Electronics Forum | Wed Dec 06 22:35:05 EST 2006 | davef
Questions are: * When you say, "corner of some board's BGA chips", is it on the top of the package or between the board and the bottom of the package? * If between the board and the bottom of the package, does it span the distance between the board a
Electronics Forum | Wed May 24 16:40:40 EDT 2006 | samir
Yikes! Sounds like a hairy situation there. I've successfully collapsed a Pb-Free BGA (using a Sn/Pb solder paste), with a peak temperature of 220 Deg. C and Time Above SAC's Eutetic point (217) of 17 seconds. Beware of overcooking your smaller ma
Electronics Forum | Fri Dec 09 07:10:36 EST 2005 | Mity-C
Good Morning, One problem of LF BGA's in a leaded process is the temps required to propperly collapse the BGA balls. If the BGA is LF, the alloy of the balls will not reflow until the temp reaches 217-245 C. SN 63/37 reflows at 183 C. If your profil
Electronics Forum | Mon Jan 13 21:52:16 EST 2003 | davef
Haaaaaa!!!! You contractors get all the fun don't ya??? Consider: * Replacing the balls on the corners of the devices with balls composed of a "hard solder", yano something like 90/10. * Shimming to prevent excessive collapse of a heavy BGA during
Electronics Forum | Thu May 01 10:31:26 EDT 2008 | cdsullivan
Good Morning, We are seeing an increased number of our customers that specify a Pb-Free BGA when the rest of the board assembly is SnPb. Of course when we reflow at the SnPb profiles, we don't always get a properly collapsed BGA. So we end up rewor
Electronics Forum | Wed Jun 08 10:57:20 EDT 2011 | pcbrookie
We recently got our last BGA X-Ray results back (no X-ray in house yet) and had more than one board/BGA look like the attached image. The balls on one corner are completely collapsed (so much so that bridges appear) and raised on the opposite corner
Electronics Forum | Thu Nov 19 07:53:08 EST 2009 | edmaya33
Check your profile, it might not have collapsed completely.
Electronics Forum | Thu May 08 09:36:23 EDT 2008 | ck_the_flip
CSullivan, On the great SMTNet archives, there was much discussion about how to run in this scenario. Here is one such thread: http://www.smtnet.com//forums/index.cfm?fuseaction=view_thread&CFApp=1&Thread_ID=10483&#Message42337 Also, I wouldn't "
Electronics Forum | Wed Jan 17 20:33:19 EST 2001 | davef
The corner balls are supposed to collapse, but at roughly the same time as the other balls collapse. Also, those balls are located in the place that isthe easiest to get hot. Think about cranking-up the bottom heat, waiting, and slowing down the pr
Electronics Forum | Thu Jan 05 15:42:26 EST 2006 | samir
Grant, The strength of the joint in a CCGA is the column for one...it's more ductile, made out of 90% Pb, and it's meant to compensate for the massive CTE mismatches between the ceramic and the board (ie the columns flex to relieve stress from the e
