PCB News - Circuit board factory: the reason for the blackening of the electroplated gold layer in PCB processing

Circuit board factory: the reason for the blackening of the electroplated gold layer in PCB processing

Recently, I have received e-mails and QQ contacts from my counterparts from Shenzhen Circuit Board Factory, talking about the causes and solutions of the blackening of the electroplated gold layer. Due to the actual production lines of PCB factories, the equipment and potion systems used are not exactly the same. Therefore, it is necessary to conduct targeted analysis and processing solutions based on the product and the actual situation. Here are just three common causes of problems for your reference.

1. The thickness control of the electroplated nickel layer of the circuit board

Everyone must think that the editor is dizzy. When it comes to the blackening of the electroplated gold layer, how can it be about the thickness of the electroplated nickel layer. In fact, the electroplated gold layer of PCB circuit boards is generally very thin, reflecting that many surface problems of electroplated gold are caused by poor performance of electroplated 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 item to be checked by factory engineers and technicians. Generally, the thickness of the nickel layer needs to be electroplated to about 5 um to be sufficient.

2. The potion status of the electroplated nickel tank

Still have to talk about the nickel tank. If the potion of the nickel tank is not well maintained for a long time, and the carbon treatment is not carried out in time, then the electroplated nickel layer will easily produce flaky crystals, and the hardness of the plating layer will increase and the brittleness will increase. Serious problems will cause black plating. This is a control focus that many people easily overlook. It is also often an important cause of problems. Therefore, please carefully check the potion status of the production line of your circuit board factory, conduct comparative analysis, and carry out thorough carbon treatment in time to restore the activity of the potion and the cleanness of the electroplating solution. (If you don't know how to deal with carbon, it would be even bigger)

3. The control of the gold cylinder

Now it comes to the control of the gold cylinder. Generally, as long as good syrup filtration and replenishment are maintained, the contamination 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) Is the addition of Jinju supplements sufficient and excessive?

(2) How about the PH value control of PCB processing potion?

(3) How about the conductive salt? If there is no problem in the inspection result, use the AA machine to analyze the impurity content in the solution. The potion status of the margin tank. Finally, don't forget to check if the golden cylinder filter core has not been replaced for a long time. If it is, then your control is not strict. Don't change it soon.