I use no-clean flux.

 

I must have misread one of the TS posts. He’s going to remove the components to clean off the flux, right? Then, after cleaning, he plans on reassembling the board, ADDING MORE FLUX?

 

Answers off the top of my head.
1) I already answered this above by pointing out that I either:
A: Used a fresh side.
B: Reapplied the flux and retested.

What you said was:

In the case of the particular product having "A little" effect then you might be correct about the additive properties. But I was careful to retest, or I happened to use a fresh side, when a product was effective.

That is a classic error. What if the prior treatment prevented the second product from being effective? Then the second product would not have been tested further. That effect is not just hypothetical.

2) There are 3 points here. I'll address them as A, B, and C.<snip>

Yes, fluxes remove contaminants and oxides. They facilitate solder bonding and flow.

Cleaning is not just for esthetics. Fluxes after soldering can be corrosive and slightly conductive. It is important to clean them off boards that need to maintain high resistance and to prevent corrosion after soldering. Note that the metal oxides flux removes and can be quite conductive, even if the flux before use is non-conductive. Not all fluxes need to be cleaned in all cases.

3) My original post contains the information. I applied the flux and allowed it to dry. I then cleaned the board. No soldering was done.<snip>

As for cleaning off the fresh flux vs. flux and whatever it picked up from soldering, yes, there will be a difference. I don't know how much, but if the cleaner removes the rosin, and rosin is flux and flux has contaminants in it then the cleaner should remove the contaminants also.
There's always a chance that a chemical reaction took place which causes part of the rosin to change form, but not being a chemist, and wanting a reproducible testing method, makes me have to use the simple method I used.

That is my point. Products of pyrolysis are often much harder to remove than the unheated starting materials. Flux is partially pyrolyzed in the process of heating to 300°C or whatever during soldering. Consider how hard it is to remove baked on stuff from a cooking utensil even if it is not heated to soldering temperature.

 

I just received an email from Circuit Specialists advertising some liquid flux remover
https://www.circuitspecialists.com/...-53368057&mc_cid=ceaec7573c&mc_eid=44be31c4c4

 

I just received an email from Circuit Specialists advertising some liquid flux removerView attachment 197025
https://www.circuitspecialists.com/...-53368057&mc_cid=ceaec7573c&mc_eid=44be31c4c4

Really? I am surprised. That is not denatured ethanol. Are you sure there are not minor constituents listed? In other words, except for the taste, it could replace vodka from China. How much is a 5th?

 

Really? I am surprised. That is not denatured ethanol. Are you sure there are not minor constituents listed? In other words, except for the taste, it could replace vodka from China. How much is a 5th?

 

What you said was:

That is a classic error. What if the prior treatment prevented the second product from being effective? Then the second product would not have been tested further. That effect is not just hypothetical.

In order to change that I'd have to use NUMBER_OF_PRODUCTS amount of fresh boards. I'll have to count how many I have...

...
That is my point. Products of pyrolysis are often much harder to remove than the unheated starting materials. Flux is partially pyrolyzed in the process of heating to 300°C or whatever during soldering. Consider how hard it is to remove baked on stuff from a cooking utensil even if it is not heated to soldering temperature.

Ah! So, my data is valid BUT only for unheated flux. I'll have to retest with heating the boards as both states of flux can exist simultaneously on a project.

Incidentally, "Rosin flux is made from pine tree rosin, minus the turpentine solvent, which is cooked off and captured. " -- https://www.eham.net/forum/view?id=topic=118854.0
Here's another 2 threads on flux removal: http://cs.trains.com/mrr/f/744/t/243789.aspx https://www.avrfreaks.net/forum/how-best-clean-flux

I'm not trying to be an authority on the subject. I'm trying to stop all these people who keep saying, "X works for me" and turn it into, "X works". There's no research about the household cleaners that can work for this purpose AFAIK.

 

I'm not trying to be an authority on the subject.

You can't please everybody, but I'm satisfied with your results. I'm going to give Scrubbing Bubbles Bathroom Grime Figher a try.

Thanks for your efforts.

 

I'll let the "revenuers" deal with it. The price is roughly $30/L or not very competitive with cheap vodka. Maybe ethyl acetate and IPA are sufficient as denaturents to be "denatured", but they are not enough to discourage a real alcoholic.

EDIT: Reference 27CFR Subpart D (https://www.law.cornell.edu/cfr/text/27/part-21/subpart-D)
It appears the MG Chemical product may meet the requirement of "specially denatured" ethanol, §21.37. That is, application specific denaturation because of its IPA concentration. Neither IPA nor ethyl acetate is particularly toxic compared, for instance, to methanol. I still prefer good Scotch.

In other words, it is not much more than pure ethanol with some stuff added to make it taste bad and pass regulations without a tax sticker..

 

I'm not trying to be an authority on the subject. I'm trying to stop all these people who keep saying, "X works for me" and turn it into, "X works". There's no research about the household cleaners that can work for this purpose AFAIK.

You have not even shown that "x" works for flux that has not been heated to soldering temperature and used for soldering. Your sequential testing is a non-starter. In a broad sense, it is called a Type II error. That is , falsely rejecting something that might have worked, except for the pre-treatment your fresh flux underwent.

 

@jpanhalt That occurred to me, but if the dish detergents and bathroom cleaners left a residue then we'd be eating it every day from touching the faucets and dishes. AFAIK that would not be good for you, therefore I should not have that problem with that.
But I'll redo both to satisfy you.

 

@ballsystemlord
You might find this link interesting.
https://www.kester.com/Portals/0/Documents/FAQs/White_Residue.pdf
Kester is a major manufacturer of equipment and supplies for soldering. So far as I know, the "white residue" is really only a problem with flux that has been used to solder. At least, that is the only time I have encountered it.

If you are repeating the study, you might consider getting a piece of PCB or using what you have. Put a thin layer of flux on it, then soldering a dimple or short dash to pyrolyze some of the solder. Test that.