No, it only means that currently there is no commercial electroplating bath
that utilizes soluble gold anode. Certainly, if someone knows about one it
would be nice to let us know. Since my last communication I have learned
that, besides solutions dedicated for gold etching and electroplishing only,
some commercial plating bath do have a very limited degree of gold
dissolution and smoothing effect (probably not much help against the "edge
effect") in anodic sweep at certain operating conditions. Usually one would
expect that in the presence of excess of complexing agent, such as sulfite
or cyanide, that may be possible. The key is probably to maintain such
excess by providing sufficient liquid transport and/or by pulsing. This
information should be available from the suppliers.
Igor Kadija
www.fibrotools.com

At 11:39 PM 2/11/02 -0600, you wrote:
>Does it mean that electropolishing of gold is not possible?
>
>Abhinav
>
>On Wed, 30 Jan 2002, Igor Kadija wrote:
>
>> It is true, Gold does not dissolve when used as an anode. That seems to be
>> the generally accepted fact in electroplaters community. That makes it even
>> more important to have a viable MEMS design including geometry of features
>> and/or "dummy sites" and, a good control of the process including equipment,
>> anode shape and location, mixing and solution quality.
>>
>> Igor Kadija
>> [email protected]
>>
>>
>> At 01:47 PM 1/29/02 -0500, you wrote:
>> >I would only add to this that current density is not always uniform across
>> >all plated areas if you have a photoresist mask and there are some very
>> >small features and some larger features.  The current can distribute itself
>> >so that the smaller features have a higher current density than the larger.
>> >
>> >Also, I'm not sure reverse pulse plating has any effect on gold - the gold
>> >plates out of solution, but it does not plate back into solution if the
>> >voltage is reversed.  (This is certainly true of the solution I use, which
>> >is  Enthone BDT-200 - does anyone know if it's true for all solutions?)   In
>> >other words, if you used a gold anode while plating, it would not lose any
>> >mass.
>> >
>> >David Nemeth
>> >Ph: (703) 961-9573 x206
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