Space may be the final frontier, but the orbiting satellites that provide this planet’s satellite communications (satcom) outer infrastructure may seem even more inaccessible. In what may be one of the most hostile operating environments for electronic equipment, these satellites contain circuits that absolutely must not fail. The satcom systems in those satellites demand circuit materials capable of maintaining excellent performance and high reliability even under those stressful, in-orbit conditions. Few circuit materials can handle the challenging requirements of satellite systems; the ones that do have the special characteristics that make it possible.
The TMM® family of thermoset circuit materials from Rogers Corp. is a lineup of ceramic, hydrocarbon, thermoset polymer composites with a proven track record of high reliability in satellite circuit applications. Available with dielectric constants (Dk values) from 3.27 to 12.85 in the z-axis (thickness), they exhibit a particular set of characteristics that are well suited to the challenging operating environments of orbiting satellites.
What type of material characteristics are needed for space? Low outgassing is one critical requirement for any circuit material that must survive the vacuum environment of a satellite. Outgassing is the release of gas trapped within a solid, such as a PCB material. Once released, the gas can condense on different surfaces within a satellite, potentially causing problems with some circuits and subsystems. (For more on outgassing, check out the ROG Blog from November 19, 2010: “What Is Outgassing And When Does It Matter?”)
The outgassing process typically occurs very slowly, over a long period of time, and requires meticulous testing to determine a circuit material’s amount of outgassing. A testing procedure has been developed by the American National Standards Institute (ANSI) and is defined in the ANSI/ASTM E595-84 standard. NASA, which uses that test method along with its own SP-R-022A test procedure to evaluate materials for outgassing based on changes in mass under vacuum conditions, has found materials based on polytetrafluoroethylene (PTFE), such as RT/duroid® from Rogers Corp. as well as the TMM hydrocarbon composite circuit materials, to be highly resistant to outgassing.
In addition to a vacuum, circuit materials in space must deal with temperature extremes that exceed most applications. Space is often thought of as cold and dark, and satellites in the shadow of Earth and without the moderation from the atmosphere can reach quite cold temperatures. Conversely, when exposed to sunlight without that atmosphere, a satellite’s operating environment can achieve furnace-like temperatures. It is this cycling between temperature extremes during a satellite’s normal orbiting paths, whether geosynchronous or geostationary that can place tremendous temperature-based stress on a circuit material, requiring a PCB material with outstanding thermal properties for satellite applications.
One of these key thermal characteristics that can be used to gauge a circuit material’s suitability for satellite applications is how much the material’s Dk changes with temperature over the operating temperature range. Ideally, a circuit material for space will not only handle a wide temperature range, but exhibit very little change in Dk over that temperature range. This material parameter, the thermal coefficient of dielectric constant (TCDk), serves as a barometer for material stability in applications that must endure wide temperature swings, in commercial, industrial, and military systems as well as in space. For the 50-Ω impedance that is characteristic to most high-frequency circuits designed for satcom use, a change in circuit material Dk will cause a change in impedance, resulting in variations in circuit performance, such as shifts in the amplitude and phase characteristics of high-frequency transmission lines.
For in-space circuit applications, it is important to use a circuit material with the lowest possible TCDk value, to minimize performance variations due to changes in Dk with temperature. The TMM materials are formulated for an operating temperature range of -55 to +125°C to handle the temperature extremes of space and satellite environments. These materials also change very little in Dk value over that wide temperature, with Dk increasing slightly for the TMM materials with the lowest Dk values and Dk decreasing in very small amounts for TMM materials with Dk values at 6 and higher.
For example, for TMM 3 laminate with a Dk of 3.27 in the z-axis (thickness) at 10 GHz, the TCDk is a very low +37 ppm/°K. The other TMM material with a slight positive shift in Dk with temperature is TMM 4 laminate, with a Dk of 4.50 in the z-axis at 10 GHz. The Dk decreases almost insignificantly with temperature with the TMM 6 material, which has a Dk of 6.00 in the z-axis and an extremely low TCDk of -11ppm/°K. Typically, a TCDk with an absolute value of 50 ppm/°K or less is considered quite good.
The TMM family of circuit materials offers circuit designers the options of designing with a wide range of Dk values, making it possible to save space in a satellite through the circuit miniaturization depending upon the choice of material Dk. This can be accomplished by using PCB materials with higher Dk values (achieving transmission lines with the same characteristic impedance as circuits with larger dimensions on PCB materials with lower Dk values). The tradeoff for such circuit miniaturization is usually poor TCDk, although this is not the case with the higher-Dk-value TMM materials. For example, TMM 10 material, with a Dk of 9.20 in the z-axis at 10 GHz, has a low TCDk of -38 ppm/°K. For extreme miniaturization, the TMM 13i circuit material has a Dk of 12.85 in the z-axis with a still reasonable TCDk value of -70 ppm/°K.
