Screen shot 2014-08-08 at 1.33.54 PMNow you can access Rogers’ PCB materials resources with the ROG Mobile App. Quick and easy access to calculators, literature, technical papers. You can even request samples on your smartphone or tablet

  • The app has tools and technical information to assist you with Rogers printed circuit board materials.
  • The Microwave Impedance Calculator assists with microwave circuit design in predicting the impedance of a circuit made with Rogers High Frequency circuit materials and also provides capabilities for predicting transmission line losses.
  • The ROG Calculators assist RF engineers with thermal and mechanical simulations for microwave PCB designs.
  • Data sheets and fabrication guides can be downloaded and material samples can be ordered.

ROG Mobile for iPhone and iPad devices:

Apple App Store

Available for the iPhone and iPad in the Apple App Store

ROG Mobile for Android devices:

Android Play Store

Available for Andoid devices in Google Play


In this video, John Coonrod discusses why there are so many different dielectric constants (Dk) that are used in the microwave printed circuit board industry.

Send us questions/comments by tweeting us @Rogers_ACM!

This post authored by John Coonrod originally appeared on the ROG Blog hosted by Microwave Journal.

Designing high-frequency microwave circuits and, with increasing frequency, millimeter-wave frequencies require for the most part laying out carefully conceived transmission lines to carry those high-frequency signals across a printed-circuit board (PCB). Of course, if the task of fabricating the PCB was simply a matter of adding circuit elements, such as resistors, capacitors, and inductors, to create the necessary frequency-domain/time-domain response for the PCB, it might go somewhat easier. But every PCB with high-frequency transmission lines must also manage any number of circuit discontinuities and junctions as part of that design—these are those locations where signals must pass some change in the transmission-line path, such as a transition in the width of a transmission line, a gap between sections of transmission line, even an abrupt change in direction for the transmission line. In all cases, a high-frequency signal that has been propagating along a straight and consistent transmission line must now navigate some form of obstruction, such as an abrupt change in direction, a difference in transmission-line width, or a gap in the transmission line path. Since these and similar discontinuities can be found on all but the simplest of RF/microwave circuits, the question is, “How can the effects of these discontinuities be minimized through the thoughtful choice of PCB material?”

Using a microstrip transmission line as an example that most microwave engineers understand, this circuit configuration is comprised of RLGC properties. A simple representation of these properties as they relate to microstrip-transmission-line features is shown in Fig. 1.

ACM_Taming_fig1As can be seen, an alteration of the signal conductor will cause changes in inductance and the capacitance is affected by a change in the cross-section area between the signal conductor and the ground plane below. The simple circuit drawing is meant to represent the RLGC attributes of a microstrip transmission line. Another way to think of this is by using these properties as an infinitesimal piece of transmission line with unit-per-length representations of the circuit elements as shown in Fig. 2.

ACM_Taming_fig2A change in conductor width of the transmission line will impact the RLGC configuration in the area of the circuit with the change. Some common changes to a microstrip transmission line, also known as discontinuities, are shown in Fig. 3 with their associated RLGC impacts.

The 90° bend is actually a change in the cross-sectional conductor area in the region of the bend between T1 and T2. The change in area is easiest to picture if a diagonal line is drawn from the inside corner to the outside corner of the bend and just that area is considered.

ACM_Taming_fig3The middle section of Fig. 3 shows a gap in the transmission line, often used to adjust coupling for certain microwave circuit functions. The slit in the transmission line shown in the right-hand circuit of Fig. 3 is often used in tuning filters or for mode velocity adjustments in couplers.

The differences in the RLGC circuit influences for the discontinuities can also be related to complex impedance. The impedance values of the discontinuities have normal variations due to the process of circuit fabrication and the materials used.

How can the choice of PCB material ease the effects of circuit discontinuities and junctions? Consistency is vital for a material, so that it will perform as expected, according to CAE simulations and according to the real world. Because a discontinuity will introduce a shift in impedance, it is hoped that the PCB substrate will provide the most stable basis for a circuit design’s target impedance, usually 50 ?, as possible. But certain attributes can impact a PCB’s impedance consistency and predictability.

The thickness tolerance of a high-frequency circuit material might be its most significant variable when trying to achieve consistent, repeatable impedance. Even slight variations in the thickness of a PCB material represents a difference in the effective dielectric constant for a microstrip transmission line, and a variation in the impedance of the circuit from its nominal value. Although the changes in impedance from discontinuities and junctions are to be expected, and should be included in any CAE model for a design, the variations in the thickness of the PCB material are typically not accounted for as a cause of variations in impedance. Circuit materials are generally offered in a variety of thicknesses, with different thickness tolerances as a function of thickness.

