Cause of Problem And Solution in PCB Nickel Plating Process

This article lists the possible faults and troubleshooting methods that may occur during PCB nickel plating process.

1. Porkmark:

Porkmark is the result of organic pollution. Large porkmark usually indicate oil pollution. If the stirring is not good, the air bubbles cannot be expelled, which will form porkmark. Wetting agent can be used to reduce its impact. We usually call small porkmark as pinholes. Poor pre-treatment, metal quality, too little boric acid content, and too low bath temperature will all produce pinholes. Plating bath maintenance and process control is key, and the anti-pinhole agent should be used as a process stabilizer to supplement it.

2. Roughness and Burrs:

Roughness means that the solution is dirty, and it can be corrected by sufficient filtration (Extremely high PH will easily form hydroxide precipitation and should be controlled). The current density is too high, the anode mud and the impurity of the supplementary water will bring in impurities, which will cause roughness and burrs in severe cases.

3. Low Adhesion:

If the copper coating is not fully deoxidized, the coating will peel off, and the adhesion between copper and nickel will be poor. It will cause the nickel coating itself to peel off at the interruption point if the current is interrupted, also it will occur when the temperature is too low.

4. Brittle Coating And Poor Weldability:

When the coating is bent or worn to a certain degree, it will usually be exposed to be brittle. This indicates that there is organic or heavy metal pollution. Too much additives, entrained organics and electroplating resists are the main sources of organic pollution and must be treated with activated carbon. Insufficient additives and high PH will also affect the brittleness of the coating.

5. Dark Plating And Uneven Color:

Dark plating and uneven color indicate metal contamination. Because copper is generally plated first and then nickel is plated, the copper solution brought in is the main source of pollution. It is important to reduce the copper solution on the hanger to a minimum. In order to remove the metal contamination in the tank, especially the copper removal solution, a corrugated steel cathode should be used. At a current density of 2 to 5 A/sq. ft., 5 amperes per gallon of solution is plated for one hour. Poor pretreatment, poor low plating, too small current density, too low main salt concentration, and poor contact of the electroplating power circuit will all affect the color of the plating.

6. Coating Burns:

Possible reasons for coating burns: insufficient boric acid, low metal salt concentration, low working temperature, high current density, high PH or insufficient stirring.

7. Low Deposition Rate:

Low PH or low current density will cause low deposition rate.

8. Blistering or Peeling of The Coating:

Poor pre-plating treatment, excessively long intermediate power-off time, organic impurities pollution, excessive current density, low temperature, high or low PH, and serious influence of impurities will cause blistering Or peeling phenomenon.

9. Anode Passivation:

The anode activator is insufficient, and the anode area is too small and the current density is too high.