Anyone make their own rosin flux? What's it like?

[tooki]

You know what, I think you're right. Realistically, I go through such a small amount of flux per year (like you said, less than $10) that it probably doesn't make sense to waste my time and effort trying to devise my own, when it would have the potential to perform much worse than commercial offerings (in wetability, corrosiveness, cleanability, etc.).

Thank you.

100%. I went through the same process of researching it and experimenting, and the results were disappointing. It’s easier and cheaper (especially when you consider the value of your time) to just buy a good flux.

[jpanhalt]

SP-44 is what I use, and the tin is still at least half full.  I'm set until 2050.  I will remember to have it in my coffin -- I wonder if it can stand that much heat?

Kester still advertises 44 rosin flux-cored solder and calls it "activated:" https://www.kester.com/products/product/44-flux-cored-wire  The formula may be a little different.  The current analysis shows chlorine at 0.5 ppm and doesn't specify its form.  Bromo-compounds are below detectable levels.

[Shock]

Aside from the composition and viscosity at room temp, you also have to consider the evaporation rate or working time, intended alloy, the activation/deactivation working times and temp, if residue remains hydroscopic, if fumes/solids reactive, cleaning method, toxicity to the operator. Lots to consider in a good flux.

[tooki]

SP-44 is what I use, and the tin is still at least half full.  I'm set until 2050.  I will remember to have it in my coffin -- I wonder if it can stand that much heat?

Kester still advertises 44 rosin flux-cored solder and calls it "activated:" https://www.kester.com/products/product/44-flux-cored-wire  The formula may be a little different.  The current analysis shows chlorine at 0.5 ppm and doesn't specify its form.  Bromo-compounds are below detectable levels.

I’m fully aware that Kester 44 solder wire is still sold — it’s my favorite solder, which I use every day at work.

Nonetheless, the 44 paste is unavailable to anyone who doesn’t already have it, so it’s not useful in terms of purchasing advice for today. (Sadly. I liked SP-44. I still have half an old tin of it.) There are really similar-looking products from MG Chemicals and Chipquik that are still available today.

[jpanhalt]

Does the MG SDS say what's in it?  My sexperience is that MG is more secretive than Kester was, but even Kester is trying to hide more now.  As one example, its recipe for 5768 water-based flux remover was in the SDS/MSDS.  That has now seemed to have changed.  A seemingly older version is still available on the site for a local supplier: https://gokimco.com/products/kester-5768-bio-kleen-flux-remover-1-gallon-63-0000-5768  dated 2017.  That is, of course, why I started using ZEP acrylic floor stripper for that-.

[LooseJunkHater]

Does the MG SDS say what's in it?  My sexperience is that MG is more secretive than Kester was, but even Kester is trying to hide more now.  As one example, its recipe for 5768 water-based flux remover was in the SDS/MSDS.  That has now seemed to have changed.  A seemingly older version is still available on the site for a local supplier: https://gokimco.com/products/kester-5768-bio-kleen-flux-remover-1-gallon-63-0000-5768  dated 2017.  That is, of course, why I started using ZEP acrylic floor stripper for that-.

Wow, the observation of the ZEP acrylic floor stripper having some of the same ingredients (in lower concentrations) is an amazing observation! I've previously had some mild success with the Zep Citrus Cleaner in my ultrasonic cleaner, which is slightly better than hot water, but still not great. Guess when I run out of the Citrus Cleaner, I'll give the acrylic floor stripper a try.

It makes me kinda want to look at a bunch of the commercial flux cleaner products, compare SDS's, and see if there are cheaper products in-stores, advertised for different uses... But again, that may end up sending me down the same rabbit-hole of wanting to create my own flux lol

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Edit: Wow, it looks like the Branson ultrasonic cleaning fluids also contain a significant amount of the ethanolamine, as does the Kester 5768...

[jpanhalt]

Dilute the stock ZEP product 1 part ZEP to 3 parts total.  No need to measure accurately, and you have the same stuff.   I was amazed after my first try.  Be sure to clean thoroughly with deionized water.  The boards glisten.  I use an old ultrasonic for about 1 to 2 minutes in the cleaner.  The rinse is about the same.  Don't go too long in the initial ZEP cleaner.  The rinse time doesn't seem to matter much.

