Intaglio printing plate electroplating process - nickel plating process conditions
Release Time:
Jun 09,2017
The standardized management of electroplating processes for roller plating is a method for treating gravure substrates and an important means to extend the service life of gravure. However, due to the special relationship between electroplating theory and practice, each plate-making company relies on its own experience. When problems arise, they tend to treat symptoms rather than the root cause, leading to a variety of control methods without forming a scientifically sound and guiding process specification. This results in numerous issues during production, causing many rollers to require rework.
This article summarizes efforts to help some plate-making companies implement standardized management of electroplating processes, attempting to explore a set of practical control methods to effectively and stably improve electroplating quality.
The temperature of the nickel plating solution is generally controlled at 40°C ± 1°C. Increasing the temperature of the plating solution can enhance the solubility and conductivity of salts in the solution, accelerate the diffusion rate of nickel ions to the cathode, reduce the internal stress of the plating layer, and make the plating layer flexible and ductile. Additionally, higher cathodic current density can speed up deposition and increase the current efficiency of both anodes and cathodes. However, raising the temperature increases the evaporation of the plating solution, and nickel salts are also prone to hydrolysis, forming nickel hydroxide precipitate. Particularly, if iron impurities in the plating solution hydrolyze, they produce iron hydroxide precipitate, which can lead to an increase in pinholes and burrs in the plating layer. Therefore, when using high-temperature and high-current density plating solutions, the amount of boric acid should be increased.
2. Cathodic Current Density
During the nickel plating process, the cathodic current density is closely related to temperature, nickel ion concentration, pH value, and stirring degree. Generally, when the solution concentration is high, the pH value is low, and accompanied by heating and stirring, a higher cathodic current density is permissible. Conversely, when both temperature and solution concentration are low, only a smaller cathodic current density can be used. In actual production, the plating current density is 3 to 4 A/dm².
3. Baume Degree (Be°)
For Baume degree, some companies specify 17 to 20, while others specify 20 to 22. Note that a high Baume degree can easily lead to the formation of pitting; in actual production, it should be strictly controlled within the optimal range.
4. Plating Time
The plating time is generally 15 to 20 minutes.
5. Anode in Nickel Plating Tank
The anode in the nickel plating tank is an electrolytic nickel plate.
Nickel Solution Purification Equipment
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