Electronics Forum | Fri Jun 20 03:47:24 EDT 2008 | philip
Hi all, any good recommendation for PbF paste application to reduce voids underneath the QFN thermal pad (stencil thickenss? opening? via hole? reflow profile etc)? We have tried few stencil opening design but no significant improvement as seen. Ther
Electronics Forum | Fri Jun 20 18:32:55 EDT 2008 | hegemon
Back when I used to do a lot of these style devices we ran into the same problem you are describing. Use a pattern for the center pad area and keep the total coverage to about 68% of the pad area. Diagonal Stripes, tic tac toe, cloverleaf, dot array
Electronics Forum | Thu Aug 15 15:58:12 EDT 2002 | robertnguyen
To whom this may concern, I recently ran into the problem with vias on pads of BGA when place BGA and reflow gas trap on vias escape and result in ball having void greater than 50% of BGA diameter. The BGA pad is measured at 20 mils and the vias mea
Electronics Forum | Fri Aug 16 09:59:49 EDT 2002 | dason_c
We baked the board first and print 2 mil water soluble paste at the BGA location and reflow. Wash and baked before the production run.
Electronics Forum | Fri Aug 16 10:00:03 EDT 2002 | davef
You have a very bad situation. It�s tough for the gas, flux material, er whatever to escape when the BGA is sitting on top of it and the blind via is blocking it from the other side. Obviously the vias should have been: * Placed on the edge of the
Electronics Forum | Mon Sep 19 07:56:19 EDT 2005 | Pop
How we can improved the Solder voids on QFN Packaging. Actually we adjust the time for solking to long . But is not affected. Pls advise. ThANK YOU
Electronics Forum | Tue Jan 12 15:29:40 EST 2010 | davef
What is your concern regarding voiding in QFN solder connections?
Electronics Forum | Mon Jan 11 13:31:54 EST 2010 | cbart
I know IPC is working on a spec for voiding for QFN'S. However since its not released I'm curious what others have defined as the max allowable % voiding on the leads (not center ground).
Electronics Forum | Sat Apr 15 14:28:26 EDT 2006 | Dan Mendoza
This may sound like advertasing, but I ran a DOE with five solder paste/flux manufacturers and somehow, the voids went away with the AIM solder.
Electronics Forum | Mon Sep 19 09:08:25 EDT 2005 | siverts
Search the SMTnet archives first. Ex. http://www.smtnet.com/Forums/index.cfm?fuseaction=view_thread&CFApp=1&Thread_ID=8877&#Message35126
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