Solvent for soldering paste ?

Thread Starter

Externet

Joined Nov 29, 2005
1,816
Hi.
My jar with soldering paste (not soldering flux) is getting drier and drier to the point of not being a paste. :( What solvent can bring its consistence back to more fluid ?
It is the microspheres type same as used/applied with stencils to PCBs
 

Yaakov

Joined Jan 27, 2019
5,476
This will depend on the flux used in the paste. Is is specified? If it is mildly activated rosin flux, which is a good possibility, I would take a small sample and test compatibility with ethanol (denatured alcohol). IPA might work but it's less likely to give good results.

If the ethanol is effective, use the minimal amount that gets a workable consistency.

If for some reason your paste uses water based flux, well then... water, deionized (distilled) of course. If you use tap water the mineral deposits will make a mess of your PCBs.
 

dl324

Joined Mar 30, 2015
14,303
I use liquid rosin flux to rejuvenate my Kester R560. I tried isopropyl alcohol first and it made the paste splatter.
 

MisterBill2

Joined Jan 23, 2018
11,556
Hi.
My jar with soldering paste (not soldering flux) is getting drier and drier to the point of not being a paste. :( What solvent can bring its consistence back to more fluid ?
It is the microspheres type same as used/applied with stencils to PCBs
If a flux is listed as "Clean up with water" then use water. Otherwise alcohol or "solder flux remover" which was used at one place where I worked. I never read the fine print on the label to see what was in it.
Probably somebody reading has some and can read the ingredients. There are a lot of readers.
 

MisterBill2

Joined Jan 23, 2018
11,556
And some that don't. This isn't about removal but is about rejuvenation of solder paste that has dried out.
I suggested checking what works for cleanup as a source of what kind of solvent will work to thin it. I thought that was rather obvious, but I guess that I was not clear enough.
The concept being that a solvent suitable for cleanup would also work for thinning the mix. Like thinning water base paint with water and oil based paint with linseed oil. Like usually dissolves like.

Quite enough throwing stones, really.
 

dl324

Joined Mar 30, 2015
14,303
The technical data sheet for Kester R560 mentioned that it was "an organic acid, water soluble solder paste formula" that was "an extremely stable water soluble formula". The safety data sheet indicated that the flux was rosin. Even if it wasn't, I would have used rosin flux because that's what I use for everything else.

I found it odd that adding isopropyl alcohol to the solder caused it to splatter, but adding liquid rosin flux that I thin with isopropyl alcohol doesn't.
 
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