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?

[KL27x]

and halides. The last I haven't found what is.

Halides are ionic compounds that include an element from the halide column, the most typical in fluxes being zinc chloride.

Zinc chloride dissociates at soldering temp and becomes acidic. It basically turns into hydrochloric acid. The chloride ions have the tendency to borrow the electron from neighboring water molecules and/or other agreeable hydrocarbons, increasing the probability of a free proton in any given space at any given time, which is essentially what acidity is.

Halides are among the most corrosive part of a flux. Definitely not a first choice for electrical work, although plenty of electric fluxes contain some zinc chloride. (Zinc chloride is the main ingredient in plumbers flux). These halides essentially leave salt behind in the residue, and it embeds in the pores of the metal. It cannot be effectively cleaned away. This is a problem on ferrous metals, in particular. If you have ever tried to clean rusty metal with HCl, you know this is not a good method. You will get the metal sparkly clean, but no matter how well you wash it, it will rust within days.

As for making your own flux with acid and alcohol, that is fine. But you probably ought to clean the board after. What makes rosin so special it is made from super long chain acids. The rosin is at once the acid that dissolves the metal oxides and the residue that binds the end products. It just happens that rosin is acidic enough to dissolve copper oxide, and that it is a viscous fluid which is very liquid at 150+C but essentially solid and highly insoluble in water at under 50C.

Some of the rosin-free no-cleans work on the same principle, of leaving a hard, non-hygroscopic residue. Others are deemed no-clean for having a very low solids content (and therefor also a very low activity), so that when the carrier is completely evaporated there's not enough "crap" leftover to be problematic.

[Halvmand]

KL27x:Good explanation. That makes sense.

My citric acid / alcohol flux was just an experiment to see if citric acid worked as a flux. It haven't shown signs of corrosion yet, but i think you're right, cleaning it off the board is a good idea.

[MrSlack]

KL27x:Good explanation. That makes sense.

My citric acid / alcohol flux was just an experiment to see if citric acid worked as a flux. It haven't shown signs of corrosion yet, but i think you're right, cleaning it off the board is a good idea.

Definitely want to clean it off. You can etch boards with citric acid.

[KL27x]

Personally, my more immediate concern is that citric acid flux residue could be measurably conductive from humidity in the air.

All fluxes dissolve metal oxides, and therefore they could all theoretically (in combination with an oxider and in sufficient quantity - an in some cases sufficient temperature) etch a board, if you were determined to do it.

I don't know of a reason that citric acid residue would be particularly corrosive, other than every water soluble flux residue should be cleaned off for the potential conductivity. Continued corrosion is certainly a concern. If you want to completely erode a copper trace on your powered circuit board, human sweat is about as bad as anything, largely because of the halides and the water.

[KL27x]

No clean is a rating? It seems kinda of like it's a category of fluxes, and I don't really agree with it, always.

E.g. rosin and RMA and RA are not called "no clean," but the description of them usually says something to the effect of non-conductive, non-corrosive, and/or "residue may be left on non-critical circuitry."

The fact that RA does not meet milspec unless the residue is washed off does not bother me, either. Rosin fluxes are the ONLY fluxes that meet milspec, at all. I'm sure one day I will have a problem from RA residue (RF signals, perhaps). But if I can't measure conductivity and my circuits work, I can't see a problem.

I do not really care what the manufacturer says about a flux. I have my own understanding. I do my own testing. And I come to my own conclusions. I clean my boards when they need to be cleaned. Esthestically, I don't care unless the residue interferes with inspection. As long as the residue does not collect dirt/dust nor is it conductive or corrosive. All of the rosin fluxes meet my own personal standard of "no clean," and they also meet my personal standards or being easily cleaned, if I want. Only some of the manufacturer branded "no clean" products meet my own personal standards.

[free_electron]

real men grow their own pines, topple them by biting through them with their teeth , grow their own corn to distill the alcohol. ( in a hand build distillery system by digging their own copper ore , smelting it and forging the kettle and cooler spiral from it. )

wimps with their rosin stuffed solder core..

[TechItApart]

So many replies, awesome. I think I will have a go at doing it. I've bought 100g of "best quality pine resin" from eBay for cheap. Will post back with results.

[RobertBG]

I did it once at 1 am when I ran out of flux.I simply used rosin from my sisters violin and alcohol but after finding out what it cost to replace a small tin of the stuff I wont be doing it again    I forget the size but it couldnt have been more than 80-100 grams and it was 30$ or so at Guitar center lol.Needless to say it was a expensive experiment in hindsight I think a pinch of the rosin and a eye dropper would've got me through the night without my sis knowing.

[macboy]

So many replies, awesome. I think I will have a go at doing it. I've bought 100g of "best quality pine resin" from eBay for cheap. Will post back with results.

You didn't buy the raw stuff that people use as incense did you? Don't use that. Buy the refined stuff in the little cardboard carton. Look for one that is as light colored as possible.

[nanofrog]

Buy the refined stuff in the little cardboard carton. Look for one that is as light colored as possible.

FWIW, there's some that comes in metal tins as well (usually Russian made, but I've seen some Polish, Romanian, and even German made on occasion as well). Looks rather decent too based on eBay photos. 

There's also some solid RMA in tins (RA too, and Polish made IIRC), that you could solve into a liquid using alcohol or acetone (or a mixture of both). Not sure it's all that cost effective though, so I never bothered to try it out.  Easier, more convenient, and cost effective to buy MG Chemicals 835 IME (or Kester 186 in small bottles from Dickie's Garage Sale for those in North America). 

Skycraft Surplus breaks down Kester 1544 into ~2oz. for $3.95, though I suspect you'd only be able to get this in person (i.e. bottles could leak during shipping, and they don't want the hassle). But if you're ever in Orlando, FL, the place is worth a look if you've the time. 

[rdl]

Youtube Cody's Lab.

Thanks for that.

I just watched all the "Cody's Mine" episodes. I'd never even consider attempting a project like that, but he just decided it might be cool and started digging. I'll definitely be watching his other more "sciency" stuff.