Best Soldering Flux For Electronics

Best Soldering Flux

Looking for the best soldering flux but haven't a clue where to start? Well, don't worry because you certainly aren't alone! The debate over which flux is currently the best on the market is a surprisingly ferocious one. Surely you'd expect there not to be too much difference between pastes and glues? Wrong!

Part of the problem is that it depends considerably upon your own soldering style - and of course what components you are dealing with. To make sure you end up with a suitable flux you need to think past the notion of it being a kind of 'metal glue'. Look instead for a clean product that is easy to apply, reliable, and ideally also non-acidic for an easier cleanup.

But as we shall see, there's a lot more to soldering flux than may meet the eye. We've selected five popular products to review for this purpose, so with an open mind and in no particular order, let's check them out.

Who & Where Uses The Soldering Flux?

Flux is a crucial part of soldering and serves three key functions. It:

  • Removes oxidized metals from surfaces.
  • Seals out air to reduce/prevent further oxidizing.
  • Provides wetting for the soldering purpose.

They are scored using a relatively recent system - the J-STD-004 - which rates each product according to type (rosin, resin, organic, inorganic) cross-referenced by reliability and electro-conductivity. What this serves to do is make it easier for people to select a best soldering flux for eletronics appropriate to their specific needs. Professional electricians and engineers will likely carry a variety depending on the work being undertaken.

All this being said, the golden rule is that for a soldering job to be carried out well it must involve the use of flux. Sure, it can take a while to get it right - at least until you are used to a particular product at least - but it will play a huge part in ensuring the final job is as good as it can be.

#1. MG Chemicals 8341

We'll start by taking a look at this popular - yet also quite polarizing - flux paste. This product is without question a good all-rounder, being suitable for both leaded and lead-free purposes. 

RoHS compliant and matching J-STD-004B requirements, you can at least be pretty certain not to be picking up a dud. While it performs pretty much as advertised there's a couple of things to be aware of.

First of all, this flux paste dries fast - sometimes too fast which means it is advisable to take it through a practice run before taking on a serious project. While this may take a little getting used to for those who are more used to gel-based flux, the final result is very impressive when care is taken.

The most significant issue is the pneumatic dispenser. Even halfway through the tube, you still need to allow for a 'suck back' when applying to control the speed it is dispensed at. Again - when you get used to it, that's fine but some will be frustrated by such a simple yet irritating issue!

#2. Delcast Rosin Soldering Flux Paste 50G

Designed primarily for use in electrical soldering but also passable for copper style work, this flux paste is best applied liberally but fret not - this 50g pot will last a good while. it does a good job cleaning and preventing oxidation, and despite being easy to use most certainly does leave a strong and reliable bond.

While not the most popular style of soldering, it can also be used as a wetting agent - but consider that application for short-term fixes instead of long-term solutions.

Overall, this is a quality addition to any soldering kit and will reward those who take time and care on their projects. It may seem a little untidy at first but in this case 'more actually is more'. Apply a good amount and you ought to see impressive results.

#3. AMTECH NC-559-V2-TF

This is a flux that is going to be a real crowd pleaser. Thanks to being slightly tacky - and of course viscous - the beauty of this product is that it doesn't dry as soon as your iron gets close but also doesn't run everywhere.

Used carefully - which the quality syringe application certainly does help with - and you will be as close as it gets to a guaranteed great finish. Residuals are easy

to brush away and there is absolutely no reason why you shouldn't end up with a smart, strong and tidy job.

Plenty of people consider this to be a real star performer and it is rare for a flux to be so widely appreciated. On the flipside, there are more economical choices out there but you can be assured here of genuine quality.

#4. MG Chemicals Liquid Rosin Flux

Here we have a perfect example of a super thin flux liquid - something which automatically may not be to everyone's taste - but please hear us out! Despite being thin, it is also rosin-based meaning that it is very sticky (and carries quite an odor).

You will want to keep this for inside only purposes as despite being thin it will harden pretty quickly if exposed to fresh air. This is because it is also used to increase friction as a secondary purpose.

Where this product really stands out from the crowd is when used with slightly worn or older materials. It has a natural cleaning property that can transform such connections, and remember that a little does stretch a long way. Overall it serves as an excellent flux for all kinds of indoor soldering.

