The Design Process for Radio Frequency PCB

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The Design Process for Radio Frequency PCB

Last Updated on March 5, 2023 by

The design process for Radio Frequency PCB is unique compared to traditional PCB design. The main differences are Impedance matching, decoupling, and layer management. Here’s a detailed look at the key elements for designing a high-frequency circuit board. To start, learn more about Impedance matching and thermal robustness. Identify your specific needs, and then use our expert design tools to make sure your final product meets the highest standards.

High-frequency printed circuit boards

Designing high-frequency printed circuit boards involves many steps. Various factors should be considered, including dimensional stability, the material being used, and environmental temperature. It is also important to consider the signal frequency of the PCB, which should be set for the voltage and power planes, as well as the noise level. Once these factors are determined, the board stackup plan should be developed. It is also important to note the demands and constraints of the different layers. To avoid interfering with each other, a floor plan should be divided into distinct sections for each component. The dielectric material used should be the same temperature as the copper layer, as different temperatures can cause it to break apart.

Impedance matching

Impedance matching is a vital design consideration for radio frequency PCB. If an RF PCB fails to match the impedance of the RF transmission lines, it could result in product recall and cost the device manufacturer money. Impedance matching networks are simple to design and can be simulated using a basic circuit simulator. To understand the importance of this design factor, let’s look at the following examples.

Thermal robustness

The thermal robustness of radio frequency PCB is dependent on the material and the range of frequencies that they operate in. One important factor that helps determine the thermal robustness of RF PCB is the Coefficient of Thermal Expansion (CTE), which refers to the changes in size of RF PCBs due to different temperatures. This factor also affects assembly and drilling processes. It is important to choose an RF PCB that can withstand extreme temperatures and high-frequency operation.

Surface finishes

Surface finishes on radio frequency PCB have three main categories: Lead-free Hot Air Surface Levelling (HASL) and Immersion Silver (ENIG). Choosing the correct finish is critical because different finishes require different processing methods. HASL, for example, requires changes to flux and heat cycle rates to achieve the required results. Immersion Silver is a better option for RoHS compliant boards. The thickness of the finished board varies from 0.12 to 0.40 mm.

Shielding

In order to shield a radio frequency PCB, it must be made of a material that can effectively conduct RF signals. Various factors affect the shielding ability of a PCB, including its permeability and conductivity. The thickness and mechanical strength of the shield also play an important role. Some shields incorporate holes to allow airflow and reduce thermal buildup in circuit sections. This article provides an overview of different shielding techniques.

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