Materials

Laminates, Prepreg Materials Lend Themselves to Higher-Frequency PCBs

June 8, 2023

For proper operation, high-frequency circuits require PCB materials with appropriate performance and characteristics.

This article is part of our IMS 2023 coverage.

In Booth 2235 at IMS 2023, Isola Group will display its array of laminates and prepreg materials for RF, microwave, millimeter-wave (mmWave), and photonics circuits. With RF/microwave circuits moving to higher frequencies of operation, PCB materials must follow suit. Their ability to carry signals of smaller wavelengths requires high performance in terms of thermal qualities and dielectric stability. They must also exhibit the characteristics required for repeatable manufacturability.

To that end, Isola Group’s Astra MT77, available in laminate and prepreg forms, features a low dielectric constant (Dk) of 3.00 as measured through its thickness or z-axis at 10 GHz. The material has extremely low loss when used for PCBs at high frequencies, denoted by a dissipation factor (Df) of 0.0017 at 10 GHz. It maintains consistent electrical and mechanical attributes across wide operating temperature ranges in support of commercial and military applications at mmWave frequencies, including automotive advanced driver-assistance system (ADAS) radars and airborne radar systems.

Designers seeking circuit materials with higher Dk values will be interested in the company’s I-Tera MT40 laminate and prepreg materials, which exhibit slightly higher loss with Df of 0.0034 at 10 GHz. But these materials are available with a choice of Dk values: 3.38, 3.45, 3.60, and 3.75, all as measured through the thickness or z-axis of the material at 10 GHz. The higher Dk values enable miniaturization of circuit structures for a given frequency or wavelength, in support of reduced circuit size, weight, and power (SWaP) in military and aerospace applications.

Also on display will be the Tachyon 100G laminates and prepregs. They feature the electrical and mechanical traits that make them strong building blocks for high-speed digital (HSD) circuits. They are similar in behavior to Astra MT77, with Dk of 3.02 through the z-axis at 10 GHz and Df of 0.0021 at 10 GHz. However, they're tailored for HSD circuits operating at speeds of 100 Gb/s and more.

They exhibit thermal behavior closely matched to Astra MT77, too, as evidenced by their similar coefficient of thermal expansion (CTE) values for a wide operating temperature range of –55 to +125°C. The thermal compatibility makes Astra MT77 and Tachyon 100G laminates and prepregs good candidates for hybrid PCBs, where one material holds RF/microwave circuits and the other handles HSD circuits.

Finally, Isola Group will be showing its halogen-free materials, with example circuits on its TerraGreen laminates and TerraGreen 400G laminates and prepregs. TerraGreen features a Dk of 3.45 in the z-axis of the material at 10 GHz with Df of 0.0031 also at 10 GHz. TerraGreen 400G laminates and prepregs exhibit lower Dk of 3.05 in the z-axis at 10 GHz and lower Df of 0.0018 at 10 GHz, delivering the performance needed for ultra-high-speed digital circuits requiring halogen-free circuit materials.

For more information, visit the company's website.

For more IMS 2023 coverage, visit our digital magazine.

About the Author

David Maliniak | Executive Editor, Microwaves & RF

I am Executive Editor of Microwaves & RF, an all-digital publication that broadly covers all aspects of wireless communications. More particularly, we're keeping a close eye on technologies in the consumer-oriented 5G, 6G, IoT, M2M, and V2X markets, in which much of the wireless market's growth will occur in this decade and beyond. I work with a great team of editors to provide engineers, developers, and technical managers with interesting and useful articles and videos on a regular basis. Check out our free newsletters to see the latest content.

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In his long career in the B2B electronics-industry media, David Maliniak has held editorial roles as both generalist and specialist. As Components Editor and, later, as Editor in Chief of EE Product News, David gained breadth of experience in covering the industry at large. In serving as EDA/Test and Measurement Technology Editor at Electronic Design, he developed deep insight into those complex areas of technology. Most recently, David worked in technical marketing communications at Teledyne LeCroy, leaving to rejoin the EOEM B2B publishing world in January 2020. David earned a B.A. in journalism at New York University.