My worry would be the LED. Although you say they work when removed, do they continue to work through mechanical or thermal stress? (hot gas pencil, freezer aerosol?) Did the tight clinch make the LED wire bond to the lead frame intermittent? Rex Waygood Technical Manager PartnerTech Poole Ltd Benson Road Poole Dorset BH17 0RY United Kingdom Tel: +44 (0)1202 674333 Fax: +44 (0)1202 678028 DDI: +44 (0)1202 338222 Mob: +44 (0)7887 997403 [log in to unmask] www.PartnerTech.co.uk -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea Sent: 03 June 2008 12:55 To: [log in to unmask] Subject: [TN] Intermitent contact on LEDs Dear Technos, I am investigating some returns from the field and can't really figure out what the problem is. On boards having 200+ TH LEDs we see 4 to 10 malfunctioning ones, but if pressure is applied on the component it starts functioning. Under my regular microscope I cannot see any problem with the joints and when removed, the LEDs work properly. One unpleasant thing though is that the LEDs were machine inserted and clinched to the board pretty tightly, so the solder did not wick up on the leads too much, but if the joint was somehow fractured, applying pressure on the component would only widen the gap, since the bulk of the joint is on the opposite side of the pressure point, am I right? The PCB is a regular 0.062" thick 2 layer board, with the regular 1oz of Cu on each layer, of pretty impressive dimensions, 22"x10". There is no pattern in the disposition of the malfunctioning LEDs. Besides cracked PTH, which we will investigate since I am preparing to send out some boards for cross-sectioning, can it be anything else? Thanks, Ioan --------------------------------------------------- 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 ----------------------------------------------------- ------------------------------------------------------------------------------- The information contained within this e-mail and any attachments contained therein may be confidential and/or legally privileged and is for the use of the intended recipient only. If you are not the intended recipient please delete it from your system and notify the sender by return e-mail. The content of this e-mail may not be copied or disclosed to any third parties without prior permission from the sender. E-mail is susceptible to data corruption, interception, tampering and viruses. We do not accept any liability for any such incidents or any consequences thereof. --------------------------------------------------- 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 -----------------------------------------------------