Paul Greene,
we are doing some jobs with hard gold on electroless nickel/immersion gold.
The procedure is to apply soldermask, then ENIG, plating resist, acid clean,
hydrochloric activation and electrolytic gold.
This process is running with a fairly high yield, except if the electroless
nickel for some reason has been passivated. This can be due to long hold
times after ENIG or some parameters in the ENIG-process itself or - of
course - inadequate activation.

I would never ever apply soldermask after ENIG, before hard gold as you are
introducing another step, increasing the possibilities that the nickel has
been passivated or condensation of soldermask components, which depedent on
the mask can be hard to remove. This will eventually lead to yieldloss.

Good luck

Jan Thuesen
 -----Oprindelig meddelelse-----
Fra:    tech [mailto:[log in to unmask]]
Sendt:  24. august 2001 19:27
Til:    [log in to unmask]
Emne:   [TN] Immersion gold with hard gold fingers

We have a requirement to produce boards with immersion gold before
s.mask with hard gold fingers (edge connector). Doing immersion after
mask with hard gold fingers is our nornal process.We plate the fingers ,
apply mask , tape or peelable mask protect the fingers and immersion
gold the board. Doing the immersion befor the mask means there will be
an interface between the two golds. Is anyone doing this and if so what
are the pitfalls or advantages to the potential processes. This is a
tight design with little room between the top of the fingers and
adjacent open vias.
Paul Greene

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