George, Do you have some pictures of what to look for? -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of George H Franck Sent: Monday, December 15, 2003 10:41 AM To: [log in to unmask] Subject: Re: [TN] Problem With PCB Opens I concur with everyone's comments made so far. This (my opinion) is the last Printed Wiring Board defect which can slip through all the quality and inspection processes and create a field failure. The causes of the opens will point back to poor process controls on some rather mundane chemical tanks in your supplier's process. Having run a board shop in the 1980's, I learned this the hard way. (Continued thanks to Ken Nevar, a now retired Shipley rep. He had Shipley Employee number 6.) If the defect is caused by process controls in the chemical process, the defect can be expected to develop in every board in that lot, (and probably a few other lots too.) You might want to consider a recall of the boards, if yours is that kind of product. The beginnings of these defects can be seen during cross section analysis. I have been able to verify that some evidence is present in the lot acceptance cross sections of boards I had returns on. However, I usually could only identify the innerconnect defects prior to particular cross section treatment. This treatment is done to the cross section to bring out the grain structure and interfaces in the metal. This is done with a light etchant applied to the polished cross section for a few seconds. This etching tends to mask the defect. Also, if the cross sections are not well polished, the innerconnect defect can also be masked. It is a very easy defect to miss in typical cross section inspections processes. I have brought section mounts on my visits to suppliers (only one with known innerconnect defect in it ) to have their operators prepare and inspect them to see what defects they find. If they don't find the defect, I point them out, and then do some training to help them to find them in the future. One of the responses suggested the use of electrical test to find this defect, looking for higher resistance connections. While this will find some of the defects, it will not find them all. Neither will it fix the problem in the chemical tanks. You will also find that suppliers will begin to charge you more for this testing, as they will test boards multiple times to get them to pass. Usually the high resistances are caused by higher test pin to board resistances, not innerconnect defects, which is why they will run the board multiple times to get a better contact. This takes more time on the test equipment, which is usually a limiting step in the suppliers mfg process, hence the higher charges. Be sure you consider this experience when you next select a supplier for your PWB needs. Good Luck, George Franck, CID+ Quality Assurance 703 295 2635 Eric Stellrecht <estellrecht@DRS To: [log in to unmask] -EWNS.COM> cc: Sent by: TechNet Subject: [TN] Problem With PCB Opens <[log in to unmask] > 12/15/2003 09:10 AM Please respond to "TechNet E-Mail Forum."; Please respond to Eric Stellrecht Technet Members, We have identified a field return trend in a line of circuit boards. The problem is occurs which a trace separates from the plated through hole causing an open circuit. Unfortunatly, we had to destructively analyze two boards to reach this solution. The failure analysis points to a manufacturing defect that will potentially affect an entire lot of boards. We are looking for a non-destructive way to analyze this lot of boards to determine whether or not a particular board suffers from a partially or intermittant open condition, on its way to becoming a hard open. Any recommendations would be greatly appreciated. Thanks in advance... --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------