なぜ PCB electroplating gold layer turn black？

1. Potion status of electroplated nickel tank

Still have to talk about the nickel tank. If the nickel tank potion is not well maintained for a long time, and the carbon treatment is not carried out in time, the nickel layer after electroplating will easily produce flaky crystals, the hardness of the plating layer will increase, and the brittleness of the coating will increase. In severe cases, blackening of the coating will occur. This is because many people tend to overlook the key points of control. It is also often an important cause of problems. Therefore, please carefully check the potion status of your factory’s production line, conduct comparative analysis, and conduct thorough carbon treatment in time to restore potion activity and clean the electroplating solution.

2. Thickness control of electroplated nickel layer

Everyone must be talking about the blackening of the electroplated gold layer, how can it be the thickness of the electroplated nickel layer. In fact, the PCB plating gold layer is generally very thin, reflecting that many of the problems on the surface of the plating gold are caused by the poor performance of the electroplating nickel. Generally, the thinning of the electroplated nickel layer will cause the appearance of the product to be whitish and black. Therefore, this is the first choice for factory engineers and technicians to check. Generally, the thickness of the nickel layer needs to be electroplated to about 5 um to be sufficient.

3. Gold cylinder control

Now it comes to the gold cylinder control. Generally, as long as you maintain good potion filtration and replenishment, the pollution and stability of the gold cylinder will be better than that of the nickel cylinder. But you need to pay attention to check whether the following aspects are good:

(1) Are the supplements of the golden cylinder sufficient and excessive?

(2) How is the PH value of the potion controlled? (3) How about the conductive salt?

If there is no problem with the inspection result, use the AA machine to analyze the impurity content in the solution. Guarantee the potion status of the gold tank. Finally, don’t forget to check if the golden cylinder filter core has not been replaced for a long time.