The TMM 13i material is formulated to be highly isotropic, with a Dk value close to12.85 in all three axes. Most materials are anisotropic, with a z-axis Dk value that differs from the Dk values of the x and y axes. For most circuits, such as microstrip and stripline circuits, the z axis is the direction of interest, since the electromagnetic fields (EM) of those transmission lines are mainly through the thickness of the material. But for circuits with EM fields in the x-y plane, an isotropic material will provide more predictable performance. For designs requiring isotropic circuit materials, the TMM 10i material is an isotropic version of the standard anisotropic TMM 10 material. The price for the highly isotropic behavior in TMM 10i material is a slightly higher Dk than TMM 10 material, at 9.80 in the z-axis at 10 GHz, compared to 9.20 for TMM 10 material.
Because changing temperatures play such a strong role in the choice of circuit material for space, another key material parameter for satellite circuit designers is coefficient of thermal expansion (CTE), which gauges how a circuit material changes dimensionally with heating and cooling. Since most materials will contract with extreme cold and expand with heat to some degree, it is rare to have a material with a CTE value of 0 ppm/°K. Ideally, the value should be as low as possible or as close to the value of conductive materials, such as copper (at about 17 ppm/°C), used on the PCB so that dielectric and metal will contract and expand together for minimal stress with temperature. In all three axes, the TMM materials exhibit CTE values ranging from 15 to 26 ppm/°K–quite close to that of copper for high circuit reliability even in the wide range of temperatures in satellite environments.
Download the ROG Mobile app to access Rogers’ calculators, including the popular Microwave Impedance simulation tool, literature, technical papers, and the ability to order samples of the company’s high performance printed circuit board materials.
Ask an Engineer
Do you have a design or fabrication question? Rogers Corporation’s experts are available to help. Log in to the Rogers Technology Support Hub and “Ask an Engineer” today.
Marc Cotnoir has announced his retirement from Rogers to occur as of the end of 2016.
Marc began his career with us 37 years ago. He has held several roles over the years including marketing management, sales management, and most recently EMS Director of Sales, North America.
Marc’s contributions to Rogers are unparalleled. He is dedicated, talented, and brings out the best in his team and associates.
We wish him the best as he embarks on the next steps of his journey. Enjoy your retirement, Marc!
Meet some of our hard-working employees. For years, they have been part of our Elastomeric Material Solutions group. Lynn Hardell has been with us for 6 years, Eric Beaudry for 15 years, and Nicole Perry for 20 years.
“We make wearable impact absorption material that protects and adds a visible technology advantage.”
Our Elastomeric Material Solutions group helps designers create the products that protect our world. We are dedicated to constant innovation and the creation of the best materials…materials that are lighter, stronger, flexible, and more reliable. Whether it’s ultra-thin protection for sensitive electronics or flexible impact protection for sports apparel or robust gasketing for automotive applications, our materials are engineered for superior performance.
About our Employees
Throughout our organization, our cultural behaviors describe how our employees work and are judged by our customers, business partners, investors, and each other.
- Live Safely: I actively prevent injuries for everyone, everywhere, every day.
- Trust: I respect people and trust them to do the right thing.
- Speak Openly: I courageously seek and speak the truth.
- Innovate: I create market-driven solutions that lead to customer success.
- Just Decide: I make informed decisions rapidly to drive progress.
- Simply Improve: I continuously simplify how I do things to achieve excellence.
- Deliver Results: I align and achieve my goals to deliver our “Must-Do” results.
Together, we are changing our culture as we help change the world around us. For over 180 years, the employees of Rogers Corporation have focused on our customers, delivering world-class solutions to meet their most demanding materials challenges.
By Michael Orfitelli, Principal EHS Engineer
One of Rogers’ seven “Cultural Behaviors” is Live Safely and over the past several years the company has made great progress in reducing on-the-job injuries. Attention to safety also extends to home safety, as evidenced by this fun activity for employees led by Rogers’ EHS team.
This autumn our Environment, Health, and Safety (EHS) group encouraged all employees to assemble a team of treasure hunters in their family and complete the EHS Home Safety Treasure Hunt. The goal was to complete the home safety checklist and see how many safety controls were in place, update existing safety items, and encourage families to talk about home safety.
Congratulations and thank you to the 366 Rogers Associates who participated, and to the 13 contest winners at our major sites.
While the treasure hunt started out as an inspection, it evolved into an action plan document, and the comments people wrote in the margins of their checklist told a great story about home safety improvement. I can attest that there were a few funny moments in our house as we completed our treasure hunt. Here are some of the stories:
When asked if there was a home security system in place, one associate answered that the family dog was the security system. The team decided not to validate this claim on-site, but rumor has it that the Chihuahua in question has a vicious streak a mile wide. I can relate to those who have yet to install a home security system. Growing up, we never locked the door, even when we went on vacation. When my wife insisted that we get a security system, I was initially reluctant, but now I see the benefit. And with all of the tech features and home management tools built into today’s systems, it kind of makes the pain of implementation a bit more bearable.
