Generally speaking, standard SMT reflow soldering is also the eight-temperature zone reflow soldering. Of course, there are SMT reflow soldering machines with any temperature zones in actual use. And this is based on the actual soldered products and the actual consideration of SMT processing manufacturer. Overall, the more SMT reflow soldering temperature zone, the better the soldering effect. If the soldering quality requirement is relatively high for the circuit board, many manufacturers use SMT reflow with ten temperature zones and twelve temperature zones. Usually, the common SMT reflow soldering on the market is the SMT reflow soldering with eight temperature zones.
The temperature zone of lead-free solder paste SMT reflow soldering is generally divided into preheating zone, constant temperature zone, soldering zone and cooling zone. So what are the differences between these temperature zones? What are their respective temperature standards?
1. Preheating zone: It takes about 100S for the preheating zone heat up to 175 degrees, so that the heating rate of the preheating zone can be obtained.
2. Constant temperature zone: The high temperature in the constant temperature zone is about 200 degrees, and the time to reach the temperature is 80S. The difference between high temperature and low temperature is 25 degrees.
3. Reflow zone: The high temperature of the reflow zone is 245 degrees, the low temperature is 200 degrees, and the time to reach the value is about 35S; the heating speed of the reflow zone is: 45 degrees/35S=1.3 degrees/S.
4. Cooling zone: In cooling zone, It takes about 100S for the temperature drops from 245 degrees to about 45 degrees, and the cooling speed is 2 degrees / S.
SMT reflow soldering eight-temperature zone temperature setting: 160°C in the first zone, 180°C in the second zone, 185°C in the third zone, 185°C in the fourth zone, 210°C in the fifth zone, 250°C in the sixth zone, 275°C in the seventh zone, and 250℃ in the eighth zone. The temperature settings of these temperature zones also need to be adjusted according to the reference temperature curve value given by the solder paste manufacturer and the actual production situation.
In fact, the temperature setting of the eight-temperature zone of SMT reflow soldering is not fixed, it can also be flexibly adjusted, but the adjustment needs to be determined according to the quality of the SMT solder paste, the actual soldered products and the SMT reflow soldering machines. Therefore, for the temperature zone standard of SMT reflow soldering, this article is only for reference of general setting.