PCB has a hidden danger of "black soldering", pay attention

Shenzhen xinmaolong precision circuit Co,.LtdRelease Time:2022-01-15

The circuit board has a hidden danger called "black disk", which is produced by the circuit board manufacturer doing chemical nickel-gold surface treatment. This hidden danger generally produces batches of failures when the product is in the hands of the customer. The "black disk" of the PCB will have a catastrophic impact on the reliability of the solder joints, resulting in quality accidents of electronic products, and in severe cases, it will bring huge losses to the enterprise. However, domestic electronic product companies PCB circuit board "black disk" quality accidents are not uncommon!


Why do PCB "black soldering" accidents occur frequently? Today, the editor of the circuit board manufacturer will take you to analyze the doorway inside to help you avoid "black soldering" as much as possible.


The PCB circuit board is the base part of the electronics industry. Almost all electronic equipment, ranging from electronic watches and calculators that can be seen everywhere in daily life, to computers, communication electronic equipment, aircraft, radar, etc., as long as there are electronic components such as integrated circuits The electrical interconnection of the device will inevitably use the PCB.


Why does the "black disk" appear on the PCB circuit board? Simply put, the gold plating is too thick, causing the nickel to oxidize and corrode to form a blackened pad. It will make poor soldering of the pads. This is when there are a large number of dense small pad icon devices, such as BGA, QFP, SOP packaged devices, black disks will be formed especially.


Because the small pad is compared with the large pad, the gold immersion time per unit area is short. The immersion gold of the small pads has met the thickness, but the large pads have not. It also needs to prolong the gold sinking time. In this way, when the large pad is immersed in gold, the gold of the small pad is a little too thick. If the gold is too thick, the probability of the underlying nickel being oxidized is high.


Therefore, when the customer asks the PCB manufacturer to do chemical nickel-gold surface treatment, the PCB circuit board manufacturer will inform the customer that it is not suitable for components with dense small pads.


Sometimes the OSPicon process is used in the dense small pad area, and the nickel-gold process is used in other areas to avoid the generation of black disks.


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