> Another possibility could be that a piece or pieces of metal debris might have shorted several leads of the QFPs. > Ramon > > -----Original Message----- > From: Steve Gregory [SMTP:[log in to unmask]] > Sent: Tuesday, April 27, 2004 2:08 PM > To: [log in to unmask] > Subject: [TN] Interesting Occurance... > > Hi All! > > Just had an interesting occurance that I thought I'd share with you. We build > this 14-layer assembly here that has 10 Altera FLEX 240-pin QFP's on it...4 > on one side, 6 on the other. We've been building this assembly for some time > now with no problems. > > After SMT, the board goes through AOI, gets some connectors hand soldered on, > then goes to ICT. After ICT it goes into a Thermotron for some power-on > thermal cycling for eight hours. > > Last week, after a cycle was done, the test technician went to retrieve the > boards from the oven. Upon opening the oven door, he noticed this funky > smell....kinda like burnt fiber glass. At one of the twelve positions in the test > rack he found this: > > Go to http://www.stevezeva.homestead.com and look at "Smoking Hole" and > "Smoking Hole 2" (NOTE: DUE TO THE GRAPHIC NATURE OF THESE IMAGES, PARENTAL > DISCRETION IS ADVISED) > > We don't have a clue how this happened. ICT on this assembly was fine, there > were no problems found in the test fixture position in the oven (other > assemblies have gone through the temp cycle in the same position without a problem). > And supposedly, there is only 5V and 3.3V being applied during the thermal > cycle. > > Obviously there had to be more voltage than that to cause the kind of damage > you see in the pictures, but nobody knows where it came from. Smoking Hole is > a QFP on one side of the board, and Smoking Hole 2 is on the other. The leads > are vaporized in the pictures. This only happened to one board, and the > fixture was loaded up with another 11-assemblies. > > I don't expect we'll ever figure out what happened unless it somehow happens > again. I know one thing, if it does, I don't want to be anywhere near the > oven! > > Thought you might find the pictures interesting...these are $4000 images. > > -Steve Gregory- > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 1.8e > 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 > ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------