Phil,
We normally like to see finished copper weight on all layers. That way we can determine starting copper weight depending upon copper additive process (plating) and inner layer processing. Regarding dielectric material thicknesses... unless you need a specific layup (build) we recommend leaving it up to the supplier. There are general stack ups for 4, 6, 8, etc. layers. One thing you may want to specify is that there is to no single ply construction. We always try to at least to use a minimum of two plies of pre-preg (b-stage).
Dan S.

>>> [log in to unmask] 09/28/06 02:45AM >>>
Dear Fellow TechNetters,

Would you please share how you communicate your PCB build structures to PCB fabricators, or, if you are a fabricator, how those which are easiest to understand are presented to you.

For copper, is it best to quote (i) Nominal start weight or thickness, (ii) minimum finished thickness to IPC-2221A tables before and/or after plating if applicable?

For dielectric thickness, (i) specify value, (ii) give range (iii) leave open?

Your advice and expertise is greatly appreciated.

Many thanks and regards,

Phil



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