[LooseJunkHater]

Dilute the stock ZEP product 1 part ZEP to 3 parts total.  No need to measure accurately, and you have the same stuff.   I was amazed after my first try.  Be sure to clean thoroughly with deionized water.  The boards glisten.  I use an old ultrasonic for about 1 to 2 minutes in the cleaner.  The rinse is about the same.  Don't go too long in the initial ZEP cleaner.  The rinse time doesn't seem to matter much.

I've never used any professional flux cleaner products before, but with your ZEP cleaner, do you feel it works "good enough" at room temp, or do you generally heat it up to 50C+?

[RoGeorge]

The advantage with rosin as flux, either solid or dissolved, is that you don't have to clean the board afterwards, because rosin is a very good insulator, and it doesn't corrode the traces.

On the contrary, many commercial fluxes must be cleaned after soldering, or else the leftover flux might be very conductive and disturb the circuit, or might corrode the traces in time.


As for preparing your own rosin based flux, don't overthink it.  Crush some solid rosin and pour the dust in a small glass bottle, together with some alcohol.  Add more rosin until it thickens.

Long ago, we as kids at a pioneers' club (the equivalent of today's maker's clubs) were using medicinal alcohol, because it was the only one available as kids.  Medicinal alcohol didn't work very well as a solvent for rosin, and some residues were always on the bottom of the bottle.  Not sure if the precipitate-like residues were the result of some chemical reaction, or just impurities from the rosin.

However, the resulting solution was en excellent flux for soldering, and at the same time an excellent protection cover for the copper traces at the same time.

We used to hand made PCBs and etch them ourselves, with fumic nitric acid (very strong HNO3). 

After rinsing with tap water, then drying, we were painting the entire PCB area with dissolved rosin (dissolved rosin was about  as thick as a paint).  Once dried the layer of rosin, it was keeping the copper traces shiny forever, and also serve as an already applied layer of flux at the soldering pads.

[jpanhalt]

I've never used any professional flux cleaner products before, but with your ZEP cleaner, do you feel it works "good enough" at room temp, or do you generally heat it up to 50C+?

I don't heat it intentionally.  It gets a little warmer in the ultrasonic during the 1 to 2 minutes.  As for how it works, I'd say excellent, not just good enough.

I used to use neat organic solvents, namely absolute ethanol and sometimes added acetone for difficult residues.  I still use that for spot cleaning after minor rework or adding things, like button switches, that I do not want to have retained water.  When I first tried ZEP, after water rinsing under a faucet, the board is virtually dry.  Solder resist is hydrophobic, and the only water left was a tiny bit under components.  I blow dry with compressed air from an oilless compressor.  That's breathable air, not gas from a can of compressed gas/ difluoroethane.  No haze is left; whereas, with the neat solvents, they may leave a slight haze after evaporation unless they are completely fresh. I was rinsing  2 or 3 time to get rid of it.  Also, "white residue" left by organics does not occur.

I have checked the MSDS/SDS sheets for a few other water-based cleaners, and they have similar mixtures of the same classes of chemicals.  Namely, they are  mostly hydroxy ethers (aka glycol ethers, e.g., cellosolves, https://en.wikipedia.org/wiki/Glycol_ethers) and a little ethanolamine to raise the pH.

I started using that ZEP recipe based on the MSDS/SDS from Kester for its aqueous cleaner, not by hit or miss testing of every household cleaner I had.  That is my go to.  I have not used neat solvents for full-board cleaning since I started using ZEP a few years ago. 

ZEP is only a brand name, numerous other products have virtually the same recipe.  In speaking with a chemist at ZEP, I was told it is not distributed in Australia.  He did not know why, but given its utility for cleaning and polishing floors, I suspect there are equivalent products there, assuming enough people do that there.

[JoeS]

Got some old sap from a vintage collecting tin. It worked fine. Residue cleaned up with acetone. Good in a pinch, but prefer the stuff I use in the injector. Don't have a fume extractor. Stunk up the garage