John,

As I ponder IPC-6012A with amendment 1, my interpretation of Section
3.5.4.6 is that it deals with metal finish coating only (ie: Gold, Tin,
Solder, etc not to include OSP) and allows some percentage of exposed
copper in non soldered areas. Rework of theses exposed copper areas is
not easily accomplished and if attempted could cause problems.
Section 3.8.1 deals with solder resist coating only and does not allow
any exposed metal. Touch up of the solder resist is easily accomplished.
Therefore I do not see a conflict and that the Sections identified are
very appropriate.

Steve Nolan
MTS Manufacturing
SGI
715-716-5524
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John Perry wrote:
>
> 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)
> [log in to unmask]