Cleaning the flux: 99.8% isopropyl vs 70% isopropyl + 30% ethanol mix?

[LearningToRepair]

Hi!

I would like to know which one is better for cleaning up soldering flux from pcb after soldering?
One option is 99.8% isopropyl alcohol
Other option is 70% isopropyl and 30% ethanol mixed together solution.

And also what would be the process? Do I just put it on pcb and let it evaporate or should I wash this off once it absorbed all the flux?

I also read that isopropyl is bad for pcb, but I am not sure what to think of it or what other alternative to use in that case?

[stj]

Re: Cleaning the flux: 99.8% isopropyl vs 70% isopropyl + 30% ethanol mix?

ipa is harmess.
but you need to wash the flux off with it - not just melt it into a pool

[momaka]

Re: Cleaning the flux: 99.8% isopropyl vs 70% isopropyl + 30% ethanol mix?

^correct

Acetone is the one to avoid, or at least use sparingly if there is no other alternative, as it can damage the PCB coating.

[stj]

Re: Cleaning the flux: 99.8% isopropyl vs 70% isopropyl + 30% ethanol mix?

acetone will also remove the print / paint from components leaving you with a mystery-pcb!!

[budm]

Re: Cleaning the flux: 99.8% isopropyl vs 70% isopropyl + 30% ethanol mix?

https://www.techspray.com/cleaning-e...propyl-alcohol
https://www.digikey.com/en/maker/blogs/cleaning-pcbs

[Donomite]

Re: Cleaning the flux: 99.8% isopropyl vs 70% isopropyl + 30% ethanol mix?

Toothbrush or cotton bud. Dip either in your isopropyl then scrub the area with flux. I like to follow up with a cut up tshirt put over the wet area then use toothbrush over shirt to soak up the flux/isoprop solution.

[LearningToRepair]

Re: Cleaning the flux: 99.8% isopropyl vs 70% isopropyl + 30% ethanol mix?

Thanks for info. Now I know not to use acetone. but how is that mixture of 70% isopropyl and 30% ethanol that I mentioned in first post compared to 99.8% isopropyl? is there any difference?

[momaka]

Re: Cleaning the flux: 99.8% isopropyl vs 70% isopropyl + 30% ethanol mix?

Thanks for info. Now I know not to use acetone. but how is that mixture of 70% isopropyl and 30% ethanol that I mentioned in first post compared to 99.8% isopropyl? is there any difference?

A quick search online suggests Ethanol is also safe, and sometimes used in place of IPA (Isopropyl Alcohol, not the beer ) due to being cheaper.

I've also used and seen others use "medical-grade" rubbing alcohol (~70% IPA and 30% water) without issues for cleaning electronics. So if that worked, then the mixture you suggest above will probably work even better - maybe just as well or nearly so as 99+ % IPA.

[eccerr0r]

Re: Cleaning the flux: 99.8% isopropyl vs 70% isopropyl + 30% ethanol mix?

Depends on the flux you're using. If you're using natural rosin as flux, you need isopropanol as the solvent to clean it, 70%-99% doesn't matter.

If you're using a water soluble flux, you should use...guess what? Water.

Guess what also will clean up water soluble flux? 70% isopropanol, though not perfect, it has 30% water that will clean water soluble flux too.