Jack, Based on additional information the landscape has changed, I thought it was an anomaly. I assumed it was in the cross-section of a coupon and IPC looks at this as a pin hole in a ground area. You have enough evidence to suspect that the lot has an issue with an etch down condition that does not withstand thermal excursion process as the copper trace does not have enough metal mass to move with the Tg of the material. This may explain why the boards pass electrical test at the fabrication house. With your additional information it appears the problem is much wider spread. If this condition is from the board it appears that the etch down condition may be more wide spread. If the condition you showed in the section is on a trace it will lead to electrical opens as the board goes through thermal excursions. ________________________________ From: Jack Olson [mailto:[log in to unmask]] Sent: Thursday, February 07, 2008 10:28 AM To: Kerry Bode Cc: TechNet E-Mail Forum Subject: Re: [TN] FAB: Thin Trace Failures Thanks for the response. We have random failures on assemblies that have been heated up, only on one batch of boards. The guy doing the cross-section implied that he found this almost by accident. By recommending a "referee" sample are you saying we should we see the same thing in the same spot on a different board (from the same lot)? I'm curious how you could accept this condition on planes and not suspect that there would be trace layers with the same condition. I'm not disputing what you say, just trying to understand... Jack On 2/7/08, Kerry Bode <[log in to unmask]> wrote: Jack, This condition is most likely to occur when the board fabricator was processing the inner layer. The resist coating used for imaging may have had an air pocket at that location causing a lifted resist condition. Then during the etching process the chemical etch solution undercut the resist. From my prospective this is an anomaly and is classified as an etch down condition. If the remainder of the sections do not exhibit the condition, a referee cross-section of the same serial number would acceptable. Based on the cross-section photo it appears to be a ground or power layer, if so IPC specification allowance for this condition. Regards -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson Sent: Thursday, February 07, 2008 8:33 AM To: [log in to unmask] Subject: [TN] FAB: Thin Trace Failures Has anyone ever seen a cross-section like this? http://www.frontdoor.biz/PCBportal/opentrace.jpg (ignore the words on the pic, just a guess) Can you point me in the right direction for cause? thanks, Jack --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------