Elementary Mr. Watson: Ensuring a Smooth Handoff From PCB Design to Fabrication
The Shaughnessy Report: Breaking Down the Language Barrier
Connect the Dots: Designing for Reality—Routing, Final Fab, and QC
Beyond Design: Faster than a Speeding Bullet
March 9, 2016 | Barry Olney, In-Circuit DesignEstimated reading time: 1 minute
In a previous Beyond Design column, Transmission Lines, I mentioned that a transmission line does not carry the signal itself, but rather guides electromagnetic energy from one point to another. The speed of a computer does not depend intrinsically on the speed of electrons, but rather on the speed of energy transfer between electronic components. Electron flow in a multilayer PCB is extremely slow—about 10 mm per second—so, how does the signal travel so fast, how fast does it actually transfer information and what are the limitations?
In optical communications, electrons don’t carry the signal—photons do. And we all know that photons travel at the speed of light. So surely, optical fibers must transmit information much faster than copper wires or traces on a multilayer PCB? Actually, photons and electrons transmit data at the same speed. The limiting factor is the relative permittivity (dielectric constant) of the medium in which the signal propagates.
An optical fiber is a cylindrical dielectric waveguide made of low-loss materials such as fused silica glass. It has a central core in which light is guided, and embedded in an outer cladding of slightly lower refractive index. The silica glass used has a dielectric constant (Er or Dk) = 3.78 @25GHz. Whereas, for instance, Panasonic’s new Megtron 7, low Dk, glass PCB laminate has an Er = 3.3 at the same frequency.
To read this entire article, which appeared in the February 2016 issue of The PCB Design Magazine, click here.
Share on:
Suggested Items
ICT Spring Seminar: Nickel Not Welcome Here
03/12/2025 | Pete Starkey, I-Connect007After a miserable, dull, and damp English winter, a really pleasant nearly spring day with the sun shining and daffodils in bloom greeted delegates to the Institute of Circuit Technology Spring Seminar at Puckrup Hall near Tewkesbury, March 5, in Gloucestershire, UK.
Multicircuits Expands Capabilities with State-of-the-Art Automated Copper Via Fill Process
03/10/2025 | MulticircuitsMike Thiel, president of Multicircuits, a leading provider of high-reliability printed circuit boards, has announced the addition of a state-of-the-art automated copper via fill process to their advanced manufacturing capabilities. This strategic investment enhances the company’s ability to deliver cutting-edge solutions for demanding industries, including aerospace, defense, medical, and high-speed telecommunications.
EIPC 2025 Winter Conference, Day 2: A Roadmap to Material Selection
02/20/2025 | Pete Starkey, I-Connect007The EIPC 2025 Winter Conference, Feb. 4-5, in Luxembourg City, featured keynotes and two days of conference proceedings. The keynote session and first-day conference proceedings are reported separately. Here is my review of the second day’s conference proceedings. Delegates dutifully assembled bright and early, well-rested and eager to participate in the second day’s proceedings of the EIPC Winter Conference in Luxembourg.
Designers Notebook: Addressing Future Challenges for Designers
02/06/2025 | Vern Solberg -- Column: Designer's NotebookThe printed circuit board is and will probably continue to be the base platform for most electronics. With the proliferation of new generations of high I/O, fine-pitch surface mount semiconductor package variations, circuit interconnect is an insignificant factor. Circuit board designers continually face challenges such as component quantity and complexity, limited surface area, and meeting the circuit board’s cost target. The printed circuit design engineer’s prominent position demands the development of efficiently manufacturable products that perform without compromise.
DesignCon 2025, Day 2: It’s All About AI
01/30/2025 | Marcy LaRont, I-Connect007It’s hard to get away from the topic of artificial intelligence, but why would you? It’s everywhere and in everything, and my time attending presentations about AI at DesignCon 2025 was well worth it. The conference’s agenda featured engaging presentations and discussions focused on the technological advancements in AI, big data centers, and memory innovations, emphasizing the critical relationship between processors and circuit boards.