The composition of lead-free solder paste is very complex, usually made by mixing metal solder powder, flux and other chemical additives evenly. Through a series of operations by the solder paste manufacturer, a milky mixture will be formed later. Solder paste will have a certain viscosity at room temperature. During the SMT patching process of the circuit board, the electronic components can be firmly adhered to a specific position. The factory does not collapse after the solder paste is patched during the SMT patching process. Stabilize electronic components.
During the secondary soldering process of reflow soldering, with the continuous volatilization of some solvents and additives in the solder paste, the solder paste will collapse slightly. Melted to form a strong metallurgical bond between the circuit board and the electronic components, thereby permanently connecting the soldered electronic components and the circuit board.
There is flux in the composition of lead-free solder paste. This material can not only remove metal oxides from circuit boards and electronic components, but also adhere to the surface of electronic components and circuit boards after melting, thereby preventing The two are oxidized twice, and the flux component in the lead-free solder paste forms a liquid after melting, and can also achieve the effect of assisting heat conduction. The components in the flux can promote the melting of the metal components in the solder paste and wet the metal surfaces waiting to be soldered on circuit boards and electronic components. At the same time, it can also reduce the tension on the surface of the solder paste. The flux components in the lead-free solder paste not only play the above important roles, but also can be used as a carrier of metal alloy powder in the production process of Xinfujin solder paste manufacturers.
The main components of lead-free solder paste can be mainly divided into the above-mentioned: activator, thixotropic agent, resin and solvent, etc. Among them, the flux is also the activator. The choice of flux is very important, usually a good one Lead-free solder paste should have good wetting properties, thermal collapse resistance, and good bonding properties, which are mainly reflected by the composition of the flux.