James, What your vendor is proposing is the foil construction method of PWBs vs. core construction. For some vendors, foil construction saves a little money, provides easier manufacturing (fewer innerlayer cores to process), reduces warpage, and possibly a few other benefits one of the fab gurus could comment on.. In the end you have the same, but possibly better, board. Most of our boards are foil construction, and we have seen no problems with this form of PWB construction. Roger M. Stoops, C.I.D., PCB Designer Spectra Precision Inc./Trimble Navigation Ltd. 5475 Kellenburger Rd. Dayton, OH 45424-1099 USA Ph: 937.233.8921 or 937.233.4574 ext 288 Fax: 937.233.7511 "Marsico, James" <James.Marsico@D To: [log in to unmask] P.AIL.COM> cc: Sent by: TechNet Subject: [TN] MULTILAYER BOARD LAY-UP <[log in to unmask] > 11/06/00 08:21 AM Please respond to "TechNet E-Mail Forum."; Please respond to "Marsico, James" Dear Techneters: I have a six-layer board design which requires three polyimide cores bonded together with two layers of prepreg. Our PWB supplier is recommending using two cores bonded together with prepreg, then bonding copper foil on both outside layers also using prepreg. The resultant dielectric thickness' would remain similar to the original design. Are there any drawbacks to this approach? What is the benefit? Thanks, Jim M. --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 --------------------------------------------------------------------------------- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------