Analysis of the Main Causes of Blackening of Electroplated Gold Layer in PCB Processing
Recently received a peer EMAIL and QQ continue to contact, talking about the black gold plating problem and solutions. Due to the actual factory production lines, the use of equipment, syrup system is not exactly the same. Therefore, the need for product and the actual situation of targeted analysis and processing solutions. Here only talked about three common cause of the problem for your reference.
1, nickel layer thickness control.
We must think that the old dizzy, that black gold plating problem, how can we say that the thickness of the nickel plating. In fact, PCB plating gold is generally very thin, reflecting the surface of the gold plating a lot of problems due to poor performance caused by nickel plating. Nickel plating generally thin will cause the appearance of the product will have white and black phenomenon. So this is the first choice of plant engineering and technical personnel to check the project. Generally require plating to about 5UM nickel layer thickness is sufficient.
2, electroplating nickel cylinder syrup status
Still have to say nickel cylinder thing. If the nickel cylinder syrup long-term not well maintained, there is no timely carbon treatment, then plating out of nickel layer will easily produce flaky crystals, coating hardness increases, increased brittleness. Serious black hair will have a problem. It is easy for many people to ignore control points. It is also often an important reason for the problem. Therefore, please carefully check your factory production line syrup status, a comparative analysis, and promptly conducted a thorough carbon treatment to restore potion activity and plating solution clean. (That’s even bigger if you do not deal with carbon.)
3, Golden cylinder control
Now it comes to gold cylinder control. In general, if the well filtered and replenished syrup is maintained, the gold cylinder will be more contaminated and more stable than the nickel cylinder. But need to pay attention to check the following aspects are good: (1) gold cylinder supplements added enough and excessive? (2) syrup PH value control how? (3) conductive salt situation? If the test results no problem, then analysis of the AA machine solution impurity content. Margin cylinder potion status. Finally do not forget to check the cylinder filter cotton core is not replaced for a long time ah. If it is, then it is your control is not strict ah. Not happy to change.