Electronics Forum | Wed Jul 17 12:07:48 EDT 2002 | dragonslayr
DaveF is correct in directing you to the archives. This problem type has been discussed many times, it is quite common. Questions to ask yourself and provide us with answers are: It always happens or random? All assemblies or just one? solder paste
Electronics Forum | Sat May 12 08:58:23 EDT 2012 | davef
On mixing paste: There could be a lot of hand wringing about the need to minimize solvent evaporation, flux separation, and chemical activity. [True alarmists will throw in oxidation of the alloy.] But I think the real concern is a change in viscosit
Electronics Forum | Mon Apr 01 17:20:45 EDT 2013 | davef
In thinking about troubleshooting tombstoning {TS} defects, seek balance: * Pads the same size * Same amount of paste on each pad * Component placed with the same amount of contact on each pad * Heating the same on each pad, no via connection to a gr
Electronics Forum | Tue Jan 23 22:21:15 EST 2001 | rpereira
We have evaluated 4 different AOI machines and the General Scanning 8200 machine was the best. Great G R&R. As far as paste height goes, it is very paste dependant. I recently completed a DOE comparing laser stencils to EFab, varying 0.5 mm pitche
Electronics Forum | Thu Jul 19 22:52:43 EDT 2001 | davef
Most paste manufacturers talk about a 12 month shelf life for paste. They give the user half of that time. The remainder is used-up in processing and distribution. We'd give it a shot. You paste supplier should be able to give you a much clearer
Electronics Forum | Tue Sep 21 11:28:26 EDT 1999 | Dave F
| I've had some trouble pasting a test board for a MicroBGA trial. Most of the paste remains in the stencil apertures. | The stencil is 6 mil thick, laser cut and electo-polished. | The apertures are 12 mil in diameter with 20 mil pitch. | We are usi
Electronics Forum | Sat Aug 14 08:43:17 EDT 2004 | davef
Russ makes good points. Your printer supplier can give good advice on machine setup also. We know we're printing well when: * Paste at least as big in diameter as your thumb is rolling across the stencil * Paste is filling the apertures * Squeegee
Electronics Forum | Thu Mar 20 09:55:11 EDT 2008 | swag
We have a class 3 SMT build that requires the paste conforms to J-STD-005 RE LO. We have not used a low activity flux in the past and would prefer not to have to change our wash process or change to no-clean paste for these builds. I have researche
Electronics Forum | Fri Jun 27 13:02:28 EDT 2014 | spitkis2
Is this fluxed / solder paste or flux-less reflow process? Are you soldering in a nitrogen or vacuum oven? From my experience having gold-tin connections go through reflow a 2nd time does not yield defects or quality issues. However, I cannot comm
Electronics Forum | Thu Jun 19 10:36:54 EDT 2003 | Jacob
Hi all I am having a reflow problem. Recently we started using a through hole connector with solder flux bearing technology on a densly populated board. The connector reflows at the same time as the smt components through reflow. The problem I am ha
