Electronics Forum | Thu Jan 02 07:04:57 EST 2020 | dontfeedphils
Pretty large solder-ball. Looks like it may have come from the ground pad since it's so large, in which case I would reduce the print coverage on the middle/ground pad and see how it works for you. You verified that these parts have the groundpad a
Electronics Forum | Thu Apr 01 13:16:56 EST 2004 | Jimmy
>When these boards are built new do we not have solder >>paste on the ground pad and then reflow? Has this caused >>any misregistration for you? We didnt assemble these boards so I have no knowledge of the manufacturing process that was implemented h
Electronics Forum | Fri Oct 30 08:24:12 EDT 2009 | rajeshwara
thnx davef & all With the help of all at last i solved the problem , The vias are not caped from bottom , so solder paste draining through the via to the floor which creates voids between IC ground pad and e-pad. Tnhx all again
Electronics Forum | Fri Sep 09 05:32:11 EDT 2016 | jasltd
Are your solder relief pads connected to anything in terms of ground planes that would increase the thermal load or are they floating copper? I take it your talking about wave solder relief pads?
Electronics Forum | Fri Jul 20 13:50:22 EDT 2018 | vchauhan
This question is regarding stencil design: I am having voids under QFN TI P/N LMZ20502SILT. I have attached component pic. Signal pin is 18X16 mils. Center pads are 31 mil sq. Initially I had stencil done with one mil per side reduction on signal pad
Electronics Forum | Thu Oct 26 10:29:03 EDT 2006 | Mike
First, Voiding under thermal pad is unavoidable(pardon the pun), unless you can find a way to add sufficient amount of solder paste to cover the area, and match that solder volume on your terminal leads. I build HVM qty's of "QFN" components w/ therm
Electronics Forum | Tue Sep 22 08:35:47 EDT 2009 | cman
Did you try pre-tinning your board on this suspect pad/s to see if it improved wetting/solderability prior to printing/SMT placement and reflow? Does the pad/s not soldering tie to a ground layer? I would connect a T/C to each pad of the same part an
Electronics Forum | Thu Feb 06 09:53:38 EST 2003 | genny
Actually, the most common reason I have seen vias in pads is for grounds in RF applications where the frequencies are high enough that you need a ground RIGHT THERE!... not .1" away. Vias and traces have RF properties of capacitance and inductance,
Electronics Forum | Thu May 08 19:52:40 EDT 2014 | hegemon
There are many different style LGA packages, but don't sweat it. Stick with the manufacturers recommendations for PWB pad geometry for a start. Voiding can be reduced by careful profiling, and also by pre-tinning the devices. QFN style packages can b
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
