Folks, Thanks for the initial input and interest. 1) The first two photos exhibit what was initially thought to be, as many of you have or will suggest. ESD/EOS damage. The supplier, unnamed concurs. 2) The plot thickens as the other images show several possibilities: Acuoustic studies show signifigant voiding in the die attach eutectic material. The heat sink, for this device, also has significant voiding it its initial design as a prototype - not yet a die casting. The device has some coplanarity issues associated with its mounting and thermal dissipation capabilities. As my company has elected not to go with thermal grease, this could contribute to the problem. The initial junction temperature was 180C and, with sinking, went to 150 C. Could the part, a high power/speed amplifier with clearly shown 4 transistors be too sensitive to the commercial assembly operations now being used as we successfully assembled and tested about 60 parts in house before going outside and finding the parts. We have known cleanliness issues but to what extent, I don't know yet as the supplier is being audited for all factors including ESD/EOS and cleanliness issues, among others. A bit late in the ball game to be qualifying suppliers - in my mind. An interesting point is the failure seems to be propagating from the drain side toward the input gate. Interesting to anyone? Could a combination of all the above, or just one, or a bad design, or a component issue, be causes. Of course, but where to go as we had four labs, and the big customer, working on the problem before my arrival. We have run every test imaginable including loose particle. Still, we need to find root cause. I have to run back to work now and I will be online all day there. Any help MUCH appreciated. 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 the following message: SET Technet NOMAIL 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 ---------------------------------------------------------------------------------