Hi Inge Vibrations around? I just had recently a similar problem in an industrial environment. Failure analysis showed fretting on socket spring- contacts. When I made vibration measurements I found quite a spectrum of low level vibrations on the floor but a clear resonance at 28Hz in the rack. Best regards Guenter >-----Ursprüngliche Nachricht----- >Von: TechNet [mailto:[log in to unmask]] Im Auftrag von Inge >Gesendet: Dienstag, 22. September 2009 21:34 >An: [log in to unmask] >Betreff: [TN] Knock, knock, knock on the heaven's door > >Well, not exactly that, but knock, knock, knock on a earthly board. One >customer needs fix a intermittent problem asap. 19 inch racks with >hundreds >of PTH double sided boards, old technology, no BGAs, no QFMs etc, but >lots, >lots of DIPs. The edge contact fingers have a very thick and good gold >over >nickel, and the backplane connectors have really stiff double tongues. >The >contact pressure/sq is extremly high and I think the contact spots are >really gastight once the board is plugged in. Now, they have electrical >issues, and they've found, that the signals are interrupted or coming >back >when they knock on the boards. Someone is going to take a flight the >other >day to fix the problem. The electricians believe, stubborn as mules, >that >the only think needed, is to take out the boards and clean the edge >contact >fingers with a solvent and that will fix it. Myself, with quite many >year's >experience from connectors, I don't think that is the problem, because >when >such robust contact springs wipe along the contact fingers, they slide >pretty deep into the gold and makes good connection. Each spring has >double >contact ridges, so the risk that some dirt should cause interrupts is >minimal. There is more that talks against their theory, namely, that the >problem is still there after plugging, deplugging more than once. I'm >sure >there is a solder joint issue, or maybe a bond wire problem in the >packages. >Logically, this later is more likely because you have thousands of >solder/bond joints vs, just some one hundred edge connector ditto. A >ratio >like 10,000/100 per board. Without knowing all details, what is your >general >experience between the index finger and the big toe? > >/Inge > >--------------------------------------------------- >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 -----------------------------------------------------