Electronics Forum | Fri Jul 20 17:09:10 EDT 2001 | davef
Circuits Assembly magazine 09/99 "Defluxing with Ultrasonics" by Les Hymes. [There's more but I can't find it right now. I'll add to this as I find the junk, er very nice stuff.] J-STD-001C states that its OK to use ultrasonics for cleaning so lon
Electronics Forum | Thu Sep 12 10:45:29 EDT 2002 | pbarton
We have used a laser cut stencil 0.15mm (0.006") thick with 0.3mm (0.012") square apertures radiused in the corners 0.06mm (0.0025") to aid paste release. This approach with the (type 3) paste we use has proven successful on thousands of devices plac
Electronics Forum | Sat Sep 18 08:26:10 EDT 2004 | davef
Carol: If you would have problems both covering the via and keeping mask from the BGA pads, maybe you via are too close to the pads. Maybe some of the IPC pad design guidelines would help.
Electronics Forum | Tue Feb 29 21:53:46 EST 2000 | Kelvin Chow
Dear Robert, On PBGA assembly, BGA sphere shrinkage number depends to the following factors, a. BGA Sphere size (before reflow) b. Solder mask opening diameter As far as I know, no formular has been established yet. Most of my friends just collect
Electronics Forum | Tue Feb 29 21:53:46 EST 2000 | Kelvin Chow
Dear Robert, On PBGA assembly, BGA sphere shrinkage number depends to the following factors, a. BGA Sphere size (before reflow) b. Solder mask opening diameter As far as I know, no formular has been established yet. Most of my friends just collect
Electronics Forum | Tue Sep 14 14:52:22 EDT 2004 | Carol
During processing, the solder in the vias reflows and forms solder balls. PCBs have solder in random PBGA vias from the board manufacturer.The manufacturer says this is a result of the HASL process and is unavoidable. We use HASL finish, multilayer,
Electronics Forum | Tue Sep 14 19:47:16 EDT 2004 | davef
use something other than HASL. "The rest of the world seems to be processing with no problems..." [Hello!!! Earth to Carol. This is a test.] Things you are considering could be more trouble than they�re worth. "1) Reduce via hole size" [If you re
Electronics Forum | Thu Feb 11 14:36:42 EST 1999 | Evelyn York
Hey, has anybody experienced problems with solder balls falling off BGA's? I have not been able to identify a contaminant nor any physical problems that would cause this. On packages with 'good' adhesion I have not observed any intermetallic form
Electronics Forum | Tue Dec 12 17:54:04 EST 2000 | ralph
I've had this problem myself, though in using water soluables. But the process to eliminate it is still the same. There are three possible causes for this to occure. Too much humidity, to much solder, and too much heat. Are you leaving the paste
Electronics Forum | Thu Jul 17 04:42:47 EDT 2003 | sanjeevc
Hi! One technique: 1. Remove all balls 2.Make > a mask(stensil)for reballing.The holes of the > mask must be 0.8-0.9 the size of the pads. 3. > Reball chips 4. Reflow chips Good luck Hi Yes,we have done quite a bit of reballing of BGAs with
