This post authored by John Coonrod, Technical Marketing Manager, and team originally appeared on the ROG Blog hosted by Microwave Journal. 

Recipes are often refined with time, in hopes of improving the results. Such is the case with RF/microwave circuit laminates, created from carefully blended mixtures of materials, with the goal of achieving the best possible results in electrical and mechanical performance. Over the years, many different formulations have been applied to create high-frequency circuit materials. The efforts have led to a variety of current circuit laminate choices for a wide range of high-frequency applications and performance requirements.

The high-frequency material perhaps most familiar to users of circuit laminates is polytetrafluoroethylene, more commonly known as PTFE. It is a synthetic thermoplastic fluoropolymer formed of carbon and fluorine. It has a high molecular weight and low coefficient of friction, the main reason it is often used to create “non-stick” surfaces. With a dielectric constant (Dk) of 2.1, PTFE has excellent dielectric properties at microwave frequencies.

PTFE has been a “building-block” material for microwave circuit laminates for some time. It is combined with other materials to modify its electrical and mechanical properties to the requirements of high-frequency circuit designers. For example, PTFE-based circuit materials are typically reinforced with woven glass for improved mechanical stability. The woven-glass reinforcement will raise the material’s Dk value and also decrease material expansion as a function of temperature, better matching the coefficient of thermal expansion (CTE) of the circuit material to that of its copper conductors. PTFE-based laminates also use ceramic fillers to achieve higher Dk values and to fine-tune other material properties, such as CTE.

At one time, the choice of circuit laminates for high-frequency, thin-film circuits came down to almost an “either/or” decision for circuit designers: fabricate it on lower-cost FR-4 circuit material or on higher-performance (and higher-cost) PTFE-based laminates (or alumina ceramic substrates, in the case of high-frequency thick-film circuits). FR-4 really refers to a family of circuit materials based on woven-glass-reinforced flame-retardant epoxy. The material is popular for its low cost and ease of circuit fabrication, but suffers degraded electrical performance at higher frequencies, typically above about 500 MHz, and many circuit designers had learned their own “cutoff frequency point” below which they could use FR-4 and above which required a PTFE-based circuit laminate.

While well-established and accepted for high-frequency circuits, PTFE is just one of a number of “ingredients” in currently available high-frequency circuit laminates, which also include thermoplastic materials such as polyphenyl ether (PPE), polyphenylene oxide (PPO) epoxy resin, and hydrocarbon-based materials with ceramic fillers. Some high-frequency and high-speed applications have encouraged the development of even more exotic circuit laminate formulations, such as liquid-crystalline-polymer (LCP) materials for flexible circuits and polyetheretherketone (PEEK) thermoplastic materials for extremely high operating temperatures (to about +200°C). In fact, for circuits at microwave frequencies, the number of circuit laminate options seems to grow with time, with newer material formulations promising improvements in the key characteristics that define circuit laminate performance for printed-circuit boards (PCBs), including Dk, dissipation factor (Df), coefficient of thermal expansion (CTE), thermal coefficient of dielectric constant (TCDk), thermal conductivity, moisture absorption, and long-term aging.

Comparing Compositions

How do these different high-frequency material compositions compare? First of all, it is important to note that not all PTFE-based circuit laminates are created equal. Early PTFE-based laminates were reinforced with woven glass to reduce the inherently high CTE of PTFE alone. Further improvements in performance were possible for PTFE-based circuit laminates by adding micro-fiber glass to the mixture in RT/duroid® 5880 circuit material from Rogers Corp. PTFE-based laminates were further improved by adding special ceramic materials as fillers, not only to modify the Dk but to alter certain properties of the material to make them easier to process when fabricating PCBs.

In the case of RT/duroid 6002 circuit board material from Rogers Corp., it is based on PTFE but without woven-glass reinforcement. By adding special ceramic filler, the Dk of the base PTFE material is raised to a value of 2.94 that is highly consistent (within ±0.04) through a sheet of RT/duroid 6002 and with low Df (0.0012) and CTE through the z-axis (thickness) closely matched to that of copper for reliable plated through holes. In fact, the process of adding ceramic filler to a base material such as PTFE allows “fine-tuning” of the material’s ultimate Dk value, so that PTFE-based circuit laminates can be formulated with many different Dk values.

