PCB board in the process of processing, there may be a lot of small problems, including plating stratification as we mentioned before. Today we'll take a look at another common problem -- tin beads. At the same time, we will bring the PCB board tin bead formation reason, for your reference.
When the PCB circuit board leaves the liquid solder, it is very easy to form tin beads. This is because when the PCB board and tin wave are separated, a tin column will be pulled between them. However, when the tin column is pulled off and falls back to the tin cylinder, the solder will sputter out, and the solder will fall on the PCB board to form tin beads. Therefore, when designing tin wave generator and tin cylinder, attention should be paid to reducing the falling height of tin. A small landing height helps reduce tin slag and tin splashing.
The second reason for the formation of tin beads is the release of volatile matter in PCB line plate and solder resistance layer. If there is a crack in the metal layer of the PCB through the hole, the gas from these substances will escape through the crack and form tin beads on the component surface of the PCB.
A third cause of tin bead formation has to do with flux. Flux may remain under components or between the PCB circuit board and the transporter (tray used for selective welding). If the flux is not sufficiently preheated and burns out before the PCB circuit board touches the tin waves, tin splashes and beads form. Therefore, the pre-heating parameters recommended by the flux supplier should be strictly followed.
This is the big three cause of solder ball on PCB board, small, of course, there are many other reasons can also cause the production of tin beads, but with the development of science and technology, the technical personnel in the face of tin beads have also started to have a lot of experience, these experiences can also quickly found a way to cope with the help of technicians, maybe that is the charm of science and knowledge.
