Electronics Forum | Wed May 02 09:28:20 EDT 2012 | almoore
The surface tension of lead free solder alloys doesn't self align as well as it does with leaded alloys. Taking the guesswork out of alignment would negate the need for expensive split vision systems and make the parts hand reworkable.
Electronics Forum | Tue May 01 20:39:41 EDT 2012 | davef
Good luck with that. A couple of things to think about ... * BGA self-align during reflow, just get 'em on the pads * Add a box [or four corner] legend on the bare board to help you position BGA
Electronics Forum | Fri May 29 20:15:15 EDT 1998 | Steve Gregory
Whoo-doggies Jason, you said a mouthfull!! (GRIN) Anyways, 'member what I said about me being a pack-rat? Guess what? I found some documentation that I've had for a while that does document the self-alignment forces that goes on when reflowing. I ha
Electronics Forum | Wed Aug 22 09:17:15 EDT 2001 | steven
if do not have x-ray inspection machine, how to verify the 1st board out from the smt placer that the BGA is placed accurately onto the solder pads. the diameter of the solder ball is 1mm. could it self align during reflow?
Electronics Forum | Fri Nov 07 11:32:36 EST 2003 | Gabriele
we experimented round pad for 0402, it improves chip self alignment and reduce tomb stone effects. On 0603, half round shape also gave guud results. G
Electronics Forum | Thu May 14 16:09:49 EDT 2015 | hottchkisu
Hi All, > > On occasion we see components that > have gone through pick and place and are slightly > misaligned. Currently, operators manually adjust > these misaligned components to prevent reflow > failures. However, I am wondering if this >
Electronics Forum | Mon Jan 14 22:52:48 EST 2008 | davef
Using larger pads on the corners is fairly common to improve self-alignment of BGA and CSP. For example, "9.3.2.8 Large corner pads and overprint The self-alignment of BGA or CSP can be improved through a design change. By utilizing a large board pad
Electronics Forum | Wed May 09 13:19:53 EDT 2012 | markhoch
I'm with Dave on this one. In my opinion, it'd be much more cost effective to add an alignment legend. Speaking from experience, as I've hand placed many BGA's, all you really need to do is hit the pads. Even with Pb Free Chemistries, the part should
Electronics Forum | Wed Jun 28 21:50:18 EDT 2006 | adihsr
BGA is better- in terms of 1.0 no bent leads or coplanarity problems 2.0 self align on solder pads 3. easy solder printing 4. large pitch ...I think those who goes for QFP have not had a strong SMT experience. Do not be hurt byt this is a basic SMT D
Electronics Forum | Fri Sep 16 14:51:06 EDT 2011 | isd_jwendell
I recently did a layout for a Freescale accelerometer and the mfg recommended pad layout did something similar. They where very specific in the pad layout dimensions. They stated the reason was "With the correct footprint, the packages will self-alig
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