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 | Thu Jun 29 08:41:24 EDT 2006 | russ
I agree that a BGA may be the better/easier process overall, but it is not 3 dollars per assy better, I am in agreement that you should be able to handle QFPS just as well as a BGA. PBfree BGAs do not self align BTW, so one needs to keep that in mi
Electronics Forum | Wed Aug 22 10:57:59 EDT 2001 | wbu
Hi Steven, BGA�s are known for their ability to self align and from own experiance they do. There�s enough documentation on this one available (...don�t have the links present like Dave but I�m sure he will give you enough to spend some evenings rea
Electronics Forum | Thu Apr 04 05:33:19 EST 2002 | ianchan
Hi, hope this helps : 1) BCC (bump chip carrier) production for us, was with a 5mils Stencil. The outer perimeter smallish pads are not much of a problems. For the central large pad, we split the paste print (corresponds to the Stencil apperture op
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 | Mon Sep 24 17:38:18 EDT 2001 | mparker
First question - do you have a rework station? If so, are you experiencing the same type of failures there? I have successfully used no-clean on uBGA's in the past. 6 mil solder bumps, 10 mil spacing. 88 sites. Are you reusing previously soldered uB
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 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 | Tue May 22 17:21:43 EDT 2001 | davef
BGA require placement accuracy of only 0.3mm (�12 thou), compared with a required placement accuracy of 0.08mm (�3 thou) for fine pitch devices. Even with this level of misalignment, plastic BGA self-center / self-correct during reflow due to symmetr
