ROG Blog

The Rog Blog is contributed by John Coonrod and various other experts from Rogers Corporation, providing technical advice and information about RF/microwave materials.

ACM ROG Contest: What’s New?

The holidays are a time to share your favorite stories—so let’s hear yours!   From now until May 1 2012, tell us how you and your team have used Rogers’ materials to design your award-winning application in one of six categories: Best Digital Application, Under the Most Extreme Conditions, Most Challenging Board Build, Most Innovative Design, Longest Product Life and Most Unique and Creative Use of Material.  One winner will be selected from each category. Winners will be featured in a full-page ad with their story and team photo. Winners will also receive a  free  Ad in Microwave Journal for their company and a...
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Measurements Help In Sorting Materials

Selecting a high-frequency PCB laminate from the many commercially available choices may sometimes seem like an impossible task. But it can be simplified by sorting materials by their key parameters, such as dielectric constant, dissipation factor, thermal conductivity, and CTE, and using those parameters to help match a material to an application. Of course, this also assumes confidence in the values of those key parameters as published by different materials suppliers, and such confidence comes from an understanding of the measurement methods used to determine the values of those key parameters.

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Match Material Specs To Application Needs

Selecting a PCB laminate for a high-frequency application is like picking a foundation for a new building: the strength of the whole project relies on the right choice. The previous blog introduced a strategy to help simplify the PCB laminate selection process, by relating the requirements of an application to laminate specifications. Each RF/microwave application is unique, with its own requirements. But at least one laminate will usually offer the right set of specifications to best meet those requirements.

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Do You Have an Award Winning Application?

We want to hear from YOU! Tell us how Rogers’ materials helped you design your award-winning application and you could WIN! From now until May 1, 2012, The ACM ROG Contest is collecting entries in six categories: Best Digital Application, Most Extreme Conditions, Most Challenging Board Build, Most Innovative Design, Longest Product Life, and Most Unique and Creative Use of Material.  One winner will be selected from each category to receive: a full-page ad featuring  your story and team photo; a free Ad in Microwave Journal for your company; and a cool ROG Display Trophy. Winners will be announced...
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Selecting A Suitable High-Frequency Laminate

Previous blogs examined some of the key material parameters pertaining to high-frequency laminates, such as dielectric constant, thermal conductivity, coefficient of thermal expansion (CTE), and even flexibility when used in conformal circuits. But how does an engineer combine all this information about a material’s electrical and mechanical properties when trying to choose the perfect substrate for a particular application? It can be a complex process, but it may be possible to simplify that process.

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Bending and Forming RF/Microwave PCBs

Bending and forming RF/microwave printed-circuit boards (PCBs) around a curved shape are sometimes part of the design process, such as when fabricating conformal antennas. While this may not be commonplace, for those times that it is necessary, it is important to know several things about the high-frequency PCB material for the project. This includes the correct type of material to use, by how much the material can be flexed without damage, and what types of mechanical and electrical effects are to be expected by bending and forming an RF/microwave PCB. Quite simply, picking the wrong PCB material for bending and forming applications can result in mechanical cracks and damage to the circuit board.

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Aiming For The Perfect Wire Bond

Wire bonds keep everything in place on a printed-circuit board (PCB). They are used to attach passive and active components as well as integrated circuit (ICs) to a circuit substrate, and even to connect one circuit substrate to another. Wire bonds can be formed with a variety of different wire bonding machines, including manual and automatic models. In all cases, the goal is to achieve a low-resistance connection with good mechanical integrity and high reliability. But this seemingly simple goal depends not only on the type of substrate material and its parameters but numerous wire-bonding parameters, including the temperature, time, and applied force when making a wire bond.
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Taking A Measure Of Copper Surface Roughness

Conductor surface roughness in printed-circuit boards (PCBs) is a material parameter that should not be overlooked. As detailed in the previous Blog in this series, the surface roughness of a PCB’s conductor layer can have a great deal of impact on signal losses through the conductors. If the effects of conductor surface roughness are not accounted for at the design stage, when using a commercial computer-aided-engineering (CAE) software simulation program, the predicted performance results of the simulations can deviate. These deviations can be significant from the actual performance measured from a designed prototype circuit. The differences can add up to lost design time, added design iterations, and added time and expense when creating a new circuit.
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Sizing Up PCB Laminate Surface Roughness

Designing an RF/microwave circuit requires some knowledge of printed-circuit-board (PCB) qualities, especially when selecting a PCB material for a particular application. Modern computer-aided-engineering (CAE) simulation tools can help predict the electrical performance of circuits on different PCB materials, using material parameters such as relative dielectric constant in the calculations. But one PCB material parameter that is often overlooked in the design process is the surface roughness of the conductors. In the past, conductor surfaces were assumed to be perfectly smooth. What happens when they are not?
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Modeling A PCB’s Thermal Behavior

Temperature effects on a printed-circuit board (PCB) can make it difficult to achieve target performance goals, even with the best PCB substrate materials. Modeling these effects takes imagination—to visualize different sources of heat, for example, and thermal paths where the heat might travel. It also requires an understanding of both thermal-mechanical and electromagnetic (EM) relationships to account for the assortment of variables that can influence PCB performance with changing temperatures. As a result, modeling thermal effects on PCB performance combines predictions provided by the heat diffusion equation as much as from Maxwell’s equations for EM fields.
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