Electronics Forum | Wed Sep 26 12:16:44 EDT 2012 | bwjm
Hi Guys,recently i am facing an issue. Refer to the attached photo. This PCB is high RF speed, gold immersion single layer. After reflow, my solder seems to have black stains on it. I tried with SAC305 paste water soluble and no-clean, both results a
Electronics Forum | Thu Oct 20 05:56:56 EDT 2016 | fadzril
Basically, what is the main issue which requires you to use black fiducials? Stencil mark recognition issues? Solder printer machines have ability to adjust the brightness or contrast.
Electronics Forum | Sat Oct 06 05:33:47 EDT 2001 | spchua
I had recently encounter the "black and grey" pads problems for the BGA pad after the convection re-flow. The pads shows in in "black and grey" color and a litter solder in it, and it happen in ramdom, when applied heat and solder on the "black and g
Electronics Forum | Sat Oct 06 08:42:21 EDT 2001 | davef
Please give us additional background on your board, solder, process, etc. If you are talking about black pad in ENIG solderability preservative, check the fine SMTnet archives to get started.
Electronics Forum | Mon Dec 30 12:36:20 EST 2019 | emeto
Thanks Rob, this is excelent
Electronics Forum | Tue Dec 31 02:10:54 EST 2019 | sssamw
The video showing wave contact is not consistent and not stable from width size, make it better.
Electronics Forum | Tue Dec 31 02:10:04 EST 2019 | sssamw
It looks like solder dross there or flux residue that not activated well. Your speed is 43cm/60s, wave width contact is 2cm, so dwell time is 2x43/60=1.43s, it's short also.
Electronics Forum | Sat Jan 18 12:44:35 EST 2020 | anteiv
We made much better contact of wave with board. There was not enough solder in bath. We increased it so wave height is higher with same pump power And now board is pushing dirty wave to the other side and board is much cleaner!
Electronics Forum | Fri Dec 27 12:12:29 EST 2019 | slthomas
As has already been mentioned, black residue is usually either from dross or just a dirty pot, pump, baffles, etc.. I also saw that maaaany years ago in a system that used a flawed oil intermix "feature" but hopefully those systems are long gone.
Electronics Forum | Fri Dec 27 11:42:18 EST 2019 | emeto
I could not see pictures of your board - please attach one or two. So to answer your questions: 1. wave should not overflow over your board - mostly we use pallets as carriers to protect the assembly. 2. Solder dross is caused because your wave is no
