Causes and Elimination of Faults in PCB Electroplating Nickel Process:
a) Makeng: Makeng is 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 pinholes. Poor pretreatment, poor metal quality, too little boric acid content and too low bath temperature will cause pinholes. And process control is the key, anti-pinhole agents should be added as process stabilizers.
b) Roughness and Burrs: Roughness means that the solution is dirty, which can be corrected by full filtration (the PH is too high to form hydroxide precipitation and should be controlled). If the current density is too high, the anode slime and the impure water will bring in impurities, which will cause roughness and burrs in severe cases.
c) 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. If the current is interrupted, it will cause the nickel coating to peel off at the interrupted place, and it will also peel off when the temperature is too low.
d) Coating Brittleness and Poor Weldability: When the coating is bent or subjected to some degree of wear, the coating is usually brittle. This shows that there is organic or heavy metal pollution. Too many additives, entrained organics and electroplating resists are the main sources of organic pollution. They must be treated with activated carbon. Insufficient addition and high pH will also affect the brittleness of the coating.
e) The coating is Dark and the Color is Uneven: the coating is dark and the color is uneven, which means there is metal pollution. 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 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 amps/square foot, 5 amps per gallon of solution for one hour. Poor pretreatment, poor low coating, too low current density, too low main salt concentration, poor contact of the electroplating power circuit will affect the color of the coating.
f) CoatingBurn: Possible causes of coating burn: Insufficient boric acid, low concentration of metal salt, too low working temperature, too high current density, too high pH or insufficient stirring.
g) Low Deposition Rate: Low pH or low current density will result in low deposition rate.
h) Blistering or Peeling of the Coating: Poor pre-plating treatment, excessively long interruption time, organic impurity pollution, excessive current density, too low temperature, too high or too low PH, and serious influence of impurities will cause blistering or peeling phenomenon.
I) Anode Passivation: The anode activator is insufficient, the anode area is too small and the current density is too high.
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