Electronics Forum | Tue Nov 05 12:34:54 EST 2013 | rgduval
3-6 months, say, depending on the environment), I might consider a ramp-soak-spike profile to allow sufficient time for the flux to clean any potential contaminants. Cheers, ..rob
Electronics Forum | Wed Nov 06 03:51:28 EST 2013 | cuperpeter
Hi rob, Thank you very much for your response. Profiling was made exactly on the pad, which showed dewetting, so the values are mentioned for this pad. PCB's is about a week old. It is possible that the surface of pads is already oxidized? I will t
Electronics Forum | Wed Nov 06 10:03:59 EST 2013 | rgduval
Hi, Peter, I'm not an authority on surface finish thickness, and it's effect on reflowing, so, I can't advise on that front. If the boards are a week old, and ENIG, I would not suspect surface contamination. It's always a consideration, of course,
Electronics Forum | Wed Jan 11 09:21:19 EST 2017 | rgduval
Do you have some pictures of the condition that you are facing? Your description of the issue sounds more like dewetting, rather than cold solder. A picture would help us better understand what you're facing. Cheers, ..rob
Electronics Forum | Thu May 20 07:52:36 EDT 2010 | rgduval
In general, cleaning with deionized water is acceptable for most component. Open switches and contacts, in general, do not get damaged in this process. A good drying is required, of course, after washing. However, you've described dewetting issues
Electronics Forum | Tue May 13 20:48:10 EDT 2008 | davef
Rob On your thermal recipe: Above liquidous for nearly 2 minutes seems to be a scoush long. Not sure you're doing anything positive with things like that. On the article: * SMT Magazine, October, 2002, p24 'Q & A: BGA Dewetting' * "Q: Our manufactu
Electronics Forum | Wed Jul 07 11:02:07 EDT 2010 | davef
Rob gave you very good analysis and suggestions for troubleshooting your non-wetting issue. We agree with his sequence of troubleshooting. The following comments are meant to be a line to supplement Rob's plan of attack. This adds to Rob's comment
Electronics Forum | Wed Jul 26 11:56:40 EDT 2017 | rgduval
Ah...the joys of subjective analysis! At a glance, these pictures look fine to me. Other than the IC's, which you've indicated were masked, and, maybe R12 in the last picture and CC1384 in the first image, coating looks uniform and well distributed
Electronics Forum | Wed May 14 12:42:16 EDT 2008 | rgduval
Dave, Realized I didn't respond to one of your questions. We pasted and reflowed one board, with no components. This board exhibited extreme dewetting on all pads. The board was LF-HASL, and the paste was Qualitek (which we've used for approximat
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