Ive seen yellow staining on immersion silver boards in the presence of
rinse water with high content of chlorides or sulfides.  If the rinses are
not DI water this can occur very easily, you might want to check your
chloride levels in the water, this might be the easier test to perform.  If
you dont have a chloride probe, you could just drop some silver into the
rinse water in a beaker and see if it percipitates out, this is a quick and
dirty test.
Hope this helps.
Lisa Angle





Ken Mc Gowan <[log in to unmask]>@IPC.ORG> on 04/09/2001 01:49:18 PM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
      to Ken Mc Gowan <[log in to unmask]>

Sent by:  TechNet <[log in to unmask]>


To:   [log in to unmask]
cc:

Subject:  Re: [TN] Immersion silver boards tarnish



Hi David,

Normal mechanisms of Ag tarnishing are:

Diffusion of copper (do you have a brrier layer of  Ni/Pd??)

Presence of sulphides in the atmosphere.

Organic stuff in packaging materials.

Best Regards,

Ken McGowan.
----- Original Message -----
From:  David
To: [log in to unmask]
Sent: Monday, April 09, 2001 1:53  AM
Subject: [TN] Immersion silver boards  tarnish

Has anyone ever exeprienced immersion silver MSP  boards tarnishing, turned
yellow after stored in ambient  condition?




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