What is solder flux? Things you need to know

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Solder flux is a very common active ingredient in soldering electronic circuits. Is this substance toxic? The article below will help you answer this question as well as learn all the information related to this substance.

Learn about fluxes


Solder flux is an electronic chemical commonly used in the soldering process. The main component of this substance is a mixture of turpentine or acid radicals, specifically as follows:

  • ZnCl2 – Zinc Chloride — accounted for 8-10%
  • NH4Cl, or ammonium chloride, accounts for 18–20% of the content.
  • H20 – Water accounts for more than 65% of the total.
  • Cleansing enhancer 2.5%
  • Heat-resistant strengthening agent accounts for 2.5%

Solder flux


Currently, flux is classified into 3 main types: alcohol-based (high VOC), water-based (VOC-free), and amphoteric (low VOC). Each type will have different characteristics, as follows:

  • Alcohol-based flux (alcohol-based, VOC): has a strong alcohol smell, is flammable and volatile at room temperature, and is not suitable for manual soldering.
  • Water-based flux (water-based, VOC-free): no alcohol smell; non-flammable at room temperature; low volatility; suitable for spot welding, dip welding, or new technology welding.
  • Flux amphoteric (low VOC) is a type that combines the characteristics of both water and alcohol bases.


In soldering electronic circuits, flux exhibits many effects, such as:

  • Clean and remove rust on the surface of components.
  • Anti-oxidation, limiting rust on the surface of components
  • Reduce the surface tension of joints, increase uniformity, help zinc adhere firmly thanks to the film created by flux, and reduce the maximum amount of zinc slag.
  • Create a beautiful shine for the weld.

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Answer the question: Is solder flux toxic?

Is flux toxic? is a question that receives a lot of attention today. As the composition table has been analyzed before, flux is made up of a mixture of many different active ingredients in certain proportions, such as ZnCl2, NH4Cl,… These substances, when added, will show different properties. Various uses such as cleaning, preventing corrosion, and protecting metal surfaces,… These are chemicals that are always toxic if accidentally splashed in the eyes or swallowed. However, under the condition of compliance with occupational safety and the necessary protective equipment, the use of flux is not dangerous to human health.

Solder flux

Normally, using flux when soldering electronic components will produce odors and smoke. Of course, this smoke is very toxic if inhaled. Therefore, factories will treat this smoke by installing smoke extraction and air filtration systems. At the same time, choose fluxes that do not contain halogen in the composition to reduce the lack of harmful gases.

View more: Solder Flux

Address to provide genuine, quality standard solder flux

To get a beautiful, shiny weld, solder flux is indispensable. But it must be a genuine solder flux that meets quality standards to achieve the desired welding results. Understanding the importance of this active ingredient, businesses always want to find a reputable product supplier with a good price. If you still cannot find a satisfactory supplier, you can come to TheTech. This is the address for supplying electronic materials and chemicals that have been trusted by many businesses for many years.

Solder flux

The products provided by us all have invoices and documents proving their origin clearly. The tech always buys goods directly from the manufacturer, without intermediaries, so it can ensure product quality for customers.

In addition, The tech also has attractive discounts for customers when buying in bulk. At the same time, we also support delivery to the location of the customer needs it. Above are the answers related to the question of whether flux is toxic. I hope this article has provided you with useful information. If you need to learn more about flux products, contact The tech immediately for more specific advice!

View product: Liquid Solder flux

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