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how to clean execess flux ?

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hi guys,

how do i clean the excess flux that put on my pcb to ensure good soldering. it just looks bad.

shud i use alcohol to clean it or what ?

thx in advance,

Dean Huster

Well-Known Member
Flux flusning

I can be nasty looking stuff, can't it? It's also difficult to judge the quality of a joint with the flux present. Commercial boards are cleaned of flux and there's no reason why hobbyists shouldn't, either.

I use either lacquer thinner or acetone to do the job, but beware that you don't want to inhale too much of that stuff. Alcohol is slower, though safer. Most solvents that will remove common flux are flammable.

Certain specialized boards require that you use alcohol to remove flux or you'll destroy the board substrate. Polysulfone boards, used in Tektronix oscilloscope attenuators in their production items of the late 1960's through the 1980's.



Active Member
Most of the manufacturers use Isopropyl Alcohol for cleaing excess flux. This can be obtained from any electronics component shop. One more thing I would like to tell you is that never use extra flux paste while soldering. This is a bad soldering practice. Instead use a good quality flux-cored solder wire. This would make a neat solder joint.

Dean Huster

Well-Known Member

If you don't want to pay through the nose for your chemicals, buy your acetone, lacquer thinner or IPA from a home supply place (here in the U.S., that would be Wal-Mart, Lowe's or Home Depot as examples). The little 5 oz. bottles that you get as a specialized chemical costs as much as a quart at Wal-Mart. And I tend to buy a gallon at a time in most cases, as I use mine in the wood shop as well.

Alcohol just takes too long for me which is why I go the acetone route. However, you have to make sure that you don't get too liberal with it or you may attack some plastics in switches, etc. with it. :(

I also tend to do large areas using a paint brush dipped in the solvent. I trim the brush bristles to a length of about 3/8" to make them more stiff. If you do use the harsher acetone or lacquer thinner, follow up with IPA (isopropyl alcohol) to clean the last little bit of diluted flux off.

The fluxes used in commercial board production are water-soluable, which makes cleaning a lot easier, especially with alcohol.

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