I imagine you've tried ferric choloride, but Transene should have a
quality mix:
    http://www.transene.com/cu_etchant.html

If not, one of their engineers could point you in the right direction.
-Steven


Werner Karl wrote:

>Dear All,
>
>     I am looking for a good copper wet-etchant, that allows the controlled
>and uniform etching of fine structures.
>     The "standard" solutions I have tried so far, all etch either very
>rapidly, resulting in large undercut, or non-uniform. Thanks for your help,
>
>Werner.
>
>Werner J. Karl
>Imperial College, London
>[email protected]
>
>
>
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