Recently, I talked with my colleagues about the causes and solutions of blackening of the electroplated gold layer. Due to the actual production lines in each factory, the equipment used and the potion system are not exactly the same. Therefore, it is necessary to carry out targeted analysis and processing for the product and the actual situation. Here are just three common causes for your reference.
1.Thickness control of electroplated nickel layer
Everyone must think that I’m dizzy, and talk about the blackness of the electroplated gold layer, how can it be said about the thickness of the electroplated nickel layer. In fact, the PCB electroplated gold layer is generally very thin, reflecting that many problems on the surface of electroplated gold are caused by poor performance of electroplated nickel. Generally, the thinning of the nickel plating layer will cause the appearance of the product to appear white and black. Therefore, this is the first item to be checked by plant engineering technicians. Generally need to be electroplated to about 5UM nickel layer thickness is sufficient.
2.Potion of nickel plating tank
Let’s talk about nickel tanks. If the nickel potion is not well maintained for a long time, and the carbon treatment is not performed in time, the nickel layer will be prone to flake crystals, which will increase the hardness and brittleness of the coating. Severe blackening problems may occur. This is the point where many people tend to overlook control. It is often an important cause of problems. Therefore, please carefully check the potion status of your factory production line, perform a comparative analysis, and perform a thorough carbon treatment in time to restore the potion activity and clean the plating solution. (If it is not carbon treated then it will be even bigger …)
3.Gold cylinder control
Now it comes to golden cylinder control. Generally, as long as good potion filtration and replenishment are maintained, the pollution degree and stability of gold cylinders will be better than nickel cylinders. But you need to pay attention to check whether the following aspects are good: (1) Is the golden cylinder supplement added enough and excessive? (2) How is the PH value of the potion controlled? (3) What about conductive salts? If there is no problem with the inspection result, use AA machine to analyze and analyze the impurity content in the solution. Guarantee pot state. Finally, don’t forget to check if the gold cylinder filter cotton core has not been replaced for a long time. If so, it is because you do not have strict control. Can’t change it quickly.
