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Analysis of Main Reasons for Blackening of Electroplated Gold Layer in PCB Processing
Recently, I have continuously received EMAIL and QQ contacts from peers and talked about the causes and solutions of black gold plating. Due to the actual factory production lines, the equipment and potions used are not exactly the same. Therefore, it is necessary to carry out targeted analysis and resolution of products and actual conditions. Here are just three common and common reasons for your reference.

1. Thickness control of electroplated nickel layer

Everyone must think that the old high-headed dizzy, said the black gold plating problem, how could it be said that the thickness of the nickel plating layer. In fact, the PCB plating gold layer is generally very thin, reflecting many problems in the surface of the gold plating due to the poor performance of the nickel plating. The general thinning of the nickel plating layer will cause the appearance of the product to appear white and black. Therefore, this is the project that the plant engineering technicians first choose to check. It is generally necessary to plate to a nickel layer thickness of about 5 um to be sufficient.

2, the electroplating nickel cylinder syrup status

Still have to say nickel cylinder thing. If the nickel cylinder's potion is not maintained for a long time and carbon treatment is not performed in time, the electroplated nickel layer will easily produce flaky crystals. The hardness of the coating will increase and the brittleness will increase. Severe black plating problems. This is a control point that many people easily overlook. It is also often an important cause of problems. Therefore, please carefully check the syrup status of your factory's production line, conduct comparative analysis, and perform thorough carbon treatment in a timely manner so as to restore the potency of the medicine and the cleanness of the plating solution. (If you don't carbonize it, it's even bigger.)

3, the control of the gold cylinder

It is now only the control of the gold cylinder. In general, the gold tank will be more contaminated and more stable than the nickel tank if only good syrup filtration and replenishment are maintained. However, care should be taken to check whether the following aspects are good: (1) Is the addition of the gold tank supplement adequate and excessive? (2) How is the pH of the medicine controlled? (3) How about conductive salt? If there is no problem with the inspection results, use an AA machine to analyze and analyze the impurities in the solution. The state of the potion of the deposit pot. Finally, don't forget to check if the gold filter wick has not been replaced for a long time. If yes, then it is because your control is not strict. Still not quick to replace it.

Let's talk about these three major aspects of control!
Welcome everyone to exchange control methods in this area. The wrong place in the article also hopes everyone corrects!