Another key material characteristic impacting a circuit’s impedance (with or without discontinuities) is the PCB material’s dielectric constant (Dk). Not only does every high-frequency PCB material have a Dk value relative to the unity of a vacuum, but the nominal Dk value also has a tolerance and some materials are much better controlled for Dk than others.

As an example, RO3003™ laminates from Rogers Corp. are ceramic-filled polytetrafluoroethylene (PTFE) materials engineered for a Dk value of 3.00 at 10 GHz in the z-direction. The material is specified for a remarkable Dk tolerance with ±0.04 across a circuit board, so that impedance variations due to changes in dielectric constant will be at a minimum with this material. The material also maintains stable dielectric constant with temperature, as measured by its low thermal coefficient of dielectric constant (TCDk) of 13 ppm/°C at 10 GHz for temperatures from 0 to +100°C. By ensuring that a PCB material maintains consistent Dk across the material and across a temperature range of interest, essentially one more design variable can be eliminated—variations in impedance due to variations in a circuit substrate’s Dk value—when designing and fabricating high-frequency circuits.

To examine another example, RO4350B™ laminates from Rogers Corp. are reinforced hydrocarbon/ceramic laminate materials with dielectric constant of 3.48 at 10 GHz and room temperature. Like RO3003 laminates, they are manufactured to an extremely tight thickness tolerance, which contributes to maintaining tightly controlled impedances for transmission lines and circuit structures. Like the RO3003 material, RO4350B material delivers outstanding Dk tolerance across a circuit board to tightly control the impedance of transmission lines and other circuit structures. The Dk tolerance remains within ±0.05 across the circuit board or multiple circuit boards when measured at 10 GHz. The TCDk is somewhat higher than that of RO3003 material, at 50 ppm/°C at 10 GHz, but still acceptable for a variety of designs.

Of course, achieving and maintaining consistent impedance for any PCB in large part depends on the precision and repeatability of the circuit-fabrication process, and reliable circuit fabrication techniques are needed for predictable results in terms of maintaining consistent impedance. But choosing a PCB material with tightly controlled thickness and tightly controlled dielectric constant can support consistent impedance across a circuit board, and make it more straightforward to model all the discontinuities and junctions that might be found in a high-frequency circuit.

Do you have a design or fabrication question? John Coonrod and Joe Davis are available to help. Log in to the Rogers Technology Support Hub and “Ask an Engineer” today.


A message from Bruce Hoechner, CEO, Rogers Corporation:

Read the corporate financials news release: Rogers Corporation Reports 2014 Second Quarter Results.

Screen shot 2013-11-01 at 10.53.55 AMI would like to start by offering some insights regarding Rogers’ 2014 second-quarter results. The momentum we have gained over the past several quarters continues. We achieved strong top-line performance and continued to improve our gross margins and operating profit.

In addition, we continue to see the benefits of the decisive actions taken over the past two years, which has helped us improve operational efficiencies, pricing capabilities, and capacity utilization. Given our strong top-line growth, we believe the time is right to accelerate our investments in our business systems and processes, which we call the Rogers work smart initiative, and enhance investments in our M&A evaluation activities.

While these investments will affect our near-term S&A expenses, we are confident they will enable us to scale the Company more efficiently and effectively to support our growth and profit objectives. Our very strong first-half performance in revenue growth also drove a significant increase to bonus accruals in Q2. We have adjusted these bonus accruals based upon our current belief in strength of our businesses.

In Q2, we saw robust demand in our megatrend categories of Internet connectivity and clean energy, as well as substantial sales increases in safety and protection applications, such as automotive safety sensors, consumer impact protection. In particular, we experienced strong demand for applications in telecom infrastructure, x-by-wire, energy-efficient motor drives, and automotive safety sensors. Thanks to strong market demand, dedicated employees, and operational improvements we achieved our sixth consecutive quarter of year-over-year quarterly sales growth in Q2.

Rogers’ overall and printed circuit materials individually achieved all-time record quarterly sales. I’m pleased to note that all three of our business segments contributed to year-over-year sales growth in Q2.

Screen shot 2014-07-31 at 4.46.45 PMRogers sales grew by 15.9% in Q2 to an all-time quarterly record of $153.5 million. In addition, we improved gross margins to 37.2% from 33.9% and operating margins to 10.6% from 10.1% on a non-GAAP basis. As I mentioned, the printed circuit materials business segment achieved an all-time quarterly sales record with sales up 34.9% over Q2 2013. This was driven primarily by the global growth of 4G LTE wireless infrastructure in base station power amps as well as wireless antenna, automotive safety sensor applications, and Internet connectivity applications for handheld devices.

