Nitrogen closed-loop control method and system

Abstract

The invention provides a nitrogen gas closed-loop control method and a system which are used for adjusting the oxygen concentration in the hot zone of each unit requiring nitrogen protection in a reflow soldering furnace. An oxygen content analyzer is used for the on-line detection of the oxygen content of the gas inside the reflow soldering furnace; and a PID adjustor periodically adjusts the opening degree of a proportional control valve based on the closed-loop feedback, thereby controlling the nitrogen flow. The control method and the system can automatically detect the gas environmental conditions inside the reflow soldering furnace, automatically control the oxygen concentration in each hot zone inside the reflow soldering furnace, ensure that the oxygen concentration reaches the desired preset value as quickly as possible, and maintain the oxygen concentration at the preset value. The control method and system have the advantages of stable soldering environment, high soldering quality, low nitrogen consumption and low production cost.

Description

technical field [0001] The invention relates to the field of reflow soldering furnaces, in particular to a method for controlling the oxygen concentration value of each unit in the reflow soldering furnace that needs nitrogen protection, in particular to a nitrogen closed-loop control method and system. Background technique [0002] Currently, reflow ovens are used for surface soldering of printed circuit boards. During production, electronic components are pressed into a paste that is a mixture of flux, goo, adhesives and other components. The adhesive in the solder paste holds the component on the printed wiring board. In the reflow oven path a conveyor carries the printed circuit board and the electronic components through zones of the reflow oven with different temperatures, each zone performing a specific step in the reflow process, including preheating, holding, reflow and cooling zones , the solder paste melts to solidify to form a finished electronic circuit. The ...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to solve the problems of large nitrogen consumption, high production cost, and poor reliability of oxygen concentration adjustment in the existing reflow soldering furnace that needs nitrogen protection in the oxygen concentration control method of each unit. The analyzer periodically samples the oxygen concentration in the reflow area of ​​the furnace, and performs PID adjustment through the proportional, integral, and differential regulators to control the nitrogen closed-loop control method and system of the oxygen concentration in each temperature zone in real time, so as to meet the requirements of the actual product. Temperature profile and satisfactory soldering effect

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