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How to reduce electromagnetic interference in PCB design and development?

2021-12-03

How to reduce electromagnetic interference in PCB design and development?

Dongguan Changsen Electronic Technology Co., Ltd. is a professional PCB design and development enterprise

During PCB design and development, when the signal frequency rises to radio frequency ("RF") or microwave frequency band, the digital signal will cause system electromagnetic interference ("EMI") and reduce power integrity, and the resulting electromagnetic compatibility problem is also very obvious; EMI generated by high-frequency digital signals will not only cause mutual interference within the system, but also produce strong electromagnetic radiation, resulting in exceeding the limit standard of electromagnetic compatibility EMC. This phenomenon occurs at the edge of multi-layer RF circuit board ("PCB").
For PCB design and development, the rule of 20h is often used in EMI design, that is, the RF line end should be away from the ground plane with a dielectric thickness of 20 times. The design can effectively reduce electromagnetic radiation. When the RF line end is 20h away from the grounding layer, 70% of the electromagnetic radiation will be absorbed,
In PCB design and development, the grounding via layer is often used as the shielding wall to achieve the above design effect. For higher frequency microwave circuits, the signal wavelength is further reduced. At this stage, the PCB manufacturing technology can not meet the hole spacing of 1 / 20 wavelength. The general electroplating board edge technology makes up for the lack of grounding vias. However, with the development of PCB along the thinner and smaller direction, it is difficult to make the above 20h or 1 / 20 signal wavelength. How to balance the contradiction between the distance between the RF line end and the shielding wall and the production process, the technology R & D team of Dongguan Changsen Electronic Technology Co., Ltd. came into being the following electroplating edge selective removal process. By accurately controlling the distance between the RF line end and the electroplating edge conductor, the ideal EMI effect was realized and the requirements of the customer's RF line EMI design were met.