Hi IPC Specs gurus, I have question regarding rigid multilayer , say 16 layers , to be manufactured according to Class 3 with 1-2 vias. The question is on copper thickness in 1-2 vias. We can manufacture such PCB in two ways : 1) Final PCB, laser drilled blind microvia to layer 2 , plated as blind structure. 2) Double side core, drilled , plated as 2 layers via core , and then laminated as final PCB Looking into tables 3-3 , 3-4 and 3-5 it seems, that in case 1 fall into definition of microvia covered by table 3-4 ( average copper thickness 12 microns) while the second case, it should follow requirements of table 3-5 ( average 15 microns) rather than of table 3-3 ( average 25 microns). What are other opinions? Edward Szpruch|Manager of Process Engineering | Eltek Ltd. | | +972 (3) 939 5098 |+972 (54) 807 4298 | +972 (3) 939 9581 | [log in to unmask] | www.eltekglobal.com ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________