The subject here isn’t all that glamorous, however, the requests about high-frequency printed circuit board (PCB) have increased significantly, which makes me think we have more that can be said on the subject of high-frequency applications
Let’s begin to dig in and try to put together some clarity on the basis of this specialized type of circuit board, outlining who uses it, what is available for material, and where you should start.
What is a High-Frequency PCB?
By definition, a high-frequency printed circuit board application requires special transmission of radio frequency signals. These signals are critical to communications such as wireless, radar systems, satellite, and medical electronics. When we manufacture PCBs, the files provided for this type of product almost always define a laminate choice, unlike standard production consumer products.
More often than not, the standard FR4 with a Tg of 170 minimum is what is used for production, and always the minimum for RoHS-compliant boards. Specialty products with communication also require special materials to be able to accurately communicate through whatever the end product is.
Applications for High-Frequency PCBs
Let’s look at the applications a little closer and the differences between them. For example, wireless communications, the most common product most of us can relate to, we use this technology every day, from cell phones to GPS devices to Wi-Fi routing; these items operate off radio signals on a high-frequency PCB.
The technology of the PCB will contain features to assist the technology, specialty-built in antennas, amplifying, and RF components. Along with built-in technology used by design developers, the devices themselves have improved their lives globally. Students have research at their fingertips, and parents are a call or GPS check away. Traveling interstate or across the country is easily navigated without the bi-folding map from the gas station; just put in the address and go.
As we have kept our eyes on the sky for travel, we count on more than just the weather. Traveling across the ground to get to the airport alone can add stress to the day. Flights are ever-growing. Whether it is business, pleasure, or family fun, the amount of traffic in the skies is exponentially increasing globally. Radar systems rely on high-frequency PCBs to process radar signals, interpreting airport flights, accurate weather, as well as some military applications. Air traffic control is one job I think I would take a pass on; the responsibility is unimaginable and relying on systems to accurately pinpoint all the traffic at speeds, distances, and heights … wow!
Satellite communications or microwave/RF designs are an older technology, which, if you remember Sputnik (the year was 1957, before my time). However, I do remember hearing about it. The start of the U.S. vs. U.S.S.R. space race shocked the U.S. with the Soviets’ beachball-sized satellite circling the Earth every 98 minutes or so. In 1958, 1959, and 1962, the U.S. followed with its own satellites, with the communication in 1963 pinging radio waves from location to location.
Last but not least, medical electronics such as monitoring devices for daily wear for diabetes, heart, or neurological issues, to complex surgical procedures and diagnostics without communications, where would we be today?
Materials for High-Frequency PCBs
Materials are the basis of all things PCB-related, and no doubt since manufacturing began, the material industry has advanced, allowing for this technology to thrive. We have so many options for circuit boards in general using FR4 flavors such as Shengyi, ITEQ, Isola, Nanya, and Hong TAI, to name a few, but what about when it comes to speed and communications, what other options are available?
Rogers
As the market develops specifically for high-speed, high-frequency manufacturing, the options for a material have developed alongside. The most common brand we use is Rogers type PTFE in the 4000 series. This hydrocarbon ceramic laminate has low DK loss, fits the FR4 process, controlled DK in a wide range of DF, UL 94V-0, low z-axis expansion, and is perfect for lead-free assembly.
Example of a printed circuit board manufactured with Rogers material.
The 4003 material type was the original material used for microwave/RF applications, with an increase in the use of the 4350 type. Fortunately for us, Rogers is very willing to share data sheets for comparison to select appropriate material.
Isola
Isola is right up there with Rogers, great for sharing data sheets, comparison, and downloads, as for ease of type searching, not second to Rogers, but to be honest, my favorite specialty material supplier to dive into when I need information. Terragreen 400G, Astra MT77, Tachyon 100G, and I-Tera MT40 are the typical go-to types for this specialty product.
Panasonic
Finally, the third manufacturer, but not as popularly used is Panasonic, with their Megtron family of materials they are another great option, Meg6, Meg7, Meg8 are the ones we see the most, the different flavors are used in different applications however customers seem to like the performance, and we have seen an increase in quote requests.
The downside is that they seem to come with a longer lead time to get to production. It’s not a common stock, and it is a higher cost for us for those reasons. Low volume and low demand don’t entice one to load up the shelves with all flavor options. Taconic and Arlon are a couple of additional players you can check out for material options.
Summary
No matter what your application is, there are options for many different laminates to produce the product you need and to meet your requirements. Research the manufacturing webpage for data sheets, ask for stack-up assistance from Epec's 24/7 engineering staff, we will be most happy to assist you.
It’s a good idea to have a couple of options that will meet the functionality and give your supplier choices. However, the truth regarding materials, although there are many options available when you select a brand and type, often it is more expensive, MOQs are involved, lead time is added, and it can pose this problem on every build. Choose wisely, involve your supplier, and know your choices.
Key Takeaways
- High-Frequency PCBs Are Essential for Advanced Communication Systems: These boards are critical in wireless communications, radar systems, satellites, and medical electronics, where precise signal transmission and low signal loss are required.
- Standard FR4 Often Isn’t Enough for RF/Microwave Designs: While FR4 is common, high-frequency applications demand materials with low dielectric loss and controlled impedance, such as Rogers 4000 series, Isola Tachyon, or Panasonic Megtron.
- Material Choice Directly Affects Performance and Manufacturability: Selecting the right laminate influences the board's ability to handle high-speed signals, withstand lead-free assembly, and remain dimensionally stable at high frequencies.
- Availability, Cost, and Lead Times Must Be Considered: Specialty materials like Rogers or Megtron may have longer lead times, higher costs, and minimum order quantities, so having multiple approved options helps avoid production delays.
- Collaborating with Your Supplier Saves Time and Prevents Issues: Involving your PCB manufacturer early and using their engineering resources can help optimize your stack-up, compare materials, and ensure your design is manufacturable and cost-effective.
