What is a High Frequency PCB?

A high frequency printed circuit board, whether it’s rigid or flex, offers faster signal flow rates and a frequency range of up to 100 GHz. It’s important to note that there are numerous materials designed to operate at high frequency levels. HF PCBs are defined by lower dielectric constant (Dk), lower dissipation factor (Df), and low levels of thermal expansion. They are used regularly for HDI technology. They are also used extensively in high speed communications, telecommunications, and RF microwave technology.


Applications for HF PCBs

High frequency rigid and flex PCBs are used in many products and across many industries, including:

  • Cell phone
  • Telecommunications
  • Military and aerospace
  • RF microwave
  • Automotive (mainly LIDAR, which is a mini radar that communicates a vehicle’s surroundings)
  • High-density interconnect and high-speed design applications
Applications for HF PCBs


Special materials are required to achieve the high frequency provided by this type of PCB. There are a variety of substrate materials that will support your design and may differ based on signal speeds required and the application/environment of the circuit board.

In terms of price, FR4 is the least expensive compared to dedicated high speed materials  and Teflon, with Teflon being the most expensive. Though, FR-4 starts to drop off in performance when signal speed edges above 1.6ghz

Newer generation substrates, Teflon, and flex circuits are the best options when it comes to Dk, Df, water absorption, and survivability in the environment

If a printed circuit board requires a frequency above 10GHz, newer generation substrates, Teflon, and Flex substrates are your best option since they are far superior to traditional FR-4 material.

The most common suppliers of high speed substrates are Rogers, Isola, Taconic, Dupont, and Megtron materials by Panasonic. All of these materials typically are lower Dk and lower loss.

Materials Used for HF PCBs


Design & Test
2 mil trace width, 3 mil air gap, IPC class 2/IPC class 3, Flying probe net list test, Differential impedance, TDR testing, Automatic optical inspection
Drill & Rout
Counter sinks/counter bores, Scoring/rout and retain, Laser route, Blind vias/buried vias, Stacked vias
1-30 layers, Vacuum lamination, Sequential lamination
Conductive via fill, Non-conductive via fill, Plated edges, Plated radii (castellation), Plated milling cutouts, Hard gold body, Soft bondable gold, Immersion gold, Immersion silver, HAL standard, HAL lead-free (ROHS), ENTEK (OSP)
Flex and rigid-flex, Kapton™ and non-Kapton, RF and high-speed materials, Mix materials/FR-4-Teflon, Metal back boards (LED/power distribution ), Heavy Cu 6 oz. finish rigid and rigid-flex

High Frequency PCB Design

When designing a high frequency PCB, it’s important to select the correct material that will support the high frequency design requirements. For cost reasons, hybrid designs should be considered where you only use the more expensive and higher speed materials for the layers that need it; the rest of the board is built with FR-4.

High Frequency PCB Design


When it comes to high frequency PCB design, it’s important that the design engineer collaborate with the PCB supplier to select the materials for the desired frequency performance requirements and to establish the correct stack-up. Cirexx has deep engineering capabilities and experience with control depth drilling, control depth milling, and back drilling, unlike some of our competitors. This means we have the technology, the experience, and the knowledge to help you design and build the right high frequency PCB from the start.

We differentiate ourselves by being able to take on all complex jobs — all the way from layout through assembly — and we do this under one roof with state-of-the-art technology and an extensive engineering team. This end-to-end expertise allows us to excel at the entire process and be the best PCB provider in the country.

Cirexx's HF PCB Capabilities

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