This is the question I sent before - we really need your input so that what 
we put into the board specifications is correct.  Please respond

Good Morning
In the current rigid board spec 6012A and in 6012B, soon to be released, 
there is a note in the Dielectric Thickness para that states:  "Minimum dielectric 
spacing may be specificed to be 30 um (0.00118"); however, low profile copper 
foils should be used and the voltages employed should be taken into 
consideration so as not to cause breakdown between layers....When the nominal 
dielectric thickness on the drawing is less than 90 um (0.0035"), the minimum 
dielectric spacing is 30 um (0.00118").

I have had advice from some that the thinner dielectric is for "special" 
materials and not the routine epoxy and polyimide materials typically used.

Where is there guidance as to what materials can be taken down to 1 mil 
between layers?

Thanks for any help you can provide.

Susan Mansilla
Robisan Lab

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