The most important process in PCB circuit board processing during soldering plays a decisive role in the quality of the circuit board. So, what conditions must be met for PCB circuit board welding?
1. The weldment has good weldability
Solderability refers to the performance of an alloy that forms a good combination of the metal material to be welded and the solder at an appropriate temperature. In order to improve solderability, measures such as surface tin plating and silver plating can be used to prevent oxidation of the material surface.
2. The surface of the weldment must be kept clean
Even for weldments with good weldability, due to storage or contamination, it is possible to produce oxide films and oil stains on the surface of weldments that are harmful to wetting. Be sure to remove the dirty film before welding, otherwise the welding quality cannot be guaranteed.
3, to use the appropriate flux
The function of the flux is to remove the oxide film on the surface of the weldment. Different welding processes should choose different fluxes. When welding precision electronic products such as printed circuit boards, in order to make the welding reliable and stable, rosin-based flux is usually used.
4. The weldment should be heated to an appropriate temperature
When welding, the function of heat energy is to melt the solder and heat the welding object, so that tin and lead can obtain enough energy to penetrate into the crystal lattice on the surface of the welded metal to form an alloy. If the soldering temperature is too low, it is easy to form a virtual joint; if the soldering temperature is too high, the solder will be in a non-eutectic state, which will reduce the quality of the solder.
5. Appropriate welding time
Welding time refers to the time required for physical and chemical changes during the whole welding process. It includes the time for the metal to be welded to reach the welding temperature, the melting time of the solder, the time for the flux to function and the time for generating the metal alloy. When the welding temperature is determined, the appropriate welding time should be determined according to the shape, nature, and characteristics of the workpiece to be welded.
