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  • Cleaning PCB

    Hello,

    wich is the best way to clean the PCB, after soldering with flux?

    I've tried isopropilic alcohol, but sometimes it is worse...

    How do you do it?

    thanks.

  • #2
    It depends on the flux.
    Rosin: scrub with lots of isopropyl alcohol (IPA), dab dry with kitchen towel.
    Water based: water with a little non foaming detergent ( i.e floor cleaner). Flush then dry with towel and gentle heat gun.
    "No clean", either leave the slight residue or scrub with IPA and then water wash as above.
    Experience is something you get, just after you really needed it.

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    • #3
      We have some cans of Flux Off at work for heavy jobs, but mainly isopropyl alcohol, tooth brush and scrub away from board.

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      • #4
        I do not use any soldering paste. 1)
        I use string caliphony for soldering. 1)
        For cleaning of solder points only nitro diluent or acetone with cotton ear stick.
        Last edited by vintagekiki; 11-16-2019, 06:02 PM. Reason: 1)
        Who does not know and knows that he does not know - teach him Confucius)
        Who knows and does not know that he knows - wake him Confucius)

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        • #5
          The best way for me is:

          Neutral soap with distiled water and tooth brush. Later, isopropyl alcohol, and hair dryer.

          It's nonsense? jeje

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          • #6
            Careful with nitro thinner or acetone. Might dissolve more than you want (like components' coatings and markings, solder mask, many plastics etc.). Quality flux doesn't need to be removed. It actually protects solder and copper from corrosion. In case of doubt I just scratch with a screwdriver between tracks or eyelets. Or use denatured alcohol on a Q-tip.
            Last edited by Helmholtz; 11-16-2019, 06:29 PM.
            - Own Opinions Only -

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            • #7
              I just work into a '63 Dynacord Bass-King. Rectified alcohol and ear sticks (a lot) works for me. Be careful at any holes which are not solder sealed as the dirty liquid can leak on the other side doing the face with components a mess, or can leak directly into sockets if there are printed one.
              "If it measures good and sounds bad, it is bad. If it measures bad and sounds good, you are measuring the wrong things."

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              • #8
                D-limonene (CAS 5989-27-5) based cleaners can work well for water based flux, Goo Gone has a small percentage (1-5% w/v) and is widely available. I then rinse with distilled H2O

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                • #9
                  Originally posted by Helmholtz View Post
                  Careful with nitro thinner or acetone. Might dissolve more than you want (like components' coatings and markings, solder mask, many plastics etc.).
                  Exactly right.

                  Quality flux doesn't need to be removed. It actually protects solder and copper from corrosion. In case of doubt I just scratch with a screwdriver between tracks or eyelets. Or use denatured alcohol on a Q-tip.
                  I would agree with this as well. I use MG Chemicals rosin flux 835, which I keep in a small plastic bottle with a syringe applicator. I love it. A small amount applied on anything from a broken board solder joint, to a point on a large steel chassis, seems to really help speed up the process and provide a quality solder connection. I tend to clean boards after using this now as I've run into a couple of issues in the past. One thing is to be careful around pots. I've had it migrate internally to the pot and harden essentially ruining the pot for all practical purposes (this has only happened once. But when an amp come back because of this and have to explain it to your boss, happening twice is too many times).
                  The other thing I've run into is on old circuit boards, like you find in vintage Ampegs. Often there is so much build up and dirt on the boards, that even though it cleans the solder connection, it can mix with the surrounding material and contaminate the creepage between board connections. V4's seem to be really susceptible to this for some reason.
                  I've had good success using 99.9% Isopropyl Alcohol to clean up after I'm done, and if needed, a solder tool to get the harder residue out between traces
                  If I have a 50% chance of guessing the right answer, I guess wrong 80% of the time.

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                  • #10
                    I am not familiar with water soluble flux and just learned that it must be completely washed off because residues are corrosive
                    (so I wouldn't use it in electronics):

                    https://www.pillarhouse.co.uk/wp-con...ux-11-2016.pdf

                    My earlier statement confines to rosin flux, which keeps moisture off. I would avoid/remove any stuff that feels sticky after drying, though.
                    Last edited by Helmholtz; 11-17-2019, 03:17 PM.
                    - Own Opinions Only -

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                    • #11
                      I've been using nitro thinner or acetone forover 20 years and I have no bad experience.
                      PCB after treatment is absolutely clean, and what is important is after some repairman always remains a trace of solder.
                      Who does not know and knows that he does not know - teach him Confucius)
                      Who knows and does not know that he knows - wake him Confucius)

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                      • #12
                        Click image for larger version

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                        the use of (potentially) very toxic and volatile solvents is OK on the small scale but effort must be made to abate the solvent without any living thing being exposed to the concentrated fumes
                        An active vent to the outside or a (regularly replaced!) activated carbon absorber is needed to be safe. Many solvents mixtures are only fully understood toxicologically years after they are commonly used*

                        *look up the sad example of the View-Master company of Portland OR where exposure to a nasty chlorinated solvent resulted in a mini epidemic of kidney cancer in long term employees.

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