Responses to emergency flashlight preparedness ran the spectrum from those who have flashlights (and extra batteries) available in every room, to those who would rather fumble around in the dark and stub your toes during a midnight power outage. Most of us have flashlights, but the batteries have been dead since the last time the Cubs were in the World Series. If walkie-talkies and robot dinosaurs all run for cover because you’ve come to harvest their batteries, it may be time to think about stocking up. And if you’ve explained one too many times why the life-size Darth Vader doesn’t talk when you push his buttons, here’s a potential solution. While it was once a tool only marketed to buyers of the waterproof towel (groan), there are solar powered flashlights available now that will actually hold a charge for several hours. This may put an end to those frantic pitch-black battery hunts once and for all.
One colleague wrote that his first aid kit was 27 years old. When I read this, I first imagined Indiana Jones unearthing a rusty old tin box inscribed, “In life, there are only two guarantees: Band-Aids, and smoking on a plane.” Or maybe it was stolen from the medical tent at a Garth Brooks concert? Most likely, this first aid kit is a household institution deserving of a medal of honor, heroically serving the family on many occasions over the last 3 decades. This is a good opportunity to remind everyone that you need to regularly inspect your first aid kits; make sure to replace missing items, check expiration dates, and update the ointments, medicine, and other items when necessary.
As for our house, the kids take emergency preparedness very seriously and they definitely know how to get out of a smoke-filled house. For example, our kitchen smoke detector is more easily set-off than the Chihuahua we mentioned earlier. Needless to say, my burnt toast triggers the alarm every Saturday. And at about this same time my son leaps from the kitchen table, hits the dining room floor, and does the military crawl to the front door, heading for the Magnolia tree in the side yard.
Clearly, everyone who participated embraced the spirit of this challenge. One family has 10 smoke detectors in their house (their ears would never survive breakfast at our house), and many reported that multiple family members are trained in First Aid/ CPR.
The Treasure Hunt generated many excellent safety action items: some employees scheduled to have the chimney cleaned, created
evacuation maps, or installed exterior lighting during the contest. One of our colleagues took it upon himself to translate the contest into Portuguese and sent it to relatives in Brazil so they could make their homes safer as well.
These are a few of the many ways Rogers Employees demonstrate their commitment to Living Safely. If we live our daily lives with this mindset, we will continue to strengthen and sustain our workplace safety culture.
Download the Home Safety Treasure Hunt checklist here: treasure-checklist.
Many antennas depend on the durability and repeatability of the printed-circuit-board (PCB) materials on which they are formed. The type of material has a strong impact on the size and performance possible from an antenna. A printed-circuit antenna is typically fabricated on a PCB material composed of a dielectric layer with copper on one or both sides. For reliable electrical performance, that combination of copper and dielectric must be consistent, over time and over temperature. Understanding some of the key PCB material parameters and how they relate to antenna performance can pay large dividends for those working with PCB-based antennas. Here are some of our newest products and technical resources for antenna designers.
PIM and PCB Antennas: Guide to Circuit Materials for Low PIM Antennas
Passive intermodulation (PIM) can result from many factors in a circuit or system. Even the thickness and dielectric constant (Dk) of a laminate can affect PIM by contributing to the physical dimensions of transmission lines. This can lead to higher current densities in densely spaced circuits. To address the need for low-PIM antennas, the Advanced Connectivity Solutions group developed the RO4500™ & RO4700JXR™ series thermoset laminates and the AD series™ woven-glass,
polytetrafluoroethylene (PTFE)/ceramic antenna circuit materials. With these circuit laminates as starting points, antenna designers can be assured of an opportunity to create antenna designs with the lowest PIM possible. Download the PIM and PCB Antennas Guide.
VIDEO: AD300C™ Antenna Grade Laminates
Our AD300C high frequency circuit materials are featured in this video that highlights topics from datasheet properties and measured results showing insertion loss, dielectric constant, and PIM performance. The information in this video explains why AD300C antenna grade laminates are a popular choice for PCB based antenna applications.
New UL 94 V-0 Circuit Material for Cost Effective, High Performance PCB Antennas and Active Antenna Arrays for 4G, 5G, and IoT
The RO4730G3™ UL 94 V-0 antenna-grade laminates are designed to meet present and future performance requirements in active antenna arrays and small cells, notably in 4G base transceiver stations (BTS) and Internet of Things (IoT) applications as well as emerging 5G wireless systems. These flame-retardant (per UL 94V-0), thermoset laminate materials are an extension of Rogers’ dependable RO4700™ circuit materials, which are a popular choice for base station antennas. RO4730G3 laminates provide the low dielectric constant (Dk) of 3.0 favored by antenna designers, held to a tolerance of ±0.05 when measured at 10 GHz. Download the Antenna Grade Laminates data sheet.