Overall, this performance was the result of robust market demand and continued dedication and hard work from our printed circuit materials team.

The power electronics solutions business segment achieved sales growth of 5.2% over the second quarter of 2013. Strong demand in energy-efficient motor drives, rail traction, and x-by-wire was tempered by lower demand in the laser diode market as well as specific EV/HEV applications due to customer internal supply-chain constraints.

High performance foams sales grew 7.2% versus Q2 2013. Increased demand for consumer impact protection, HEV battery applications, and mass transit vibration management was partially offset by relatively flat demand in general industrial and mobile Internet devices.


For the second quarter, 63% of Rogers sales were in our strategic megatrend categories as we continued to provide our customers with engineered materials solutions to support their robust growth in these areas of increasing global demand.

In the clean energy category, sales were up 11.2% over Q2 2013, with increased demand for power modules used in energy-efficient motor drives and automotive x-by-wire systems. The ongoing global buildout of the wireless telecom infrastructure contributed to an impressive 51.3% growth in year-over-year revenues in support of Internet connectivity. We continue to benefit from the increase in 4G LTE base station deployment around the world, especially in China.

We also experienced an increase in orders from one major mobile Internet device OEM for high-frequency circuit materials in applications that improve wireless connectivity. Overall, demand for these applications continues to remain very robust.

Rogers sales in the mass transit category grew 9.2% over Q2 2013 with increased demand across all major segments. Beyond our strategic megatrend categories, demand for radar-based automotive safety systems drove growth for Rogers printed circuit materials business. We believe we will benefit from further adoptions around the world as governments increase their mandate for automotive safety measures and as consumers become increasingly aware of the safety advantages of such systems.

Higher sales of impact protection materials into the consumer markets also drove growth in safety and protection applications. Overall, safety and protection applications were a significant contributor with growth of 38% over Q2 2013.


In terms of growth enablers, our team in the Rogers Innovation Center is taking shape and a number of new R&D projects are now underway, which we believe offer exciting opportunities for our customers. The unique partnership Rogers has with Northeastern University is enabling us to apply emerging technologies to commercial opportunities in a timely and cost-effective way.

At the end of the second quarter in our targeted megatrend categories of clean energy, Internet connectivity, and mass transit we were tracking a cumulative total of 834 major design opportunities, which is an increase of more than 11% from Q2 2013. Also in Q2, there were 475 opportunities in the design-in phase of the selling process, up from 425 in Q2 of 2013. During the quarter we moved 31 megatrend opportunities from design into production. Keeping our pipeline of opportunities growing is a helpful indicator of our future business growth.

Our R&D, marketing, and new business development teams are collaborating with customers to develop engineered solutions to address real global market needs, enabling a new generation of technologies. We are balancing a long-term and short-term approach to building a robust sales pipeline that we will continuously refill as we convert projects into sales.

Our collaboration with customers is not limited to our R&D efforts. We are in the midst of a cultural transition to ingrain market-driven or outside-in behavior across the Company. Globally we are conducting workshops and challenging all employees to find and adopt the best practices of global organizations to improve processes and serve our customers better. This includes more outreach to our customers to learn what they need so we can be their partner of choice.

As we have discussed, Rogers is actively pursuing an acquisition strategy that is aligned with our current businesses. Our business processes and systems optimization projects, the Rogers Work Smart Initiative, are preparing us for integrating potential acquisitions through standardized systems and processes. We remain committed to our investments in operational improvements across the organization. Here, too, we are taking an outside-in view, ensuring these improvements reflect industry best practices across all departments.

Read the full transcript here.

View the accompanying presentation here.


This post authored by John Coonrod originally appeared on the ROG Blog hosted by Microwave Journal.

RF/microwave power applied to a printed-circuit board (PCB) will generate heat. A key to designing a practical circuit on a given PCB material is to understand how different circuit material properties can impact the heating patterns on an RF/microwave PCB, and to work within the limits of a high-frequency circuit material.

PrintFor any RF/microwave PCB, the heat generated by a circuit element, such as a high-power transistor, will follow a general heat-flow model, flowing from the source of the heat to a heat sink or cooler part of the PCB. The properties of the circuit material will have a great deal to do with how the heat flows across the PCB and how heating patterns develop.

