Characteristics of the Flux Used in Soldering in PCBA Processing

In PCBA processing, flux is a necessary processing raw material, and the soldering process requires flux to play an important role, and it will directly affect the quality of chip soldering. Soldering is the main process in electronic assembly. Flux is an auxiliary material used during soldering. The main function of flux is to remove oxides on the surface of the solder and the base material to be soldered, so that the metal surface can achieve the necessary cleanliness. It prevents the re-oxidation of the surface during soldering, reduces the surface tension of the solder, improves the soldering performance, and the performance of the flux directly affects the quality of electronic products.

The main component of the flux is rosin, which will be decomposed by tin at about 260 degrees Celsius, so the temperature of the tin bath should not be too high. The flux is a chemical substance that promotes soldering. In solder, it is an indispensable auxiliary material, and its role is extremely important. The flux has the following characteristics:

1. It is stable in storage at room temperature.

2. Non-stick property, hands will not stick after welding, and the solder joints are not easy to sharpen.

3. The residue after welding is easy to remove, and has the characteristics of non-corrosion, non-hygroscopicity and non-conductivity.

4. No welding bead splashing, poisonous gas and strong irritating odor will be produced during welding.

5. Wetting and spreading speed is faster than melting solder, and it is usually required to expand by about 90% or more. 

6. the melting point is lower than that of solder. Before the solder is melted, the flux must be melted first to give full play to the role of soldering.

7. Viscosity and specific gravity are smaller than solder. The high viscosity makes it difficult to infiltrate and spread, and the high specific gravity cannot cover the solder surface.

8. Remove oxides on the soldering surface to prevent re-oxidation of the solder and soldering surface during soldering and reduce the surface tension of the solder.

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