Elementary, Mr. Watson: Rein in Your Design Constraints
Target Condition: Are Autorouters Friend or Foe?
Fresh PCB Concepts: Assembly Challenges with Micro Components and Standard Solder Mask Practices
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
I-Connect007 Editor’s Choice: Five Must-Reads for the Week
07/11/2025 | Andy Shaughnessy, Design007 MagazineThis week, we have quite a variety of news items and articles for you. News continues to stream out of Washington, D.C., with tariffs rearing their controversial head again. Because these tariffs are targeted at overseas copper manufacturers, this news has a direct effect on our industry.I-Connect007 Editor’s Choice: Five Must-Reads for the Week
Digital Twin Concept in Copper Electroplating Process Performance
07/11/2025 | Aga Franczak, Robrecht Belis, Elsyca N.V.PCB manufacturing involves transforming a design into a physical board while meeting specific requirements. Understanding these design specifications is crucial, as they directly impact the PCB's fabrication process, performance, and yield rate. One key design specification is copper thieving—the addition of “dummy” pads across the surface that are plated along with the features designed on the outer layers. The purpose of the process is to provide a uniform distribution of copper across the outer layers to make the plating current density and plating in the holes more uniform.
Trump Copper Tariffs Spark Concern
07/10/2025 | I-Connect007 Editorial TeamPresident Donald Trump stated on July 8 that he plans to impose a 50% tariff on copper imports, sparking concern in a global industry whose output is critical to electric vehicles, military hardware, semiconductors, and a wide range of consumer goods. According to Yahoo Finance, copper futures climbed over 2% following tariff confirmation.
Happy’s Tech Talk #40: Factors in PTH Reliability—Hole Voids
07/09/2025 | Happy Holden -- Column: Happy’s Tech TalkWhen we consider via reliability, the major contributing factors are typically processing deviations. These can be subtle and not always visible. One particularly insightful column was by Mike Carano, “Causes of Plating Voids, Pre-electroless Copper,” where he outlined some of the possible causes of hole defects for both plated through-hole (PTH) and blind vias.
Trouble in Your Tank: Can You Drill the Perfect Hole?
07/07/2025 | Michael Carano -- Column: Trouble in Your TankIn the movie “Friday Night Lights,” the head football coach (played by Billy Bob Thornton) addresses his high school football team on a hot day in August in West Texas. He asks his players one question: “Can you be perfect?” That is an interesting question, in football and the printed circuit board fabrication world, where being perfect is somewhat elusive. When it comes to mechanical drilling and via formation, can you drill the perfect hole time after time?