With the application of reflow soldering technology, solder paste has become the most important process material in surface mount technology (SMT), and it has developed rapidly in recent years. In the reflow soldering of surface mount components, solder paste is used to connect the leads or terminals of the surface mount components to the pads on the printed circuit board. Solder paste coating is a key process of surface assembly technology, and it will directly affect the welding quality and reliability of surface assembly parts. Defects caused by solder paste account for 60%-70% of defects in SMT, so it is particularly important to have a thorough understanding of solder paste and standard and reasonable use of solder paste.

 

At room temperature, the solder paste can initially bond the electronic components to the predetermined position. When heated to a certain temperature, as the solvent and some additives volatilize, the alloy powder melts, so that the soldered components and the pad are connected together. , Cooling to form a long-term connection solder joints. The requirement for solder paste is to have a variety of coating methods, especially good printing performance and reflow soldering performance, and stability during storage.

Solder paste (solder paste) is a paste formed by uniformly mixing solder alloy powder and stable flux in a certain proportion. During soldering, the leads or terminals of the surface mount components can be alloyed with the soldering pads on the printed circuit board. This kind of material is very suitable for the reliable soldering of the automated production of surface mount, and is a high-tech product of the current electronics industry.

 

     Applied to SMT solder paste printing station, through scraper, steel plate, printing machine and other carriers, the quantitative solder paste is accurately coated on the fixed-point solder pads (Pads) of the PCB, and maintains good viscosity (Tacky) , In order to complete the electrical and mechanical connection between the soldering pad and the part foot after the reflow.