulfonate, pyridine compounds or sulfur-containing propane sulfonates) and 0 to 100 mg/l lead as lead(II) acetate or lead(II) sulfonate.