John,
I do not see a conflict between these two sections.  It is clear to me that
3.5.4.6 is dealing with final finishes which are defined in 1.3.4.3.
Section 3.8.1 is dealing with the solder resist coverage and therefore does
not conflict with the final finish criteria.  Section 3.3.8 and Table 3-4
does allow for exposed copper at the junction of gold plating to a solder
finish so maybe section 3.5.4.6 should reference the percentages in addition
to this criteria.

Another note, MIL-PRF-55110 Section A.3.5.2.5 allows for .010 of exposed
base metal between the solder resist and the final conductor finish.  This
may have come about for selective tin lead strip / SMOBC technology, so does
6012 cover this anywhere?  This is an easier criteria to measure as compared
to a percentage.

Best regards,
Scott A. Bowles
Director of Quality and Technology
Sovereign Circuits Inc.
12080 DeBartolo Dr.
North Jackson, OH 44451

Phone:   (330) 538-3900  x211
Fax:       (330) 538-2434
Cell:       (330) 717-2125
email:   [log in to unmask]

----- Original Message -----
From: "John Perry" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, May 08, 2002 5:45 PM
Subject: [IPC-600-6012] EXPOSED COPPER/FINAL FINISH


Do we have a conflict here within the IPC-6012a?


In IPC-6012a, Section 3.5.4.6, it states that exposed copper on areas not to
be soldered is permitted on 1% of the conductor surfaces for Class 3 and 5%
of the surfaces for Class 1 and Class 2.

But, Section 3.8.1 Solder Resist Coverage sub-paragraph a.  states "Metal
conductors shall not be exposed or bridged by blisters in areas where solder
resist is required."

The percent allowance issue has been discussed before at Expo 2001 but we
did not walk away from that meeting with a clear cut definition of what
constitutes X percentage on a board, let alone potential conflict with
section 3.8.1.

Best Regards,



John Perry
Technical Project Manager
IPC
2215 Sanders Road
Northbrook, Il 60062
1-847-790-5318 (P)
1-847-509-9798 (F)
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