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June 2013

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From:
"Wenger, George M. [Contractor]" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Wenger, George M. [Contractor]
Date:
Thu, 27 Jun 2013 12:13:27 -0500
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Dee,

If you are asking about Immersion Silver the IPC specification is IPC_4553 and it calls out 0.12um (5u") minimum and 0.4um (16u") maximum.

We've used immersion silver for over 13 years and our internal specification back in the 1990's when AlphaLevel was the only immersion silver commercially available was 2 to 10 micro-inches.  When other vendors introduced their immersion silver chemistry we changed our specification to 2 to 20 micro-inches.  We use the 2 to 20 micro-inch as a typical range rather than as an absolute minimum and maximum.  Although we've almost never have received PCBs with less than 2 micro-inches of immersion silver there have been many occasions where we've received PCBs where the immersion silver on very small features has been 23 to 26 micro-inches thick.  We've never any issues with the 23 to 26 micro-inch thickness and we don't typically reject PCBs unless the silver is over 30 micro-inches. 

Regards,
George
George M. Wenger
Failure Signature & Characterization Lab LLC
609 Cokesbury Road, High Bridge, NJ 08829
(908) 638-8771 Home (732) 309-8964 Mobile
E-mail: [log in to unmask]
[log in to unmask]

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dee Stover
Sent: Thursday, June 27, 2013 12:56 PM
To: [log in to unmask]
Subject: [TN] spec for silver finish on pcb

I have only specified ENIG in the past, this next job is silver plating. I don't have the correct IPC to specify this on my fab drawing.
Can someone please share the proper note for silver finish including any  necessary diffusion barrier.

Thanks,

:-) Dee Stover  [log in to unmask]   520-318-8489
CAD Design Lead
National Optical Astronomy Observatories www.noao.edu 


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