Years ago, I once had a lot of panels where there were resin voids bridged traces under the soldermask. These filled up with foam flux (or water from the wash) and never completely dried. Since the panel had 30 Mohm circuits, we had intermittant shorts caused by flux and water inside the PCB. This is the only "flux short" that I have seen. Aric ------------- Original Text From: C=US/A=INTERNET/DDA=ID/ERiemer(a)eskimo.com, on 3/11/98 3:23 PM: Christy, For what its worth ... I've seen intermittent internal shorts in printed wiring boards that were later found to be caused by etch defects that had left copper in a ground plane clearance zone around a via. The copper was nearly touching the via land but not quite, and when the board warmed up there was enough movement to cause the board to short. Ed Hare SEM Lab, Inc. -- SEM Lab, Inc. Scanning Electron Microscopy and Failure Analysis Snohomish, WA (425)335-4400 http://www.eskimo.com/~eriemer/SEMLab.htm Christy Graham wrote: > TechNet, > > I was told recently of a printed circuit card assembly that, when the > assembly is powered up in the morning, the board runs, but that by the > afternoon, it fails. Next day, same board, same results. The engineer > thinks this problem is due to a "flux short". Is this possible? > > Christy Graham > [log in to unmask] > > ################################################################ > TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c > ################################################################ > To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: > To subscribe: SUBSCRIBE TechNet <your full name> > To unsubscribe: SIGNOFF TechNet > ################################################################ > Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. > For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 > ################################################################ ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################ ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################