#5. SRA Soldering Products PEN_RMA SRA #99-20

Here we have a real all-rounder. You can be assured that this flux can be used for all kinds of purposes, ranging from high tech computing/telecoms through to automotive and outdoor works.

Interestingly enough, it also happens to be the first ever environmentally friendly soldering flux thanks to being totally chloride free. Even after use, it leaves behind no unpleasant residue, making this a very dependable use for those who like to think green.

The pen style may be a little imprecise for some very intricate tasks, but taken overall it does serve as a quality flux that will serve well for 99% of jobs. Quite a few electricians have adopted this as their favorite flux for all kinds of jobs, as it is an easy clean product that is renowned for its reliability.

How to use soldering flux

Soldering various metals together is the best way of keeping them secure for an extended period, and soldering flux offers that by making the bond stronger. Despite being safe when not melted, soldering flux is very corrosive when hot. By knowing the type of soldering flux you would like to use, you can learn how to make soldering last for a long time. Therefore, in this article, we shall discuss how to use soldering flux.

#1. Having the right equipment

When it comes to having the right equipment there are various factors you will need to consider including:

  • Electrical soldering: When removing oxidation from a wire, you should consider using the rosin-based flux, which works best with electrical soldering. This flux is perfect for use with electronics since they are fragile and have thin wires which do not require a corrosive flux.
  • Pipe soldering: For pipe soldering, you will need something more corrosive, and the acid flux works perfectly. Always pipes that are made from copper will require acid flux or tinning flux since it helps in oxidizing a larger area.
  • Electronic: Working with delicate electrical wires can be challenging; that’s why leaded solder is the best flux for working with electronics. Leaded solder often melts at low temperature, which makes it perfect for delicate electrical wires.
  • Soldering pipes together: If you have a big soldering project which involves pipes, using silvered solder is the best due to its high melting point. When working with pipes that transport water do not use lead-based solder since it will lead to lead poisoning. However, working with lead-based solders is relatively easy, but it is not durable when compared to silvered based solder.
#2. Soldering wires using soldering flux

Here is how to use soldering flux in soldering wires:

  • Twisting together the exposed ends of a cable. You should overlap both ends and make a small cross symbol; then, you twist them together over and around each other. Afterward, continue wrapping the wires together till both ends are pushed down into the other wire. When doing this, you should make sure that there are no pointed ends; instead, you should have an intertwining pattern along the wire.
  • Coating wires using soldering flux. Use your finger or a small paintbrush in scooping a small amount of the soldering flux. Afterward, the area on the wire where you will be soldering should be spread with the flux. Furthermore, you should ensure that the cables are fully covered. Before soldering, wipe out the excess flux.
  • Melting the flux. Once the flux is evenly distributed on the cable, use the soldering cable on one side to melt the flux on the wire. You should ensure the soldering iron is hot before pressing it against the cord. When using the soldering gun, the wax will melt quickly into liquid and the cable. Continue holding the iron until the flux melts entirely before it starts producing bubbles.
  • Using solders to hold the wire together. As the iron is still pressing against the cord whole hot, press the solder’s tip on the opposite side of the cable. If the wiring is very hot, the solder will melt immediately as you continue pressing the wire. Before removing the iron, you should ensure that all the cables are well coated.
  • Let it cool. Once the cable is well coated, you should let the solder cool and harden. Taking the iron away from the welding will start the cooling process. The solder will solidify with a few seconds, and once it has set, there should be no wires exposed. Furthermore, the two wires should be firmly connected.


You really can't look past the AMTECH NC-559-V2-TF Solder Flux for scoring top marks on all categories. It is an all-rounder who can match the best of the rest at their own special characteristics. It is ideal for those totally new to soldering and will still be the top pick for people who have been using their iron for fifty years.

Notable mentions ought to go to a couple of others. Silver goes to the Delcast Rosin Soldering Flux Paste which is just as good for simple electric/circuitry work despite a couple of drawbacks. As for bronze, the MG Chemicals 8341 No Clean Flux Paste will serve experienced users who can keep up with the fast drying speed very well.

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