The single ply / 2 ply minimum requirement has flip flopped over the years, particularly in the US Military specifications. Since early 1990's the single ply acceptance has been the rule and the latest IPC documents have moved away from determining your design constraints and leaving this condition up to the design activity. The economics of single ply constructions both in base material and fabrication are there, certainly on the higher layer count designs where the cost savings opportunities are good. Jeffrey Bush Director, Quality Assurance and Technical Support VERMONT CIRCUITS INCORPORATED 76 Technology Drive - POB 1890 Brattleboro, Vermont 05302 Voice - 802.257.4571 ext 21 Fax - 802.257.0011 <http://www.vtcircuits.com/> -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of "Sefika ÖZKAL" Sent: Friday, March 24, 2006 9:13 AM To: [log in to unmask] Subject: [TN] prepregs Hi Technetters, In some stackup examples, I have seen that one prepreg may also be used as an inner layer. Normally two or three prepregs are preferred. What are the rules or limits while choosing the prepreg number according to manufacturing? I would like to look at IPC specifications and military standards for my questions. Could you please recommend me the appropriate specifications? Thanks in advance. Regards Sefika OZKAL Dikkat : Bu elektronik posta mesajı kişiseldir. Eğer, gönderilmesi gereken kişi değilseniz lütfen göndericiyi bilgilendirip mesajı siliniz. Firmamıza gelen ve giden mesajlar virüs taramasından geçirilmekte, hukuki nedenlerle log kayıtları tutulmaktadır. Mesajdaki görüşler ve bakış açısı göndericiye ait olup Aselsan A.Ş. resmi görüşü olmak zorunda değildir. Attention : This e-mail message is private. If you are not the intended recipient please delete the message and notify the sender. E-mails to and from the company are, monitored for virus protection and in accordance with lawful business practices. Any views or opinions presented are solely those of the author and do not necessarily represent the views of Aselsan A.S. --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------