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 | Wed Nov 02 11:01:56 EDT 2022 | tommy_magyar
Ellaborating on Evtimov's answer: - solder paste type, think about solder granulation and viscosity. Both of these will directly affect print quality if wrong print parameters used. You will normally find recommended print parameters on the solder pa
Electronics Forum | Wed Feb 25 21:37:12 EST 2015 | dinhhuunam
Hi Bartel , 1.1 Profile Solution to Cold Soldering Cause for Cold soldering The peak temp of reflow is too low. The preheating temp is too high and it takes too long Solution Lower the preheating temp and increase the peak temp in the reflow zone
Electronics Forum | Wed Mar 14 09:07:34 EST 2001 | blnorman
We just ran a study to try to determine this. We exposed the paste to 85% humidity to simulate worst case manufacturing. At various times we removed the paste from the chamber and tested it for tack, solder balling, wetting (copper coupon), and vis
Electronics Forum | Mon Oct 20 11:48:34 EDT 2003 | blnorman
Who said there was NO evaluation? The paste we chose was evaluated based on a 20 point test score as well as material compatibility. Once we introduced it to manufacturing each line had problems. For one manufacturing treated it as a drop in repla
Electronics Forum | Tue Feb 12 18:48:48 EST 2008 | larryd
Thanks for the spare change. Questions are good and I did miss one item. Process has 100% solder paste inspection with a 3D inspection machine that has very few false calls or accepts. Ramp to peak is less than 1.5C/sec. Profile looks good, solder
Electronics Forum | Sat Jan 24 00:13:57 EST 1998 | Scott
| What is the lifetime for a typical solder paste ? | How long can boards be stacked waiting before the paste goes off ? Lifetime and tack time depends on: - Manufacturer - Flux/mixture - Environmental conditions Typical lifetime is dependent on stor
Electronics Forum | Thu Jun 24 23:00:36 EDT 2004 | yukim
Tried with several lots of solder paste, manufactured in Feb and March this year. Work ambient: 25C, 60~70%. Is this humidity too much? I'll reduce the ramp in our profile. One change: We changed the conveyor motor in our reflow oven just before the
Electronics Forum | Tue Dec 23 17:34:07 EST 2008 | davef
We hear you talking two main issues: 1 Solder paste release 2 Thoughts on using two passes of solder paste on the stencil 1 Solder paste release * Check your aperture & aspect ratios [Search the fine SMTnet Archives for more] * Do a better job with
Electronics Forum | Fri Oct 05 15:35:19 EDT 2018 | davef
Paste sticking to squeegee: * Squeegee is heavily magnetized * Some pastes stick more than ... * Plastic squeegees stick more than metal * Old metal squeegees stick more than new * Paste needs to be worked * Paste needs to be at room temperatur
