Flux - Page 1
Forum section: electronics / general

author: bostonman
author_rank: Super Contributor
timestamp: January 02, 2020, 07:53:33 pm
content: I'm confused on flux and know I briefly looked into this before.The stuff I use is in the picture, but seems no matter what I've used in the past, no matter how much alcohol I use, I get a white haze after it dries.I even use electronic cleaner (it comes in a red can) and still get white haze.What am I doing wrong?

author: bostonman
author_rank: Super Contributor
timestamp: January 07, 2020, 07:24:59 pm
content: Am I not cleaning the boards well or am I just using junk flux?

author: mariush
author_rank: Super Contributor
timestamp: January 07, 2020, 08:04:18 pm
content: You would clean them with isopropyl alcohol, and it should be clean.As for why, you have the MSDS (material safety datasheet) so you can compare the ingredients with the ingredients of other fluxesThe MSDS is linked on the Radioshack page for that flux :https://cdn.shopify.com/s/files/1/0953/5270/files/SDS-E-6400022_v30.pdfThe datasheet says:WW GUM ROSIN 8050-09-7 50-60%DIETHYLENE GLYCOL DIBUTYL ETHER 112-73-2 15-25%DYMEREX ROSIN 65997-05-9 15-25%I'm using a no-clean flux made by a Polish company, which is liquid and has a more common formula:https://www.tme.eu/ro/details/flux-tk_500/fluxuri/ag-termopasty/art-agt-075/It's basically <85% isopropyl alcohol, 20-25% rosin, <5% benzoic acid and <5% adipic acid.You can basically make your own flux by mixing isopropyl alcohol with rosin (and adding maybe a drop or two of glycerin would help)

author: SMTech
author_rank: Frequent Contributor
timestamp: January 07, 2020, 09:12:10 pm
content: IPA is often not enough on its own, flux removers while often IPA based have additional compounds in there that help clean up your white haze. All fluxes are not created equal however, some are more awkward than others, doesn't hurt to try a few.

author: KL27x
author_rank: Super Contributor
timestamp: January 28, 2020, 01:37:42 am
content: While you solder, any metal oxides are dissolved into the flux/acid as ions. When the flux dries out, these ions turn into salts... this is the white stuff. When you put alcohol on the board, you dissolve the rosin binder, and this white stuff will partly dissolve, but mostly it will just float around in the alcohol.Do not leave the alcohol to dry on its own. After you put alcohol on the board, scrub between the pins with a small paint brush to break up rosin and salts and to get as much of the salts into suspension. Then immediately blot up the alcohol. You just removed 98% of the salts. Do it again, and you removed 99.5% Repeat as necessary.When you take a bath, the water is dirty. But you still get clean. It's a percentages game.

author: ebastler
author_rank: Super Contributor
timestamp: January 29, 2020, 06:56:13 am
content: Quote from: bostonman on January 02, 2020, 07:53:33 pmAs KL27x said, what you are doing wrong is that you let the solvent dry. When you dissolve the flux in alcohol (or whatever solvent you use), the flux molecules do not magically disintegrate. They are still there, in solution, and if you let the solvent evaporate, the flux molecules will stay around -- now nicely spread out as a white film.Either blot the alcohol/flux solution off quickly, or rinse if off with generous amounts of solvent which you let drip off the board. As explained by KL27x, you may have to repeat the procedure another time to remove (most of) the residual flux molecules which you didn't manage to wipe or rinse away in the first round.

author: FreezeSSC
author_rank: Contributor
timestamp: January 31, 2020, 12:18:13 am
content: One thing I do that helps is to place a kimwipe on top of the board and then use a brush to apply the solution.