Copper Etching Solution Recovery via Organic Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional acid etching solutions for printed circuit boards result in economic and environmental burdens due to low pH values and inefficient copper recovery, leading to the need for a method that can circulate and regenerate the etching solution to maintain a stable copper ion content and reduce chemical consumption.
Innovation Solution
An etching and recovery method that maintains a high copper content (90-260 g/l) and chloride content (100-350 g/l) in the etching solution, with a pH above 1.5, using a recovery process that involves mixing the etching solution with an organic extraction solution containing a complexing compound to form a copper complex, which is then separated and reused to restore the divalent copper ion content, and utilizing a pH-buffering acid-base pair to control the etching solution's composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional acid etching solution is used with low pH value, then etching process can be carried out, but hydrochloric acid consumption increases and environmental burden increases
Solution Approach 1:
The patent implements a recovery process that captures and regenerates hydrochloric acid from the spent etching solution. The system recovers HCl through chemical reactions involving copper ions and oxidizing agents, then returns the recovered acid to the etching process, thereby reducing net acid consumption and eliminating the need for continuous acid addition.
Solution Approach 2:
The patent employs a feedback mechanism where the concentration of copper ions and pH levels in the etching solution are continuously monitored. Based on this feedback, the system automatically adjusts the addition of oxidizing agents and copper salts to maintain optimal etching conditions while minimizing acid consumption. The recovery process is activated when copper ion concentration reaches a threshold, creating a self-regulating system.
2Productivity
If conventional acid etching solution is used, then etching can be performed, but copper recovery is inefficient and environmental burden increases
Solution Approach 1:
The patent converts the harmful effect of copper ion accumulation in the etching solution into a beneficial recovery process. The spent etching solution, which would normally be discarded as waste containing harmful copper ions, is instead fed to a recovery system that precipitates copper metal through reduction reactions. This transforms the environmental hazard into a valuable copper recovery stream.
Solution Approach 2:
The system recovers copper from the spent etching solution through a multi-step process involving pH adjustment, copper ion precipitation, and filtration. The recovered copper metal is then returned to the etching process or sold as a byproduct, eliminating the need to discharge copper-containing waste into the environment.
3Stability of the object's composition
If etching solution is circulated and regenerated, then copper ion content can be maintained, but process complexity increases
Solution Approach 1:
The patent divides the etching and recovery process into distinct operational modules: an etching chamber, a recovery unit, and a circulation system. Each module performs a specific function and can be operated independently. The recovery process is segmented into sequential steps (pH adjustment, precipitation, filtration) that can be performed in series or parallel depending on system configuration, making the overall complex process more manageable.
Solution Approach 2:
The patent designs the circulation system to serve multiple functions: it transports etching solution between chambers, monitors solution composition, triggers recovery operations when copper ion thresholds are reached, and maintains optimal pH levels. This multi-functionality reduces the need for separate dedicated systems for each function, thereby managing complexity while achieving stable copper ion content.
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
This method allows for the recovery of high-purity metallic copper, reduces hydrochloric acid consumption by up to 95%, and maintains a consistent etching rate by controlling the divalent copper ion content, while minimizing environmental impact and operational costs.
Implementation Method 1
mixing the etching solution with an organic extraction solution containing a complexing compound to form a copper complex
Implementation Method 2
mixing the etching solution with an organic extraction solution containing a complexing compound to form a copper complex, which is then separated
Implementation Method 3
an oxidising agent for oxidising said monovalent copper ions to divalent copper ions
Implementation Method 4
The use of a pH-buffering acid-base pair in the etching solution makes the extraction method advantageous from a technical and economical point of view
Implementation Method 5
etching chemicals including divalent copper ions for oxidising metallic copper to monovalent copper ions
Data Source
Figure 1
Figure 2
AI summary
An etching and recovery method is described, wherein articles made of copper are etched with an acid aqueous solution of etching chemicals containing Cu2+ for oxidising Cu0 to Cu+, chloride ions, oxidising agent which oxidises Cu+ to Cu2+, and pH-adjusting hydrochloric acid. The technical problem to be solved is to make it possible to circulate the etching solution between the etching process and the recovery process during the recovery of used etching solution in such a manner that a closed circuit can be maintained between the processes. This is effected in that a regenerated etching solution containing a lower quantity of Cu2+ than the used etching solution is produced and in that the recovery process has an extraction step in which removed etching solution is mixed with an organic extraction solution of a complexing compound with which Cu2+ forms a copper complex which can be extracted in the organic extraction solution, after which the two mixed liquids are separated once again in order to obtain an organic extraction solution containing said copper complex, and regenerated etching solution. The method is carried out with an etching solution having a pH above 1.5 and a high copper content.