Intaglio printing plate electroplating process - Copper plating: The main components of the copper plating solution!
Release Time:
Jul 07,2017
Gravure printing electroplating process - Copper plating: The main components of the copper plating solution!
Gravure electroplating uses sulfate copper plating, with the basic components of the plating solution being copper sulfate and sulfuric acid. Copper sulfate provides copper ions in the plating solution, while sulfuric acid helps prevent the hydrolysis of copper salts, improves the conductivity of the plating solution, and reduces cathodic polarization. Due to the high current efficiency of the plating solution (close to 99%), a thicker plating layer can be achieved. Of course, the purity and stability of various chemicals must be ensured. The main components of the copper plating solution are as follows:
(1) Copper sulfate (CuSO4·5H2O)
Blue crystals, with particle sizes like rice grains, should be as free of yellow as possible, and industrial grade is acceptable. Depending on production conditions and different requirements, some companies specify copper sulfate content as 200-250g/L, some as 210-230g/L, and others as 180-220g/L. Low copper sulfate content results in low allowable working current density and low cathodic current efficiency. The increase in copper sulfate content is limited by its solubility, and in electroplating, as the sulfuric acid content increases, the solubility of copper sulfate correspondingly decreases. Therefore, the copper sulfate content must be below its solubility to prevent precipitation.
(2) Sulfuric acid (H2SO4)
significantly reduces the resistance of the plating solution and prevents the hydrolysis precipitation of copper sulfate. Its chemical reaction formula is as follows: CuSO4+2H2O==Cu(OH)2+H2SO4 If a smell like ammonia is emitted, there is a problem. If the concentration of the bath solution is not appropriate, monovalent copper ions (Cu+) will be produced, causing pitting and pinholes on the copper plating surface. When sulfuric acid content is low, the plating layer is rough, and the anode is passivated. Increasing sulfuric acid content can improve uniform plating ability, but some brighteners are prone to decomposition. Some companies specify its content as 40-60g/L, some as 55-65g/L, and others as 60-70g/L. Some companies control the copper sulfate content at 180-270g/L and the sulfuric acid content at 55-65g/L, achieving very good results, making the copper layer reach optimal hardness and extending the storage period. At a temperature of 15°C, the corresponding relationship between copper sulfate + sulfuric acid content and Baume degree is shown in the table.
(3) Chloride ions (Cl-)
) are obtained by adding a small amount of hydrochloric acid. Chloride ions are an essential non-polar anion in acidic bright copper plating. Without chloride ions, an ideal bright copper layer cannot be obtained, but excessive chloride ion content can cause pitting on the copper layer and affect brightness and smoothness, and should be used according to the requirements of the additives.
Gravure electroplating additives, it is recommended to use the KY-Z series of acidic fast electroplating hard copper process imported from Japan by Maituo Company.,推荐使用脉拓公司的日本原装进口酸性快速电镀硬铜工艺KY-Z系列。
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