Electronics Forum | Thu Jun 02 08:42:06 EDT 2016 | emeto
Several important things to watch. 1. More paste can result in more voiding(I usually shoot for 50-65% coverage) 2. Make a different grid(windowpane) for you pad - try with more smaller windows 3. Try both ramp to spike or Soak profiles and see whic
Electronics Forum | Mon Sep 30 09:00:26 EDT 2002 | arcandspark
Russ, I have been reworking BGA's for over five years now and have never been able to remove voids in the solder balls without removing the BGA itself. Your thermal profile can also cause the voids along with a poor solder paste. I have experimented
Electronics Forum | Wed Oct 09 19:08:37 EDT 2002 | russ
AJ, I have bought and used 2 DRS24's in the past. It is a good machine. (I don't think that I will bring up the fact that a certain package that I had kept shorting so I sent them a couple to help with the profile and all of them came back shorted
Electronics Forum | Mon Oct 07 18:03:16 EDT 2002 | russ
David, Guess what, Today I happened to try my new sample of Kester HM531 and I also was blown away by the results! I could not find voids anywhere! (same profile etc...) One thing I noticed during my testing however was that it seemed like after I
Electronics Forum | Mon Sep 30 09:26:04 EDT 2002 | itempea
Russ, first step would be to get IPC-7095 on BGAs. A few notes: There can be voids in solder balls, or at the solder joints to the BGA, or at the solder joints to the PCB. Various sources or reasons can be responsible for these voids. Voids can be
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 | Mon Oct 07 13:15:41 EDT 2002 | razorsek
Russ, this post doesn't specificly address your original post but I thought it is relevant to your situation and future production. I have been having problems with voids using Kester's R596L paste. I contacted them for a solution to my problem. T
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 | Wed Oct 09 17:44:46 EDT 2002 | alj
I guess you don't use one. Call them and I'm sure they will solve your problems and teach you a little bit about BGA rework profiling... CHEERS!
Electronics Forum | Wed Oct 09 16:59:35 EDT 2002 | davef
Russ, as I told Eric the other day ... The steadfast rule of thumb is: In order to get reliable reflow, you need to be at or higher than [liquidus + 20�C] for about 5 to 10 seconds, rather than those old "60 seconds above 183�C" guideline. This prov
