I'm looking for some guidance with regards to dielectric thickness requirements. We are currently fabricating boards for a customer in which IPC-6013 is invoked on the drawing. Within IPC-6013A you will find the following: "3.7.15 Dielectric Thickness: The minimum dielectric spacing shall be specified on the procurement documentation." Well, that's pretty clear. However, it is not on the procurement documentation, and it very rarely is. Since IPC-600 is invoked within IPC-6013 as a sub-tier acceptability document, I figured I'd head down that road. IPC-600G specifies the following: "3.1.8 Acceptable - Class 1, 2, 3: The minimum dielectric thickness meets the minimum requirements of the procurement documentation. If not specified, must be 0.09 mm [0.0035 in] or greater." Okay, so as a result of this statement one may interpret this as the controlling requirement (0.0035" in this particular case). Unless of course you head back to IPC-6013 which states the following in section 2: "2 Applicable Documents: The following specifications form a part of this specification to the extent specified herein. If a conflict of requirements exists between IPC-6013 and the listed applicable documents, IPC-6013 shall take precedence. So at this point, I'm right back to where I started. There is no defined dielectric thickness specified on the procurement documentation. Additionally, the cross sectional view on the drawing does not define the number of ply's between layers. This is obviously desirable for the manufacturer to ensure they/we have the freedom to develop the construction based on a balance between the customers needs and the manufacturing "sweet spot". However from a compliance stand point, I'm in a quandary. If I had a multilayer construction with a single ply of 1080 prepreg between two 1/2 ounce layers (one signal, one ground), would the resulting board comply to the spec? In looking for further clarification, I deferred to IPC-6012B, IPC-2222 and IPC-2221A and found the following: IPC-6012B = .0035" minimum IPC-2222 = .0035" minimum IPC-2221A = Shall be specified on procurement documentation I hope the use of direct quotes is acceptable here. It's the only way for me to really characterize my problem. Has anyone out there come across this issue? I've searched the archives, and similar issues have not been discussed (as far as I can see) since 96'/97'. Brian Guidi R&D/Quality Systems Specialist Teledyne Printed Circuit Technology Tel: (603) 889-6191 X:310 Fax: (603) 886-2977 E-mail: [log in to unmask] Visit us @ http://www.tetpct.com