Folks, For those caring, my final summary of this thing is as has been stated. As Werner puts it, the first thing bad is the asymetric device construction. This means coplanarity is compromised because of the aluminum heat sink atop the part and attached directly to the hot Silicon part. This causes the PCB substrate to warp. The second issue points to the reason Tessera is successful. They used a compliant flex layer to ensure CTE matchibng characteristics are not compromised as in the case of the TI device wheren its die is directly attachd to the PCB substrate. Therefore, two failure mechanisms are at work. Each or both are capable of effecting poor initial quality solder joints and negatively impact long term reliability. Thanks all on and off line, Earl Moon --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------