Ok Guys, I've read an abundance of responses regarding technical possibilities. However, I would like to submit a probability. Ask you board shop if they Hi-pot high resistance shorts. Some time ago it was common to hi pot a high resistance short. These are boards that repeatedly fail test but probing with a standard ohm meter does not show any conductivity. A long time ago, in a place far far away, we used to simply take a hi pot and blast the damn thing out. Then it would pass test. What we were dealing with was a very small fine line ( typically less than .001 ) short or what I call copper dust. This is where the etcher leaves fine copper particles embedded in the glass. It takes on the appearance of copper dust when you see it. Over time we learned that hi potting out shorts was not a good thing. Someone technical and a lot smarting than I pointed out that the current would carbonize the small amount of copper inside the board and leave a "track" for potential future shorting. Although the board would not pass and immediate retest, I would think a reliability issue would remain . In any case, I do believe this is still fairly common practice among many shops. Especially when you just need that one board to make the order. Perhaps you are dealing with a board that failed test initially and has been "reworked" with a hi pot. Just my thoughts... Ed Cosper Director Quality Assurance and Engineering American Board Company. ----- Original Message ----- From: Jon Moore <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, September 10, 1999 8:04 PM Subject: Re: [TN] Internal fab shorts that happen over time... > Steve, > My first place to try would be Robisan Labs. Call them at 317-353-6249 > > Jon Moore > > ############################################################## > TechNet Mail List 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://www.ipc.org/html/forum.htm) for additional > information. > If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or > 847-509-9700 ext.5365 > ############################################################## > ############################################################## TechNet Mail List 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://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################