George;
Attached is some debate from the IPC-600-6012 committee.  Perhaps we should
discuss this at one of our 4-14 confcalls or at New Orleans?

Phil and others;
George Milad is the chair for a group of us who are attempting to set
specifications for ENIG (Immersion Gold.)
In brief, ENIG is a widely used solderable and contact finish on PCB's.  It
differs from electroplated soft or hard gold.  Our 4-14 group is not
attempting to change the spec's for electroplated gold at this time.
Due to differences in measuring equipment and chemical supplier processes,
our team has not set an upper limit on Immersion Gold thickness. We do,
however state that the preferred thickness is 3-5 microinches.  Our group
has not tackled the Black Pad issue for inclusion into the spec since it is
a contentious issue as yet unresolved.  I believe the members of our group
would form a consensus that thick immersion gold (over 8) is an indication
of the propensity for Black Pad.
As for electroplated gold, some discussion of late indicates that <3% w/w
of gold in a solderjoint is still too much.

Don Cullen
Director - OEM and Assembly Applications
MacDermid, Inc.
203 575 5658


Phil Wittmer,
Manufacturing Technology Team Leader
   For Adhesives & Coatings
Delphi Delco Electronics Systems
PH: 765-451-7199         M/S  8-186
Lotus Notes: Phil W Wittmer/DELCO@DELCO
Internet e-mail: [log in to unmask]