><<Has anybody found a functional defect in multilayer pwb's due to >nailheading???>> > >Hello- >PCB design falls into my design requirements, but I'm not very knowledgeable >about them... > >could you pls define what nailheading is to me? > >Thanks in advance... > >Regards- >Brad Martin Nailheading is a condition where, at the interface of the inner layer of a multilayer pwb and the drilled hole wall, there is a deformation of the thickness of the internal copper layer. Usually expressed as a percentage of the original copper foil thickness, a copper deformation greater than 150% has been generally considered "rejectable". hope this helps... [log in to unmask]