The Best Soldering Flux for Electronics


If you think solder is enough to bond wires and circuit boards, you’re missing an important factor. It turns out that oxidation can weaken solder. To prevent that, you should consider buying the best soldering flux for electronics.

Before we reveal our top picks, you’re probably curious why flux can prevent oxidation. Simply put, the main purpose of flux is to seal out air and remove oxidized sections from surfaces.

Without further ado, here’s the product we highly recommend for both novice and professional technicians:

Our Pick: SRA #135 Rosin Paste Flux

Perfect for repairing electronics, SRA #135 Rosin Paste Flux works efficiently with tin/lead as well as lead-free alloys. It is really handy because of its container shaped like a hockey puck.

As you can see, this soldering flux is labeled as the rosin or petroleum type. It doesn’t contain zinc ammonium chloride. And, the best part, it can produce a protective top layer all over the solder.

Runner Up: MG Chemicals 8341 No Clean Flux Paste

Because of its instant wetting feature, MG Chemicals 8341 No Clean Flux Paste guarantees high-quality fluxing. It also leaves rosin residue just like the first product. The result is a non-corrosive surface that’s resistant to fungus and moisture.

Whether you’re going to work with lead or a lead-free metal, this thixotropic paste is super-effective. Since safety should also be a priority, the quality of this product has managed to receive the RoHS Compliance Certification. That means it doesn’t contain harmful substances like hexavalent chromium and dibutyl phthalate.

Also Great: ChipQuik SMD-291 No Clean Flux

One of the worst things about removing components from a quad flat package (QFP), plastic leaded chip carrier (PLCC), small outline integrated circuit (SOIC) and chips is the cost of work. Thankfully, with ChipQuik SMD-291 No Clean Flux, you don’t have to spend a lot of money. All you need to do is use it with soldering irons or rework equipment.

Aside from having a top-notch wetting ability, this soldering flux has a low melting point. That’s why it’s safe and convenient for delicate parts.

Also Great: DIYPHONE Mechanic Solder Flux Paste

Practical for phone circuit board repairs, DIYPHONE Mechanic Solder Flux Paste has a low melting point, too. It is only a bit higher than the melting point of solders.

Contained in a convenient and durable aluminum jar, this pH-neutral substance ensures a high level of bonding strength. It will also make the surface smooth and insulated for a safer, more effortless work.

Also Great: La-Co 22101 Regular Soldering Flux Paste

With the water-soluble properties of La-Co 22101 Regular Soldering Flux Paste, it won’t produce residues in water piping. Other than the fact that it meets the standards of ASTM B813, it doesn’t contain zinc chloride as well to prevent corrosion.

Effective for any weather condition, this soldering flux is ideal for different climates. It can withstand the environment’s hot or cold temperature.

Additionally, this non-toxic substance isn’t acidic. It is also lead-free to remain safe. It automatically cleans pipes for easier application of solder.

Budget Pick: MISOL Soldering Rosin Flux Pen

Convenience is the best thing about MISOL Soldering Rosin Flux Pen. Yes, it is the most affordable one here, but being a no-clean flux in a handy design seals the deal. You just have to push the tip to make the substance flow.

With careful use, this 10-milliliter flux pen can last for a couple of years. Simply store it in a place with a temperature of more or less 25 degrees Celsius. And, never forget to keep the cap on during storage.

How to Use the Best Soldering Flux for Electronics

Not everybody knows how to handle a rosin paste flux. Some people prefer liquid flux and other variations. To expand your knowledge about the rosin paste type, we’re here to explain how to use products similar to the best soldering flux for electronics. Check out the following steps:

  1. Remove paint, grease, rust, or dirt from the surface by rubbing steel wool, wire brush, or sandpaper on it.
  2. Wipe the surface with a rag soaked in isopropyl alcohol to remove the residues.
  3. Apply the soldering flux on your target areas with a toothpick or other similar objects (you may also dip components directly into the paste).
  4. Heat the surface with a soldering iron.
  5. Melt the solder.
  6. Remove the soldering iron.
  7. Wait for the surface to cool down.
  8. Wipe the surface with a clean rag if there are residues.

How to Choose the Right Soldering Flux for Your Project

Is rosin paste really the right type of soldering flux for your task, skill level, and personal preferences? Let’s find out by learning more about the following variations:

  • Rosin Flux

Before we proceed to the benefits of rosin flux, we should understand first its composition. It is basically natural resin from pine trees. However, not all products have pure rosin.

Rosin flux is classified into three subtypes – R, RMA, and RA. If the label simply says “rosin flux,” that means the product is made of 100% rosin. That’s enough for clean surfaces.

Meanwhile, rosin mildly activated (RMA) flux is active enough to remove some impurities on solder-coated surfaces. It is ideal for mild repairs.

On the other hand, rosin activated (RA) flux is the strongest one. It produces more residues than the other two because it cleans sections thoroughly.

Regarding availability, rosin flux is usually in the form of a paste. It is typically contained in pocket-sized jars and syringes.

  • Organic Acid Flux

Also referred to as water-soluble flux, it contains natural substances just like the rosin type. To be honest, it guarantees better performance than rosin flux because of its wetting ability. However, it can be too aggressive for novice technicians.

Using organic acid flux requires meticulous cleaning of the components. If you fail to ensure this, you have to deal with flux contamination.

This particular type of flux is generally formulated to be a liquid substance. It can even be contained in special pens, which is more convenient for repairing mobile phones and other devices with small circuit boards.


We believe that the top product should be safe and convenient for both beginners and pros. That’s why we chose SRA #135 Rosin Paste Flux as the best soldering flux for electronics. It can keep surfaces resistant to corrosion for years.