Reflow soldering is an important process in the SMT production process. It mainly consists of temperature zones such as preheating, infiltration, reflow and cooling, which can determine key issues such as whether the PCB board is deformed, whether cracks are formed, and whether there is cold soldering. The reflow soldering furnace temperature curve configuration should be appropriately adjusted according to the differences in reflow soldering machine models. The following are different reflow soldering processes:
1. Traditional reflow soldering
Traditional reflow soldering is still in use today and is the most common reflow soldering process. It melts the solder paste through the process of heating and cooling to form a bond between the components and the PCB board. The temperature setting of traditional reflow soldering is determined by the alloy melting point of the solder paste and the thermal conductivity of the components. It is divided into four temperature zones: heating zone, preheating zone, reflow zone and cooling zone. The temperature setting of the heating zone should be 2 to 4℃/second, the preheating zone is 130 to 190℃, the peak temperature of the reflow zone is set at 240 to 260℃, the melting time is 30 to 40 seconds, and the cooling zone rate is 4℃/second.
2. Infrared hot air reflow
Infrared hot air reflow soldering is the most commonly used reflow soldering process. It uses infrared hot air heating to melt the solder paste and achieve soldering between components and PCB boards. The temperature setting of infrared hot air reflow soldering needs to be tested based on the product. Only after the temperature setting is reasonable can batch reflow soldering operations be carried out.
3. Vapor phase reflow
Vapor phase reflow soldering equipment is not a mainstream surface mount soldering equipment. It heats the gas to melt the solder paste to achieve soldering between components and PCB boards. The temperature setting of vapor phase reflow soldering needs to be tested based on the product. Only after the temperature setting is reasonable can batch reflow soldering operations be carried out.
4. Laser reflow
Laser reflow soldering equipment uses optical fiber dispersed laser beam technology to achieve multi-point simultaneous soldering. It melts the solder paste through laser heating to achieve soldering between components and PCB boards. The temperature setting of laser reflow soldering needs to be tested based on the product. Only after the temperature setting is reasonable can batch reflow soldering operations be carried out.
5. Nitrogen filling reflow
Nitrogen reflow can prevent and reduce oxidation, improve welding wetting force and speed up wetting. It melts solder paste by filling nitrogen to achieve welding between components and PCB boards. The temperature setting of nitrogen reflow needs to be tested for the first piece according to the product. Only after the temperature setting is reasonable can batch reflow soldering operations be carried out.
6. Induction reflow
Induction reflow soldering uses a principle of inductive eddy current, but it is easy to make mistakes if the technology is not good enough. It melts the solder paste through induction heating to achieve welding between components and PCB boards. The temperature setting of induction reflow soldering needs to be tested for the first piece according to the product. Only after the temperature setting is reasonable can batch reflow soldering operations be carried out.
The above are different reflow soldering processes, each of which has its own advantages and disadvantages and needs to be selected according to specific production requirements and product characteristics.