The heating patterns on a PCB are related to the current density patterns on that PCB, and the way that current is transformed to heat within a PCB might be best described by the PCB material’s thermal conductivity (TC). The TC, which is typically measured in watts of power per meter of material per degree Kelvin (W/m/K), is often used to compare different rates of energy loss as heat through different materials. Quite simply, higher TC values mean better heat flow through a material. Since PCBs are comprised of different materials, such as copper conductors with very high TC value and dielectric materials with very low TC values, heat flow through a PCB will occur at different rates, resulting in heating patterns such as at where the edges of conductors meet dielectric substrates.

High TC values usually denote materials engineered for high-power applications, where heat flows more efficiently through the material. PCB materials with lower values of TC will exhibit less heat flow through the material, with an increase in circuit temperature.

As a comparison, copper is a good electrical conductor and a good thermal conductor, with an extremely high TC value (typically 400 W/m/K). Heat energy will flow quickly and easily along copper conductors according to standard heat-flow models, with thermal energy moving from an area of higher temperature to an area of lower temperature, such as a heat sink. The dielectric materials used in PCBs have very low TC values and behave more like thermal insulators. For example, polytetrafluoroethylene (PTFE) circuit materials provide good dielectric properties but have a much lower value of TC (typically 0.20 W/m/K), so that much less thermal energy will flow through the material compared to copper. For a circuit material to generate less heat for the same power, it must exhibit a higher value of TC, such as RT/duroid® 6035HTC circuit material from Rogers Corp., with a typical TC value of 1.44 W/m/K.

Dielectric constant (Dk) is another circuit material parameter that can impact the heating patterns through a PCB. Dk is an important circuit material parameter in terms of determining the dimensions of different circuit structures. It also has a great deal to do with the heat flow across a high-frequency PCB, since a material’s Dk helps determine circuit dimensions for a given characteristic impedance. For typical 50-? microstrip circuit designs, for example, PCB materials with lower Dk values support the use of wider conductors for a desired signal frequency compared to circuit materials with higher Dk values.

Additional material parameters that can impact the heating patterns across a PCB include dissipation factor (and how it relates to the loss of the material), copper conductor surface, and even the thickness of the PCB material. As noted earlier, the dielectric material content of a PCB is more like a thermal insulator than a thermal conductor, so a thinner circuit material offers a shorter heat-flow path than a thicker circuit material, resulting in less heat buildup in the dielectric material.

To minimize heat at higher power levels, a PCB material with smaller dissipation factor (Df) is better since this low dielectric loss translates to RF/microwave circuits with lower insertion loss. Lower circuit insertion loss means less heat produced at higher RF/microwave power levels. Copper conductor surface roughness is also related to circuit material loss, with smoother copper conductors usually yielding lower conductor loss, and lower heat produced for a given amount of RF/microwave power handled by a circuit. Copper conductor roughness tends to yield frequency-dependent effects, with some differences in heating at different frequencies.

One additional circuit material parameter, a circuit’s maximum operating temperature (MOT), can be useful for comparing PCB materials intended for high-power use. This is a measure of the maximum temperature at which a circuit can be operated for an indefinite period of time.

To better understand the thermal behavior of typical PCB materials, heat rise testing was performed on a number of different microwave PCB materials, using 50-? microstrip transmission lines to conduct high-power test signals and measure the resulting temperature rises through the PCB materials. Differences in the materials included many of the key material parameters already noted, such as dielectric thickness, copper conductor surface roughness, dielectric constant, insertion loss, and TC.

A worst-case example involved transmission lines fabricated on FR-4 circuit material with Dk value of 4.25, Df of 0.0200, low TC of 0.25 W/m/K, and relatively high insertion loss of  0.37 dB/in. of microstrip transmission line at 3.4 GHz. A best-case example involved RT/duroid 6035HTC circuit material with Dk of 3.60, low Df of 0.0013, much higher TC of 1.44 W/m/K, and low insertion loss of 0.11 dB/in. For 85-W test signals applied at 3.4 GHz, the difference in heat rise for the two materials was startling. For the worst-case material, the temperature rise was +74°C; for the best-case material, with the same test signal, a temperature rise of only +14°C occurred.

Ideally, the heat flow through a PCB construction will follow established heat flow models and the heat produced by an applied source or an on-circuit active device will channel from an area of high temperature to an area of much lower temperature. The various PCB material parameters, such as TC and Df, help provide some insight into how various heating patterns will develop across different PCB materials at higher RF/microwave power levels, and how those PCB material parameters can be consulted when choosing a circuit material for higher power levels.

Do you have a design or fabrication question? John Coonrod and Joe Davis are available to help. Log in to the Rogers Technology Support Hub and “Ask an Engineer” today.

Page 30 of 73« First...1020...2829303132...405060...Last »