Ron,
        Have you conclusively determined that it's a Phos. issue and not a thermal profiling issue?

        Jeff Perkins
        Photocircuits


-----Original Message-----
From:   Ron Hollandsworth [SMTP:[log in to unmask]]
Sent:   Monday, September 21, 1998 12:38 PM
To:     [log in to unmask]
Subject:        [TN] Phosphorous In The Nickel Barrier

     We are currently producing a number of printed wiring boards utilizing
     a Ni/Au plating for the final finish.  The majority of these boards
     perform well throughout the process, but we have experienced
     solderability issues on a few assemblies that contain heavy copper
     (ground and/or power planes) on multiple layers. One of the causes is
     the presence of Phosphorous in the Nickel Barrier Level.  Each thermal
     excursion the board is subjected to after the plating operation
     results in a higher level of phosphorous being present at the
     solderable surface.


     Are there any printed wiring fabrications shops out there that utilize
     what is referred to as a "low phosphorous nickel" (<6%) for plating
     versus a "medium phosphorous nickel"  (6-9%)?  To date, all the shops
     we have contacted utilize the "medium phosphorous nickel>

     Need some help.

     Thanks
     Ron Hollandsworth
     [log in to unmask]

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