Electronics Forum | Wed Aug 25 15:02:04 EDT 2010 | spitkis2
I am printing solder paste directly onto a QFN device. Any recommendations on the type of solder paste to use? Namely I am concerned about getting a good release from the stencil. Thanks
Electronics Forum | Mon Dec 04 15:23:31 EST 2017 | kojotssss
A new stencil has been purchased. to be continued.
Electronics Forum | Wed Aug 25 15:24:07 EDT 2010 | mikesewell
Whatever you would normally use to print that size part on the pcb should work. Same aspect ratio rules apply for release.
Electronics Forum | Tue Sep 14 13:43:25 EDT 2010 | rayguide
Use No-Clean fine-particle solder paste from Kester. http://www.suite101.com/content/solder-paste-and-its-application-in-smt-a249514
Electronics Forum | Sat Nov 11 11:11:28 EST 2017 | spoiltforchoice
One suggestion I have seen for packages like this is to have the device balled first.
Electronics Forum | Fri Dec 01 13:30:08 EST 2017 | kojotssss
Stencil thickness is 4 mil. Via's are plugging from bottom. Gas may be developed under the component? Take Reflow Ovens Thermal Profiling changes? In your opinion?
Electronics Forum | Fri Dec 01 14:11:24 EST 2017 | kojotssss
EMIL, The first stencil was with 4 squares. then there was a worse percentage. Changed to the circles. Is better, but still not perfect. Stencil thickness did not change. I added 2 types of stencil openings. Pictures of watch:
Electronics Forum | Fri Dec 01 14:50:30 EST 2017 | kojotssss
How about step down in the middle of thermo pad? I mean 0.075mm This can help?
Electronics Forum | Fri Dec 01 14:55:51 EST 2017 | kojotssss
Rework said that with hot air gun, heated the solder paste comes out of the middle part out to the side terminals and soldering extending beyond is perfect.
Electronics Forum | Fri Dec 01 15:22:46 EST 2017 | kojotssss
Recommended land and solder pattern says: VIA wall plating, via holes should be tented with solder mask on the backside and filled with solder. Solutions at this moment ? Thanks for all :)
