Electronics Forum | Fri Apr 29 14:16:16 EDT 2011 | ppcbs
Below is the long explanation. This defect is most commonly found with BGA components, but can arrise with all components. I see it happening more now with lead free boards that are being assembled with a no clean flux. Best short term remedy is t
Electronics Forum | Thu Nov 15 09:29:03 EST 2007 | jaimebc
Just to add to the subject, we experienced insufficient solder on our QFN's at our prototype level. To correct it, we went to a 5 mil stencil, 20% reduction on QFN pertures and used QFN's with solder bumps on the pads. We had great results using thi
Electronics Forum | Fri Nov 10 22:31:27 EST 2017 | myke03o
Hi, we are experiencing insufficient solder and bridging solder. Any recommendation on the inner pad (LGA) and stencil thickness. Any suggestion will be very helpful. link: http://www.latticesemi.com/~/media/LatticeSemi/Documents/ApplicationNotes/
Electronics Forum | Thu Oct 28 09:25:35 EDT 1999 | Dave F
Chris: Typical non-wetting causes are: * Poorly controlled soldering process * Incorrect material * Surface contamination * Insufficient preheat * Misapplied solder mask * Shadowing Without intending to insult you, all of the causes of non-w
Electronics Forum | Fri Jul 13 18:25:09 EDT 2007 | seankim10
It sounds like more has to do with plating. you may also check out the voiding issue especially if you have new FAB or the supplier. I had problems with a RF chip in QFN package due to insufficient grounding that voiding caused. This ground is often
Electronics Forum | Thu Jul 05 13:47:10 EDT 2007 | arun2382
QFN assembled on a PCB indicates paramteric fails when tested. When the QFN on PCB is reflowed a second time, it recovers and passes testing. Visual, X-ray inspection revealed no anomalies. Cross-section images of solder joint revealed no anomalies (
Electronics Forum | Wed Nov 15 12:52:21 EST 2017 | georgetruitt
IMO – Look into nano-coatings for your stencil and radius all square apertures This should help out with solder paste releasing from the stencil helping with insufficient solder QFN LGA aperture design, try a stencil cut with a few different apertur
Electronics Forum | Wed Jan 17 10:14:37 EST 2007 | slthomas
2-3mm would seem close enough to affect the air flow and I was thinking it could be displacing the qfn. However, if you ran a failed board back through reflow and it was functional after that, I'd put my money on insufficient reflow. I suppose it's
Electronics Forum | Tue May 31 09:40:23 EDT 2005 | mattkehoe
We have some boards that exhibit poor solder wetting when reflowed. Nothing fancy, smallest pitch size .050. See photo's at http://www.sipad.net/SnPbwetting.htm Is this ; Contamination on the HASL finish? Insufficient solder,not enough to cover pad
Electronics Forum | Mon Nov 25 09:34:52 EST 2002 | davef
You're correct excessive temperature can cause dewetting, but that usually means realeeee hot. Excessive time at above liquidous will cause dewetting also.
