not a qualified expert in the field but first principals tell me you may have a combination of problems.
When the solder process is correctly managed solder will form joints that have extremely good electro mechanical integrity but which are vulnerable to thermal stresses: repeated expansion and contraction caused by thermal cycles. Even a good joint eventually may fail in this way. A cause of 'dry' joints is relative motion between the wire and the pad during the transition from molten to solid solder. The essentials for a good solder joint are: cleanliness heat time In your situation I would look for two specific things: what is stopping the joint from being good in the first place? solder contamination? failure of wetting on one or other surface? failure to bring the surfaces up to temperature (especially if one the surfaces have big differences in thermal mass) vibration of the parts during solidification? what is causing the joints to fail after soldering? direct mechanical stress from thermal expansion or misalignment between parts; is the test fixture causing a stress? can the fault be induced by thermal cycling alone? does it make any difference if the power is on or off? Is some one or something interfering with the process (go and watch)? Maybe you knew all this already? Good Luck Best Regards Ted Rook, Console Engineering, ext 4659 Please note our new location and phone numbers: Crest Audio Inc, 16-00 Pollitt Drive Fair Lawn, NJ 07410 USA 201 475 4600 telephone receptionist, 8.30 - 5 pm EST. 201 475 4659 direct line w/voice mail, 24 hrs. 201 475 4677 fax, 24 hrs. ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