Through experimentation, it was also found that ceramic filler could also be used to fine-tune the Dk values of circuit materials other than PTFE, such as the thermoset hydrocarbon resin materials that are the basis for the TMM® laminates from Rogers Corp. For example, through the addition of different amounts and types of ceramic filler, TMM laminates achieve Dk values ranging from 3 to 13. These resin-based materials are somewhat easier to process into PCBs than PTFE-based circuit laminates, although the absence of glass reinforcement does result in some other challenges for circuit fabrication. To overcome those challenges, a circuit laminate formulation based on ceramic-filled hydrocarbon resin, but with woven-glass reinforcement—RO4350B™ circuit material from Rogers Corp.—was created to provide improved CTE and temperature stability while also maintaining the ease of PCB processing associated with hydrocarbon (non-PTFE)-based circuit laminates.

More recent circuit material formulations have included thermoset hydrocarbon-based PPE and PPO circuit laminates, typically reinforced with woven glass for improved mechanical stability. As noted earlier, such materials can offer unique benefits, such as ease of circuit fabrication and improved long-term aging characteristics. However, they are also limited to lower Dk values and tend to exhibit more rapidly increasing dielectric loss (Df) with frequency than PTFE-based materials and ceramic-filled, hydrocarbon-based circuit laminates.

This sampling of different circuit material compositions hints at some of the differences among the material choices. For example, whether they are glass reinforced or not, special ceramic fillers which are used in PTFE-based circuit materials contribute to good CTE and TCDk performance levels; they also make possible a wide range of Dk values for PTFE-based circuit laminates, from about 3 to 10. Without ceramic filler, PTFE-based circuit materials achieve better loss characteristics (low Df), but with degraded CTE and TCDk compared to ceramic-filled PTFE-based materials. As a general trend, PTFE-based circuit laminates with higher Dk values will exhibit higher Df values and are more anisotropic with increased Dk.

Ceramic-filled, hydrocarbon-based circuit laminates fortified with woven glass typically have higher Df (greater loss) than PTFE-based materials, although they also offer typically better CTE, TCDk, and thermal conductivity than PTFE-based circuit laminates. PPE and PPO-based circuit laminates also have higher Df values than PTFE-based circuit materials, or about the same values as hydrocarbon-based circuit laminates when tested at about 10 GHz or less. For the special features of those PPE and PPO-based circuit materials, including excellent long-term aging characteristics, they suffer higher moisture absorption than the other types of high-frequency circuit laminates.

For high-frequency circuit designers, more choices in circuit laminate compositions are available than ever before, each with its own benefits and tradeoffs. The requirements of a particular application can usually help to speed up and simplify the choice.

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By Jill Malczewski, Marketing Communications Supervisor

Imagine it’s your first day at a new job. You arrive at the company and no one is expecting you. After walking around in circles, you locate your desk where you can’t log into your computer nor use the phone. Your supervisor is nowhere to be found and you start thinking, “Hmmm, did I make the right decision?”

Jill_M_2017_laptopWell, no reason for fear here! Being a new employee at Rogers Corporation has been refreshingly accepting and enlightening. From the start I felt welcomed, comfortable, prepared, and supported. The onboarding process can vary across the organization as Rogers expands and relocates its headquarters to Chandler, Arizona, but one thing remains consistent – the culture. It is evident Rogers invests in its employees’ success, focusing on satisfaction and retention.

Almost immediately, the lines of communication were established between my direct supervisor and Human Resources, outlining first day expectations (parking, arrival time, paperwork, agenda, etc.). It began with a building tour along with face-to-face introductions, followed by an orientation meeting with HR and meeting my Sponsor. The next few weeks included colleague engagements within the divisional business units, building knowledge on the organization/recent acquisitions and specific projects. It was enlightening to learn about the company’s recent advancements and growth in high frequency circuit materials for automotive advanced driver assistance systems, aerospace/defense, and 5G applications within the Advanced Connectivity Solutions (ACS) group, as well as the strategic focus of the other divisions.

Often times the smallest experiences can provide validation and a feeling of importance. For me, it was when setting up my computer went seamlessly, a personalized welcome lunch was organized for me and I participated in a meet & greet with the CEO, who shared details about new, innovative endeavors on the horizon in advanced mobility and connectivity.

