If the amount of Au is small and, more or less, evenly distributed, there is
not likely to be a problem in terms of the reliability of your solder
connections.  HOWEVER, you have no guarantee that the Au surface layer on the
component terminations will always remain thin enough regardless of what your
specification says.  Further, depending on the soldering process the Au may
not always get fairly evenly distributed.  Because of the sad experiences in
the industry with Au, the ANSI/J-STD-001 position on Au exists.
Unfortunately, ANSI/J-STD-001 has no such position on Ag, which is not any
better than Au, and the industry seems to have forgotten the previous
experience (much less numerous than those with Au since Ag-plating was not
used very much) with Ag.

Werner Engelmaier
Engelmaier Associates, Inc.
Electronic Packaging, Interconnection and Reliability Consulting
23 Gunther Street
Mendham, NJ  07945  USA
Phone & Fax: 201-543-2747
E-mail: [log in to unmask]

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