Make your own flux?

[TechItApart]

Hey guys,

I've seen a few videos and articles (linked below) with people making their own liquid soldering flux at home, has anyone given it a try?

Looks like the ingredients are:

• Powdered pine resin
• Isopropyl alcohol
• Glycerin

Seems pretty simple right? Pine resin is easily available on eBay and I've got alcohol and glycerin already - should I have a go?

Cheers

http://www.instructables.com/id/Make-your-own-Eco-friendly-soldering-flux/

[thejoggingmat]

Hey guys,

I've seen a few videos and articles (linked below) with people making their own liquid soldering flux at home, has anyone given it a try?

Looks like the ingredients are:

• Powdered pine resin
• Isopropyl alcohol
• Glycerin

Seems pretty simple right? Pine resin is easily available on eBay and I've got alcohol and glycerin already - should I have a go?

Cheers

http://www.instructables.com/id/Make-your-own-Eco-friendly-soldering-flux/

As a lad with a chemical background, I will strongly not recommend it unless you can get minimum reagent-grade (ie >95% pure), or even better analytical grade (~>99.9% pure) composition of ingredients. Most of the stuff you can get on the tom/dick/harry street most certainly will contain impurities. There is absolutely no telling what the unknown impurities would do at elevated temperatures.

Solder flux is very inexpensive and a small quantity of it will last for years after years; might as well just use the store-bought flux.

[nanofrog]

I'd also recommend getting a bottle of commercially available flux suitable for electronic use. 

Now if you want to make of that commercial flux into a gel or paste, that's doable. 

BTW, the above flux recipe you found would make R, which has no activators (R = Rosin, RMA = Rosin Mildly Activated, or RA = Rosin Activated; from least to most active). R is good for fresh boards and parts, while most repairs have oxidized, and parts hobbyists have on hand tend to sit around a lot longer than in a production setting, so are more oxidized as well.

[pickle9000]

I've heard people dissolving musical instrument rosin into alcohol as cheap solder flux, but I've never tried this.

Violin rosin, from any music store. Crush it as best as you can, put in jar, just enough 99% iso to cover and leave for a couple days. If there are still lumps give it a shake and add a bit more iso.

Not as good as a commercial product but I used it as a kid and it works. For people that do not have good access to materials it will work. The thicker the better, if too thin leave the cover off the jar to evap and thicken.

When comes to the smoke / vapors, it's all harmful as far as I'm concerned, use a fan to keep the smoke away.

[ataradov]

I did it like 20 years ago, when liquid flux was not as readily available (especially in Russia). No Glycerin though, just rock pine rosin and alcohol.

Worked just fine, but with liquid stuff so readily  available, why bother?

[KL27x]

I've heard people dissolving musical instrument rosin into alcohol as cheap solder flux, but I've never tried this.

Well, it would take an interesting definition of cheap to make this true on most scales. Maybe if you just want to make a little and you already play the violin??

The cost of a liter of MG 835 is roughly comparable to the average price of a lb of solder wire.

A bar of rosin for a stringed instrument lasts a really, really long time, and price doesn't necessarily equate to the actual quantity. It can be a hella lot more expensive than flux. I think in some cases, the fancy box costs more than the rosin.

[Brumby]

I would think that this would be a good MacGyver exercise out of necessity - or just to know you can do it, but I wouldn't be looking at this as a serious long-term source, even if you could make it up for free.

Decent flux makes the job easier and has fewer surprises.

[pickle9000]

I did it like 20 years ago, when liquid flux was not as readily available (especially in Russia). No Glycerin though, just rock pine rosin and alcohol.

Worked just fine, but with liquid stuff so readily  available, why bother?

Same here, No Glycerin. Except more than 40 years ago, and not Russia.

[TechItApart]

I did it like 20 years ago, when liquid flux was not as readily available (especially in Russia). No Glycerin though, just rock pine rosin and alcohol.

Worked just fine, but with liquid stuff so readily  available, why bother?

Very true, I probably won't be trying it but it seemed like fun. Is the consensus that MG 835 is good stuff? I see some no-name liquid fluxes on eBay but I think they are mostly just alcohol.

[MrSlack]

Am I the only one on this forum who likes a bit of cheap ass Loctite 60/40 multicore solder and doesn't bother with the flux love? What am I missing?

[ion]

I've heard people dissolving musical instrument rosin into alcohol as cheap solder flux, but I've never tried this.

Violin rosin, from any music store. Crush it as best as you can, put in jar, just enough 99% iso to cover and leave for a couple days. If there are still lumps give it a shake and add a bit more iso.

Not as good as a commercial product but I used it as a kid and it works. For people that do not have good access to materials it will work. The thicker the better, if too thin leave the cover off the jar to evap and thicken.

