RF PCB Design Guidelines and Considerations

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What are RF PCBs

An RF PCB is a printed circuit board that utilizes RF frequency. There can be analog or digital devices integrated into a single board in RF PCB design. The high-frequency operation of an RF PCB requires a different PCB substrate material other than FR4. Similarly, analog and digital components in RF PCBs make mixed signal boards, and the integration needs to be done carefully to avoid signal transmission and integrity problems.

The RF PCB can be either low-power or high-power. RF PCB design guidelines will undergo slight changes depending on the power and range of frequency.

A standard low-power RF PCB can be defined by the following:

  • A PCB substrate material showcasing good insulation and uniform dielectric properties. For low-power applications, standard FR4 will work. 

  • Any RF PCB design demands the shortest connection between components. Components are closely packed in RF PCBs. 

  • Most RF PCBs include analog as well as digital devices and components. In such a mixed-signal layout design, the digital circuits must be separated from the analog and RF sections. The recommended distance is greater than 20mm. However, in space-constrained RF PCB design, it should be at least 10 mm. 

  • To mitigate grounding issues in RF PCBs, keep the digital ground away from the RF section. 

  • It is not mandatory to use surface mount components in RF PCBs. However, using surface mount devices (SMD) improves the space utilization in RF PCBs. SMD components are small with shot component pins. 

Microwave PCB and RF Circuits–Common Problems and Solutions

RF circuit boards, and Microwave PCBs, are especially difficult to design compared to traditional PCB layouts. This is due to the problems that could arise in receiving or transmitting the radio signals. Some of the main problems are noise sensitivity, and tighter impedance tolerances

Compared to traditional circuit boards, radio and microwave signals are very sensitive to noise and also require much tighter impedance tolerances. The best solution for these problems is to utilize ground plans and use a generous bend radius on impedance controlled traces. These solutions will ultimately allow the RF/Microwave PCB to achieve the best performance.

RF PCB Layout Considerations

There are different parameters to consider before starting an RF PCB layout design.

Frequency Considerations

One of the primary factors to consider when developing an RF PCB design is the operating frequency range. The choice of frequency range influences the selection of components, material characteristics, and routing techniques. RF circuits typically operate at high frequencies, often ranging from a few megahertz to several gigahertz.

To ensure optimal performance, it is crucial to carefully select the appropriate PCB material with low dielectric loss and consistent impedance characteristics across the frequency spectrum. High-frequency laminates such as Rogers or Taconic materials are commonly used for RF PCB designs due to their excellent electrical properties.

Additionally, proper trace width and spacing become critical at higher frequencies to maintain controlled impedance. Transmission lines, such as microstrips or strip lines, should be designed with precise dimensions to match the desired characteristic impedance. Utilizing controlled impedance calculators or specialized design tools can aid in determining the optimal trace dimensions.

Component Placement And Layout

The strategic placement of components on the RF PCB plays a significant role in minimizing signal interference and optimizing performance. Careful consideration should be given to the location and orientation of high-frequency components, connectors, and antennas.

To reduce parasitic effects, it is advisable to keep sensitive RF components away from noisy digital circuits. Separating analog and digital sections can help minimize electromagnetic interference(EMI) and crosstalk. Placing RF components closer to the antenna and utilizing shorter traces can reduce transmission line losses and improve signal integrity.

Thermal management is another important aspect to consider during component placement. The heat generated by power amplifiers or other heat-producing components should be efficiently dissipated to avoid performance degradation. Adequate spacing, heat sinks, and thermal vias can assist in managing temperature levels.

Furthermore, the layout of the PCB traces should be carefully designed to minimize signal degradation and EMI. Employing proper grounding techniques, such as a dedicated ground plane and stitching vias, can help reduce noise and maintain signal integrity. Routing high-frequency traces as short as possible and using proper shielding techniques, like ground or power planes, can also enhance RF performance.

