Reflow soldering is a production process with many applications of SMT technology. It's mainly suitable for the soldering of surface mount components and printed boards. 

By remelting the paste solder pre-allocated on the printed board pads, the solder ends or pins of surface mount components can be connected to the printed board and micro-welding can be achieved. Soldering of mechanical and electrical connections between the pads on the board, so as to realize the circuit function with certain reliability. 

The main process characteristics of reflow soldering as belows:

1. Reflow soldering does not require the components to be directly immersed in molten solder like wave soldering, 

    so the thermal shock to the components is small;

2. Reflow soldering only applies solder on the required parts, which greatly saves the use of solder; 

3. Reflow soldering can control the amount of solder applied and avoid defects such as bridging; 

4. When the component placement position is deviated, due to the surface tension of the molten solder, 

    as long as the solder placement position is correct, the reflow soldering can automatically correct this small deviation

 so that the components can be fixed in the correct position.