When comes to the smoke / vapors, it's all harmful as far as I'm concerned, use a fan to keep the smoke away.

I've found the opposite - better to thin it out otherwise it leaves a mess after soldering that takes quite some effort to clean.

I've tried it with a drop of glycerine (since I had it anyway), and found it to be a decent flux.

[sleemanj]

See post i made a few weeks back...
https://www.eevblog.com/forum/repair/rossmann's-repair-videos-using-tons-of-liquid-flux-for-no-apparent-reason/msg819578/#msg819578

[ataradov]

What am I missing?

Reliable solder joints and no unwanted solder straps?

[MrSlack]

Never had a problem with them without it

[nanofrog]

Am I the only one on this forum who likes a bit of cheap ass Loctite 60/40 multicore solder and doesn't bother with the flux love? What am I missing?

Think drag soldering. Flux core solder just doesn't have enough for this application. Without it, you won't get it right (bridges). It's also an absolute necessity for BGA, though this isn't exactly a hobbyist friendly package.

FWIW, I can't recall needing additional flux for PTH, so this is definitely a much more recent requirement due to SMD IME.

[KL27x]

Am I the only one on this forum who likes a bit of cheap ass Loctite 60/40 multicore solder and doesn't bother with the flux love? What am I missing?

Well, look on the flip side. Are you also one of those guys that does primarily thru hole and/or has a helping hands octopus contraption on your bench?

The reason for using flux is not only for oxidized parts. It's also so you can hold down SMD parts with tweezers while you solder them, using only two hands.

You probably think applying solder to the joint is the "proper" way to solder. You notice how the solder flows better that way? If you apply solder to the tip of the iron and then bring it to the joint, it doesn't flow? That's because the flux you are using is in the solder and it burns off before it makes the joint. If you had flux on the joint, it would work the same as when you apply the fresh solder wire to the joint.

Do you know how to remove the impurities from lead? You melt it. All the dross separates to the top. When you melt solder wire to say the tip of an iron, the surface tension of the solder pulls it into a ball, and all the flux gets pushed out to the surface, where most of it drips off and/or gets sucked up the side of the iron tip, instantly. The surface of the bead and the tip of the iron is hot, so what little doesn't immediately drip off burns up rather quickly and is no longer helping. Then what's left is just dry solder. When you apply the solderwire to the joint, the flux pools up around the bead and helps for much longer.

If you put flux on the joint, it's where it needs to be, and you free up a hand. You get the same result without needing to feed the solderwire.

I use flux because I don't have a little elf to apply solder wire to my joints for me. If you have ever used a third hand, you could have used flux. If I ever need a third hand, it would have been your fourth.

[pickle9000]

Flux is a necessary tool for surface mount, no question.

[MrSlack]

Ok I don't do SMD (yet) so makes sense. I've toyed with the idea a few times but never managed to jump off the ledge.

[VK5RC]

Have a try with SMD,  I think it is quicker,  no more flipping the board and components half falling out,  but yyo need magnification and lighting.
I use a flux pen minimally but do clean the board beforehand.
The make your own flux seems a bit of fun,  but wouldn't bother myself.

[MrSlack]

I'd love something to be quicker. If I'm honest, dead bug with through hole is about as quick as I have seen so far.

Have ordered a cheap SMD exercise board and a flux pen of RS. Have a surgical loupe and lots of lights already

[suicidaleggroll]

Flux is a necessary tool for surface mount, no question.

I do almost entirely SMD, and while I have a flux pen, I very rarely use it.  It's most certainly not necessary, but sometimes it can make things a little easier, depending on the solder you're using, the part you're working on, and your technique.

Multicore solder has a crap-ton of flux inside, I very rarely find that I need to add even more.

[suicidaleggroll]

The reason for using flux is not only for oxidized parts. It's also so you can hold down SMD parts with tweezers while you solder them, using only two hands.

...

I use flux because I don't have a little elf to apply solder wire to my joints for me. If you have ever used a third hand, you could have used flux. If I ever need a third hand, it would have been your fourth.

You don't need 3 hands or an elf to solder SMD without a flux pen...it's very easy.  Put a dab of solder on one of the pads, doesn't matter which.  Put the solder down.  Hold the part in one hand with tweezers, iron in the other, line it up, and tap the pad you soldered with the iron.  The part will sink into the solder and attach to the pad.  It won't be a clean or pretty joint, but that doesn't matter.  Put down the tweezers, pick up the solder, do the other pins, and when you're done you can go back to the original pad to clean it up.

[Halvmand]

I'd say have a go at it.

What i've found is that you can make a perfectly fine R or RMA liquid flux hat home.

