Jorge, Seems like we're on the same page having never met. I have, since the beginning, been involved with near CTE matching requirements for components and boards. In the late 70's through today, I have worked with 7-9 ppm boards using constraining or tailoring core materials as well as Kevlar while meeting initial quality and long term reliablity needs of ceramic at 5-7 ppm/C requirements. That's all well and good. Now, as exemplified by my recent posts, I'm again embroiled with the issue concerning ceramic BGA's and "normal" boards with modified epoxy resin systems. I go back and reference all the stuff from the past as well as try to keep up with IBM's and TI's publications as well as kind individuals like Per-Erik Tegehall who has done extensive reliability studies for the European Space Agency. I'm continuing with some options as: 1) socket or not here I come 2) constraining/tailoring core materials in MLB structures 3) go to "very precise" and recommended design rules for blind micro vias and buried dog bones with blind interstitial vias using sequential lamination 4) punt. This ain't easy stuff in a commercial/cheap environment. However, I try to teach this ain't normal cheap. It's hi-rel cheap and it ain't cheap. Mail me if you wish, MoonMan --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------