hdi pcbs designs
When you are designing high-density circuit boards, maintaining signal integrity is a challenge. Signal degradation is caused by a wide range of factors, from cross-talk between adjacent traces to a lack of proper grounding. These problems can lead to EMI and other issues that compromise performance. Fortunately, you can avoid many of these issues with a few simple steps.
EMI/RFI shielding can be implemented in two ways: either at the board-level or enclosure-level. At the board level, metal shielding cans can be custom fabricated and mounted around noisy circuits to suppress EMI. Alternatively, elastomer shielding materials can be used to target specific components and connectors in the hdi pcbs layout to suppress electromagnetic radiation.
Enclosure-level EMI shielding is often done by connecting the copper planes of the ground layer to each other using stitched vias. This helps to prevent EMI from getting into the signal layers and contaminating the circuits. However, adding this extra layer to the PCB significantly reduces its flexibility and can be a problem for dynamic flex circuits that need to bend in an irregular manner.
How do you handle EMI/RFI shielding in hdi pcbs designs?
Another approach is to use ferrite beads to reduce EMI. These small, cylindrical beads reduce EMI by absorbing and dissipating EM energy. They can be added to the PCB’s power bus to help minimize EMI noise and improve signal quality.
Controlled impedance routing is also an important part of any EMI mitigation strategy. This technique ensures that signals travel efficiently with minimal reflections and degradation. This requires careful trace placement, and using the right dielectric material to achieve low impedance. In addition, you should always use the proper termination methods to maintain signal integrity.
Finally, it is important to use proper trace widths and lengths. Traces that are too close together can create EMI interference by creating an inductive loop that induces current into the neighboring trace. To avoid this issue, you should keep a minimum distance of twice the trace width between two parallel traces.
Increasing the distance between signal lines can also be effective. This can help to eliminate cross-talk between traces, which is one of the main causes of EMI interference in high-speed circuits. Additionally, it is a good idea to make sure that your traces are not overloaded and that you have adequate solder mask clearance between the traces and pads.
Keeping these tips in mind will help you avoid the majority of EMI/RFI issues in your HDI pcbs designs. You can further improve signal integrity by utilizing the best component selection and fabricator partnerships, maintaining solid grounding practices, ensuring design rule checking (DRC) and layout versus schematic (LVS) verification, and utilizing design automation tools to catch errors early in the design process. With these strategies in place, you can be confident that your HDI PCBs will meet the stringent requirements of demanding applications.