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October 1997

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Date:
Wed, 15 Oct 1997 15:11:04 -0700
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     First, I can only assume that the "selective solder reflow" was an SMT
     assembly, not a flux and wave solder operation.  If flux is added to the
     board and then subsequently washed off, all bets are off!

     Secondly, I question the need for "oxidation arrest paper" for OSP boards
     exposed to a selective solder reflow.  From the inforamtion provided by
     Enthone, the supplier of ENTEK-106A, the first thermal cycle actually
     increases the chemical resistance of the OSP that covers unmasked copper.
     The reflowed solder joints have already removed the OSP and replaced it
     with Sn/Pb. The OSP coating can normally withstand up to 8 thermal cycles
     before it becomes too thin to protect the copper.  Therefore, why add
     unnecessary storage costs to the process?

     If you are concerned with environmental intrusion while in storage, try
     packaging the boards in plastic bags (e.g. the bags in which the boards
     were shipped to you from the PCB fabricator) and place them back on the
     shelf.  The additional covering also provides a scratch protector against
     normal handling damage prior to the second assembly process.

     Just some food for thought.

     Bill Fabry
     Plantronics, Inc.
     [log in to unmask]

______________________________ Reply Separator _________________________________
Subject: [TECHNET] ASSY -OSP-Preserving Solderability
Author:  "TechNet Mail Forum." <[log in to unmask]> at INTERNET


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