Flux paste is a general term. Rosin and flux paste belong to flux paste. The most critical purpose is to increase the wetting effect of the solder and the material to be soldered during soldering (if the infiltration is not good, the flux paste cannot be well attached to the soldered material, which is easy to be cool soldered), and others such as removing oxidation, assisting heat conduction, reducing the surface tension of the metal, and making the solder joints beautiful and so on. Flux paste is divided into three categories: one is inorganic flux paste, the other is organic flux paste, and the third is rosin. Inorganic solder pastes are generally some acids or salts, such as orthophosphoric acid H3P04, and organic solder pastes are mainly some organic acids or organic halogens.

Solder paste

Relatively speaking, inorganic flux pastes have the strongest activity and the best oxide film removal effect, but are also highly corrosive, which can easily damage metals and solder joints, and generally cannot be used in soldering electronic products. Soldering paste is an inorganic soldering paste emulsified with engine oil. It can be cleaned with a solvent after soldering, but some parts of the circuit board with soldering paste are better cleaned.

The main components of rosin are rosin acid and pimaric acid, which are generally neutral. Liquid rosin has a certain activity and is weakly acidic. It can react with oxides on the metal surface to form compounds such as copper rosin acid, which are suspended on the surface of the solder. And when used, there is no corrosion, and the insulation is strong.

Generally speaking, rosin is the best raw material for soldering paste commonly used.

Difference and function:

Rosin: solid pine resin, the raw material for making flux.

Soldering paste: thick paste, the main components are isopropyl alcohol, rosin, organic acid, etc.; used for soldering parts of electronic circuit boards, removing oxides on pads, helping solder flow and expansion.

Solder paste: paste-like viscous body, the main components are metal powder, rosin, organic acid, thixotropic agent, active agent. Soldering for SMT automatic placement process. It is an upgraded substitute for flux and soldering process, with high automatic program and high welding precision.