Hi Helena, Richard provided: > http://www.taconic-add.com/pdf/taconic-laminate_material_guide.pdf > This Material Guide does not give Tg, or the modulus of elasticity; the CTE values given are compatible with FR-4; you do not say what Ni plating is used [be careful with electroless Ni, it can lead to much earlier failures of the vias; electrolytic Ni enhances via relaibility]. I would still be worried about PCB warpage during the soldering process(es) as the result of the asymmetric lay-up. Werner ************************************** See what's free at http://www.aol.com. --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 -----------------------------------------------------