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Fluxes Fluxes
Component soldering flux
Component soldering flux

Component soldering flux

Flux is an indispensable auxiliary material in the SMT welding process. In wave soldering, flux and solder are used separately, while in reflow soldering, flux is an important component of solder paste. The quality of welding effect is not only related to the welding process, components and PCB quality, but also to the selection of soldering flux.

Unibright Component soldering flux characteristic

1. Remove oxides from the welding surface to prevent re oxidation of the solder and welding surface during welding, and reduce the surface tension of the solder.

2. The melting point is lower than that of solder, and before the solder melts, the flux needs to melt first in order to fully exert its soldering effect.

3. The viscosity and specific gravity are smaller than those of solder, which makes it difficult to infiltrate and diffuse. If the specific gravity is large, it cannot cover the surface of solder.

4. During welding, there is no spatter of welding beads, no toxic gas, and no strong irritating odor.

5. The residue after welding is easy to remove and has characteristics such as non-corrosions, non hygroscopicity, and non-conductivity.

6. Non stick, will not sticky to hands after welding, and solder joints are not easy to tip.

Component soldering flux application

1. The flux should have an appropriate active temperature range. It starts to function before the solder melts and effectively removes the oxide film and reduces the surface tension of the liquid solder during the welding process. The melting point of the flux should be lower than the melting point of the solder, but it is not easy to have a significant difference.


2. Fluxes should have good thermal stability, with a general thermal stability temperature not less than 100 .


3. The density of the flux should be less than that of the liquid solder, so that the flux can evenly spread on the surface of the welded metal, covering the solder and the surface of the welded metal in a thin film shape, effectively isolating air and promoting the wetting of the solder on the base metal.


4. The residue of the flux should not be corrosive and easy to clean; Toxic and harmful gases should not be released; It is necessary to have water-soluble resistance and insulation resistance that comply with the regulations of the electronic industry; No moisture absorption, no mold production; Stable chemical properties and easy storage.


Other precautions:


1. During the process of using flux, due to long-term contact with air, the flux will oxidize and absorb water vapor in the air, causing changes in flux concentration and resulting in a decrease in concentration. Attention should be paid. So, in daily life, it is important to promptly close the bottle cap


2. The prepared soldering flux, due to prolonged storage time, can cause changes in the composition of the flux, deteriorate its activation performance, and affect welding quality. Therefore, soldering flux that has been stored for too long should not be used. It is necessary to regularly replace the soldering flux.


3. The insulation performance of soldering flux drops sharply at high temperatures exceeding 60 , causing the residue of soldering flux to have a significant impact on heating components (such as high-power transistors, resistors, etc.), and even causing short circuits. So, we need to do it. Clean thoroughly after welding.

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