Nitrogen closed loop system: Precise flow control and practical process improvement in low-oxygen environments

Development of nitrogen applications

In the early 1970s, nitrogen was found to be able to create an inert environment, effectively preventing the reaction with oxygen, and it was gradually used in the field of electronics manufacturing;
With the rise of surface mount technology (SMT) in the 1990s, welding quality and reliability were inseparable from low-oxygen environments, and manufacturers began to standardize the use of nitrogen in reflux processes.
Today, the trend of miniaturization and precision of electronic components continues to drive the demand for nitrogen applications, and nitrogen reflow has long been the preferred configuration in high-quality electronics manufacturing.

How to achieve accurate nitrogen flow control

The nitrogen closed loop system is an automated control system used to control the oxygen concentration range within the required PPM value during the welding process, ensuring a low or no oxygen environment in the welding.

▲ Write the PPM value to be controlled in the nitrogen setting interface
The control value is then written into the oxygen separator

▲ Proportional valve closed-loop system controls the nitrogen flowmeter
The nitrogen input can be adjusted without manual operation

The nitrogen closed-loop system effectively avoids nitrogen consumption and cost increase due to inaccurate nitrogen control flow rate. And frequent adjustment of welding parameters caused by rework, thereby reducing production efficiency.

▲ PPM change curve: When the input set value is 500
The control accuracy of the full closed-loop control sampling oxygen separator is effectively controlled within the range of ±50ppm

The actual process improvement brought about by low oxygen environment

In practical applications and tests, the following welding processes can be improved by using a nitrogen closed-loop system.

Finer crystal structure

The solder joint surface is bright

Reduce fine-pitch bridging

Reduce oxidizing spot welding

Cavity rate reduction

At present, the KT series reflow welding has realized the quantitative control of nitrogen in the whole process, and the independent closed-loop control of each temperature zone, so that the oxygen concentration range is controlled in 50-200ppm

▲KT full series nitrogen consumption diagram

The nitrogen closed-loop system significantly improves the stability and reliability of the welding process. We firmly believe that with continuous technological progress and process optimization, we can continue to maintain advantages in the fierce competition and provide customers with higher quality products and solutions.