In SMT processing, rosin, flux, flux paste, and solder paste
are all relatively common welding materials. With the continuous development of technology, people process substances with different components into a more useful material. Therefore, some People often confuse rosin, flux, flux paste, and solder paste.
Rosin is an early welding auxiliary material, which mainly helps to remove oxides on the pads in the welding of circuit board parts, which is conducive to the welding of solder.
Flux is also an auxiliary material for welding, but flux is composed of rosin, activator and some additives. It is processed on the basis of rosin. It has stronger performance and is easier to use than rosin. It is processed into a kind of Liquid, you can tell by its name.
3. Soldering paste
Soldering paste is a paste-like soldering substance prepared from raw rosin and special chemical substances. It is a substance that plays an auxiliary role in the soldering process and can remove the surface oxide of the pad. It is often used in BGA. Chip soldering, generally a substance that must be added to solder paste in the production process, is often used together with solder paste, or is used for soldering and repair welding after the patch is completed.
The main function of the flux paste is to remove the surface oxides. Because of the oxygen in the air, various substances are actually surrounded by a layer of oxides. During soldering, the oxide film will inevitably prevent the solder from wetting the base metal, and soldering cannot Therefore, it is necessary to apply flux paste on the surface of the base metal to reduce the oxide on the surface of the base metal, so as to achieve the purpose of eliminating the oxide film. On the other hand, the high temperature of soldering tends to oxidize the surface of the solder material, and the flux paste helps to prevent the oxidation process.
Another function of the flux paste is to reduce the surface tension of the material. The surface tension of the material will affect the quality of soldering. Another function of the flux paste is to reduce the tension of the material. The surface tension of the molten solder prevents it from flowing to the surface of the base metal, preventing normal wetting. When the flux covers the surface of the molten solder, the surface tension of the liquid solder can be reduced, so that the wetting performance is significantly improved.
4. Solder paste
Solder paste is a paste-like mixture formed by mixing solder powder, flux and other surfactants, thixotropic agents, etc. It is a new type of welding material that came into being with SMT, and is mainly used for the welding of electronic components such as PCB surface resistance, capacitors, and ICs in the SMT industry.
Rosin, flux, solder paste and solder paste have different raw materials, their respective properties are also different, and their melting points are also different. When choosing a product, you must understand its properties and functions before deciding which product to use.