http://www.flexiblecircuits.co.uk/Flex_rigid.asp The above is a link to a good explaination of the technology comparison with more traditional structures. You can also look at US Patent 4800461 if you wish. The title and abstract are below Multilayer combined rigid and flex printed circuits Abstract Multilayer rigid flex printed circuits are fabricated by a novel process to provide structures having rigid sections incorporating insulator materials which, when subjected to elevated temperatures, do not expand sufficiently in the Z direction to cause difficulties, including delamination and cracking of plated through barrels. The flex section includes flexible insulator materials which extend to but not a substantial distance into the rigid section. Hope this helps. Joe --------------------------------------------------- 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 -----------------------------------------------------