Starting thinner and plating up means more copper in the vias. In general that sounds good to me but watch out for via plugging. Through holes that were tight to begin with could end up too small unless the holes are drilled a little bigger. Bob K. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Nagaraj Shanmugam Sent: Wednesday, August 07, 2013 9:18 AM To: [log in to unmask] Subject: [TN] Starting copper foil thickness on External layers Hi All, We have pcb fab notes calling as - "starting copper weight can be 0.5oz as long as the finish copper weight is 1 oz" (or 2oz on high power designs) Now, few fabricators started to ask for deviation to use 3/8oz for starting copper instead 0.5oz and will make finished copper thickness required in plating. What are the pros and cons of having smaller copper foil thickness as starting copper weight? I am concerned about the planarity of the surface due to longer plating time on 3/8oz. Appreciate any information on this. Thanks, Nagaraj. ______________________________________________________________________ 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] ______________________________________________________________________ ______________________________________________________________________ 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] ______________________________________________________________________