Thanks for your input Arnaud.  

Soldering land spacing will fall into the A6 category, and solder mask between exposed pads shall not be considered an insulator between pads which is why it is not accounted for in the table.



As far as your 0603 example, I have to say that Yes, it cannot be used in a  >100V circuit as the pads for an 0603 are slightly under the 0.8mm requirement.



Cheers,

Murray



 



-----Original Message-----

From: GRIVON Arnaud [mailto:[log in to unmask]] 

Sent: Friday, September 06, 2019 9:36 AM

To: TechNet E-Mail Forum; Campbell, Murray

Subject: RE: Table 6.1 conductor spacing



Dear Murray and TechNetters,



Unfortunately, I won't have no clue to provide but also share the same kind of understanding concerns with this IPC-2221 6.1 table for PCBA electrical conductor spacings...



Your question was "what category should be used for covered trace to component pad spacing?", mine would be " what category should be used for soldering land spacing?".



For soldering lands, there is usually a solder mask dam between the lands. I know solder mask is not a good insulator, but this is not air either... I don't see it taken into account in the table. This may be intentional but not clarified.



Take a C0603 500V ceramic chip capacitor with standard 5-sided square-end terminations that has typically a gap <0.8mm between terminations, both on the top and bottom (PCB side) sides..

This is not compatible with 6.1 table spacing requirements that should be >1.5mm (A6, no conformal coating) or >0.8mm (A5, with conformal coating) : does this mean a C0603 500V cannot be used, or what?

What spacing requirements would be applicable to the distance between soldering lands (that is part of the C0603 component footprint design)?



Have a nice week-end.



Arnaud Grivon



-----Message d'origine-----

De : TechNet [mailto:[log in to unmask]] De la part de Campbell, Murray

Envoyé : jeudi 22 août 2019 19:05

À : [log in to unmask]

Objet : [TN] Table 6.1 conductor spacing



Hey All,

In regards to conductor spacing,  assuming typical  B4/A6 combination, it is my understanding that adjacent conductors shall be covered to allow B4 spacing requirements.   Does B4 spacing still allow for a covered trace to open pad spacing?  Or does a covered trace to open pad fall into the A6 category?  I guess the short question should have been “what category should be used for covered trace to component pad spacing?”

Thanks,



Murray Campbell



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