A couple of years ago we had a similar problem that proved to be a right PIA. Not quite the same connector but sounds like similar problem; due to tight test parameters we had lots of failures, quite often at full EPU assembly stage so rectification was a costly job! Eventually identified the problem as being the product of wave soldering, the flux was vaporising (RMA) and wicking up the connector pins. The only way to spot the ultra fine coating was to make / unmake a mating connector and look for the witness under a Mantis but even then it needed almost a trained eye to spot it, in fact the person best placed to spot the problem was the test engineer..........who wasn't very happy being used as goal keeper. The fix was to place mating slave connectors to the boards prior to wave soldering (which req'd cleaning periodically!), this helped a lot but the only wave to eradicate the problem completely was to clean the boards post soldering using Ultra-Sonics......fortunately the boards were motherboards! Hope this helps. Regards, Iain. -----Original Message----- From: Dave Seymour [mailto:[log in to unmask]] Sent: 04 January 2005 07:09 PM To: [log in to unmask] Subject: [TN] flux wick-up? *** WARNING *** This mail has originated outside your organization, either from an external partner or the Global Internet. Keep this in mind if you answer this message. We had a batch of boards with high fall out. Below are a couple of statements from the CM building our cards. The socket mentioned below is a 370 pin CPU ZIF socket with a locking arm. We have manufactured this double sided SMT/Through hole mix card for 4 years. My questions are, Is there such a thing as "flux wick-up"? Is the hole supposed to stop flux from getting onto the top side of the PCBA? I figured that flux is supposed to go up into the PCB hole ( and maybe even getting into the socket contact area) to prepare the hole for soldering. Then the cleaning operation washes away any residue. Any comments or help would be appreciated. Thanks Dave Seymour >From CM: "On a failed board we reviewed CPU sockets and removed the lid off the socket and viewed the gold contacts under a microscope and found some evidence of contaminants/foreign matter on the gold contacts. " "Got 23 CPU sockets from Stock and removed lids and there was no contaminants found on sample of 4 parts." "MFRG's data sheet and hole pattern recommendation is .030" 2 plc's = 0 tolerance. Fab DWG shows hole dia to be .033" +.004 -.001. Board hole dia is oversized compared to mfgr recommendations. " "Can this possibly allow flux to wick-up?" "We are continuing to investigate the findings and working to determine what the contamination is...." -- Dave Seymour, CID+ Catapult Communications Inc. 800 Perimeter Park Dr, Suite A Morrisville, NC 27560 Direct: (919)653-4249 Main: (919)653-4180 Fax: (919)653-4297 [log in to unmask] --------------------------------------------------- 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 847-615-7100 ext.2815 ----------------------------------------------------- ******************************************************************** This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. ******************************************************************** --------------------------------------------------- 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 847-615-7100 ext.2815 -----------------------------------------------------