Electronics Forum | Wed Nov 14 01:00:20 EST 2007 | reypal
recently, we also have problem with QFN around 3% defect related to soldering. from the cross section it turns out to be solder crack. it could be the paste volume on the center pad is too much causing QFN to float that eventually will cause crack on
Electronics Forum | Sun Dec 02 20:02:23 EST 2007 | chs
Hi, There are QFN 32,40,48 pins with middle pad. Body size are 7x7 and pitch 0.5mm. I means as compared to 2 sided package, QFN are easily damaged by external mechanical / thermal force. Phenomenon observed are mold cap open which further caused wire
Electronics Forum | Sun May 24 21:12:59 EDT 2009 | keith78
I have a problem recently to qualify QFN package on solder joint reliability. The pcb thickness stated in IPC-9701 is 2.35mm but from the in-house test, QFN surface mount on 2.35mm thickness PCB board have a short cycle to failure due to higher CTE m
Electronics Forum | Fri Oct 09 00:57:05 EDT 2009 | jjmag921612000
SteveO, I had personal experience with this using a Panasonic MPAV2B. It took a while, but I believe the end result was to have some additional "Z" travel to press the QFN into the paste. Also, the design of the paste on the ground was key to keep t
Electronics Forum | Wed Feb 24 15:00:41 EST 2010 | wrongway
We just stencil the part not the pads if you stencil both then you probaly have to much paste the QFN will lift becuse of the center pad. if the question is screen the part or the pad our boards have parts so close to the QFN that stenciling the pcb
Electronics Forum | Fri Dec 01 09:29:36 EST 2017 | kojotssss
Hello. We have a problem with QFN type. Component is elevated. Stencils are reduced. Vias is without holes. What are the solutions to fix the fault. Look at the photo. Attachment: https://drive.google.com/open?id=1OIgaXUz2yoKP3fWZg2rUsrmZMBWidk6_
Electronics Forum | Tue Feb 11 09:26:57 EST 2020 | astarotf
Hi everyone I have problems welding QFN components in a 10-zone reflux oven, we cannot make a welding fillet that covers the entire QFN pin. Currently we use paste T4 - 63Sn / 37Pb. I enclose the curve of the oven profile. Any help or support on this
Electronics Forum | Tue Feb 11 11:00:13 EST 2020 | astarotf
hello Evtimov Thanks for your answer. I will analyze the curve with our pasta supplier to reconfirm if it is adequate. It would also be helpful if you could share the tin lead curve profile to analyze. The location of the QFN is assembled by the top
.gif)
