PCB Tech - ​ How to avoid false welding in PCBA processing and welding?

How to avoid false welding and false welding defects in PCBA processing and welding as much as possible? Many technical friends know that if there are false soldering and false soldering defects in the PCBA soldering process, they are generally caused by various reasons, and the main reason is that the solder cannot fully infiltrate the pads and component pins, components and circuits The board pad cannot be fully soldered. In the production process, how can PCBA processing avoid false welding and false welding defects?

1. Moisture-proof storage of components

The components are placed in the air for too long, which will cause the components to absorb moisture and oxidize the components. As a result, the components cannot be fully removed from the oxide during the welding process, resulting in the defects of false welding and false welding. Therefore, during the welding process, the components with moisture should be baked and the oxidized components should be replaced. Generally, the PCBA processing plant will be equipped with an oven to bake the components with moisture.

2. Choose solder paste from well-known brands

The false soldering and false soldering defects that appear in the PCBA soldering process have a great relationship with the quality of the solder paste. The unreasonable configuration of the alloy composition and flux in the solder paste composition can easily lead to weak flux activation during the soldering process, and the solder paste cannot fully infiltrate the pad, resulting in false soldering and false soldering defects. Therefore, you can choose solder paste from well-known brands such as Senju, Alpha, and Victory.

3. Adjust printing parameters

The problem of false soldering and false soldering is largely due to the lack of tin. In the printing process, the pressure of the squeegee should be adjusted, and the appropriate steel mesh should be selected. The steel mesh opening should not be too small to avoid too little tin.

4. Adjust the reflow soldering temperature curve

During the reflow soldering process, it is necessary to control the soldering time. The time in the preheating zone is not enough to fully activate the flux and remove the surface oxides on the soldering area. If the time in the soldering zone is too long or too short, it will cause false Welding and false welding.

5. Try to use reflow soldering and reduce manual soldering

Generally, when using an electric soldering iron for manual soldering, the technical requirements of the soldering personnel are relatively high. The temperature of the soldering iron tip is too high or too low, or the soldered components become loose during soldering, which can easily cause false soldering and false soldering. Use reflow Welding can reduce man-made external factors and improve the quality of welding.

6. Avoid too high or low temperature of the soldering iron

In the post-welding processing and maintenance of PCBA welding, manual welding is required with an electric soldering iron. When using an electric soldering iron, improper operation causes the temperature of the soldering iron tip to be too high or too low, which can easily cause false soldering and false soldering. Therefore, when soldering, keep the soldering iron tip clean, choose different power types of soldering irons according to the size of different parts and solder joints, and device shapes, and control the soldering temperature between 300°C and 360°C.

The false welding and false welding caused in the PCBA welding process are caused by many factors. The above is just a list of some of the more common reasons. Through the above preventive measures, combined with the actual situation, the false welding can be effectively reduced. Welding defects with fake welding.