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Flux Remover Video User's Guide

Flux Remover Video User Guide


Flux removers are used to clean flux off printed circuit boards (PCBs), which is left behind after the soldering process. It's critical to clean off flux residue because it can cause corrosion or create what’s called “dendrites”. Detrites  are ionic particles chained together between contact points. Dendrites can cause current leakage and ever short out the board.

Although the most popular flux remover is isopropyl alcohol (IPA), Chemtronics offers the Flux-Off brand of cleaners that can do the job more effectively and efficiently.

Many choose to clean flux with a swab saturated with isopropyl alcohol. This isn’t considered the best method for cleaning circuit boards because it often smears the residues around. Flux residues need to be physically removed, and won't necessarily evaporate off the surface with the solvent. 

Aerosols have the advantage of being sealed, so they are always free of contamination, don’t evaporate away as they sit on your bench, and the pressure provides extra agitation.

Always remember to disconnect power to the board, which includes on-board batteries. To prevent damage to sensitive electronics, use proper procedures like grounding yourself with a wrist strap. Safety glasses are always recommended, in addition to nitrile gloves if you are solvent sensitive.


Cleaning with an Overall Spray

A good way to clean the board overall, or as a final rinse after the cleaning process, is to use an aerosol without any attachments. Make sure you hold the ciircuit board at an angle so the cleaner and residues can run off.

To clean specific areas of the board, keep the area wet with solvent. Partially dissolved flux residues tend to settle down to form white residues, which are often even more difficult to clean than flux. By keeping the PCB wet, it will be easier to rinse everything off at the end of the process.

Focus the spray over solder joints, where flux residues are more concentrated. Allow the solvent to flow around and under components for more thorough cleaning.


Cleaning with an Extension Tube / Straw

Aerosol flux removers usually include an extension straw or tube for pinpoint accuracy. The straw also increases the spray pressure to increase agitation.  You can trim the straw if a shorter one is easier to manage.

  1. Insert the straw into the spray button or trigger sprayer. Make sure you point it away from your eyes in case it accidently sprays.
  2. Use the straw to focus your cleaning on just one area of the board. For example, around a component you just replaced.
  3. For the most thorough cleaning method, spray on each corner of the component, with drives the solvent under it.
  4. Then spray over the leads.
  5. Finally, remove the straw and rinse the entire area.

If you have an aerosol can with a trigger sprayer, the straw can be stored in the back, or under the trigger to lock and prevent accidental spraying. Otherwise, it can be snapped into the top of the cap.


Cleaning with a Brush Attachment

When you have stubborn flux residues, you can use a brush, swab or wipe to provide extra agitation. Remember, if you do that, make sure you finish off with a rinse.

Some Flux-Off flux removers come with a brush attachment. The solvent flows through the brush, so you can scrub and saturate the area with solvent at the same time.

You have 2 ways to use this brush…

  1. You can directly clean around components. Just pull the trigger to release solvent as you move the brush over heavily fluxed areas. Make sure you gently scrub so you don’t damage fine leads. Keep the area wet as you go through your cleaning process. When you are done, remove the brush and give the PCB a final rinse.
  2. If you have a very isolated area to clean, and you don’t want to risk cross contamination, you can use a wipe to absorb the flux residues. Simply place the wipe over the component, pull the trigger to release the solvent, and scrub through the wipe. This breaks up the flux residues and allows them to absorb into the wipe.


If you run into any problems, feel to call or email us, or go to chemtronics.com.

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