Problems And Troubleshooting Methods During PCB Nickel Plating:
1 Plating Burn
Possible causes of coating burns: insufficient boric acid, low concentration of metal salts, too low working temperature, too high current density, too high pH or insufficient stirring.
2. Low Deposition Rate
Low pH or low current density can result in low deposition rates.
If the copper coating is not activated and deoxidized, the adhesion between copper and nickel will be poor, and the coating will peel off. If the current is interrupted, it may cause the nickel plating to peel off. If the temperature is too low, peeling will also occur.
3 The coating is brittle and has poor solderability.
When the coating is bent or subjected to some degree of wear, the brittleness of the coating is usually revealed, which indicates the presence of organic or heavy metal contamination. Too many additives will increase the organic matter and decomposition products entrained in the coating, which is the main source of organic pollution, which can be treated with activated carbon. Heavy metal impurities can be removed by electrolysis and other methods.
4. The coating is dark and uneven in color.
Darkening of the coating and uneven color indicate metal contamination. Because copper is usually plated first and then nickel is plated, the copper solution brought in is the main source of pollution. It is important to minimize the copper solution on the hanger. In order to remove the metal pollution in the tank, the corrugated steel plate is used as the cathode, and the electrolytic treatment is carried out under the current density of 0.12-0.50A/dm2. Poor pretreatment, poor bottom coating, too low current density, too low main salt concentration, and poor conductive contact will affect the color of the coating.
5. Coating Blistering or Peeling
Poor pre-plating treatment, too long interruption time, organic impurity pollution, too high current density, too low temperature, too high or too low pH value, and serious influence of impurities will cause foaming or peeling.
6 Anode Passivation
The anode activator is insufficient, the anode area is too small, and the current density is too high.
7 Hemp Pit (Pinhole)
The pits are the result of organic pollution. Large hemp pits usually indicate oil contamination. Poor agitation fails to dislodge the air bubbles, which creates pits. Wetting agent can be used to reduce its influence. We usually call small pits as pinholes. Poor pretreatment, metal impurities, too little boric acid content, and too low bath temperature will cause pinholes. Therefore, bath maintenance and strict control of the process is the key.
8 Rough (Burr)
Roughness means that the solution is dirty, which can be corrected by full filtration. If the pH is too high, it is easy to form hydroxide precipitation and should be controlled. If the current density is too high, the anode slime and the supplementary water are impure and bring in impurities, which will produce roughness (burrs in severe cases). ).
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