Kevin,

Yes it is possible to remove Sn and then do ImAg plating.  Actually many PCB fabricators use Sn as an etch relief when they fabricate circuitry on PCBs and then etch the Sn off before a final surface finish is plated.  That final finish could be almost anything (e.g., ImAg, ENIG, ImSn, HASL, etc.)

Regards,
George
George M. Wenger
Senior Principal Reliability / FMA Engineer
Andrew Corporation - Wireless Network Solutions
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 Office (732) 309-8964 Mobile
E-mail: [log in to unmask]

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Glidden, Kevin
Sent: Thursday, January 27, 2011 2:19 PM
To: [log in to unmask]
Subject: [TN] Re-finish ImSn to ImAg ?

Question of PCB finishes...

We changed specification on a PCB from ImSn to ImAg.  The PCBs were built with ImSn, so we returned them.  The PCB supplier is stating the ImSn was removed and they were replated with ImAg.  Is this possible, or did they just plate Ag over Sn?  If it IS possible, is it safe for the rest of the PCB?

Thanks,

Kevin

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