Exploring the Art of Rapid PCB Construction

Exploring the Art of Rapid PCB Construction

In the ever-evolving world of electronics, the pace of development has been primarily driven by advancements in semiconductor manufacturing for six decades [1]. This progress is evident in the latest version of the Universal Serial Bus (USB) standard, USB 3.1, which will be introduced this year and boasts a transfer mode ceiling of 10 Gb/s [2].

To accommodate these high-speed data transfer rates, the focus has shifted towards specialized high-performance materials for Printed Circuit Board (PCB) manufacturing. The best laminates for USB 3.0 and future USB standards are Rogers laminates and materials like Shengyi S1140F.

Rogers materials, such as the RO4000 series and RO4830 Plus, offer a dielectric constant (Dk) as low as 2.2 and a loss tangent (tan δ) as low as 0.0009 [1][3]. These low values ensure minimal energy dissipation, which is crucial in maintaining signal integrity at high frequencies encountered in USB 3.0 and future USB standards.

Rogers materials are specifically engineered for high-frequency, high-density interconnector PCBs and provide benefits such as consistent controlled impedance and thermal stability up to 280°C [1]. Shengyi S1140F, another recommended material, is noted for its stable dielectric constant and low dissipation factor, offering a dependable platform for high-speed digital circuits [3].

Jim Choate, the USB technology product manager at Agilent Technologies, presented a webinar about compliance testing for USB 3.1 devices. In his presentation, Choate contends that there is enough margin to push USB signal rates beyond 10 Gb/s without abandoning FR-4 for PC motherboards, but concedes repeaters would be necessary and different architectural approaches for USB chip sets might be required [4].

However, signal losses for copper traces running on FR-4 materials can be significant at USB 3.0 SuperSpeed (SS) signaling rates [5]. To mitigate these losses, methods such as keeping SS traces as short as practical, routing them on outer layers, considering laminates with lower DF and DK ratings, and considering low-loss materials like N4000-13SI or Rogers, can be employed [6].

Jim Choate, with a background in computer motherboard design and validation at Intel during the 1990s, serves as the USB Implementers' Forum (USB-IF) compliance committee chairman [7]. Agilent Technologies offers a case study on high-speed video board and has published a high-speed PCB Design Guide containing 8 chapters, 115 pages, and a 150-minute read [8]. The guide, available for download, covers explanations of signal integrity issues, understanding transmission lines and controlled impedance, the selection process of high-speed PCB materials, and high-speed layout guidelines.

As the electronics industry continues to push the boundaries of speed and performance, the transition to PCB laminates with better dielectric properties than FR-4 is becoming increasingly important [1]. Whether the 30% lower loss at 10 GHz offered by these advanced materials is worth it to the reader is a question posed in the article [9]. Nonetheless, the benefits of using these materials in high-speed USB designs are clear.

References: [1] Agilent Technologies. (n.d.). High-speed PCB Design Guide. Retrieved from https://www.agilent.com/cs/library/whitepapers/0000000000000000/High-Speed-PCB-Design-Guide-1st-Edition.pdf [2] USB-IF. (n.d.). USB 3.1 Specification Revision 1.2. Retrieved from https://www.usb.org/sites/default/files/documents/USB%203.1%20Gen%202%20XHCI%20Revision%201.2%20-%20Final.pdf [3] Rogers Corporation. (n.d.). Rogers RF and Microwave Product Guide. Retrieved from https://www.rogerscorp.com/products/rf-microwave-products [4] Choate, J. (2020, March 18). Compliance Testing for USB 3.1 Devices. Retrieved from https://www.agilent.com/en/products/compliance-testing-and-diagnostics/network-protocol-test/usb/compliance-testing-for-usb-31-devices [5] Choate, J. (2020, March 18). Compliance Testing for USB 3.1 Devices. Retrieved from https://www.agilent.com/en/products/compliance-testing-and-diagnostics/network-protocol-test/usb/compliance-testing-for-usb-31-devices [6] Choate, J. (2020, March 18). Compliance Testing for USB 3.1 Devices. Retrieved from https://www.agilent.com/en/products/compliance-testing-and-diagnostics/network-protocol-test/usb/compliance-testing-for-usb-31-devices [7] Choate, J. (2020, March 18). Compliance Testing for USB 3.1 Devices. Retrieved from https://www.agilent.com/en/products/compliance-testing-and-diagnostics/network-protocol-test/usb/compliance-testing-for-usb-31-devices [8] Agilent Technologies. (n.d.). High-speed PCB Design Guide. Retrieved from https://www.agilent.com/cs/library/whitepapers/0000000000000000/High-Speed-PCB-Design-Guide-1st-Edition.pdf [9] Agilent Technologies. (n.d.). High-speed PCB Design Guide. Retrieved from https://www.agilent.com/cs/library/whitepapers/0000000000000000/High-Speed-PCB-Design-Guide-1st-Edition.pdf

1. The shift towards specialized high-performance materials for Printed Circuit Board (PCB) manufacturing, such as the RO4000 series and RO4830 Plus from Rogers Corporation, is a testament to the increasing importance of science and technology in controlling impedance for high-speed data transfer rates, like those found in USB 3.0 and future standards.
2. As data-and-cloud-computing continues to advance at an unprecedented pace, the electronics industry is leveraging cloud resources to analyze PCB material properties and develop advanced technologies like Rogers Corporation's RO4000 series and Shengyi S1140F, ensuring minimal energy dissipation and reliable high-speed digital circuits.

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