A Complete Solution to the Formation of Tin Beads on PCB

When PCB boards are processed, there may be many small problems, including the electroplating layering we mentioned earlier. Today, let's learn about another common problem - tin beads. At the same time, it will also give you the reasons for the formation of PCB solder beads for your reference.

When PCB leaves liquid solder, it is very easy to form solder beads. This is because when the PCB board and the tin wave are separated, they will be pulled into a tin column. However, when the tin column is pulled off and falls back into the tin cylinder, solder will splash out, and the solder will fall on the PCB board to form solder beads. Therefore, when designing the tin wave generator and tin cylinder, attention should be paid to reducing the falling height of tin. Small falling height helps to reduce tin slag and tin splashing.

The second reason for the formation of tin beads is the release of volatile substances in PCB circuit boards and solder mask layers. If there are cracks on the metal layer of the through-hole of the PCB, the volatile gas from these substances after heating will escape from the cracks and form tin beads on the component surface of the PCB.

The third reason for the formation of tin beads is related to the flux. Flux will remain under components or between PCB and carrier (pallet for selective welding). If the flux is not fully preheated and burned before the PCB contacts the tin wave, tin splashing will occur and tin beads will be formed. Therefore, the preheating parameters recommended by the flux supplier should be strictly followed.

These are the three main reasons for the production of tin beads on PCB. Of course, there are many other small reasons that can also lead to the production of tin beads. However, with the development of science and technology, technicians have begun to have rich experience in the production of tin beads. These experiences can also help technicians quickly find solutions, which may be the charm of science and knowledge.