Hi Doug,
Are these boards going through a wave solder operation? If so, what kind of
flux?
Are any kinds of chemicals being applied to the board during the processes?
How well are the boards dried after cleaning?
What is the over-all time span for the processes?
Are you using any saponifier in the wash?





Hooper Doug <[log in to unmask]> on 07/03/98 10:20:00 AM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
      to Hooper Doug <[log in to unmask]>

To:   [log in to unmask]
cc:    (bcc: Charles Barker/US/I-O INC)
Subject:  [TN] Au/Ni/Cu PROBLEM




I am experiencing a problem with my Au/Ni/Cu circuit boards. During the
cleaning process in warm (120f) DI water some of them are exhibiting a
"contamination". In certain areas (random) I am getting a discoloration
on the pads. These are non-soldered connections of the board. Other areas
on the board are soldered (hand) and have excellent
solderability/wettability/solder coverage are generally bright, smooth
and shiny. Sometimes this does not occur until the assembly has been
washed 3 or 4 times throughout the production process. The discoloration
appears brown, orange (like rust) and even dark blue to black. It also
appears to be removed with an eraser. Does anyone know what is going on
that would cause this condition to occur? I am concerned about the
condition with respect to contact resistance (keypad/dome application).
Will it get worse even if I can rub it off?

My circuit board supplier is on plant shut-down today. Any input on this
matter would be greatly appreciated! Technet or otherwise.

Douglas A. Hooper, Sr.
Process Engineer
Luminescent Systems, Inc.
[log in to unmask]
(716)655-0800 x163
(716)655-0309 fax

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