Electronics Forum | Thu Apr 16 11:58:20 EDT 2009 | ccross
We have seen this exact same problem. Our vendor agreed it was their problem and also agreed it was a moisture issue within the PCB layers, not the solder mask. We have taken to baking our boards, especially when they are manufactured during the late
Electronics Forum | Fri Apr 17 10:21:20 EDT 2009 | padawanlinuxero
have you try to change the stencil apertures to another figure like the one that look like a baseball home? I was having that problem and some solder beads and with that I was able to decrease the tombstones
Electronics Forum | Sat Apr 18 17:42:07 EDT 2009 | billwestiet
I like this suggestion the best as a "band aid", check out some of the low tombstoning solder pastes. I've seen these work.
Electronics Forum | Thu Apr 30 13:09:53 EDT 2009 | scottp
One factor I see missing is separation speed (or snap off speed). I've run experiments with different pastes where it was the biggest factor in standard deviation of print volume for small apertures.
Electronics Forum | Mon Apr 27 02:44:07 EDT 2009 | michafogel
Can someone point me to a standard, if there is any, or design rule regards with preffared spacing between PTH and SMT pads for LF wave soldering process (SAC alloy)
Electronics Forum | Tue Apr 28 04:07:56 EDT 2009 | davepick
There's a nice tool on this site - http://www.enhancetechnical.co.uk/ Click on Internet Tools and then the image - brings up a useful interactive tools which helps understand influences on wave solder bridges. Dave
Electronics Forum | Wed Apr 29 08:55:49 EDT 2009 | nibirta
was the first thing we did. No improvements. In the meanwhile we have change the lot of the components. and it seems that there is humidity absorbed by the components. we are cooking now the lot and waiting for improvemnets. thk u for the support
Electronics Forum | Tue May 05 11:08:43 EDT 2009 | timo
Check out the attached and compare your issue w/ the issue in the attached. If it's 'beading' versus 'balling' - check thru the punch list and if you've addressed all those potential causes - then it may be paste specific. The Sn/Ag alloy choice is
Electronics Forum | Sat May 02 23:31:06 EDT 2009 | kareal
Thanks davef. The defect always occurred during UHAST reliability, but not find in reflow. The key is that there is tin diffuse to copper trace under solder mask. is it a "normal" board defect and what is the potential risk for device? thanks!
Electronics Forum | Fri May 08 04:39:32 EDT 2009 | kareal
Hi Davef, I want to explain that the tin diffusion in my project is not on solder bump/Pad region. It is on copper trace between bumps. so it is very wondering for me.
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