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International Hazard
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Registered: 20-8-2018
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Silver plating mixtures
Folks,
I've been trying recently to find out how one can silver plate copper things without using electricity. In other words, to devise a suitable mixture
able to deposit a fair thickness (~ 1 µm) of metallic silver on copper (the ultimate goal is to make higher quality coils for use in RF electronics,
because at several hundreds MHz the skin effect repels all the current towards the surface of the wire).
I've figured out that there needs to be a very slow exchange between copper metal and Ag(I) ions, because dipping copper into a bare solution of
silver nitrate results in an accumulation of silver dust on the copper, but nothing really sticks (reaction is too fast). So I used various
complexants: ammonia, EDTA or sodium thiosulphate to slow it down. The last two seem to work better, but the plating is often irregular, and it seems
that it flakes off when it exceeds a certain thickness. The surface becomes shiny white, then dulls out as more silver accumulates, and brushing it
even with soft tissue results in local peel-off.
Anyways. Does anyone have a formula for a mixture that would deposit a shiny silvery layer of reasonable thickness, or what compound/current intensity
to use for electric plating?
I also read that starting with a thin layer of nickel would allow the silver plating to be much more efficient, because the nickel would not dissolve
into the plating solution?
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