How to divide the temperature zone of reflow soldering

Reflow soldering is a widely used soldering technique in the electronic manufacturing industry, used to solder electronic components onto printed circuit boards (PCBs). The temperature zone division of reflow soldering equipment is set according to the different temperature requirements at different stages of the welding process. Although the number of temperature zones for reflow soldering equipment produced by different manufacturers may vary, they generally follow the four main stages of preheating, constant temperature, welding, and cooling.

Reflow soldering equipment ranges from small reflow soldering in three temperature zones to large reflow soldering in more than ten temperature zones, mainly to meet the needs of PCB boards of different sizes and complexities, as well as different soldering requirements. The more temperature zones there are, the larger the area of each temperature zone, which provides greater assurance for controlling temperature distribution, ensuring the stability and reliability of welding quality. However, selecting an appropriate number of temperature zones is not just about the equipment itself, but more importantly, it should be determined based on the characteristics of the product and welding requirements.

The four main temperature zones of reflow soldering are:

1. Preheating zone: PCB boards and materials (components) are preheated in this area to achieve thermal equilibrium, solder paste begins to flow, and components such as flux begin to evaporate in an appropriate amount. The temperature gradually rises during this stage, preparing for subsequent welding.

2. Constant temperature zone: This area is further heated to reach the melting point of the solder paste and begin to dissolve. At this point, the oxides on the PCB board and components are removed, and the welding preparation is more thorough.

3. Welding area: The solder paste completely dissolves and forms a weld with PAD. The temperature control in this area is crucial to ensure that the solder joints are completely and uniformly formed.

4. Cooling zone: After welding is completed, the PCB board enters the cooling zone to quickly cool and solidify the solder joints, forming a stable welding structure.

In practical applications, the temperature zone setting of reflow soldering equipment needs to be adjusted according to specific welding processes and product requirements to ensure optimal welding quality.