Method for electrolysis reuse of alkaline etching waste liquid

Abstract

The invention provides a method for electrolysis reuse of alkaline etching waste liquid. The method comprises the following steps that (1) the alkaline etching waste liquid or mixed liquid of the alkaline etching waste liquid and a reducing agent serves as anode electrolyte to be added into an anode region, and the mixed liquid of the alkaline etching waste liquid and the reducing agent serves ascathode electrolyte to be added into a cathode region; (2) an electrolysis power supply is started for electrolysis operation, and metal copper is separated out on an electrolysis cathode; and (3) according to a specific alkaline etching process, ammonium chloride, ammonia, water and one or more of components contained in other alkaline etching liquid are added into anode liquid and / or cathode liquid after electrolysis operation in the step (2) to prepare regenerated alkaline etching sub-liquid capable of being reused on an alkaline etching production line. According to the method, the electrolysis copper separate-out efficiency can be improved, and the waste liquid can be prepared to form the regenerated alkaline etching sub-liquid capable of maintaining the ideal etching effect after electrolysis reuse.

Description

technical field [0001] The invention belongs to the technical field of post-treatment of etching waste liquid, and in particular relates to a method for electrolytic reuse of alkaline etching waste liquid. Background technique [0002] Etching is an important step in the existing printed circuit board (PCB) fabrication process. Etching refers to chemically removing unnecessary copper on the copper clad substrate with an etchant to form the desired circuit pattern. [0003] At present, commonly used etching solutions for circuit board production include acidic copper chloride etching solution and alkaline copper ammonium chloride etching solution (hereinafter referred to as alkaline etching solution). The main components of the alkaline etching solution are copper salts, ammonium chloride, ammonia water, water, optional carbonates, and optional additives; among them, the carbonates are usually ammonium carbonate and ammonium bicarbonate. In the actual production process, as...

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Problems solved by technology

[0014] Second, because the ammonia water itself is easy to volatilize and become ammonia gas to escape, and the ammonium ions in the electrolyte move to the cathode under the influence of the electric field attraction during the electrolysis process, resulting in the accumulation of ammonium ions near the cathode, resulting in an increase in the local ammonia concentration of the electrolyte. During the electrolysis process, the temperature of the electrolyte is higher than room temperature, which further promotes the volatilization of ammonia and wastes raw materials.

Therefore, the electrolyte near the anode is prone to low ammonia water content, so that there is not enough ammonia and copper ions in the electrolyte near the anode for complexation reaction, and it is difficult to form a soluble copper ammonium complex, so some copper ions It will precipitate in the form of copper sludge and settle on the bottom of the electrolytic cell or the slurry will stick to the anode, which increases the resistance of the electrolytic cell

In this case, electrolysis will increase the necessary electrolysis voltage between the cathode and anode, and waste electric energy.

[0015] Third, the return of the electrolyte after electrolysis to the alkaline etching production line will affect the etching quality: because the existing direct electrolysis method usually uses a large current to electrolyze copper in order to adapt to large-scale production, and the metal copper deposited on the cathode returns In the case of severe corrosion, the surface of the electrolytically deposited copper is very uneven, which intensifies the peak current effect and makes the current unstable, which in turn leads to the rough and loose metal copper layer deposited by electrolysis and easy to fall off.

However, the electrolytic solution after electrolysis contains a leveling agent. During the etching process, the leveling agent will adsorb the metal ions in the etching working solution and hinder the etching reaction, so the etching speed will be slowed down; therefore, if returning The use of alkaline etching production line will cause the etching speed to slow down and affect the quality of etching production

[0017] Therefore, the application of the existing alkaline etching waste direct electrolysis method is still difficult to popularize and promote, and no enterprise adopts the direct electrolysis method to regenerate the alkaline etching solution

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