- Managing Electroless Nickel Tank Composition and Control:
The composition of the bath solution for electroless nickel plating is typically proprietary to the supplier. However, it generally consists of nickel salt, reducing agent, and various organic additives. The pH level should be maintained between 4.6-5.2, and can be adjusted using lemon or ammonium water. When adjusting with ammonium water, it must be added slowly in small amounts and several times. The temperature of the bath should be kept above 80℃ to ensure a smooth progress of the nickel bath reaction. It’s important to monitor the phosphorus content, aiming for a range of 6-8% to maintain the proper corrosion resistance and solderability. Similarly, the Ni2+ content should be kept between 4.6-5.2g to ensure an optimal deposition rate and bath stability. Surface additives, such as complexing agents, accelerators, and stabilizers, should be monitored and adjusted as needed. Additionally, it’s recommended to heat the bath every 3-4 days, especially in summer, to maintain quality and activity, and prevent mold formation. Precipitation of the bath liquid can be prevented by treating the tank wall with nitric acid and ensuring clean auxiliary equipment. - Managing Chemical Gold Tank Ingredients:
The gold tank contains potassium aurous cyanide with a gold content of 63.8% and should maintain a pH range of 5.1-6.1. The gold plating process is based on the principle of potential displacement reaction, resulting in a fast deposition rate of 1-3µm thickness within minutes, followed by continued promotion of gold layer deposition. Continuous dissolution of nickel in the reaction causes an increase in nickel content in the gold tank. Once it exceeds 0.5y/L, it can affect the appearance and adhesion. For this reason, the gold tank should be changed every 3-4MTO to maintain optimal performance. Recommended maintenance schedules include changing the nickel tank twice and replacing the activation tank once, or changing the nickel tank twice and the activation tank once. It’s also suggested to change the activation slot twice and the gold slot once, or change the gold tank twice and the degreasing tank once. These strategies are based on long-term work experience and can serve as a reference for industry peers.
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Operating from China, WellCircuits stands as a top-tier manufacturer of premium PCBs & PCBAs.
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