Multilayers Unbalanced layup - more copper on layers 1 - 5 than 6 - 10 (for example) Warped caul (tooling) plates Weave orientation Lamination Rise time The use of aluminum vs. steel separator plates Odd layer count Doublesided Unbalanced circuitry on side one vs.two Material- I remember we used to purchase DS material from a laminator (no longer in business) that always warped - I think it was 7 ply instead of a standard 8 ply. Hope this helps. pete >From: Judy Brown <[log in to unmask]> >Reply-To: TechNet E-Mail Forum <[log in to unmask]>, Judy Brown ><[log in to unmask]> >To: [log in to unmask] >Subject: [TN] Warp & Twist >Date: Fri, 4 Feb 2005 10:45:15 -0800 > >I know I saw what I need somewhere, but I can't remember the document. I >need the causes for PCB warp and twist. > >Judy Rae Brown >Quality Assurance Manager >EXPRESS MANUFACTURING, INC. >Electronic Manufacturing Services >3519 West Warner Avenue >Santa Ana, CA 92704 >714.979.2228 - Tel >714.556.0575 - Fax >Email: [log in to unmask] >Website: <http://www.eminc.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 >----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------