Electronics Forum | Thu Oct 15 11:04:28 EDT 2009 | spitkis2
Thanks Jim. Pressing the QFN into paste was what I thought of, just wasn't sure if it would cause solder paste to be pressed outside the pad area and possibly bridge with an adjacent pad. Do you recall the ratio of paste coverage to the pad area?
Electronics Forum | Wed Sep 30 13:10:49 EDT 2009 | spitkis2
Hi guys, Can someone please clarify whether adjustment of Z axis travel is a critical parameter during placement of QFN devices. If so, to within what tolerance? In other words, should a pick and place machine position a QFN down on the board so t
Electronics Forum | Fri Oct 16 14:45:58 EDT 2009 | cyber_wolf
Many pick and place platforms rely on nozzle spring pressure to determine how hard a part is getting pushed into the paste.
Electronics Forum | Thu May 06 19:21:24 EDT 2021 | markhoch
Verify your aperture reductions in the stencil. Are the solderballs always in the same location? Same size & shape? Is the solder leaching through plated thermal holes from the opposite side of the PCB? Are you using stencil apertures designed to min
Electronics Forum | Fri Feb 17 19:23:05 EST 2023 | SMTA-64387083
Read the articles everyone else recommend. I haven't read of them but I will say this. A Solder Mask Defined pad is a copper flood that has much more thermal mass than a Non-Solder Mask Defined pad so it will heat and cool at a slower rate. I suspect
Electronics Forum | Fri Jun 20 03:47:24 EDT 2008 | philip
Hi all, any good recommendation for PbF paste application to reduce voids underneath the QFN thermal pad (stencil thickenss? opening? via hole? reflow profile etc)? We have tried few stencil opening design but no significant improvement as seen. Ther
Electronics Forum | Fri May 09 09:31:04 EDT 2014 | jorge_quijano
we are placing small QFNs with no major issues, but this one may not seem like a QFN with thermal pad... I'm attaching a picture of the component.
Electronics Forum | Fri May 17 14:56:21 EDT 2013 | davef
There's not supposed to be any effin 'drain hole.' Where's you get that from? Read this: http://blogs.smtnet.com/smt/other/qfn-btc-design-guidelines-thermal-pads-etc/ BR davef
Electronics Forum | Fri Jul 15 13:58:32 EDT 2005 | seaK
Our production is putting QFN40 and QFN56 package on board. With 80% opening on terminal, 40% on thermal pad, we found QFN56 100% forming toe fillet, but it does not work out the same to QFN40. We suspect it's because of the weight of component.....
Electronics Forum | Fri Jan 18 14:39:07 EST 2013 | davef
Main issues with LGA voiding are: * Design * Material selection * Thermal recipe For design, loo here http://blogs.smtnet.com/smt/other/qfn-btc-design-guidelines-thermal-pads-etc/ BR, davef
