Jan Thuesen wrote:
>
> Dear Technetters,
> periodically we are having problems with a dull, brownish discoloration of our electrolytic gold. The discoloration is independent of whether the gold is being plated on electrolytic or electroless nickel. LAB-analysis´ has been within spec´s each time.
> I have been proposed that the cause could be bleeding of the photoresist due to locally rise of pH > 9 in the plating bath. Roundpumping (eventually through a carbonfilter) could level the pH in the bath, but could this lead to other problems ?
> Have any of you experience with this ?
>
> With best regards
>
> CHEMITALIC A/S
> Jan Thuesen
> Process Engineer
>
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Discoloration of gold:
Reasons are...
1.Gold is porous. Any copper contamination creates  brown  and dull
  color by the time. On heating/ baking ,it is accelerated.
2.If gold works as etch resist, and panel is not rinsed properly.
3.If gold plated panel put in acidic solution for longer time.
4. At any place if it comes in cotact with acidic solution of copper and
  copper migrates in gold easily making alloy interface.

 Try to rinse by clear ammoniacal solution,then rinse by water, then
 neutralise by mild phosphoric acid solution, rinse and dry by forced
air.  I think you may get original shiny color.
  If you are succesful , Please let me know

 Fulabhai Patel            [log in to unmask]

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