As I continue along this new journey, there is no doubt I made the best decision. Fear is not an obstacle when you have the tools to succeed, I am proud to work for a company that is doing it right!

Selected quotes from our recent earnings call. Read the corporate financials news release: Rogers Corporation Reports Fourth Quarter and Full Year 2016 Results

In Q4 2016, Rogers delivered strong net sales and margin performance to close out a very good year. The company achieved net sales of $173 million, an increase of 13.1% over Q4 2015. For the year, Rogers achieved net sales of $656.3 million for an increase of 2.3% over 2015.

Bruce Hoechner, CEO, on Innovation Leadership

Our competencies are rooted in our DNA. One of our key differentiators is the way we work with our customers to identify and develop highly engineered solutions to help with their toughest material challenges. Our R&D teams are building on a long history of innovation leadership, developing a robust product pipeline of new and next-generation solutions. In addition, we completed the acquisition of DeWAL Industries in 2016 and, in early 2017, Diversified Silicone Products, augmenting the product portfolio and technology capabilities of our EMS business.


Bruce Hoechner, CEO, on Growth Drivers

We are a market-driven organization, focusing on growing global markets including wireless infrastructure, automotive safety, and e-mobility. We view two innovation growth drivers as our key priorities: advanced mobility and advanced connectivity.

Our solutions are at the forefront of advanced mobility technologies. Our ROLINX® products provide reliable interconnects for electric vehicle inverters and batteries. Our ceramic substrates enable efficient and reliable power conversion from the battery to the drive systems in electric and hybrid-electric vehicle applications. Our PORON® urethanes and BISCO® silicones seal and protect critical battery components. And in the area of automotive safety, Rogers is the leading provider of circuit materials used in advanced driver assistance systems.

Rogers has been a leader in advanced connectivity technology since the early days of 2G wireless networks and has adapted to evolving markets through innovation. Today, we are well on our way to replicating our success with 4G LTE systems into new 4.5 and 5G generations where developments are taking place faster than expected and we are delivering new material solutions for other critical connectivity components.

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Bruce Hoechner, CEO, on Rogers’ Business Units

Advanced Connectivity Solutions (ACS) has been favorably impacted by growth in high-frequency circuit materials for automotive safety, aerospace, and defense, and 4G LTE applications. Two particular indicators of growth in these areas are mobile data traffic, with a projected 45% compounded annual growth rate through 2021, and automotive safety systems, with a 29% compounded annual growth rate through 2026. We believe we have the right technologies and are developing the right products to capitalize on these opportunities.

Elastomeric Material Solutions continued its return to organic growth as a result of higher demand for portable electronics. Automotive and general industrial applications sales were slightly offset by lower demand for mass transit and certain consumer applications.

In addition to geographic expansion and investments in new product development, EMS is acquiring top-of-the-pyramid companies. DeWAL is a leading manufacturer of advanced performance polymer films and pressure-sensitive tapes that are used in industrial, aerospace, automotive, and electronics markets. Diversified Silicone Products is an innovator in custom silicone product development and manufacturing, serving a wide range of high reliability applications.

Power Electronics Solutions results were favorably impacted by increased demand in EV/HEV, variable frequency drives, and certain renewable energy applications, partially offset by lower demand in mass transit. The PES business continues to build its capabilities to serve customers in the advanced mobility category and e-Mobility applications, in particular. Rogers has a solid foothold in these applications and we are poised to capitalize on the expected market growth, which is forecast at a 28% compounded annual growth rate through 2020.

While all of our businesses are committed to operational excellence, we see significant opportunities in PES where automation and footprint changes have already led to improved results. For example, in 2016, we opened the new ROLINX power distribution busbar line at our Rogers Hungary facility.

Q4 2016, Full Year Earnings Call Full Transcript

Q4 2016, Full Year Financials Press Release

Q4 2016, Full Year Earnings Call Slides

Celebrating National Engineers Week

On February 20, 2017, in Careers/Human Resources, by sharilee

Rogers Corp. employs hundreds of engineers across the globe in such careers as New Product Development, Business Development, Chemical Engineering, Design & Manufacturing Engineering, and Market Development. Our senior management team also includes executives who started in engineering, such as our CEO, Bruce Hoechner.


This National Engineers Week, we celebrate the many contributions our engineers make to a cleaner, safer, more connected world. You can find their imprint on ceramic substrates in vehicle electrification systems, sealing for industrial enclosures and medical equipment, and high frequency laminates in antennas and satellites.

