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 | Thu Mar 29 10:28:40 EDT 2012 | thanh
Your QA don't know nothing about QFN. look at Bill Axler post, he was 100% corrected.
Electronics Forum | Fri Apr 06 11:01:34 EDT 2012 | umairzameer
Agree with Reese with my experience with QFN parts it is the reflow.
Electronics Forum | Thu Mar 29 02:46:25 EDT 2012 | johndoe0222
My company is doing a project with a lot of QFN. The question that we are not sure is how to properly solder a QFN on a PCB. QA says The alignment tab on the side of the QFN should have a physical solder from the board, like a leaded chip. After refl
Electronics Forum | Mon Nov 19 14:23:32 EST 2007 | realchunks
BINGO! Now that's engineering!
Electronics Forum | Thu Apr 05 08:21:52 EDT 2012 | rway
Yes, but no guarantee of solderability. This just puts more paste on the pads. From my experience, unsoldered QFN parts are not due to lack of solder, but reflow.
Electronics Forum | Mon Nov 12 09:13:50 EST 2007 | russ
Chunks is right, reduce center pad by 50% print the signal pads at 1:1. this will ensure you solder QFNs fine regardless of the actual part. If you are not printing then it is process capability issue and has nothing to do with QFN but rathjer small
Electronics Forum | Fri Nov 16 18:08:32 EST 2007 | mika
So you are saying that 0.13 mm stencil thichknes and 20% reduction of the middle cooling pad is working for you? Just as I said.. Best Regards, Mika Ps. Keep in mind that the QFN is designed to do some heavy work, while enough "heat transfer" occur.
Electronics Forum | Mon Jul 07 17:25:04 EDT 2008 | thughes
I'm curious to know what the pitch of the outer pads is/was on your device. Also, is this a general formula you use on all of your QFN devices or was this for one specific device?
