Does flux expire ?? Flux discussion.

[Dannyx]

Good day folks. Today I managed yet again to fail to fix a laptop board, which is actually beyond the point of this discussion, but it got me thinking about the flux I tried using: does flux expire or go bad in any way over time ? Stupid question, I know...

I've never been happy with any of the flux(es ?) I've used so far: whether at home or at my former shop, they all "vanish" pretty quickly once I start heating the part, leaving the area "dry", with nothing for the part to float in...this makes aligning QFNs an absolute misery and I hate it ! It seems to happen more with hot air rather than the iron...

I worked on this particular board at home, where I had a syringe of Amtech RMA-223-UV flux that's easily 10 years old, so I decided to use that because I had nothing better on hand. I think I bought it when I was in friggin' highschool It had turned a dark-brown color over the years from the original yellow of most fluxes, but I tried it anyway. It came out of the syringe alright and even seemed to flow nicely, but suffered from the same issue: as soon as I used my hot air nozzle, instead of the part flowing in place, the flux vanished but the chip just stood there....like a big middle finger >_>

Ironically, the flux Louis Rossmann uses is also Amtech, though a different kind, and his seems to stay liquid no matter how much he heats it up, which makes me think mine is either not the right kind or it's gone bad...

Then there's Kingbo...the guy at work who does reballings uses this stuff...don't know how good it would be for "manual" soldering...

I'm a noob at micro-soldering but I have to get my feet wet somehow, so I practice with what I have. Not spending 13 dollars on the same flux as Louis because it wouldn't see enough use to make it worth it - it may not sound like a huge amount, but it's a pretty penny to me. Cheers guys.

[stj]

Re: Does flux expire ?? Flux discussion.

flux absorbs moisture, so lifespan depends on how you store it.

btw, i like this - try it.
https://www.aliexpress.com/item/UANM...864986454.html

[Dannyx]

Re: Does flux expire ?? Flux discussion.

flux absorbs moisture, so lifespan depends on how you store it.

Although it was in the original syringe with the cap still over the end, so theoretically pretty air-tight, it WAS out in a balcony all these years which tends to get pretty damp in the winters, so yeah...

btw, i like this - try it.
https://www.aliexpress.com/item/UANM...864986454.html

Hmmm, I think I actually have that at work Never even opened it once. I have something similar at home left over from my grandpa who was a tech-whiz himself. As a kid, I used that extensively to tin stuff with: I'd dip the end of the wire into it and solder would stick beautifully to it, making soldering a joy. With the board now dead, I'll have something to try all these things on, starting with this ancient 30 year-old solder paste which I remember leaving a greasy, oily residue even when heated at full blast with my soldering GUN, so it might actually stay liquid under hot air and not evaporate

[stj]

Re: Does flux expire ?? Flux discussion.

it's not a liquid, it's a gell/cream.
and yes, it melts like a thick grease and does not evaporate.

[Dannyx]

Re: Does flux expire ?? Flux discussion.

it's not a liquid, it's a gell/cream.
and yes, it melts like a thick grease and does not evaporate.

No arguing with that When you heat it up it become more fluid. It's best when it actually stays runny like that instead of burning and disappearing.

[stj]

Re: Does flux expire ?? Flux discussion.

i use it for tinning tracks and desoldering corroded chips - it stays until you clean it off.

[llonen]

Re: Does flux expire ?? Flux discussion.

I use what I believe to be Amtech RMA-223 or at least that is what it said on the order I find it stays around for quite some time during heat application and it finds use for all my smd rework. I order a bulk amount at a time and store the unopened in a fridge, I do have a 5 litre container of liquid flux that I rescued from an old electronics factory i used to work at now that has to be at least 20 years old and was made by frys metals (Uk manufacturer).

It seems good for work other than SMD or at least anything that does not require it to stay around too long as it soon evaporates and and the carrier solvent is nasty to work with if you don't have fume extraction. I must admit to mostly going over to gel / cream flux's now even for stuff that really does not require this.

[stj]

Re: Does flux expire ?? Flux discussion.

there are 2 amtech 223's with different letters on the end.

[Dannyx]

Re: Does flux expire ?? Flux discussion.

there are 2 amtech 223's with different letters on the end.

Mine says UV.

[Agent24]

Re: Does flux expire ?? Flux discussion.

flux absorbs moisture, so lifespan depends on how you store it.

btw, i like this - try it.
https://www.aliexpress.com/item/UANM...864986454.html

I also have some of that cheap eBay paste flux, and it is indeed quite good.
Mine came in a plastic tub. I've had it for years, it doesn't seem to have gone off yet.

[stj]

Re: Does flux expire ?? Flux discussion.

yours may be different, i tried lots.
that one in the tin is water-clear and amber coloured.
the more common ones look like yellow tinted animal fat!!! (and probably are - or based on something similar)

[TacoLoco]

Re: Does flux expire ?? Flux discussion.

Ironically, the flux Louis Rossmann uses is also Amtech, though a different kind, and his seems to stay liquid no matter how much he heats it up, which makes me think mine is either not the right kind or it's gone bad...

yeah, roosmann flux always stays there no matter what and sometimes he even puts more flux and you can see the circuits and stuff drowning in flux that behaves like gel, water or something.

I can't get amtech flux at decent price in my country and the cheap ones dry out soon as you put the iron in the pad, almost immediately, leaving sticky residue, i wish i could get my hands in some of that nice stuff that louis has.

[Dannyx]

Re: Does flux expire ?? Flux discussion.

I DID find it locally, or at least on a website which ships to our country at a decent price, but it's still too expensive to be worth buying only for occasional use. A repair center could definitely afford it though, so I'll try convincing my boss to get me a syringe of that stuff just to see how well it behaves, so fingers crossed

[diif]

Re: Does flux expire ?? Flux discussion.

Rossmann uses 599. It awesome stuff. Not the cheapest but then a 30cc tube will long time. Unless you're Rossmann that is. There's loads of fakes about. The genuine stuff smells sweet and nice not that it should be smelled.

[stj]

Re: Does flux expire ?? Flux discussion.

he has sacks of it!!
https://www.youtube.com/watch?v=MpPvy4qyHg4

[Agent24]

Re: Does flux expire ?? Flux discussion.

yours may be different, i tried lots.
that one in the tin is water-clear and amber coloured.
the more common ones look like yellow tinted animal fat!!! (and probably are - or based on something similar)

Not sure what you mean by "water-clear and amber coloured"? It's either one or the other, surely?

Mine smells like flux and acts like it, and works pretty well.

[stj]

Re: Does flux expire ?? Flux discussion.

water-clear as opposed to being "foggy" like yours

[Agent24]

Re: Does flux expire ?? Flux discussion.

water-clear as opposed to being "foggy" like yours

Ah right. So mine's the pork lard then?

[stj]

Re: Does flux expire ?? Flux discussion.

yes, and mine is like beer jello

[llonen]

Re: Does flux expire ?? Flux discussion.

Pork lard, lmfao you know I cant un-see that now. I might try the refined 559 pork lard lard but the regular 'animal fat' 223 works exceptionally well for me even if it is a knock off 'cow fat' which it probably is. By the way are there any vegetarian options, and please remember not to lick the fat off your pcbs even if it tastes nice. Oh I looked at the Fry's metals flux its an R8 flux the date code for which well most of the label has long disintegrated and that looks like what I imagine industrial vinegar might look like. It is no longer made, well in that formulation and has to be be in excess of 30 years old, I would not classify that as no clean it definitely needs cleaning.