Flexible PCB Designs
Electromagnetic interference (EMI) and radio frequency interference (RFI) can occur in electronic circuits when their signals interfere with each other. These noises can disrupt a device’s functionality and affect other components. They can also impact the performance of a flexible PCB. This makes it important to address EMI/RFI shielding in your flexible PCB design. Here are some tips to help you handle this.
Flex PCBs are prone to EMI due to their flexible nature, but they can be made more resistant to this problem by implementing effective EMI/RFI shielding techniques. These include the use of ground planes and shields. These help to reduce the impact of EMI by providing a low impedance path for electromagnetic waves to flow through. They can also be used to isolate high-speed and low-speed signals. Another important step is avoiding sharp bends in your flexible pcbs traces and vias, as these can lead to variations in impedance and signal reflection.
In addition, proper trace arrangement can help minimize EMI issues. This includes making sure that signals are positioned according to the top EMC design rules, such as limiting the length of the traces. The best way to do this is by routing traces in parallel and ensuring that they are evenly spaced. Using a ground plane can also help to reduce EMI, as it acts like a large basin that can absorb ripples caused by current in the traces.
Tips for EMI/RFI Shielding in Flexible PCB Designs
Another common method of reducing EMI in flexible circuits is to use bypass or decoupling capacitors. These capacitors connect the signal to the ground reference, which helps reduce the return current. However, this can add to the total thickness of the circuit board, causing a reduction in bending capability.
Other methods of minimizing EMI in flexible circuits include using silver ink, a type of coating that’s applied to the copper layer of a flex PCB. This method is more flexible than other EMI shielding methods, but it can still be challenging to meet the bending requirements of your design. This is because it requires an extra coverlay to preserve and encase the silver ink.
Lastly, you can use shielding materials that are made of metal to help reduce the effects of EMI and RFI in your flexible circuits. This is the most effective method of EMI shielding, but it’s also the most expensive. However, it’s a cost-effective solution for high-speed, low-impedance applications that require flexibility.
No matter what type of shielding you choose for your flex PCB, it’s crucial to carefully consider the minimum bend capabilities of your design. This will help you determine what material and shielding method is right for your application. It’s also important to ensure that you’ve accurately defined and evaluated the minimum bend radius and type of bend requirement of your flexible PCB application. This will allow you to find the EMI/RFI shielding that’s right for your project.
