Hi Wee Mei! Sorry it took me so long to get your pictures posted, but Homestead was down for server maintenance yesterday. I have your pictures posted now: http://stevezeva.homestead.com/files/Q55-_burnt_site.JPG http://stevezeva.homestead.com/files/Q55_-_remove.JPG http://stevezeva.homestead.com/files/Q55_-_close_up.JPG Yep, looks like some of the metal vaporized...pretty high temperature! Steve ________________________________ From: Lum Wee Mei [mailto:[log in to unmask]] Sent: Wednesday, April 29, 2009 8:35 PM To: Steve Gregory Subject: Is fusing current current? Dear All, An engineer was trying to probe for a signal while he accidentally slip the probe pin and has it shorted between the MOSFET metal tab (power output) and the exposed area fill ( Chassis GND) beneath it. Ooop, up come the smoke and a small burnt site. The MOSFET is removed and found to be still functioning. The questions are : 1. To have the copper area blown up and fused look like we need a very high temperature. If that is the case, why we do not see any damage to the laminate epoxy glass fibre. We have a previous case, where the trace burnt and curled up and the laminate epoxy glass fibre burnt and become brittle. 2. As this PCBA is already fully populated and the damage does not seem bad, I was thinking or just sealed teh exposed laminate with epoxy, mount back a good part and use the PCBA as it is. Can I do that? or it would be good to re-mount the whole PCBA? All the PCBAs are made from Nelco-4000-11. Your kind opinion is greatly appreciated. Steve : Would appreciate you can upload this pic for me and forward to TechNet for discussion. Thanks and Regards, ~ Wee Mei ~ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 847-615-7100 ext.2815 -----------------------------------------------------