SMT reflow soldering is a commonly used electronic assembly process for soldering electronic components to a PCB. The process mainly involves different functional temperature zones, each of which has its own specific role.
The first, second, and third zones are known as the preheating zones. They are mainly used to heat electronic components and PCBs to the right temperature in advance to reduce the damage to components and materials caused by transient temperature changes, and also to help vaporize moisture on the surface of volatile components.
The fourth and fifth temperate zones are known as the dry zones. These two areas are cooler and are mainly used to remove residual moisture from components and PCBs, preventing bubbles or other quality issues during the soldering process.
The sixth temperature zone is the activation zone. The high temperature in this area activates the flux, giving it good wetting and solderability. The activation of the flux helps to improve the quality and reliability of the weld.
The seventh temperature zone is the welding zone. In this area, the electronic components and the PCB board are heated to a high enough temperature that the solder melts and reacts chemically with the components and plates, resulting in a solder connection.
The eighth temperature zone is the rapid cooling zone. After the welding is completed, the temperature of this area is rapidly lowered to reduce the thermal stress caused by the welding process and the stress inside the component, thereby increasing the reliability of the welded connection.
Finally, the ninth temperature zone is the room temperature air cooling zone. At the end of the soldering process, room temperature air cooling is used to quickly cool the solder joint, ensuring the stability of the solder joint and reducing the thermal impact on the surrounding components.
When setting the temperature of the SMT reflow zone, the temperature needs to be adjusted according to the specific soldering requirements and component type. The temperature of each temperature zone is controlled within a certain range to ensure the quality of the soldering and the reliability of the components.
The above is a brief description of each functional area of SMT reflow soldering, I hope it will be helpful to you.