Hello John,

My position on the exposed copper issue would be predicated on the assumption that that all copper must be coated with either solder resist (soldermask) or a finish plating (and probably a finish other than OSP).  If the exposed copper is a result of the design because it plans to expose the copper, then it is not a defect and therefore not applicable.  If the copper is exposed and the design cannot tolerate it due to environment (or what ever), then it is an issue of a whether it is a defect against incorrect solder resist coverage caused by the fabricator or insufficient solder coverage caused by the assembler.  Hope this helps.

Kind regards,
Ron McIlnay
Sr. Procurement Engineer
Medtronic
Phone: 425 867 4500
Fax: 425 882 3462
e-mail: [log in to unmask]



-----Original Message-----
From: John Perry [mailto:[log in to unmask]]
Sent: Wednesday, May 08, 2002 2:46 PM
To: [log in to unmask]
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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