Tin spraying is a step and process in the PCB proofing process. The PCB board is immersed in a molten solder pool, so that all exposed copper surfaces will be covered with solder, and then the excess solder on the board is removed by a hot air cutter. remove. The soldering strength and reliability of the circuit board after spraying tin are better. However, due to its process characteristics, the surface flatness of the tin spray treatment is not good, especially for small electronic components such as BGA packages, due to the small welding area, if the flatness is not good, it may cause problems such as short circuits.

advantage:

1. The wettability of the components during the soldering process is better, and the soldering is easier.

2. It can prevent the exposed copper surface from being corroded or oxidized.

shortcoming:

It is not suitable for soldering pins with fine gaps and components that are too small, because the surface flatness of the tin-sprayed board is poor. It is easy to produce tin beads in PCB proofing, and it is easy to cause short circuit for components with fine gap pins. When used in the double-sided SMT process, because the second side has undergone high temperature reflow soldering, it is very easy to re-melt the tin spray and produce tin beads or similar water droplets that are affected by gravity into spherical tin points that drop, causing the surface to be even more unsightly. Flattening in turn affects welding problems.

At present, some PCB proofing uses OSP process and immersion gold process to replace tin spraying process; technological development has also made some factories adopt immersion tin and immersion silver process, coupled with the trend of lead-free in recent years, the use of tin spraying process has been further limit.