Sorry to re-start a previous discussion, but I'm still dealing with a board failure and I'm trying to learn fast. I received a higher-resolution picture of a board problem we are having http://www.frontdoor.biz/PCBportal/corequestion.jpg<http://www.frontdoor.biz/PCBportal/corequestion.jpg> and if I look at it closely, I can see the dividing line between all ten layers of dielectric. By looking at which way the copper is located from each dividing line, I can tell which are cores and which are prepreg (because the prepreg layers will flow "around" the copper features) For example, the thin pinkish layer is a core. Am I on the right track so far? So, our problem is a 120V end-of-line test frying two out of every hundred boards right through the pinkish core material with the white streak through it (3.2 mils, which should handle a few kilovolts at least, right?) So here's the question: Should I be questioning the material quality rather than the bare-board manufacturing process itself? I realize you guys have already been generous with helping me on this, so I hope I'm not pushing your patience... onward thru the fog, Jack (aka "the new guy") --------------------------------------------------- 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 -----------------------------------------------------