Signal Integrity And EMI

Signal integrity is crucial for reliable RF communication. Ensuring proper signal integrity involves minimizing signal loss, reflections, and distortions. This can be achieved by using impedance-matched transmission lines, controlled trace lengths, and proper termination techniques.

Controlling electromagnetic interference (EMI) is equally important in RF PCB design. RF circuits are susceptible to interference from other components, nearby devices, or external sources. Implementing good EMI shielding practices, such as using shielding cans, balanced routing, and filtering components, can mitigate unwanted noise and improve overall system performance.

Grounding plays a critical role in minimizing EMI and maintaining signal integrity. It is vital to establish a solid ground reference plane that is continuous throughout the PCB. Ground vias or stitching techniques can ensure a low-impedance ground path for high-frequency signals.

Manufacturing And Testing Considerations

When designing RF PCBs, it is crucial to consider manufacturing and testing aspects to ensure successful production and reliable performance. Collaborating closely with the PCB manufacturer is recommended to address any specific manufacturing requirements.

The manufacturing process should meet the necessary tolerances for high-frequency designs. Controlled impedance testing and verification of layer stack-up are essential steps to ensure the design meets the desired specifications.

Post-manufacturing testing is crucial to verify the performance of the RF PCB. Testing techniques such as time-domain reflectometry (TDR) can identify impedance mismatches, signal reflections, or other signal integrity issues. Testing RF circuits with appropriate instruments, such as network analyzers, spectrum analyzers, and vector signal analyzers, can validate the design's performance.

PCB Design Guidelines

The upcoming section will discuss the RF PCB design guidelines for substrate selection, layer sacking, and trace design.

RF PCB Substrate Selection 

RF PCBs handle low MHz frequencies to high GHz. The material selection for a PCB is important to ensure signal integrity, reliable operation, and consistency at high frequencies. The factors to consider while selecting PCB material are:

  • Dielectric constant

  • Thermal expansion coefficient (CTE)

  • Loss tangent or dissipation

Some common materials are RO3000, RO4000, RT/Duroid, etc. The copper material selection for an RF PCB stack-up is also essential, as it influences the skin effect on signal propagation.

PCB Layer Stacks 

Special care needs to be given in RF PCB design stack-ups. Some of the areas to focus on are:

  • Isolation between traces

  • Distance between components

  • Component placement

  • Layer arrangement and count

  • Power supply decoupling 

In RF PCBs, the RF traces are routed on the top layer; the immediate layers are ground and power planes. The immediate ground plane ensures a minimum ground current return path. The non-RF traces are laid on the bottom layer to minimize interference between RF and non-RF components.

RF PCB Trace Design

RF PCB traces are vulnerable to transmission losses and signal interference issues. The main concern in RF trace design is characteristic impedance. The most commonly used RF traces are coplanar waveguides, striplines, and microstrips. Some of the best practices to follow while designing RF PCB traces are: 

  • To eliminate attenuation, keep the traces as short as possible. 

  • Never place an RF trace and non-RF trace parallel, as it introduces interference between them. 

  • Test points should be placed outside the traces to maintain the impedance-matching values of the traces. 

  • Include curved ends to improve the performance of the RF PCB.

RF PCB design guidelines start with PCB substrate material selection to develop excellent RF PCB boards. 

Capabilities Of Radio Frequency Printed Circuit Boards

RF PCBs are complex, to say the least. This is on account of several reasons such as the fact that the heat within the board needs to be managed to ensure that it survives the thermal stresses. Also, spacing of the features has an important role to play. Besides you need specialized equipment such as Plasma etch machinery and laser direct imaging equipment. At Hemeixin, we are fully equipped and have the following capabilities:

Layer Count 2-44 layers
Drill aspect ratio 15:1
Maximum Panel Size 24″ x 30″
Vias Blind / Buried Vias. & Micro Vias Via In Pad with Fill Options (Conductive, Non-Conductive, Copper Plug)
Characteristic impedance of a transmission line Controlled impedance
Minimum track and gaps 0.75mm / 0.075 mm
Metal Core thickness 58mm * 1010mm
Surface finish HASL (Lead-free), OSP, ENIg, immersion tin, immersion silver.

