Barrie:  The text of par. 5.4.1 of J-STD-001B is advice (not a requirement)
and is of course based on the need to remove gold from plated surfaces.
Notice the 2.5 micrometer thickness requirement of par. 5.4.1 for pth's.  The
old military requirement (which I helped write) called for removal of Au
plating if it were more than 100 microinches thick (reject for insufficient
thickness if <50 microinches and go ahead and solder it if Au plating was
between 50 and 100).  The information in J-STD-001B is based on the old
military requirement and applies to surfaces which were plated to military
requirements (50 to 100 microinches).  Applying the advice of J-STD-001B to
contemporary flash plating of gold (usually 20 microinches or less) is a waste
of time unless you have REALLY fine pitch and are using minimum solder
deposition.
- If in doubt, find a scrap pwa and microsection a couple of solder
connections.  If the Au content is < 3% your connections are OK as far as Au
contamination is concerned.
- Remember, the must & shall statements in the text of J-STD-001B are only
advice unless they happen to appear in Table 11-1 (see par. 1.4.1 of J-
STD-001).
Hope the above helps.  Regards, Jim Moffitt, Moffitt Enterprises Consulting

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