Yes Steve, Those were the days. Still active for some but for constraining or tailoring core requirements for CTE. Don't have that problem here as after taking one of the little beasts apart, there's really nothing inside that would override the CTE matching characteristics both on the part and the MLB. So, life is good but for getting the gold of the part's solder termination areas. No problem there either. Straigtening out the MLB's radically unbalanced construction, based on impedance requirements, has been a bit more interesting but positive as well. I have a .5 oz. plane on the bottom of the six layer structure and one on the 4th layer. The space between layer 1 and layer four has to be 39 mils. So, I made the dielectrics up of 2 plies of 7628, sandwiched between 2 plies of 1080, in each of the two dielectrics. Then I made the layer 4 plane out of 2 oz. Cu foil. The other dielectrics are all 2 ply 2113. Therefore, when fabricated in a qualified supplier's carefully managed relamination process, under specified time, temp, and pressure, with a well managed cool down cycle, the boards will be flat. Thanks and how's that for one day's work, or was it two? Earl --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------