Rf PCB Materials By Application

We can help with everything from saving cost on a simple board to manufacturing advice for cutting edge, fifty layer designs. To simplify your search, here are several recommendations for materials based on application and manufacturability:
Important Note: Within every industry, there is a wide range of applications, demands, and budgets.

The table below provides general recommendations, but to find the best PCB materials for your specific project, please contact our engineering staff.

RF ApplicationRF MaterialsBonding MaterialsAttributes
Consumer Electronics




RO3000 Series Bondply

2929 Bondply

Cost effective with dependable electrical and thermal characteristics




RO4450B / RO4450F

The best in electrical and thermal performance and environmental durability

High Power Applications




Superior thermal management



RO4400 Bondply / 2929


Versatile high performance properties to suit a range of device types





RO4400 Bondply

Excellent electrical performance compatible with standard manufacturing processeses





2929 Bondply

RO4400 Bondply

Excellent durability and environmental resistances, including oxidation

RF PCB Material Stock

Will all the different features of every RF PCB application, we have developed partnerships with the key material suppliers such as Rogers, Arlon, Nelco, and Taconic just to name a few. While many of the materials are very specialized, we do hold significant stock of product in our warehouse from Rogers (4003 & 4350 series) and Arlon. Not many companies are prepared to do that given the high cost of carrying inventory to be able to respond quickly.

High technology circuit boards fabricated with high frequency laminates can be difficult to design because of the sensitivity of the signals and the challenges with managing the thermal heat transfer in your application. The best high-frequency PCB materials have low thermal conductivity versus the standard FR-4 material used in standard PCBs.

RF and microwave signals are very sensitive to noise and have much tighter impedance tolerances than traditional digital circuit boards. By utilizing ground plans and using a generous bend radius on impedance controlled traces can help make the design perform in the most efficient manner.

Because wavelength of a circuit is frequency dependent and material dependent, PCB materials with higher dielectric constant (Dk) values can result in smaller PCBs as miniaturize circuit designs can be used for specific impedance and frequency ranges. Oftentimes high-Dk laminates (Dk of 6 or higher) are combined with lower cost FR-4 materials to create hybrid multilayer designs.

Understanding the coefficient of thermal expansion (CTE), dielectric constant, thermal coefficient, temperature coefficient of dielectric constant (TCDk), dissipation factor (Df), and even items like relative permittivity, and loss tangent of the PCB materials available will help the RF PCB designer create a robust design that will exceed the required expectations.

Some of the different material RF PCB material types that we work with are:

Ceramic-filled PTFE composites, which have exceptional electrical and mechanical stability. Rogers RO3000 series circuit materials have consistent mechanical properties, regardless of the dielectric constant (Dk) selected, which allows multi-layer board designs that use different dielectric constant materials without encountering war-page or reliability problems. The Taconic RF series of products has a low dissipation factor with high thermal conductivity possible so it will not oxidize, yellow, or show upward drift in dielectric constant and dissipation factor like its hydrocarbon-based competitors.

Ultra-low Loss, Highly Heat-Resistant, Halogen Free Megtron 6 circuit board material. With high glass transition temperature (Tg) and the low expansion ratio of hydrocarbon resin-based MEGTRON 6 - makes it ideal for High-Density Interconnect (HDI) and high speed (above 3 GHz) constructions.

Woven Glass Reinforced PTFE laminates are manufactured with very lightweight woven fiberglass and are more dimensionally stable than chopped fiber reinforced PTFE composites. Materials such as the Taconic TL family of products have a low dissipation factor, and this is perfect for radar applications designed at 77 GHz as well as other antennas in millimeter-wave frequencies.

