Thanks for all the reply.

However, has anyone studied how much sulfur or chloride could start the
tarnish?

While we still do not have any issue with solderability (use no clean paste)
there is reported contact problem in the contact compressive connector which
mates onto the tarnished silver pads (no solder added in these pads) .

How could we prevent the tarnish? There is virtually presence of sulfur
anywhere.

Is there an industrial workmanship standard e.g IPC standard to accept the
asthetic imperfection knowing that this may be an inherent limitation of
silver finishings?


----- Original Message -----
From: Furrow, Robert Gordon (Bob) <[log in to unmask]>
To: 'TechNet E-Mail Forum.' <[log in to unmask]>; 'David'
<[log in to unmask]>
Sent: Monday, April 09, 2001 9:31 PM
Subject: RE: [TN] Immersion silver boards tarnish


> David,
>
> Yes, we have seen the yellow tarnishing on some product. It has been our
> experience that the yellow tarnished product does not present assembly
> issues using noclean paste in nitrogen and VOC free wave solder fluxes. We
> do pursue the issue with our suppliers and assembly locations in order to
> resolve.  We found in some cases that if boards are placed down on a
surface
> that has sulfur on it, the yellowing becomes particularly noticeable.
>
> Thanks,
> Robert Furrow
> Printed Wiring Board Engineer
> Strategic Supply Global Account Manager
> Supply Chain Networks
> Lucent Technologies
> 978-960-3224    [log in to unmask]
>
> > -----Original Message-----
> > From: David [SMTP:[log in to unmask]]
> > Sent: Sunday, April 08, 2001 10:53 PM
> > To: [log in to unmask]
> > 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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