In SMT processing, the quality of welding plays an important role in the performance and quality of the product. Because of this, the phenomenon of poor welding is very common in SMT processing. So, what are the main phenomena of poor welding? Next, Sanjing will give you an introduction.

1. There are holes on the surface of the solder joints: mainly caused by the excessive gap between the lead and the socket.

2. Pad peeling: Generally, the pad is peeled off from the printed circuit board after being exposed to high temperature. This bad solder joint is easy to cause the failure of component disconnection.

3. Asymmetry of solder distribution: Generally, it is caused by poor quality of solder and solder in PCBA processing, or insufficient heating.

4. There are voids in the solder joints: the main reason is that the lead is poorly infiltrated, or the gap between the lead and the socket is too large. The bad solder joints will not cause any problems in a short time, but the components are prone to open circuit failures over time.

5. Too much solder: It is mainly caused by the long residence time of the welding wire and the delay of removal.

6. Too little solder: It is mainly caused by the premature removal of the solder wire; the poor solder joint has insufficient strength and weak electrical conductivity, and it is easy to cause component disconnection failure by external force.

7. White solder joints: Generally, it is caused by too high temperature of the soldering iron or too long heating time.

8. The solder joints are sharpened: the main reason is that the electric soldering iron evacuates in the wrong direction during SMT processing, or the excessive temperature causes the flux to sublimate. This bad solder joint will cause a short circuit between the component and the wire.

9. Cold welding (the surface of the solder joints is like tofu slag): Mainly due to the insufficient temperature of the electric soldering iron, or the jitter of the solder before the solder solidifies, the poor solder joints have weak electrical conductivity, and the external force can easily cause the failure of the components to open the circuit.

In addition to the above, if the solder is heated too fast during the soldering process, it will cause the solder to scatter, splash on the PCB board, and finally form tin beads and tin dross, which will also cause poor soldering. Therefore, we should strictly control every detail that is easy to be overlooked when performing SMT welding.