MG Chemicals Liquid Rosin Flux Question

I'm curious after seeing some no clean rosin flux from MGChemicals. It's
just a little bottle with liquid in it. When would i use something like
this as compared to using regular rosin flux. and how do you use this..
seems like you just dip the tip into the liquid.

 

I think you are supposed to paint the surfaces you will be
joining with solder, to improve how well the solder wets the
surfaces.

 

I think OP was using the flux to clean his iron tip.

I find that using the same liquid flux type as the solder I plan to use
gives the best results. To that end, I use a different sets of iron
tips for water soluble flux and rosin flux.

No clean flux is a bit of a misnomer. What they really mean is low
residue flux that in some cases you can get away with leaving on your
board. No clean and water based fluxes, unlike rosin fluxes, can become
conductive (and in some cases corrosive) in high humidity environments
so they are often cleaned off anyway. One trick in selecting a no clean
flux is to pick one that cleans off easily and completely.

HTH

 

Maybe I'm just an old fogy, but I would avoid "no-clean" flux like the
plague. It leaves crud on the board.

Good Luck!
Rich

 

No, no, (no!).

No-clean is no misnomer, that's the whole point of using it. It
doesn't mean low residue, that is dictated by the % of the flux. It
means the residue is less aesthetically unpleasing for the arbitrary
humans that would look at it, and that functionally there isn't
usually a need to remove it.

It does not become conductive, absorb water in general. While it is
possible you used some product years ago that was an exception, in
general we'd have to assume the typical modern formulas as what is
being referred to.

One trick is NOT picking one that cleans off easily, that is a silly
idea. The whole point of using one is if you don't want to clean it
off. I don't see how they can make it any easier to understand, when
they call it "no-clean", they really, really, really really (really)
mean it. It's not a trick.

If you have a bad solder or process and end up with stray solder
balls, maybe you would have to clean it off, not because of the flux
but because the balls exist at all.

If you don't want to leave the flux on, pick a different flux like RMA.

 

Yeah... all true. No clean is meant to be untouched. One should
make sure their PCB is very clean and well baked out to remove any
water the PCB has in it before a no clean soldering operation begins

The hygroscopy of the circuit board itself is higher than the flux
left behind. If anything, it encapsulates a solder joint in an oxygen
barrier that reduces oxidation/external attack.

I made HV supplies on unmasked FR4 medias for years, and we used
water soluble fluxes, and aqueous wash. The trick is that after the
aqueous wash, we baked our assemblies at 60C for an hour to completely
dry them out, and even vacuumed many at potting time. vacuum potting
a board that didn't get baked out, but merely air dried is a nightmare
as the water left in the FR4 boils out forever!

RMA flux and a nice, hot IPA wash works as well, though it should
still be baked out. Even "coffee breath" can cause a residue on a
multiplier section that is enough to cause a circuit failure in the HV
circuit realm.