When it comes to PCBA processing technology flow, factors that cannot be overlooked include the assembly density of PCBA components and the equipment conditions of the SMT production line. PCBA, which stands for Printed Circuit Board Assembly, involves the entire process of SMT mounting followed by DIP insertion. The choice of the process flow mainly depends on the assembly density of PCBA components and the equipment conditions of the SMT production line. When the SMT production line is equipped with both reflow soldering and wave soldering equipment, it is advisable to prefer reflow soldering for its advantages over wave soldering.
Reflow soldering does not require components to be directly immersed in molten solder, resulting in less thermal shock. By applying solder paste only to the solder pads, users can control the amount of solder, thereby reducing soldering defects such as solder bridges and voids, leading to higher reliability. Reflow soldering exhibits a self-aligning effect, where if the component placement deviates slightly, the surface tension of the molten solder automatically pulls it back to the approximate target position when all solder joints or pins are wetted simultaneously with the corresponding solder pads. Generally, impurities are less likely to mix into the solder, and when using solder paste, the composition of the solder can be accurately controlled.
Selective heating sources can be used, allowing different soldering processes to be applied on the same substrate. The process is simple, requiring minimal rework, thereby saving labor, electricity, and materials. Under typical mixed assembly conditions, when SMC/SMD and THC are on the same side of the PCB, solder paste is printed on side A followed by reflow soldering, while wave soldering is used on side B. When THC is on side A of the PCB and SMC/SMD are on side B, adhesive dispensing and wave soldering processes are adopted. For high-density mixed assembly, especially when there are few or no THC components, double-sided solder paste printing followed by reflow soldering can be used, with THC components being attached afterward. In cases where side A has a significant number of THC components, the processing sequence for PCBA involves solder paste printing on side A followed by reflow soldering, and adhesive dispensing, curing, and wave soldering on side B.
