Electronics Forum | Thu Sep 05 03:23:14 EDT 2002 | manic
Hi, I encountered a problem with pbga. One edge either warp downwards or upwards creating bridging or open. This pbga have fr4 at the bottom (compound molding at the top). The fr4 is bigger than the top compound by 3mm at each edge. Pls help. Than
Electronics Forum | Fri Mar 07 03:37:26 EST 2003 | emeto
Hi Ygwie, My experience shows there is not unique answer.Actually it depends on design,printing reflow or wave.It might be top side with lesser cmps.Top side might have fine pitch or BGA or CSP,LLGA ....,so you have better planarity when the PCB is b
Electronics Forum | Thu Oct 13 10:44:18 EDT 2011 | spitkis2
Have you considered adding adhesive / epoxy at the corners of the BGA to secure it in place?
Electronics Forum | Thu Oct 13 00:18:36 EDT 2011 | kemasta
Hi! We have many PCBA with double side BGA mounted, current practice is to put the board on reflow pallet (durastone 761) to cover BGA at bottom side so that the BGA won't lift after go through reflow oven, but this created 2 problems:- 1) We need t
Electronics Forum | Thu Oct 13 16:08:11 EDT 2011 | davef
BGA solder joint reliability is actually improved slightly from a double-sided reflow. [Jean-Paul Clech APEX 2003 Solder Joint Reliability of BGA Assemblies]
Electronics Forum | Thu Oct 13 14:24:10 EDT 2011 | dphilbrick
You can use a paste that flows at 2 different temps. (first side flows hotter than second side) Glue, as stated in other answer and capton tape covering the BGA will defect enough heat usually as well.
Electronics Forum | Thu Oct 13 23:50:50 EDT 2011 | kemasta
Hi Doug Nice idea (2 type paste), I will have a trial. We think of glue and tape too, but it involve cost, but we still keep as an option. thanks.
Electronics Forum | Thu Jan 20 20:22:16 EST 2000 | Sam Guilaume
We have run some experiments on double side BGA assembly. Our preliminary results show that complete overlap of top and bottom BGA's indicate fair results, even after reliabiltiy tests (vibrations, temperature cycles, HALT). I will be interested to h
Electronics Forum | Thu Jul 15 12:02:38 EDT 2004 | Yngwie
We have massive void problems on one of the BGA populated on the bottom side of the board. The board have 6 BGAs on the top and 1 on the bottom. No voids were observed during the first reflow (we reflowed bottom side first), but after the second refl
Electronics Forum | Fri Jul 16 03:35:34 EDT 2004 | Yngwie
We have massive void problems on one of the BGA populated on the bottom side of the board. The board have 6 BGAs on the top and 1 on the bottom. No voids were observed during the first reflow (we reflowed bottom side first), but after the second refl
