Zeolite Box Gas Recirculation for Stable Reflow Oven Atmosphere
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Solution Overview
Problem
The quality of soldered products in reflow soldering is unsteady due to difficulties in maintaining a consistent gas ratio in the reflow oven hearth, as existing separators fail to completely remove flux, leading to incorrect oxygen readings and sensor failures, and adding filters increases flow resistance.
Innovation Solution
A reflow oven design incorporating a zeolite box that further filters gases after separation, with zeolites in a polygon shape and an inner net cage to minimize resistance, connected to a nitrogen regulating system to maintain gas ratios, ensuring steady gas flow and protecting the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator is used to remove flux from gases, then the gas can be recovered and reused, but the separator cannot completely remove flux, leading to trace flux condensing at the sensor and causing incorrect readings or sensor failure
Solution Approach 1:
A zeolite box is introduced as an intermediary component between the separator and the sensor. The zeolite box further filters the gases that have already passed through the separator, removing residual flux components that the separator could not completely eliminate. This two-stage filtration approach protects the sensor from flux condensation while maintaining gas recovery functionality.
Solution Approach 2:
The gas filtration process is segmented into two distinct stages: first the separator removes the majority of flux, then the zeolite box removes residual flux components. This segmentation allows each component to specialize in a particular aspect of flux removal, with the separator handling bulk removal and the zeolite box handling trace removal, thereby protecting the sensor without compromising gas recovery.
2Reliability
If a filter device is added to remove residual flux, then the sensor is protected, but the flow resistance of gases in the filtering passage increases
Solution Approach 1:
Zeolite, a porous material with a three-dimensional framework structure containing aluminum oxide and silicon oxide, is used in the zeolite box. The porous structure provides extensive surface area for adsorption while maintaining relatively low flow resistance compared to traditional filter devices. The zeolite particles are arranged to allow gas flow through the interstices, achieving effective flux removal without significantly impeding gas flow.
Solution Approach 2:
The invention changes the filtration mechanism from mechanical filtering (which causes high flow resistance) to adsorption-based filtering using zeolite. By changing the working principle from physical barrier filtration to chemical adsorption, the system achieves effective flux removal while maintaining lower flow resistance, as the zeolite's porous structure allows gas molecules to pass through while adsorbing flux components on the internal surfaces.
3Reliability
If nitrogen is continuously input to maintain oxygen ratio below 8/10000, then soldering quality is guaranteed, but the cost increases due to high nitrogen consumption
Solution Approach 1:
The invention implements a gas recovery system where gases exiting the reflow oven hearth are not simply discarded but are instead directed through the separator and zeolite box for flux removal. The cleaned gases are then recirculated back to the hearth, maintaining the required oxygen ratio while significantly reducing nitrogen consumption. Only minimal nitrogen supplementation is needed to maintain the gas composition, rather than continuous large-volume nitrogen input.
Solution Approach 2:
An oxygen content detecting sensor is mounted between the output end of the separator and the hearth to continuously monitor the oxygen level in the recovered gases. The sensor provides feedback to a control system that adjusts the nitrogen supplementation amount, ensuring the oxygen ratio remains below 8/10000 while minimizing nitrogen consumption. This closed-loop control optimizes nitrogen usage while maintaining soldering quality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The zeolite box effectively removes residual flux, maintaining consistent gas ratios and preventing sensor failures, allowing precise control of nitrogen input to ensure stable soldering quality.
Implementation Method 1
a zeolite box, said zeolite box comprising a zeolite box inlet and a zeolite box outlet, said zeolite box inlet being connected to said separator outlet
Data Source
AI summary
The present application provides a reflow oven (100) and a gas recovery method. The reflow oven (100) comprises a reflow oven hearth (101), a separator (105), the separator inlet (110) being connected to the gas outlet (102) of the reflow oven hearth (101) so that the gases in the reflow oven hearth (101) can flow into the separator (105), a zeolite box (107), the zeolite box inlet (112) being connected to the separator outlet (111), and the zeolite box outlet (113) being connected to the gas inlet (103) of the reflow oven hearth (101) so that the gases flowing through the separator (105) can enter the zeolite box (107) and the gases flowing through the zeolite box (107) can flow out of the zeolite box outlet (113), a sensor (106), which is provided in the gas passage between said zeolite box outlet (113) and the gas inlet (103) of the reflow oven hearth (101). The reflow oven (100) in the present application enables the gases flowing through the separator (105) to enter the zeolite box (107). After most of the flux is removed from the gases in the separator (105), the flux is further removed in the zeolite box (107). In addition, polygonal zeolites have certain volumes and are supported in the zeolite box (107) to form clearances, and thus almost no resistance is brought about to the flow of the gases in the zeolite box (107).