Electronics Forum: thermal pad (Page 1 of 49)

QFN Thermal pad voiding

Electronics Forum | Fri May 15 10:04:59 EDT 2009 | aj

Hi all, Is there any standard for percentage voiding on the center thermal pad on a QFN? We use the dot matrix array for paste to allow for outgassing etc, but we have had a couple of xray inspection "fails" for voiding on this pad , in or around 3

QFN Thermal pad voiding

Electronics Forum | Mon Jun 01 16:48:16 EDT 2009 | stevezeva

Mika, Have you ever worked with a 3-row I/O QFN? QFN180 to be exact? Steve

QFN Thermal pad voiding

Electronics Forum | Tue May 19 15:06:36 EDT 2009 | c111

we had many problems with this. there is no standard that I could ever find. we came up with our own after weeks of headaches. we use 25% as our guide line we use window pain only for the center paid to allow for out gassing and reduce 15-20% globaly

QFN Thermal pad voiding

Electronics Forum | Sat May 30 01:31:49 EDT 2009 | mika

make 4 square rounded corner apertures on the ground pad and the total reduction of 20 % (80 % solder paste). Then you still be able to solder the terminals around. Don't worry to much of the void's. Just following my tips and you will be fine. The

QFN Thermal pad voiding

Electronics Forum | Wed Jun 03 13:56:09 EDT 2009 | mika

less total area of voids, which mean a much more strength in the joint and much easier to solder such a cooling pad grounded via vias, with this approach! The same goes for big cooling pads of let say Power transistors without any via etc. Always re

Solder short-BGA with thermal pad

Electronics Forum | Fri Dec 27 09:45:04 EST 2002 | emeto

what exactly do you mean by big thermal pad?

Solder short-BGA with thermal pad

Electronics Forum | Tue Feb 18 19:07:21 EST 2003 | arturoflores

Our case is not due to thermal pad print squeezing because our shorts are mostly in the outer rows of the BGA so they cannot be caused by central pad printing. We still stick to the BGA thermal pad coplanarity/height hypothesis but have not yet prove

Solder short-BGA with thermal pad

Electronics Forum | Tue Feb 18 22:15:04 EST 2003 | davef

Arturo, So, you're not shorting to a thermal pad. Given that you're shorting to outer balls, tell us about: * Location of the shorting among the outer balls. * Board construction. * BGA constuction. * Paste deposition. * Temperature measurements ta

Solder short-BGA with thermal pad

Electronics Forum | Fri Dec 27 10:04:56 EST 2002 | haran

Big pad located at the middle of the package. On the PCB,we need to have solder paste printed on the thermal pad which is at the middle and the other pads of the perimeter BGA.

Re-soldering QFP with thermal pads

Electronics Forum | Thu Oct 31 01:52:17 EST 2002 | jason

Anybody with experience on such a rework ?? The QFP has thermal pads underneath the body and needs to be re-connected when subjected for rework... Any ideas ???

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