Hi Gaby - two general rules of thumb to thick about to avoid gold
embrittlement:

1) Is there enough solder volume for the gold layer to diffusive into and
stay below a 3% by weight limit?

2) Is the solder process long enough and hot enough to allow #1 to occurr?

Most gold embrittlement problems are a result of inadequate processing
(rule #2). The JSTD 001 paragraph 5.4.1 contains the assembly requirements
for dealing with gold. You can apply the rules of thumb on pwbs too.  Also,
IPC-TP-1103 "Manufacturing Concerns When Soldering With Gold Plated
Component Leads or Circuit Board Pads" by M. Ferguson is a good reference
paper to browse.  Good Luck.

Dave Hillman
Rockwell Collins
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[log in to unmask] on 12/08/97 12:18:04 PM

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cc:    (bcc: David D Hillman/CedarRapids/Collins/Rockwell)
Subject:  [TN] Gold  plating thicknes




Hello Technetters,
  The ipc-6012 specifies, in table 3-2, gold thickness of 0.8 microns
  for all three classes, maximum , on solderable surface.
  What is usually accepted thickness for reliable surface mount
  solder joints ?
   Thank you
   Gaby
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