If you’re interested in joining the Rogers Corp. team, we have a number of engineering jobs open across the globe, including:

  • Antenna Market Development Engineer
  • Application Development Engineer
  • Application Engineer
  • Application Support Engineer
  • Chemical Engineer/Innovator-Magnetic Materials
  • Design & Manufacturing Engineer
  • Electro Mechanical Engineer
  • Lean Engineer
  • Process Engineer
  • Product Engineer
  • Quality Engineer
  • Quality Systems Implementation Engineer
  • Sales Engineer
  • EHS Engineer
  • Process Engineer
  • Quality Engineer

Search the listings and apply online at the Rogers Corp. Career Center.

Happy National Engineers Week!


Senior leaders at Rogers Corp. regularly blog for employees on topics like technology trends, safety, and leadership. This month we’d like to share our CTO’s trip to CES, the interesting technologies and trends that caught his eye, and how they relate to the value we deliver to our customers.

By Bob Daigle, Sr. VP and Chief Technology Officer, Rogers Corp.

I just attended the 2017 Consumer Electronics Show (CES). A record number of people (160,000) were in attendance. As you might imagine, it was very crowded! What I saw there makes me even more enthusiastic about Rogers’ future. The latest technologies that we enable are emerging at a faster pace than expected and we are well-positioned to capitalize on this growth.

Autonomous Vehicles

It was apparent that the e-Mobility revolution is gaining momentum. Most major automotive producers had a significant presence at the show and were proudly displaying electric vehicles and self-driving car technology.

Several of the major automakers are now committing to introduce self-driving cars within 3-4 years. Audi announced plans to introduce their first self-driving vehicle in 2020. Ford is targeting 2021. Faraday Futures, an electric vehicle start-up, introduced their first production vehicle at the CES show and stated that it will have self-driving capabilities. Cars have become a high end “Consumer Electronic Device.”

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Think about what self-driving cars could mean over the next 10 years. Will your car be able to drop the kids off at school and pick them up from soccer practice? Will you fly less because you can sleep in the car while it takes you to a distant city overnight? Will your young kids or grandchildren bother to learn to drive?

The potential benefits of self-driving cars go well beyond convenience. Elon Musk, Tesla’s CEO, has stated that over 200 million miles have been driven in self-driving mode (as shown in this Tesla self-driving car video). The safety data suggests that self-driving cars are already twice as safe as human-driven cars. And, you’d expect the technology will get even better as factors causing the collisions that do occur are analyzed and addressed with engineering improvements.

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I believe the day will come when the risk of collisions is low enough to allow safety systems like airbags and heavy structural supports designed to protect passengers in collisions to be eliminated. This means cars will be much lighter so electric vehicles will have much longer range and be even more environmentally friendly. It will also mean that the appearance of cars can be highly customized because there won’t be a need to do crash testing for every new design.

One company at CES had full-sized car bodies on display that were 3D printed. Someday, you’ll be able to change the look and feel of the car you’re ordering at a kiosk.

5G and IoT

Another theme from CES was that 5G and other technologies that will support the Internet of Things (IoT) are becoming a reality faster than people might have thought a few years back. Ericsson had a great 5G demonstration streaming live high definition video at the show. Integrated circuit makers like Qualcomm have already developed 5G chipsets, years sooner than expected.

It was also apparent that the industry is gearing up rapidly to provide higher speed solutions like WiGig for the home that will allow seamless streaming of ultrahigh definition video wirelessly between devices like your DVD player and your television.

Powering, Protecting, Connecting

What does this all mean for Rogers? Our focus on providing enabling Connectivity and eMobility solutions positions us very well to capitalize on these rapidly emerging opportunities. For eMobility applications like self-driving cars, our circuit materials are used in the vast majority of radar sensors. For eMobility applications like electric vehicles, our curamik® substrates are used in power modules, our ROLINX® busbars are used for battery and power invertor interconnects, and our PORON® urethanes and BISCO® silicone foams are used to seal and protect battery packs, and reduce noise and vibration. For 5G and WiGig systems critical to the Internet of Things (IoT), Rogers provides market leading circuit material solutions.

Technologies showcased at CES this year will revolutionize how we travel and communicate in ways we can only begin to imagine!


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