What is HASL PCB
Hot air solver leveling is a step and process flow in the production process of PCB board. Specifically, the PCB board is immersed in the molten solder bath, so that all exposed copper surfaces will be covered by solder, and then the excess solder on PCB board will be removed by hot air cutter. Because the surface of the circuit board after spraying tin is the same material as the solder paste, the welding strength and reliability are better. However, due to its processing characteristics, the surface flatness of tin spraying treatment is not good, especially for small electronic components such as BGA package type, due to the small welding area, poor flatness may cause short circuit and other problems, so a process with better flatness is needed to solve the problem of tin spraying board. Generally, the ENIG process (note that it is not gold plating process) is selected, and the principle and method of chemical displacement reaction are used for reprocessing, and Au thickness of 0.03 ~ 0.05 um or Ni thickness 6 um is added to improve the surface smoothness. There are two kinds of tin spraying boards: one is lead HASL PCB, the other is lead-free HASL PCB.
1. During the welding process of components, the wettability is better and soldering tin is easier.
2. It can avoid corrosion or oxidation of exposed copper surface.
1. The flatness in the vertical plane is poor, which is not suitable for the welding and use of fine pitch components. The flatness can be improved by adding horizontal layer.
2. High thermal stress in the process of treatment may damage PCB board and cause defects or defects.