Hydrocarbon ceramic laminates are used in microwave and millimeter-wave frequency designs as this low loss material offers easier use in circuit fabrication and streamlined properties over traditional PTFE materials. Rogers RO4000 series of products come in a wide range of DK values (2.55-6.15) and have above average thermal conductivity (.6-.8).

Filled PTFE (random glass or ceramic) composite laminates such as the Rogers RT/duroid® high frequency circuit materials have low electrical loss, low moisture absorption, and low outgassing properties that are preferred in space applications.

Thermoset microwave laminates combine low thermal coefficient of dielectric constant (Dk), a copper matched coefficient of thermal expansion and excellent mechanical reliability. Rogers TMM materials are high-frequency laminates ideal for high-reliability strip-line and micro-strip applications.

RF PCB Material Competitive Matrix

FR4 materials are acceptable for RF transmission lines and interconnects operating up to WiFi frequencies (~6 GHz). Beyond these frequencies, RF engineers recommend using alternative materials to support RF signal propagation and printed RF circuit designs. Standard FR4 laminates use resin-filled fiberglass weaves to hold components, but these fiber weave effects in certain materials could create signal and power integrity problems if fabrication procedures are not specified properly.

Alternative material systems use PTFE-based laminates and bondply materials to bond a PTFE layer with the next layer in your PCB stackup. These materials have lower loss tangent than FR4 materials, so signals can travel farther without attenuating and still fall within acceptable margins. These laminates should form the substrate that supports RF transmission lines at very high frequencies, such as 77 GHz radar, or for very long interconnects at lower frequencies, such as 6 GHz WiFi. The table below summarizes some important material properties for common RF PCB materials.

Resin SystemCategoryDk @ 10 GHZDf @ 10 GHzCompetitorsProduct NameDkDf
I-Speed Low Dk/Df 3.64 0.0094 Panasonic Megtron 4 3.80 0.0050
        TUC Thunderclad 3.90 0.0095
        AGC/NELCO N4800-20 3.80 0.0075
        AGC/NELCO Meteorwave 1000 3.70 0.0055
        Doosan DS-7409D (X) 3.80 0.0050
I-TeraMT40 Very Low Dk/Df 3.30 0.0036 Panasonic Megtron 6 3.61 0.0040
        AGC/Neclo Meteorwave 2000 3.40 0.0040
        AGC/Neclo Meteorwave 3000 3.80 0.0048
        Rogers RO4350B 3.48 0.0037
        TUC TU-993 3.40 0.0025
        Doosan DS-7409D (V) 3.65 0.0015
I-TeraMT40 RF RF 3.45 0.0031 Rogers RO4350B 3.48 0.0037
        Arlon AD350 3.50 0.0030
        Taconic RF35 3.50 0.0025
        AGC/Neclo NH9350 3.50 0.0030
Tachyon-100G Ultra Low Dk/Df 3.00 0.0021 Panasonic Megtron 7N 3.35 0.0020
        AGC/Neclo Meteorwave 4000 3.50 0.0040
        EMC EM-891K 3.10 0.0033
        Doosan DS-7409DV(N) 3.35 0.0010
AstraMT77 RF 3.00 0.0017 Rogers RO3003 3.0 0.0013
        Arlon AD300C 3.0 0.0020
        AGC/Neclo NX9300 3.0 0.0023

This is not a complete list of RF circuit board materials, although the above materials are very popular. There are many more materials available, which we have experience with so if you don’t see what you are looking for listed, send us a request for more information and we can help you design an RF or high-speed PCB to meet your requirement.


Developing an RF PCB design requires careful consideration of several fundamental issues. By considering frequency considerations, component placement, signal integrity, EMI control, and manufacturing/testing aspects, engineers can create high-performance RF PCBs.

Proper material selection, controlled impedance design, strategic component placement, and thoughtful layout techniques contribute to the overall success of an RF PCB design. With thorough planning and adherence to best practices, engineers can achieve reliable and efficient RF circuitry for a wide range of wireless communication applications.

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