Image of PCB edge plating: source Epec’s Blog
PCB edge plating, which is also known as border plating or side plating refers to a process of plating exposed copper connections along the edges of a printed circuit board. The plating is done using metallic coating material such as gold though tin coating is also used in some applications. The coating will end up forming a thin metal fabrication along the edges of a printed circuit board. Also, the PCB plating may be on one side of the circuit board or it may be on all the sides. It all depends on the needs of a PCB manufacturer.
PCB edge plating has been gaining popularity in recent years. Perhaps most PCB manufacturers have realized the numerous benefits that come with using the plating on their printed circuit boards. It guarantees the performance and as well as reliability of the PCB.
Whether you are in the PCB manufacturing industry or you want to buy PCBs, it is important to know the essentials of PCB edge plating. Well, keep on reading as we break down the details.
Reasons for PCB edge plating
It is clear that PCB manufacturers are increasingly embracing PCB edge plating. What could be the reasons for this?
Signal and power integrity
Over the years, PCBs are becoming more complex and sophisticated. One of the reasons is PCBs are becoming smaller yet they are required to perform complex roles. PCB edge plating has proven to be one of the methods that manufacturers can use to guarantee signal and power integrity on their PCBs.
There are several ways in which edge plating can guarantee the signal and power integrity of a PCB. One way is through the reduction of electromagnetic interference. This allows signals to be processed and transmitted in the PCB.
Thermal management
Edge plating has a role to play in the thermal management of a printed circuit board. It supports faster heat dissipation, especially when the performance of the core components is at its peak. An example is when the signals are being processed at a higher speed.
In relation to thermal management, PCB edge plating ensures that heat is distributed evenly throughout the body of the PCB through the existing thermal vias. Additionally, a direct connection between the edge plating and the ground plane ensures that heat is dissipated at a faster rate. Through efficient thermal management, edge plating enhances the reliability and performance of the PCB.
PCB structural integrity
Even though PCB may be strong on its own, metal coating on the edges tends to do a good job when it comes to the structural integrity of the board. They enhance the strength and rigidity of a printed circuit board. The extra support that is accorded by the plating makes it easy to handle the PCB, especially when installed into metal casing or PCB sockets. Keep in mind that most PCB damages and breakages are due to such physical activities.
Electromagnetic compatibility
An interaction of electric signals in the power plane and ground planes is likely to generate electromagnetic interference (EMI). This is quite a common case on most multilayer PCBs. By encasing the edges of the PCB with metal plating, you would have achieved maximum protection against the effects of EMI.
PCB edge plating process
There are several steps and procedures to be followed when fabricating PCB edges with metal plating. The steps are similar to the normal plating procedure only that here you have to pay attention to the edges and corners of a printed circuit board.
The first step entails cleaning the holes which will provide space for the edge contacts. Also, the outer edges of the PCB must be metalized through milling so as to create a perfect bond with the metal plating. A copper electroless is applied on the edges through an electroplating process.
A flow chart below gives a summary of the PCB edge plating process:
In case you are using gold plating, you will have to paste a dry film on the copper layer to create an opening or an etching groove This will be the area to be covered by the gold plating. You can then use electroplating to coat the areas with gold or even nickel.
Take note that when doing PCB edge plating you should hand the board with utmost precision. Improper handling will affect the quality of the work.
What are the limitations of PCB edge plating
Even as you aim to achieve the best results from your PCB plating, you are likely to encounter some challenges. They include:
- Peeling of the metal: Despite doing a perfect job, the copper plating may start peeling off after a period. The main cause of this problem is weak adhesion strength between metal and the PCB material. You can solve this by using copper which has a strong adhesion bond.
- Need gaps in the plating routes. These gaps may end up affecting the existing electric circuit traces.
- Black pad syndrome: This problem refers to the infiltration of phosphorous between the layers of gold and nickel. The layers can affect the effectiveness of the plating.
- Signal loss: If the plating is not done well, it can interfere with transmitting signals in the PCB.
Indicators a high-quality PCB edge plating?
You are buying PCBs and you are not sure whether the plating is of high quality or not. Here are some key indicators of quality PCB plating:
- Plating thickness: The thickness should support the structural integrity of the PCB
- The plating should be free of contaminants such as dirt
- The dimensions of the plating should be accurate
- The contacts of the PCB should not be affected by the plating
Conclusion
PCB edge plating is a key element that determines the performance and reliability of printed circuit boards. If you are into DIY projects related to PCBs, you should find more information on executing the plating accurately and effectively. If you are buying PCBs, you should find out whether the edges have been plated and the types of plating used. You can use a PCB sourcing agent who will give you vital information about the PCB plating.
Last Updated on October 30, 2023 by Kevin Chen
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