I'm looking for a reading on the most common version of FR4 material for 2 sided boards and for multilayer boards... based upon usage in the board manufacturers shops... I want to specify per IPC-4101/?? The best choices would have better Tg characteristics... so I was leaning toward IPC-4101/26 as my choice but there may be a suitable alternative that is more commonly used that someone can point me to. I have some old board designs that were originally build back when MIL-P-13949 was the spec and GFN FR4 was all we had to specify... It's time to update the notes... Any help appreciated... :) Best regards, Bill Brooks - KG6VVP PCB Design Engineer , C.I.D.+, C.I.I. Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510 e-mail:[log in to unmask] http://www.dtwc.com http://pcbwizards.com --------------------------------------------------- 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 -----------------------------------------------------