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Ultimate guide to cleaning PCB flux

Cleaning the Printed Circuit Board from flux is based more on myths rather than facts. Now, most of the technicians prefer to use IPS which is isopropyl alcohol for cleaning the flux post soldering. However, certain indications depict that this hygroscopic solvent is harmful to cleaning the soldered PCB. One should rather use a special flux cleaner instead. 


To make things easy for you we have tried to give you a quick guide on how to clean flux from PCB. Without any further adieu let us get into the details of the process.

What does flux mean?

When talking about Printed Circuit Board technicians use the term flux differently. In the world of PCBs flux is used to define the residual left on the board after applying solder flux paste.


 Flux if left uncleaned can slowly eat the components and damage the board completely. It might result in inhibition or etch on the PCBs. Thus, it becomes very important to clean the PCB. Besides, cleaning the flux avoids obstruction with other electrical parts as well. 

A quick guide on how you can easily clean flux

When soldering a Printed Circuit Board such as heavy copper PCB or flexible PCB with flux you will notice that it will leave a thick soapy residue. Therefore, you must clean it to avoid damage. Cleaning the flux broadly involves two steps:


  • Making the flux removal

  • Cleaning the flux

 We will discuss both the steps in detail below.


Making the flux removal

The success rate of removing the flux residue from the board highly depends on the kind of flux removal you choose. You can get some great options for the flux removal in the market however if you want you can fashion one yourself.


To make your flux removal you will require the following things:

  • 95% pure as well as tested isopropyl alcohol- 100 ml

  • 95% pure ethyl alcohol - 850 ml

  • Ethyl acetate solution - 50 ml


Use a standard measuring container to measure the chemical ingredients accurately. An important thing to note here is that the purity and quality of these chemicals are important so make sure that you purchase them from a trusted shop. 


Also, make sure to store them in an airtight container to prevent the solution from contaminating from the air. 


Finally, let’s begin with the mixing. Don’t worry it’s completely safe. Grab a mixing container and put the ethyl alcohol in it. Next pour in the isopropyl alcohol and finally add ethyl acetate solution. And you are done! Yes, you have made your homemade flux remover!


You will not use the entire solution at once so pour approximately 100 ml in a spray bottle and then use it. This solution will work for resin as well as non-resin flux and on clean flux too.


Important: Make sure that you are wearing safety gloves before dealing with the chemicals.


Cleaning the flux residue

After you have prepared the flux removing solution it’s time to move on to the next step. This step is easy yet very important. Here are the steps that you must follow to clean the flux:

  • Grab a cleaning brush. Make sure that the brush is soft and flexible. The brush should not damage the board.

  • You can either drip the brush in your homemade solution or you can even use a spray bottle to spray the chemical solution onto the board. 

  • Now hold on for a couple of minutes. This will allow ethyl and isopropyl solution to make the residue softer. 

  • Now start cleaning the board with a soft brush. Don’t apply too much pressure on the board. Rather, clean it with patience by applying gentle pressure.


The cleaning process is very straightforward, it does not require any special skill. All you have to do is be patient and gentle or else you will end up damaging the board. 



Note that this is not the only method of cleaning the flux but it is probably the easiest and safest. Although, you will have to be a little more careful while mixing the chemical solution. If you want the final look of your Printed Circuit Board to be impressive you must clean the residue immediately after soldering. 

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