Wes, I just finished a consulting assignment in Connecticut concerning the very same thing. I have done many of these contracts recently as everyone seems to be having the same problems. As I told Tom Gervascio (another Siemens person), first read my article on the SMTnet (their newsletter) in the September 1999 edition. It speaks clearly, though technically, to this and other issues concerning MLB technology. I am assuming boards, on the panel, are this type even though double sided types also may perform this way. 1) The MLB construction, beyond balanced copper planes, as material selections. Also, material availability becoming more of a problem due to glass fiber shortages (much being diverted to fiber optics industry - what a surprise!) 2) The lamination process not effectively managed as press cycle from ramp through pressure, time, and temperatures used. 3) Lamination press issues as non parallel press plattens, thermal problems as uniform heat transfer or heater elements not working, etc. 4) Number of books in each press opening along with thermal lag material, etc. 5) Total cure not effected during lamination 6) Variations in your assembly process as reflow profiles, including cool down. 7) The type scoring used and how well the process managed 8) A thin panel that is too large (how large are the panels?) especially when not effectively supported during reflow. 9) Other variables not so common Earl Moon, Proof Of Design --------------------------------------------------------------------------------- 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 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 ---------------------------------------------------------------------------------