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Date: | Thu, 20 Jul 2006 07:25:51 -0500 |
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Hi folks! One other fact to consider is that the formation of silver
sulfide will cause a significant increase in the contact resistance. I
can't seem to find the typical contact resistance value in my database (its
in there somewhere) but I'll keep looking. Silver oxide is as conductive as
elemental silver and silver chlorides only increase the contact resistance
values minimally. Leo - an immersion silver finish that has silver sulfide
on its surface would look black/dark blue/purple visually. Yellow or light
brown would indicate either chlorides or a small amount of silver sulfide.
Good luck.
Dave Hillman
Rockwell Collins
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John Burke
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07/19/2006 11:25 Re: [TN] Immersion Silver for ICT
AM
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John Burke
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Me too,
I know that silver oxide is conductive, but I do not think that the
sulphides are.
I have always printed them with solder to avoid cosmetic problems
downstream, and also as a wear surface where card guides are a factor and
the contact is used as an EMI earthing point, although in this latter
instance it is wise to break up the earthing card guide edge ground into a
dot pattern and cover the rest with solder resist.
John
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Darrel Therriault
Sent: Wednesday, July 19, 2006 8:57 AM
To: [log in to unmask]
Subject: Re: [TN] Immersion Silver for ICT
Leo,
I always included test pads in my solder stencil so they would be
soldered.
DJT
Lin Leo <[log in to unmask]>
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[TN] Immersion Silver for ICT
Hi,
Recently, I met a customer complaint for Immersion Ag boards. Immersion
Ag boards in assembly side weren't applied solder on ICT(in circuit test)
pads. After assembly, Ag surface discoloration problem and ICT failure
defect were found in those pads. Those pad were still solderable. ICT
was OK after soldering. Does anyone have similar experience? How can I
solve this problem? Does it need to suggest pre-solder before ICT? It's
chronic or excursion issue for immersion Ag surface finish?
Best regards
Leo
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