Dave,

Why call out the specific immersion silver chemistry?  Have you found problems with various suppliers chemisty?  Our fabricators have used immersion silver chemistry from at least two major suppiers and we haven't seen problems with either.  Our internal specification used to be 2 to 10 microinches and we changed it about 3.5 years ago to be 2 to 20 microinches because the chemistry from one of the two suppliers plates typically plates twice as thick as the other.  Our preference for thickness is 2 to 4 microinches but fabricators have a hard time plating 0.000003" +/- 0.000001" so we set the wide range of 2 to 20 microinches and haven't seen any problems.  In fact there have been several cases in the past 5 or 6 years that we've gotten boards outside the 2 to 20 range (boards with 0.5 to 1.5 microinches and boards with 23 to 28 microinches) and used them without any problem.

Regards,
George

George M. Wenger (908)-546-4531 
Reliability Engineer
RF Power Amplifier Group
Andrew Corporation,  40 Technology Drive, Warren, NJ 07059
[log in to unmask]



-----Original Message-----
From: Dave Hillman [mailto:[log in to unmask]]
Sent: Thursday, October 23, 2003 9:17 AM
To: [log in to unmask]
Subject: Re: [TN] inmmersion silver


Hi Jim! The 4-14 Plating Processes subcommittee is currently working on
specifications for immersion silver and immersion tin. ENIG  was covered
with the publication of the IPC-4552 specification. I would recommend you
call out the specific immersion silver chemistry, a thickness range and a
solderability requirement on your drawing note(s) until the 4-14 committee
can complete their work. Good Luck.

Dave



                      "Marsico, James"
                      <James.Marsico@DP        To:       [log in to unmask]
                      .AIL.COM>                cc:
                      Sent by: TechNet         Subject:  [TN] inmmersion silver
                      <[log in to unmask]>


                      10/23/2003 06:30
                      AM
                      Please respond to
                      "TechNet E-Mail
                      Forum."; Please
                      respond to
                      "Marsico, James"






Hello Technet:
What's the best way to specify immersion silver finish on a PWB?  In
accordance with what?  Thickness?  Anything else?

Jim Marsico
Senior Engineer
Production Engineering
EDO Electronics Systems Group
[log in to unmask] <mailto:[log in to unmask]>
631-595-5879

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