The other 3 channels, do they perform to spec, or at least uniformly? Ie, are all Channel 1's at the right level, Channel 2 is always 3dB down, Channel 3 is 10dB low, and 4 is always dead? Or is every board different? Is it possible that it was a design mistake in Channel 4, which is causing it to not work? RF transmitter, is it low enough frequency that some work with an o-scope can be done, to determine where the signal starts to give out? It sounds like it's sub-GHz, if it's standard FR-4 (or at least not many GHz). [I have to ask--as a board designer, I'm used to hearing "your board doesn't work" only to find out a component was installed wrong, or some wire was broken elsewhere in the system. Maybe Channel 4 was populated wrong? Test setup failure?] I'd think a curing issue would show up "randomly", since, if this board isn't the same size as a panel, then the design was panelized and cut out. Shawn Upton, KB1CKT Test Engineer Allegro MicroSystems, Inc [log in to unmask] 603.626.2429/fax: 603.641.5336 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Pete Sent: Tuesday, March 22, 2011 11:18 AM To: [log in to unmask] Subject: [TN] Fabrication failures in one area of board? We are trying to get an RF board functioning, and are having difficulties in the same area of a couple boards. The circuit turns on, but with drastic performance differences This board has 4 identical TX Channels, Channel 1, at the edge of the board works every time, but as we move inward, we experience more failures. Channel 4, at the center of the board will not perform properly on any board. A visual examination doesn't show any differences that might impact performance. The soldering process looks OK. Is there something that could likely vary in the fabrication process that might cause this? It's (supposed to be) a standard 170Tg, non-dicy, RoHS fab. High copper density, but the center channels are near an area of less copper density. Could an epoxy curing variation occur, that might impact getting a consistent dielectric result? What should I be looking for? These boards were not ordered from our qualified vendor, and I have some concerns. We had issues with them before. Pete ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- 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.aspx?Pageid=E-mail-Forums for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------