I've read a couple of different MSDS from different fluxes and it is often just a carrier plus activators.
Carrier could be alcohol for no clean fluxes and rosin plus alcohol for R, RMA and RA fluxes.
The activators is mostly organic acids (i have seen adipic acid in at least a couple RMA fluxes) and halides. The last I haven't found what is.

Upon this I have experimented a little my self.
I've made a rosin flux from ebay best rosin, isopropanol and glycerin.
This flux works fine, the residue is no more than is left from the flux in the solder wire. Id say the Chinese best rosin is no worse than any other. I've ordered a more clear rosin to be sure.
I'm actually using this for most stuff now.

I've made a flux with isopropanol and citric acid.
I compared it with just isopropanol by dabbing a drop of each on a sheet of uncleaned bare pcb. Then make a blob of solder on the iron and wait till the flux evaporated. I then touched it to the pcb where the fluxes was.
The citric acid mix vill make the solder wet fine where the isopropanol alone won't.

When I get some more rosin i'll make a RMA flux with with citric acid as the activator.

Citric acid was the only acid I had available, but it's boiling point is close to others I've seen mentioned used in flux.

About corosion, I'm testing some different fluxes on a pcb slide. (Isopropanol, rosin, citric acid, glycerin), (isopropanol, citric acid) and (Circuit works cw 8400).
The slide is only about 3 months old by now. The cw 8400 sees sign of corrosion, but that is an activated lead free flux so is to be expected.
The other two sees no signs of corrosion.

That is about my experience with homemade flux. I think you should give it a try if it interests you. There is no financial gain though.


Edit:
Disclaimer: I haven't used brand name fluxes of the same type to compare with. This is my intention to try out in the future though.

[KL27x]

You don't need 3 hands or an elf to solder SMD without a flux pen...it's very easy.  Put a dab of solder on one of the pads, doesn't matter which.  Put the solder down.  Hold the part in one hand with tweezers, iron in the other, line it up, and tap the pad you soldered with the iron.  The part will sink into the solder and attach to the pad.  It won't be a clean or pretty joint, but that doesn't matter.  Put down the tweezers, pick up the solder, do the other pins, and when you're done you can go back to the original pad to clean it up.

There are several major problems with this.
1. You have to decide which pad to pretin. If you're putting down more than one part, you will have to figure out which pad to tin on each part, so that you aren't tripping over your own feet. The alternative of tinning the pad immediately before placing the part would mean picking up the solder. Picking up the tweezers. Where did I put down my tweezers? Where is my solder?
2. Tacking that first pad takes time. If you think you could even tin that pad as fast as applying flux to both pads of a passive, multiply that by 5 parts and see for yourself
3. going back to the original pad to clean it up takes more time

If you add it up, dotting the pads with solder and using a CF tip to hold a big reservoir of solder makes many SMD jobs WAYYY easier. Faster. More efficient. More fun.

Especially under magnification, there are some advantages you would not even dream of without the experience.

1. When you are holding solder wire to make the joint under mag, you have no precise way to move the board around. You will reach down to touch the board between joints, or if it's big enough maybe move it around with your palm. If you preflux, you're holding the part with tweezers. Just don't let go of the part after it's done soldering. You use the part you just tacked as a handle, and you move the next joint into the center of your FOV with the tweezers, very precisely, and you always know where the tweezers are related to the FOV.

2. The tip of your solderwire is a variable. It gets used up. Repositioning your fingers on the wire takes time. Finding the tip under high magnification takes time. Tweezers are a constant. They connect your hands and eyes and board together under magnification in this dissociated little world.

These things make a huge difference to the workflow. When you add it all up, there's no comparison. If you do any sort of volume assembly, ever, you will find that out for yourself. Once you have this experience, you will groan whenever you have to do thru hole. Thru hole sucks.

[Alexei.Polkhanov]

I mostly use gel flux in syringe like one from Amtech or MG Chemicals. One from Amtech is really good, but it comes in really big syringe  - never used more than half of it in a year

TRYBENZYL DODECYL DIMETHYL AMMONIUM CHLORIDE (I am not sure about the "TRY prefix" was part of very good Flux I used to buy on flea market in USSR - I cannot find flux as good as that one ever since. I suspect its effectiveness may have been due to some additives that now deemed carcinogenic or maybe it is just not popular in Americas for another reason. Flux from Amtech is closest one.

I think most non-rosin fluxes are made by mixing Vaseline with acids like Phosphoric acid, Triethanolamine, Salicylic acid (can be replaced by Aspirin?) and as result good flux have only 6 month to a year of shelf life. I can see how it is beneficial to be able to make your own "fresh" flux, but if you can get it shipped overnight why bother?