Pinning Agent Coating EquipmentWhat performance requirements should flux meet?
① Deburring and Surface Purification Performance
Through physical and chemical action, the soldering flux should be sufficient to dissolve or break down the oxide film on the surface of the base material and the solder.
② Moisture and Protection Properties
Rosin flux should possess low surface tension, low viscosity, and good fluidity within the brazing temperature range, facilitating the wetting and spreading of the flux and molten filler on the base material surface. Additionally, the density of the flux and its reaction products should be less than that of the molten filler, allowing the flux to uniformly cover the filler and base material surface as a thin layer, effectively隔绝air and providing protective benefits.
③ Melting Performance
The melting point of the flux should be lower than that of the solder, with a minimal difference to ensure the flux effectively operates before the solder melts, removing the solder gap and the oxidation film on the material surface, preparing conditions for the wetting and spreading of the solder.
④ Heat Stability
The soldering flux should maintain the stability of its components and function during the heating process, preventing decomposition, evaporation, or carbonization of the flux components, which would otherwise result in the loss of its intended effect. Generally, the soldering flux is required to have a thermal stability temperature range of no less than 100°C.
⑤ Dreg Removal Performance
The density of the flux and its reaction products should be less than that of the molten solder to facilitate the expulsion of these materials from gaps during filling, preventing them from remaining in the solder joints to form inclusions. Additionally, the residue formed by the flux after brazing should be easily removable.
⑥ Corrosivity and Toxicity
Rosin flux and its residue should not have a strong corrosive effect on the base material weld seam, nor should they be toxic or release harmful gases during use.
Pin agents should possess reasonable economic viability.
On the basis of ensuring that the soldering paste has a series of performance characteristics, the paste should be easily accessible or easy to purchase, and offered at a lower price.
In fact, practical brazing fluxes do not always meet the aforementioned performance requirements, especially as there is often an insurmountable contradiction between the two functions: descaling ability and corrosion resistance. Typically, to meet the descaling ability requirements, process measures are employed to prevent or minimize its corrosive effects.
