Electronics Forum | Wed Aug 12 14:37:41 EDT 2009 | davef
Try this: http://www.pwbrc.org/members/pdf/works99/Hua.PDF
Electronics Forum | Thu Aug 20 13:01:40 EDT 2009 | bman
When I've seen white strands in the solder on SMT boards, it's been fibers from stencil wipes that stuck to the stencil, then transfered to the board when it was printed. I'm not sure why this would only happen with fine pitch components though.
Electronics Forum | Sun Aug 16 19:46:48 EDT 2009 | abeasia
Hi Dave F. Thanks for the suggestion, will give it a try. With Appreciation, ABE.Asia
Electronics Forum | Tue Aug 18 16:32:25 EDT 2009 | ldavis
Sergey, Try increasing the cool down time if that is a recipe option. We have witnessed the same effect on components that have rather slow cool down rates and were able to eliminate the problem by extending the cooling time.
Electronics Forum | Tue Aug 18 17:40:52 EDT 2009 | jlawson
Is the mechanics ok with the raising and lowering into the vapour ie no small movements that could be moving the part ? Most Vapour Machines have a lower and raise mechanisim so movemnt of parts can happen if not smooth, especially when coming out o
Electronics Forum | Thu Aug 20 19:07:29 EDT 2009 | smt_guy
reduce the stencil aperture to prevent tombstoning in vapor phase process. from my experience a 6 mil thick must be at least between 20 to 30 % aperture reduction for 0805's and below. cheers!
Electronics Forum | Mon Aug 24 19:08:28 EDT 2009 | rossi
Thank You for all your help. The PCBs are from the same vendor. You mention the tape test. How exactly do we perform this test? Eric
Electronics Forum | Thu Aug 27 16:03:20 EDT 2009 | jim_n_hky
We recently had a very similar issue with BGA breaking off at the pad. We sent samples to a lab for SEM / EDX and they found that there was no intermatalic with the nickel, or very little do to high phosphorus. I recommend you get a board to a lab AS
Electronics Forum | Fri Aug 21 14:16:22 EDT 2009 | dwelch123
Speedline technologies--- 1-800-737-8110. It's a product called "Kleenox". A one year supply is about $140 give or take.
Electronics Forum | Fri Aug 21 14:41:35 EDT 2009 | davef
While you're waiting for others to reply, search the fine SMTnet Archives to find threads like: http://www.smtnet.com/Forums/Index.cfm?CFApp=1&Message_ID=41020
