Electronics Forum | Mon Mar 20 22:39:03 EST 2006 | davef
Pavel Point: You suspect that solder paste can easily get to solder mask causing beading, because the aperture is larger than the component pad. Comment: Probably, this is incorrect. We overprint on solder mask all day long when doing paste-in-hol
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 | Thu Jul 26 23:43:49 EDT 2007 | gioblast
check your stencil design on the ground pad. You might have a big aperture opening that pushing the component away from the paste. Look alos the way your pcb warp. Prioritize side that has component that need flat pcb as much as possible. hope this h
Electronics Forum | Fri Jul 27 08:49:35 EDT 2007 | cman
We are currently have failures on one of our QFN > components. We are running this product with > lead free paste, lead free boards and lead free > parts. They have done a pull test on this > component and it showed that the solder joint > mai
Electronics Forum | Tue Jul 24 07:15:16 EDT 2007 | james
We are currently have failures on one of our QFN components. We are running this product with lead free paste, lead free boards and lead free parts. They have done a pull test on this component and it showed that the solder joint mainly dissconnect
Electronics Forum | Wed Jan 30 08:30:33 EST 2002 | seto
Hello Dave, Mechanically the conection between the component pad and PCB pad is good (the solder joint is very strong). The problem is associated with poor contact after the use by the customer (vibration, temperature, etc). You can see the pictures
Electronics Forum | Fri Aug 25 09:15:43 EDT 2006 | russ
We use a single large pad on board and reduce stencil aperture 50%. If you mask/reduce the thermal pad the solder will not wet out to edges and you will still see the part standoff with the open joints. the purpose of reduction is to wet the paste
Electronics Forum | Thu Aug 24 03:20:36 EDT 2006 | aj
we had problems with fillets and shifting aswell,but the recommended print aperture is reduce thermal pad by 35% and offset the lead print by 3thou...i.e. 3thou over hang on outer edge of lead which also moves the paste 3thou in from the inner edge .
Electronics Forum | Tue Aug 22 21:00:39 EDT 2006 | davef
National says: [ http://www.national.com/packaging/llp/faq.html#faq_manu ] Manufacturing FAQ's Are there any precautions that need to be taken with the LLP package? It is critical to follow National�s guidelines for successful surface moun
Electronics Forum | Wed Jul 06 14:36:05 EDT 2005 | Bob R.
The only way we can consistently get a toe fillet is to use a paste with an extremely active flux. We allow that paste on certain products, but discourage it's use because it's on the hairy edge of not meeting our lower limit in surface insulation r
