Electronics Forum | Thu Apr 03 22:56:48 EDT 2008 | davef
Potential impacts of using expired solder paste are [University of Bolton]: * Changed paste rheology. Result: poor print quality * Loss of solvents. Result: reduced flux activity * Changed flux formulation. Result: More difficult to clean flux residu
Electronics Forum | Mon Apr 07 19:12:13 EDT 2008 | kircchoffs
can we use the expired solder paste and put in a solder pot of wave machine?
Electronics Forum | Thu Apr 03 17:25:49 EDT 2008 | alexs
Hi All, I have some question about expired solder paste. What would be some of the effects regarding assembly quality. Is there any changes in flux composition toward the end of shelf life? Thanks in advance for any replies.
Electronics Forum | Fri Apr 04 14:49:51 EDT 2008 | tombstone
Flux seperation is a common problem observed due to expiration of paste. The symptom is a yellow layer of flux when you open the jar. Excess flux separation will cause priting problems such as smearing and slumping.
Electronics Forum | Fri Apr 04 08:49:45 EDT 2008 | ck_the_flip
Define "expired" though... 1 week? 6 weeks? 1 month? 6 months? Unrefrigerated life is generally 30 days. If paste has been stored refrigerated at manufacturer recommended temperatures, what would you guys do, like say, if you owned your own shop
Electronics Forum | Fri Apr 04 01:39:21 EDT 2008 | slthomas
All of what Dave says is spot on. I suspect that the most likely corresponding defects on your assemblies would be poor wetting and insufficient solder.
Electronics Forum | Fri Apr 04 14:54:19 EDT 2008 | alexs
Thanks for the reply. Just one more question. If there is less solvent but the residues are harder to clean. would there be more contaminant left on the boards? Has anyone did a cleanliness test?
Electronics Forum | Mon Apr 07 22:20:31 EDT 2008 | davef
Yes you can, although we don't think it's a good idea. Look here: http://www.smtnet.com/forums/Index.cfm?CFApp=1&Message_ID=48159
Electronics Forum | Thu Jun 24 02:31:24 EDT 2004 | yukim
Currently we are having a lot of solder balls, after a few hours of continous production. This is how we work: load new solder paste at the beginning of the shift, less than 500grms. Then, the operator loads new solder paste periodically, every 3 to
Electronics Forum | Fri Jul 06 18:17:34 EDT 2001 | davef
We find no solder balls after washing our boards. It works GREAT!!! ;-) Probably more to the point, look at "Circuits Assembly" 7/01, p 40, "Eliminating Solder Beads In No-Clean PCBs". "Solder mask type & composition are the greatest contributor t
